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Sample records for self-accumulated ag nanoparticles

  1. Silver nanoparticle accumulation by aquatic organisms – neutron activation as a tool for the environmental fate of nanoparticles tracing

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    Asztemborska Monika

    2014-12-01

    Full Text Available Water environments are noted as being some of the most exposed to the influence of toxic nanoparticles (NPs. Therefore, there is a growing need for the investigation of the accumulation and toxicity of NPs to aquatic organisms. In our studies neutron activation followed by gamma spectrometry and liquid scintillation counting were used for studying the accumulation of silver nanoparticles (AgNPs by freshwater larvae of Chironomus and fish Danio rerio. The influence of exposition time, concentration and the source of nanoparticles on the efficiency of AgNP accumulation were studied. It was found that AgNPs are efficiently accumulated by Chironomid larvae for the first 30 hours of exposition; then, the amount of silver nanoparticles decreases. The silver content in larvae increases together with the NP concentration in water. Larvae which have accumulated AgNPs can be a source of nanoparticles for fish and certainly higher levels of Ag in the trophic chain. In comparison with water contamination, silver nanoparticles are more efficiently accumulated if fish are fed with AgNP-contaminated food. Finally, it was concluded that the applied study strategy, including neutron activation of nanoparticles, is very useful technique for tracing the uptake and accumulation of NPs in organisms

  2. Construction of Ag/AgCl nanostructures from Ag nanoparticles as high-performance visible-light photocatalysts

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    Yang, Fan; Liu, Dongzhi; Wang, Tianyang; Li, Wei [Tianjin University, School of Chemical Engineering and Technology (China); Hu, Wenping [Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (China); Zhou, Xueqin, E-mail: zhouxueqin@tju.edu.cn [Tianjin University, School of Chemical Engineering and Technology (China)

    2016-11-15

    A combined strategy of in situ oxidation and assembly is developed to prepare Ag/AgCl nanospheres and nanocubes from Ag nanoparticles under room temperature. It is a new facile way to fabricate Ag/AgCl with small sizes and defined morphologies. Ag/AgCl nanospheres with an average size of 80 nm were achieved without any surfactants, while Ag/AgCl nanocubes with a mean edge length of 150 nm were obtained by introduction of N-dodecyl-N,N-dimethyl-2-ammonio-acetate. The possible formation mechanism involves the self-assembly of AgCl nanoparticles, Ostwald ripening and photoreduction of Ag{sup +} into Ag{sup 0} by the room light. The as-prepared Ag/AgCl nanospheres and nanocubes exhibit excellent photocatalytic activity and stability toward degradation of organic pollutants under visible-light irradiation. It is demonstrated that Ag/AgCl nanocubes display enhanced photocatalytic activity in comparison with Ag/AgCl nanospheres due to the more efficient charge transfer. This work may pave an avenue to construct various functional materials via the assembly strategy using nanoparticles as versatile building blocks.

  3. The mechanism of metal nanoparticle formation in plants: limits on accumulation

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    Haverkamp, R. G., E-mail: r.haverkamp@massey.ac.nz; Marshall, A. T. [Massey University, School of Engineering and Advanced Technology (New Zealand)

    2009-08-15

    Metal nanoparticles have many potential technological applications. Biological routes to the synthesis of these particles have been proposed including production by vascular plants, known as phytoextraction. While many studies have looked at metal uptake by plants, particularly with regard to phytoremediation and hyperaccumulation, few have distinguished between metal deposition and metal salt accumulation. This work describes the uptake of AgNO{sub 3}, Na{sub 3}Ag(S{sub 2}O{sub 3}){sub 2}, and Ag(NH{sub 3}){sub 2}NO{sub 3} solutions by hydroponically grown Brassica juncea and the quantitative measurement of the conversion of these salts to silver metal nanoparticles. Using X-ray absorption near edge spectroscopy (XANES) to determine the metal speciation within the plants, combined with atomic absorption spectroscopy (AAS) for total Ag, the quantity of reduction of Ag{sup I} to Ag{sup 0} is reported. Transmission electron microscopy (TEM) showed Ag particles of 2-35 nm. The factors controlling the amount of silver accumulated are revealed. It is found that there is a limit on the amount of metal nanoparticles that may be deposited, of about 0.35 wt.% Ag on a dry plant basis, and that higher levels of silver are obtained only by the concentration of metal salts within the plant, not by deposition of metal. The limit on metal nanoparticle accumulation, across a range of metals, is proposed to be controlled by the total reducing capacity of the plant for the reduction potential of the metal species and limited to reactions occurring at an electrochemical potential greater than 0 V (verses the standard hydrogen electrode).

  4. Accumulation and phytotoxicity of engineered nanoparticles to Cucurbita pepo.

    Science.gov (United States)

    Hawthorne, Joseph; Musante, Craig; Sinha, Saion K; White, Jason C

    2012-04-01

    The effect of bulk and engineered nanoparticle (NP) Ag, Au, Cu, Si, and C at 250 and 750 mg/L on zucchini biomass, transpiration, and element content was determined. The pH of bulk and NP solutions prior to plant growth frequently differed. Nanoparticle Cu solution pH was significantly higher than bulk Cu, whereas for Ag and C, the NPs had significantly lower pH. Plants were unaffected by Au, regardless of particle size or concentration. NP Ag reduced plant biomass and transpiration by 49-91% compared to equivalent bulk Ag. NP Si at 750 mg/L reduced plant growth and transpiration by 30-51% relative to bulk Si. Bulk and NP Cu were phytotoxic but much of the effect was alleviated by humic acid. The shoot Ag and Cu content did not differ based on particle size or concentration. The accumulation of bulk Au was greater than the NP, but humic acid increased the accumulation of NP and bulk Au by 5.6-fold and 80%, respectively. The uptake of NP Si was 5.6-6.5-fold greater than observed with the bulk element. These findings show that the NPs may have unique phytotoxicity or accumulation patterns and that solution properties can significantly impact particle fate and effects.

  5. Accumulation of silver nanoparticles by cultured primary brain astrocytes

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    Luther, Eva M; Koehler, Yvonne; Dringen, Ralf [Center for Biomolecular Interactions Bremen, University of Bremen, PO Box 330440, D-28334 Bremen (Germany); Diendorf, Joerg; Epple, Matthias, E-mail: ralf.dringen@uni-bremen.de [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitaetsstrasse 5-7, D-45117 Essen (Germany)

    2011-09-16

    Silver nanoparticles (AgNP) are components of various food industry products and are frequently used for medical equipment and materials. Although such particles enter the vertebrate brain, little is known on their biocompatibility for brain cells. To study the consequences of an AgNP exposure of brain cells we have treated astrocyte-rich primary cultures with polyvinylpyrrolidone (PVP)-coated AgNP. The incubation of cultured astrocytes with micromolar concentrations of AgNP for up to 24 h resulted in a time- and concentration-dependent accumulation of silver, but did not compromise the cell viability nor lower the cellular glutathione content. In contrast, the incubation of astrocytes for 4 h with identical amounts of silver as AgNO{sub 3} already severely compromised the cell viability and completely deprived the cells of glutathione. The accumulation of AgNP by astrocytes was proportional to the concentration of AgNP applied and significantly lowered by about 30% in the presence of the endocytosis inhibitors chloroquine or amiloride. Incubation at 4 {sup 0}C reduced the accumulation of AgNP by 80% compared to the values obtained for cells that had been exposed to AgNP at 37 {sup 0}C. These data demonstrate that viable cultured brain astrocytes efficiently accumulate PVP-coated AgNP in a temperature-dependent process that most likely involves endocytotic pathways.

  6. Stress sensitive electricity based on Ag/cellulose nanofiber aerogel for self-reporting.

    Science.gov (United States)

    Yao, Qiufang; Fan, Bitao; Xiong, Ye; Wang, Chao; Wang, Hanwei; Jin, Chunde; Sun, Qingfeng

    2017-07-15

    A self-reporting aerogel toward stress sensitive slectricity (SSE) was presented using an interconnected 3D fibrous network of Ag nanoparticles/cellulose nanofiber aerogel (Ag/CNF), which was prepared via combined routes of silver mirror reaction and ultrasonication. Sphere-like Ag nanoparticles (AgNPs) with mean diameter of 74nm were tightly anchored in the cellulose nanofiber through by the coherent interfaces as the conductive materials. The as-prepared Ag/CNF as a self-reporting material for SSE not only possessed quick response and sensitivity, but also be easily recovered after 100th compressive cycles without plastic deformation or degradation in compressive strength. Consequently, Ag/CNF could play a viable role in self-reporting materials as a quick electric-stress responsive sensor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Two-dimensional nanoparticle self-assembly using plasma-induced Ostwald ripening

    International Nuclear Information System (INIS)

    Tang, J; Photopoulos, P; Tsoukalas, D; Tserepi, A

    2011-01-01

    In this work, a novel Ag nanoparticle self-assembly process based on plasma-induced two-dimensional Ostwald ripening is demonstrated. Ag nanoparticles are deposited on p-doped Si substrates using a DC magnetron sputtering process. With the assistance of O 2 /Ar plasma treatment, different sizes and patterns of Ag nanoparticles are formed, due to the Ostwald ripening. The evolution of plasma-induced nanoparticle ripening is studied and a clear increase in particle size and a decrease in particle density are observed with increasing plasma treatment. From the experiments, it is concluded that the initial nanoparticle density and the plasma gas mixture (Ar/O 2 ratio) are important factors that affect the ripening process. The proposed plasma-directed Ag nanoparticle self-assembly provides a rapid method of tailoring the nanoparticle distribution on substrates, with potential applications in the fields of solar cells, biosensors, and catalysis.

  8. Differential Phytotoxic Impact of Plant Mediated Silver Nanoparticles (AgNPs) and Silver Nitrate (AgNO3) on Brassica sp.

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    Vishwakarma, Kanchan; Shweta; Upadhyay, Neha; Singh, Jaspreet; Liu, Shiliang; Singh, Vijay P; Prasad, Sheo M; Chauhan, Devendra K; Tripathi, Durgesh K; Sharma, Shivesh

    2017-01-01

    Continuous formation and utilization of nanoparticles (NPs) have resulted into significant discharge of nanosized particles into the environment. NPs find applications in numerous products and agriculture sector, and gaining importance in recent years. In the present study, silver nanoparticles (AgNPs) were biosynthesized from silver nitrate (AgNO 3 ) by green synthesis approach using Aloe vera extract. Mustard ( Brassica sp.) seedlings were grown hydroponically and toxicity of both AgNP and AgNO 3 (as ionic Ag + ) was assessed at various concentrations (1 and 3 mM) by analyzing shoot and root length, fresh mass, protein content, photosynthetic pigments and performance, cell viability, oxidative damage, DNA degradation and enzyme activities. The results revealed that both AgNPs and AgNO 3 declined growth of Brassica seedlings due to enhanced accumulation of AgNPs and AgNO 3 that subsequently caused severe inhibition in photosynthesis. Further, the results showed that both AgNPs and AgNO 3 induced oxidative stress as indicated by histochemical staining of superoxide radical and hydrogen peroxide that was manifested in terms of DNA degradation and cell death. Activities of antioxidants, i.e., ascorbate peroxidase (APX) and catalase (CAT) were inhibited by AgNPs and AgNO 3. Interestingly, damaging impact of AgNPs was lesser than AgNO 3 on Brassica seedlings which was due to lesser accumulation of AgNPs and better activities of APX and CAT, which resulted in lesser oxidative stress, DNA degradation and cell death. The results of the present study showed differential impact of AgNPs and AgNO 3 on Brassica seedlings, their mode of action, and reasons for their differential impact. The results of the present study could be implied in toxicological research for designing strategies to reduce adverse impact of AgNPs and AgNO 3 on crop plants.

  9. Differential Phytotoxic Impact of Plant Mediated Silver Nanoparticles (AgNPs and Silver Nitrate (AgNO3 on Brassica sp.

    Directory of Open Access Journals (Sweden)

    Kanchan Vishwakarma

    2017-10-01

    Full Text Available Continuous formation and utilization of nanoparticles (NPs have resulted into significant discharge of nanosized particles into the environment. NPs find applications in numerous products and agriculture sector, and gaining importance in recent years. In the present study, silver nanoparticles (AgNPs were biosynthesized from silver nitrate (AgNO3 by green synthesis approach using Aloe vera extract. Mustard (Brassica sp. seedlings were grown hydroponically and toxicity of both AgNP and AgNO3 (as ionic Ag+ was assessed at various concentrations (1 and 3 mM by analyzing shoot and root length, fresh mass, protein content, photosynthetic pigments and performance, cell viability, oxidative damage, DNA degradation and enzyme activities. The results revealed that both AgNPs and AgNO3 declined growth of Brassica seedlings due to enhanced accumulation of AgNPs and AgNO3 that subsequently caused severe inhibition in photosynthesis. Further, the results showed that both AgNPs and AgNO3 induced oxidative stress as indicated by histochemical staining of superoxide radical and hydrogen peroxide that was manifested in terms of DNA degradation and cell death. Activities of antioxidants, i.e., ascorbate peroxidase (APX and catalase (CAT were inhibited by AgNPs and AgNO3. Interestingly, damaging impact of AgNPs was lesser than AgNO3 on Brassica seedlings which was due to lesser accumulation of AgNPs and better activities of APX and CAT, which resulted in lesser oxidative stress, DNA degradation and cell death. The results of the present study showed differential impact of AgNPs and AgNO3 on Brassica seedlings, their mode of action, and reasons for their differential impact. The results of the present study could be implied in toxicological research for designing strategies to reduce adverse impact of AgNPs and AgNO3 on crop plants.

  10. Synthesis and Characterization of BSA Conjugated Silver Nanoparticles (Ag/BSA Nanoparticles) and Evaluation of Biological Properties of Ag/BSA Nanoparticles and Ag/BSA Nanoparticles Loaded Poly(hydroxy butyrate valerate) PHBV Films

    Science.gov (United States)

    Ambaye, Almaz

    Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa are the etiological agents of several infectious diseases. Antibiotic resistance by these three microbes has emerged as a prevalent problem due in part to the misuse of existing antibiotics and the lack of novel antibiotics. Nanoparticles have emerged as an alternative antibacterial agents to conventional antibiotics owing to their high surface area to volume ratio and their unique chemical and physical properties. Among the nanoparticles, silver nanoparticles have gained increasing attention because silver nanoparticles exhibit antibacterial activity against a range of gram positive and gram negative bacteria. Nanoparticles of well-defined chemistry and morphology can be used in broad biomedical applications, especially in bone tissue engineering applications, where bone infection by bacteria can be acute and lethal. It is commonly noted in the literature that the activity of nanoparticles against microorganisms is dependent upon the size and concentration of the nanoparticles as well as the chemistry of stabilizing agent. To the best of our knowledge, a comprehensive study that evaluates the antibacterial activity of well characterized silver nanoparticles in particular Bovine Serum Albumin (BSA) stabilized against S. aureus and E. coli and cytotoxicity level of BSA stabilized silver nanoparticles towards osteoblast cells (MC3T3-E1) is currently lacking. Therefore, the primary objective of this study was to characterize protein conjugated silver nanoparticles prepared by chemical reduction of AgNO3 and BSA mixture. The formation of Ag/BSA nanoparticles was studied by UV-Vis spectroscopy. The molar ratio of silver to BSA in the Ag/BSA nanoparticles was established to be 27+/- 3: 1, based on Thermogravimetric Analysis and Atomic Absorption Spectroscopy. Based on atomic force microscopy, dynamic light scattering,and transmission electron microscopy(TEM) measurements, the particle size (diameter) of

  11. Fabrication of SWCNT-Ag nanoparticle hybrid included self-assemblies for antibacterial applications.

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    Sayanti Brahmachari

    Full Text Available The present article reports the development of soft nanohybrids comprising of single walled carbon nanotube (SWCNT included silver nanoparticles (AgNPs having superior antibacterial property. In this regard aqueous dispersing agent of carbon nanotube (CNT containing a silver ion reducing unit was synthesised by the inclusion of tryptophan and tyrosine within the backbone of the amphiphile. The dispersions were characterized spectroscopically and microscopically using TEM, AFM and Raman spectroscopy. The nanotube-nanoparticle conjugates were prepared by the in situ photoreduction of AgNO3. The phenolate residue and the indole moieties of tyrosine and tryptophan, respectively reduces the sliver ion as well as acts as stabilizing agents for the synthesized AgNPs. The nanohybrids were characterized using TEM and AFM. The antibacterial activity of the nanohybrids was studied against Gram-positive (Bacillus subtilis and Micrococcus luteus and Gram-negative bacteria (Escherichia coli and Klebsiella aerogenes. The SWCNT dispersions showed moderate killing ability (40-60% against Gram-positive bacteria however no antibacterial activity was observed against the Gram negative ones. Interestingly, the developed SWCNT-amphiphile-AgNP nanohybrids exhibited significant killing ability (∼90% against all bacteria. Importantly, the cell viability of these newly developed self-assemblies was checked towards chinese hamster ovarian cells and high cell viability was observed after 24 h of incubation. This specific killing of bacterial cells may have been achieved due to the presence of higher -SH containing proteins in the cell walls of the bacteria. The developed nanohybrids were subsequently infused into tissue engineering scaffold agar-gelatin films and the films similarly showed bactericidal activity towards both kinds of bacterial strains while allowing normal growth of eukaryotic cells on the surface of the films.

  12. Ag nanoparticles formed by femtosecond pulse laser ablation in water: self-assembled fractal structures

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    Santillán, Jesica M. J. [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina); Fernández van Raap, Marcela B., E-mail: raap@fisica.unlp.edu.ar; Mendoza Zélis, Pedro; Coral, Diego [CONICET, Instituto de Física La Plata (IFLP) (Argentina); Muraca, Diego [Universidade Estadual de Campinas, Instituto de Física “Gleb Wataghin” (IFGW) (Brazil); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina)

    2015-02-15

    We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag{sub 2}O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag{sub 2}O and air–Ag core–shell Nps, Ag–Ag{sub 2}O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈D{sub SAXS}〉 = (5 ± 1) nm particles and fractal dimension d{sub f} = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension d{sub f} = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.

  13. Digestive cell lysosomes as main targets for Ag accumulation and toxicity in marine mussels, Mytilus galloprovincialis, exposed to maltose-stabilised Ag nanoparticles of different sizes.

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    Jimeno-Romero, A; Bilbao, E; Izagirre, U; Cajaraville, M P; Marigómez, I; Soto, M

    2017-03-01

    Bioavailability and toxicity of maltose-stabilised AgNPs of different sizes (20, 40 and 100 nm) in mussels were compared with bulk and aqueous forms of the metal through a two-tier experimental approach. In the first tier, mussels were exposed for 3 d to a range of concentrations (0.75, 75, 750 μg Ag/l) in the form of Ag20-Mal, Ag40-Mal, Ag100-Mal, bulk Ag and aqueous Ag (as AgNO 3 ), as well as to the concentrations of maltose used in the formulation of NPs. Mortality, bioaccumulation, tissue and cell distribution and lysosomal responses were investigated. In the second tier, mussels were exposed for 21 d to Ag20-Mal, Ag100-Mal, bulk Ag and aqueous Ag at the lowest effective concentration selected after Tier 1 (0.75 μg Ag/l), biomarkers and toxicopathic effects were investigated. Aqueous Ag was lethal within 3 d at 75 μg Ag/l; Ag NPs or bulk Ag did not produce significant mortality at 750 μg Ag/l. Ag accumulation was limited and metallothionein gene transcription was not regulated although metal accumulation occurred in digestive, brown and stomach epithelial cells and in gut lumen after exposure to AgNPs and aqueous Ag starting at low concentrations after 1 d. Electrondense particles (lysosomes and residual bodies after exposure to AgNPs contained Ag and S (X-ray). Intralysosomal metal accumulation and lysosomal membrane destabilisation were enhanced after exposure to all the forms of Ag and more marked after exposure to Ag20-Mal than to larger NPs. 21 d exposure to AgNPs provoked digestive cell loss and loss of digestive gland integrity, resulting in atrophy-necrosis in digestive alveoli and oedema/hyperplasia in gills (Ag NP), vacuolisation in digestive cells (aqueous Ag) and haemocyte infiltration of connective tissue (all treatments). Intralysosomal metal accumulation, lysosomal responses and toxicopathic effects are enhanced at decreasing sizes and appear to be caused by Ag +  ions released from NPs, although the metal was not substantially

  14. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum rind extract

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    Hui Yang

    Full Text Available Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV–Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of NH2, OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism. Keywords: Pomegranate rind, Biosynthesis, Ag/Ag+/Ag3+ nanoparticle composites, Antibacterial activity

  15. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    Science.gov (United States)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  16. Internal quantum efficiency enhancement of GaInN/GaN quantum-well structures using Ag nanoparticles

    DEFF Research Database (Denmark)

    Iida, Daisuke; Fadil, Ahmed; Chen, Yuntian

    2015-01-01

    We report internal quantum efficiency enhancement of thin p-GaN green quantumwell structure using self-assembled Ag nanoparticles. Temperature dependent photoluminescence measurements are conducted to determine the internal quantum efficiency. The impact of excitation power density on the enhance......We report internal quantum efficiency enhancement of thin p-GaN green quantumwell structure using self-assembled Ag nanoparticles. Temperature dependent photoluminescence measurements are conducted to determine the internal quantum efficiency. The impact of excitation power density...

  17. Assembly, characterization and swelling kinetics of Ag nanoparticles in PDMAA-g-PVA hydrogel networks

    International Nuclear Information System (INIS)

    Luo Yanling; Wei Qingbo; Xu Feng; Chen Yashao; Fan Lihua; Zhang Changhu

    2009-01-01

    A series of poly(N,N-dimethylacrylamide)-g-poly(vinyl alcohol) (PDMAA-g-PVA) graft hydrogel networks were designed and prepared via a free radical polymerization route initiated by a PVA-(NH 4 ) 2 Ce(NO 3 ) 6 redox reaction. Silver nanoparticles with high stability and good distribution behavior have been self-assembled by using these hydrogel networks as a nanoreactor and in situ reducing system. Meanwhile the PDMAA or PVA chains can efficiently act as stabilizing agents for the Ag nanoparticles in that Ag + would form complex via oxygen atom and nitrogen atom, and form weak coordination bonds, thus astricting Ag + . The structure of the PDMAA-g-PVA/Ag was characterized by a Fourier transform infrared spectroscope (FTIR). The morphologies of pure PDMAA-g-PVA hydrogels and PDMAA-g-PVA/Ag nanocomposite ones were observed by a scanning electron microscopy (SEM) and transmission electron microscope (TEM). TEM micrographs revealed the presence of nearly spherical and well-separated Ag nanoparticles with diameters ranging from 10 to 20 nm, depending on their reduction routes. XRD results showed all relevant Bragg's reflection for crystal structure of Ag nanoparticles. UV-vis studies apparently showed the characteristic surface plasmon band at 410-440 nm for the existence of Ag nanoparticles within the hydrogel matrix. The swelling kinetics demonstrated that the transport mechanism belongs to non-Fickian mode for the PDMAA-g-PVA hydrogels and PDMAA-g-PVA/Ag nanocomposite ones. With increasing the DMAA proportion, the r 0 and S ∞ are enhanced for each system. The assembly of Ag nanoparticles and the swelling behavior may be controlled and modulated by means of the compositional ratios of PVA to DMAA and reduction systems.

  18. Enhanced photocatalysts based on Ag-TiO2 and Ag-N-TiO2 nanoparticles for multifunctional leather surface coating

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    Gaidau Carmen

    2016-01-01

    Full Text Available The Ag deposition on TiO2 nanoparticles (Ag-TiO2 NPs and N-TiO2 nanoparticles (Ag-N-TiO2 NPs has been made by electrochemical methodology in view of improved antibacterial properties and enhanced photocatalytic activity under visible light irradiation. The particle size in powder and in dispersion showed similar values and good stability in aqueous medium which made them suitable for use in leather surface covering for new multifunctional properties development. The diffuse reflectance spectra of Ag-TiO2 NPs, Ag-N-TiO2 NPs and TiO2 NPs have been investigated and correlated with their photocatalytic performances under UV and visible light against different silver concentrations. The leather surfaces treated with Ag-N-TiO2 NPs showed advanced self-cleaning properties under visible light exposure through the hydrophilic mechanism of organic soil decomposition. Moreover the bacterial sensitivity and proven fungitoxic properties of Ag-N-TiO2 NPs leads to the possibility of designing new multifunctional additives to extend the advanced applications for more durable and useable materials.

  19. Simultaneous synthesis of polyaniline nanofibers and metal (Ag and Pt) nanoparticles

    International Nuclear Information System (INIS)

    Huang, Li-Ming; Liao, Wei-Hao; Ling, Han-Chern; Wen, Ten-Chin

    2009-01-01

    An approach for the synthesis of Ag/Pt nanoparticle-incorporated polyaniline (PANI) nanofibers and Ag/Pt nanoparticles was developed that considers both thermodynamic and kinetic aspects. Ag/Pt nanoparticles and PANI nanofibers are generated simultaneously by the reduction of Ag + /Pt 4+ ions to Ag/Pt nanoparticles and by the polymerization of aniline (ANI) to PANI nanofibers. The PANI nanofibers serve as anchor seeds for the formation of Ag/Pt nanoparticles. The simple and inexpensive route for the preparation of PANI-Ag/Pt nanocomposites can be extended to the polymerization of ANI derivatives and the formation of metal/metal oxides for applications such as sensors, direct methanol fuel cells, and capacitors.

  20. Physicochemical and antibacterial characterization of ionocity Ag/Cu powder nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, A., E-mail: ana.maria.nowak@gmail.com [A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Szade, J. [A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Talik, E. [A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Zubko, M. [Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Institute of Material Science, University of Silesia, 75 Pułku Piechoty 1a, 41-500 Chórzow (Poland); Wasilkowski, D. [Department of Biochemistry, University of Silesia, Jagiellońska 28, 40-032 Katowice (Poland); Dulski, M. [Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Institute of Material Science, University of Silesia, 75 Pułku Piechoty 1a, 41-500 Chórzow (Poland); Balin, K. [A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); and others

    2016-07-15

    Metal ion in bimetallic nanoparticles has shown vast potential in a variety of applications. In this paper we show the results of physical and chemical investigations of powder Ag/Cu nanoparticles obtained by chemical synthesis. Transmission electron microscopy (TEM) experiment indicated the presence of bimetallic nanoparticles in the agglomerated form. The average size of silver and copper nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu) basing on the X-ray diffraction (XRD) data. X-ray photoelectron (XPS) and Raman spectroscopies revealed the existence of metallic silver and copper as well as Cu{sub 2}O and CuO being a part of the nanoparticles. Moreover, UV–Vis spectroscopy showed surface alloy of Ag and Cu while Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Energy Dispersive X-ray Spectroscopy (EDX) showed heterogeneously distributed Ag structures placed on spherical Cu nanoparticles. The tests of antibacterial activity show promising killing/inhibiting growth behaviour for Gram positive and Gram negative bacteria. - Highlights: • Ag/Cu nanoparticles were obtained in the powder form. • The average size of nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu). • Ag/Cu powder nanoparticle shows promising antibacterial properties.

  1. Self-assembly of silver nanoparticles and bacteriophage

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    Santi Scibilia

    2016-03-01

    Full Text Available Biohybrid nanostructured materials, composed of both inorganic nanoparticles and biomolecules, offer prospects for many new applications in extremely diverse fields such as chemistry, physics, engineering, medicine and nanobiotechnology. In the recent years, Phage display technique has been extensively used to generate phage clones displaying surface peptides with functionality towards organic materials. Screening and selection of phage displayed material binding peptides has attracted great interest because of their use for development of hybrid materials with multiple functionalities. Here, we present a self-assembly approach for the construction of hybrid nanostructured networks consisting of M13 P9b phage clone, specific for Pseudomonas aeruginosa, selected by Phage display technology, directly assembled with silver nanoparticles (AgNPs, previously prepared by pulsed laser ablation. These networks are characterized by UV–vis optical spectroscopy, scanning/transmission electron microscopies and Raman spectroscopy. We investigated the influence of different ions and medium pH on self-assembly by evaluating different phage suspension buffers. The assembly of these networks is controlled by electrostatic interactions between the phage pVIII major capsid proteins and the AgNPs. The formation of the AgNPs-phage networks was obtained only in two types of tested buffers at a pH value near the isoelectric point of each pVIII proteins displayed on the surface of the clone. This systematic study allowed to optimize the synthesis procedure to assembly AgNPs and bacteriophage. Such networks find application in the biomedical field of advanced biosensing and targeted gene and drug delivery. Keywords: Phage display, Silver nanoparticles, Self-assembly, Hybrid architecture, Raman spectroscopy

  2. Synthesis, characterization and antibacterial study on the chitosan-functionalized Ag nanoparticles.

    Science.gov (United States)

    Biao, Linhai; Tan, Shengnan; Wang, Yuanlin; Guo, Ximin; Fu, Yujie; Xu, Fengjie; Zu, Yuangang; Liu, Zhiguo

    2017-07-01

    This study provided a facile, one-step hydrothermal method to synthesize stable Ag colloid in aqueous solution by utilizing chitosan as both reductant and stabilizer. The formation of chitosan-functionalized Ag nanoparticles was verified by UV-Vis, FTIR, TEM, AFM and XRD measurements. FTIR results revealed that the primary amine groups and amide groups of chitosan have specific interactions with the surface of Ag nanoparticles. The average diameter of the Ag nanoparticles is 10.0±5.4nm as determined by TEM. Ag nanoparticles are highly crystalline as revealed by HR-TEM and XRD measurements. The size and shape of Ag nanoparticles are also found to depend on the pH condition in the synthesis. Ag nanoparticles were the main products at pH5.0 whereas large Ag nanotriangle and truncated triangular nanoplate were dominant at pH4.0 in the synthesis. Due to its monodispersity and good stability, the chitosan-functionalized Ag colloid synthesized at pH5.0 was further tested for its antibacterial activities against gram-positive bacteria, gram-negative bacteria and fungus. The results of zone of inhibition, inhibition ratio and SEM characterization revealed that chitosan-functionalized Ag nanoparticles have great bactericidal efficiency against both bacteria and fungus. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Preparation and self-sterilizing properties of Ag@TiO2-styrene-acrylic complex coatings.

    Science.gov (United States)

    Zhou, Xiang-dong; Chen, Feng; Yang, Jin-tao; Yan, Xiao-hui; Zhong, Ming-qiang

    2013-04-01

    In this study, we report a simple and cost-effective method for self-sterilized complex coatings obtained by Ag@TiO2 particle incorporation into styrene-acrylic latex. The Ag@TiO2 particles were prepared via a coupling agent modification process. The composite latices characterized by transmission electron microscopy (TEM) study were highly homogeneous at the nanometric scale, and the Ag@TiO2 particles were well dispersed and exhibited an intimate contact between both the organic and inorganic components. The Ag@TiO2 nanoparticles significantly enhanced the absorption in the visible region and engendered a good heat-insulating effect of the complex coatings. Moreover, the Ag@TiO2 nanoparticle incorporation into this polymer matrix renders self-sterilized nanocomposite materials upon light excitation, which are tested against Escherichia coli and Staphylococcus aureus. The complex coatings display an impressive performance in the killing of all micro-organisms with a maximum for a Ag@TiO2 loading concentration of 2-5 wt.%. The weathering endurance of the complex coating was also measured. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Silver Nanoparticles in the Lung: Toxic Effects and Focal Accumulation of Silver in Remote Organs

    Directory of Open Access Journals (Sweden)

    Martin Wiemann

    2017-12-01

    Full Text Available The distribution of silver (Ag into remote organs secondary to the application of Ag nanoparticles (Ag-NP to the lung is still incompletely understood and was investigated in the rat with imaging methods. Dose-finding experiments were carried out with 50 nm- or 200 nm-sized polyvinyl pyrrolidine (PVP-coated Ag-NP using alveolar macrophages in vitro and female rats, which received Ag-NP via intratracheal instillation. In the main study, we administered 37.5–300 µg per rat lung of the more toxic Ag50-PVP and assessed the broncho-alveolar lavage fluid (BALF for inflammatory cells, total protein and fibronectin after three and 21 days. In parallel, lung tissue was analysed for DNA double-strand breaks and altered cell proliferation. While 75–150 µg Ag50-PVP per rat lung caused a reversible inflammation, 300 µg led to DNA damage, accelerated cell proliferation and progressively increasing numbers of neutrophilic granulocytes. Ag accumulation was significant in homogenates of liver and other peripheral organs upon lung dose of ≥75 µg. Quantitative laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS combined with enhanced dark field microscopy and autometallography revealed focal accumulations of Ag and/or Ag-NP in sections of peripheral organs: mediastinal lymph nodes contained Ag-NP especially in peripheral macrophages and Ag in argyrophilic fibres. In the kidney, Ag had accumulated within proximal tubuli, while renal filter structures contained no Ag. Discrete localizations were also observed in immune cells of liver and spleen. Overall, the study shows that concentrations of Ag-NP, which elicit a transient inflammation in the rat lung, lead to focal accumulations of Ag in peripheral organs, and this might pose a risk to particular cell populations in remote sites.

  5. In-situ synthesis of Ag nanoparticles by electron beam irradiation

    International Nuclear Information System (INIS)

    Gong, Jiangfeng; Liu, Hongwei; Jiang, Yuwen; Yang, Shaoguang; Liao, Xiaozhou; Liu, Zongwen; Ringer, Simon

    2015-01-01

    Ag nanoparticles were synthesized by electron beam irradiation in the transmission electron microscope chamber at room temperature and the growth mechanism was explored in detail. The sizes of the Ag nanoparticles are controlled by the electron beam current density. Two nanoparticle growth stages were identified. The first growth stage was dominated by the discharging effect, while the second stage was controlled by the heating effect. The nanoparticle synthesis method should be applicable to the synthesis of other metallic nanoparticles. - Highlights: • Ag nanoparticles were synthesized by electron beam irradiation in the transmission electron microscope chamber. • The sizes of the Ag nanoparticles are controlled by the electron beam current density. • The growth mechanism was studied, two growth stages were confirmed. • The first growth stage was dominated by the discharging effect, and the second stage was controlled by the heating effect.

  6. DNA/Ag Nanoparticles as Antibacterial Agents against Gram-Negative Bacteria

    Directory of Open Access Journals (Sweden)

    Tomomi Takeshima

    2015-03-01

    Full Text Available Silver (Ag nanoparticles were produced using DNA extracted from salmon milt as templates. Particles spherical in shape with an average diameter smaller than 10 nm were obtained. The nanoparticles consisted of Ag as the core with an outermost thin layer of DNA. The DNA/Ag hybrid nanoparticles were immobilized over the surface of cotton based fabrics and their antibacterial efficiency was evaluated using E. coli as the typical Gram-negative bacteria. The antibacterial experiments were performed according to the Antibacterial Standard of Japanese Association for the Functional Evaluation of Textiles. The fabrics modified with DNA/Ag nanoparticles showed a high enough inhibitory and killing efficiency against E. coli at a concentration of Ag ≥ 10 ppm.

  7. Core–shell-typed Ag-SiO2 nanoparticles as solar selective coating materials

    International Nuclear Information System (INIS)

    Gao, Tao; Jelle, Bjørn Petter; Gustavsen, Arild

    2013-01-01

    Silver (Ag) nanoparticles with typical diameter of about 50 nm have been prepared via a polyol process. The as-prepared Ag nanoparticles are well crystallized and exhibit a characteristic surface plasmon resonance (SPR) band centered at ∼423 nm. The SPR band shows a strong dependence on the sizes of Ag nanoparticles and the types of the dielectric medium. Core–shell-typed Ag-SiO 2 nanoparticles have also been prepared by depositing a thin layer (∼25 nm) of silica on Ag nanoparticles. The core–shell-typed Ag-SiO 2 nanoparticles show similar optical behaviors (absorption, transmission, and reflection) but enhanced stability compared to those of the Ag nanoparticles, indicating that the core–shell-typed Ag-SiO 2 nanoparticles may be used as solar selective coating materials for architectural window applications.

  8. Cu-Ag core–shell nanoparticles with enhanced oxidation stability for printed electronics

    International Nuclear Information System (INIS)

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Lee, Yung Jong; Lee, Hyuck Mo

    2015-01-01

    In this work, we synthesized uniform Cu–Ag core–shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core–shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu–Ag core–shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu–Ag core–shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu–Ag core–shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu–Ag core–shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties. (paper)

  9. Studies on electronic structure of interfaces between Ag and gelatin for stabilization of Ag nanoparticles

    International Nuclear Information System (INIS)

    Tani, Tadaaki; Uchida, Takayuki

    2015-01-01

    Extremely high stability of Ag nanoparticles in photographic materials has forced us to study the electronic structures of the interfaces between thin layers of Ag, Au, and Pt and their surface membranes in ambient atmosphere by photoelectron yield spectroscopy in air and Kelvin probe method. Owing to the Fermi level equalization between a metal layer and a membrane coming from air, the electron transfer took place from the membrane to Pt and Au layers and from an Ag layer to the membrane, giving the reason for poor stability of Ag nanoparticles in air. The control of the Fermi level of an Ag layer with respect to that of a gelatin membrane in air could be widely made according to Nernst's equation by changing the pH and pAg values of an aqueous gelatin solution used to form the membrane, and thus available to stabilize Ag nanoparticles in a gelatin matrix. (author)

  10. A novel metal-to-metal bonding process through in-situ formation of Ag nanoparticles using Ag2O microparticles

    International Nuclear Information System (INIS)

    Hirose, Akio; Tatsumi, Hiroaki; Takeda, Naoya; Akada, Yusuke; Ogura, Tomo; Ide, Eiichi; Morita, Toshiaki

    2009-01-01

    The metal-to-metal bonding has been successfully achieved via the bonding process using Ag metallo-organic nanoparticles at a bonding temperature of around 300-, which can be alternative to the current microsoldering in electronics assembly using high-temperature solders. However, further reduction of bonding temperature and/or bonding pressure is needed. In the present research, a novel bonding process through in-situ formation of Ag nanoparticles instead of the filler material of the Ag metallo-organic nanoparticles has been developed. The Ag nanoparticles can form by the reduction of Ag 2 O particles. In this study, the Ag 2 O particles were mixed with triethylene glycol as a reducing agent to form a paste for bonding. The Au coated cylindrical specimens were bonded using the paste. The Ag nanoparticles formed at around 130 to 160 through the reduction process of Ag2O particles with triethylene glycol. The Ag nanoparticles were immediately sintered each other due to a great surface energy per volume. A transmission electron microscope observation revealed that the sintered Ag metallurgically bonded to the Au substrate at around 160 and a dense Ag layer formed after further heating. The tensile strength of the joint bonded at 250 under a bonding pressure of 5MPa was around 60MPa

  11. Optical Properties of Plasmon Resonances with Ag/SiO2/Ag Multi-Layer Composite Nanoparticles

    International Nuclear Information System (INIS)

    Ye-Wan, Ma; Li-Hua, Zhang; Zhao-Wang, Wu; Jie, Zhang

    2010-01-01

    Optical properties of plasmon resonance with Ag/SiO 2 /Ag multi-layer nanoparticles are studied by numerical simulation based on Green's function theory. The results show that compared with single-layer Ag nanoparticles, the multi-layer nanoparticles exhibit several distinctive optical properties, e.g. with increasing the numbers of the multi-layer nanoparticles, the scattering efficiency red shifts, and the intensity of scattering enhances accordingly. It is interesting to find out that slicing an Ag-layer into multi-layers leads to stronger scattering intensity and more 'hot spots' or regions of stronger field enhancement. This property of plasmon resonance of surface Raman scattering has greatly broadened the application scope of Raman spectroscopy. The study of metal surface plasmon resonance characteristics is critical to the further understanding of surface enhanced Raman scattering as well as its applications. (fundamental areas of phenomenology (including applications))

  12. Nanoparticle silver coexposure reduces the accumulation of weathered persistent pesticides by earthworms.

    Science.gov (United States)

    Mukherjee, Arnab; Hawthorne, Joseph; White, Jason C; Kelsey, Jason W

    2017-07-01

    Although the use of engineered nanomaterials continues to increase, how these materials interact with coexisting contaminants in the environment is largely unknown. The effect of silver (Ag) in bulk, ionic, and nanoparticle (NP; bare and polyvinyl pyrrolidone-coated) forms at 3 concentrations (0 mg/kg, 500 mg/kg, 1000 mg/kg, 2000 mg/kg; ion at 69 mg/kg, 138 mg/kg, 276 mg/kg) on the accumulation of field-weathered chlordane and dichlorodiphenyldichloroethylene + metabolites (DDX) by Eisenia fetida (earthworm) was investigated. Earthworm biomass and survival were unaffected by treatment. At the 500 mg/kg and 1000 mg/kg exposure levels, NP-exposed earthworms contained significantly greater Ag (194-245%) than did the bulk exposed organisms; NP size or coating had no impact on element content. Generally, exposure to Ag of any type or at any concentration significantly reduced pesticide accumulation, although reductions for DDX (35.1%; 8.9-47.0%) were more modest than those for chlordane (79.0%; 17.4-92.9%). For DDX, the reduction in pesticide accumulation was not significantly affected by Ag type or concentration. For chlordane, the 3 NP exposures suppressed chlordane accumulation significantly more than did bulk exposure; earthworms exposed to bulk Ag contained 1170 ng/g chlordane, but levels in the NP-exposed earthworms were 279 ng/g. At the 500 mg/kg exposure, the smallest coated NPs exerted the greatest suppression in chlordane accumulation; at the 2 higher concentrations, chlordane uptake was unaffected by NP size or coating. The findings show that in exposed earthworms Ag particle size does significantly impact accumulation of the element itself, as well as that of coexisting weathered pesticides. The implications of these findings with regard to NP exposure and risk are unknown but are the topic of current investigation. Environ Toxicol Chem 2017;36:1864-1871. © 2016 SETAC. © 2016 SETAC.

  13. Highly luminescent material based on Alq3:Ag nanoparticles.

    Science.gov (United States)

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2013-09-01

    Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices.

  14. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    Science.gov (United States)

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  15. Study of Ag and Au Nanoparticles Synthesized by Arc Discharge in Deionized Water

    Directory of Open Access Journals (Sweden)

    Der-Chi Tien

    2010-01-01

    Full Text Available The paper presents a study of Ag and Au nanofluids synthesized by the arc discharge method (ADM in deionized water. The metallic Ag nanoparticle (Ag0 and ionic Ag (Ag+ have played an important role in the battle against germs which are becoming more drug-resistant every year. Our study indicates that Ag nanoparticle suspension (SNPS fabricated by using ADM without added surfactants exclusively contains the metallic Ag nanoparticle and ionic Ag. Besides that, the ADM in deionized water has also been employed for the fabrication process of Au nanoparticles. The experimental results indicate that the prepared Ag nanoparticles can react with the dissolved H2CO3 in deionized water, leading to the formation of Ag2CO3. Significantly different to Ag, the prepared Au nanoparticles with their surfaces bonded by oxygen are suspended in deionized water by the formation of hydrogen bonded with the neighboring water molecules.

  16. Preparation of AgBr Nanoparticles in Microemulsions Via Reaction of AgNO3 with CTAB Counterion

    International Nuclear Information System (INIS)

    Husein, Maen M.; Rodil, Eva; Vera, Juan H.

    2007-01-01

    Nanoparticles of AgBr were prepared by precipitating AgBr in the water pools of microemulsions consisting of CTAB, n-butanol, isooctane and water. An aqueous solution of AgNO 3 added to the microemulsion was the source of Ag + ions. The formation of AgBr nanoparticles in microemulsions through direct reaction with the surfactant counterion is a novel approach aimed at decreasing the role of intermicellar nucleation on nanoparticle formation for rapid reactions. The availability of the surfactant counterion in every reverse micelle and the rapidity of the reaction with the counterion trigger nucleation within individual reverse micelles. The effect of the following variables on the particle size and size distribution was investigated: the surfactant and cosurfactant concentrations, moles of AgNO 3 added, and water to surfactant mole ratio, R. High concentration of the surfactant or cosurfactant, or high water content of the microemulsion favored intermicellar nucleation and resulted in the formation of large particles with broad size distribution, while high amounts of AgNO 3 favored nucleation within individual micelles and resulted in small nanoparticles with narrow size distribution. A blue shift in the UV absorption threshold corresponding to a decrease in the particle size was generally observed. Notably, the variation of the absorption peak size with the nanoparticle size was opposite to those reported by us in previous studies using different surfactants

  17. Synthesis of Ag or Pt Nanoparticles by Hydrolysis of Either Ag2Na or PtNa

    Directory of Open Access Journals (Sweden)

    Huabin Wang

    2008-01-01

    Full Text Available Ag and Pt nanoparticles have successfully been synthesized by hydrolysis of either Ag2Na or PtNa at room temperature. The oxidation of sodium in the Pt-Na pellets was much faster than that in the Ag-Na pellets since Pt is a catalyst for H2O formation reaction from hydrogen and oxygen at room temperature. The hydrolysis byproduct, NaOH, has a high solubility and easily is removed. This method offers a simple method of preparing transition metal nanoparticles. The Ag and Pt nanoparticles prepared by this method were crystalline in nature, and spherical in shape with a mean size of around 10 nm.

  18. The bactericidal mechanism of action against Staphylococcus aureus for AgO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wenning, E-mail: shenwenning@qq.com [School of Materials Science and Engineering, Xi' an University of Technology, No. 5 South Jinhua Road, Xi' an 710048 (China); Li, Pin [School of Materials Science and Engineering, Xi' an University of Technology, No. 5 South Jinhua Road, Xi' an 710048 (China); Feng, Hui [Shaanxi Institute of Zoology, Xi' an 710032 (China); Ge, Yanfeng; Liu, Zheng; Feng, Lajun [School of Materials Science and Engineering, Xi' an University of Technology, No. 5 South Jinhua Road, Xi' an 710048 (China)

    2017-06-01

    To identify the mechanistic effects of AgO nanoparticles on Gram-positive bacteria, S. aureus cells suspended in phosphate buffer solution (PBS) and deionized water were separately treated using AgO nanoparticles at different concentrations. The phase composition changes of the bactericide after killing S. aureus and the cellular responses of S. aureus to AgO were characterized by X-ray diffraction, atomic absorption spectrophotometer, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The results show that AgO nanoparticles could kill S. aureus suspended in PBS and deionized water. The bactericidal effect of AgO bactericide against S. aureus in water was better than that in PBS, due to the formation of Ag{sub 3}PO{sub 4} from the reaction between AgO and PBS. AgO nanoparticles exerted their bactericidal activity by multiple processes. AgO nanoparticles adhered to the surface of S. aureus cells firstly, then induced physical alterations in cell morphology and released silver ions, leading to initial injuries of cell membrane. Once membrane damage occurred, they entered the cells, and damaged the intracellular materials, eventually causing severe morphological and structural injuries to the cells and leakage of cytoplasm. - Highlights: • S. aureus in water was more sensitive to AgO than in PBS, since AgO reacted with PBS and formed Ag{sub 3}PO{sub 4}. • After killing S. aureus in water, AgO did not changed. • AgO particles attached to cell surface then interacted with the cells, resulting in the increase of released silver contents. • Cell membrane damages by AgO nanoparticles were supported by the leakages of K{sup +}, proteins and DNA. • Serious cell morphological and structural changes were caused by AgO nanoparticles.

  19. The bactericidal mechanism of action against Staphylococcus aureus for AgO nanoparticles

    International Nuclear Information System (INIS)

    Shen, Wenning; Li, Pin; Feng, Hui; Ge, Yanfeng; Liu, Zheng; Feng, Lajun

    2017-01-01

    To identify the mechanistic effects of AgO nanoparticles on Gram-positive bacteria, S. aureus cells suspended in phosphate buffer solution (PBS) and deionized water were separately treated using AgO nanoparticles at different concentrations. The phase composition changes of the bactericide after killing S. aureus and the cellular responses of S. aureus to AgO were characterized by X-ray diffraction, atomic absorption spectrophotometer, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The results show that AgO nanoparticles could kill S. aureus suspended in PBS and deionized water. The bactericidal effect of AgO bactericide against S. aureus in water was better than that in PBS, due to the formation of Ag 3 PO 4 from the reaction between AgO and PBS. AgO nanoparticles exerted their bactericidal activity by multiple processes. AgO nanoparticles adhered to the surface of S. aureus cells firstly, then induced physical alterations in cell morphology and released silver ions, leading to initial injuries of cell membrane. Once membrane damage occurred, they entered the cells, and damaged the intracellular materials, eventually causing severe morphological and structural injuries to the cells and leakage of cytoplasm. - Highlights: • S. aureus in water was more sensitive to AgO than in PBS, since AgO reacted with PBS and formed Ag 3 PO 4 . • After killing S. aureus in water, AgO did not changed. • AgO particles attached to cell surface then interacted with the cells, resulting in the increase of released silver contents. • Cell membrane damages by AgO nanoparticles were supported by the leakages of K + , proteins and DNA. • Serious cell morphological and structural changes were caused by AgO nanoparticles.

  20. Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

    International Nuclear Information System (INIS)

    Jiao, Qing; Qiu, Jianbei; Zhou, Dacheng; Xu, Xuhui

    2014-01-01

    Graphical abstract: - Highlights: • Silver nanoparticles are precipitated from the borate glasses during the melting process without any further heat treatment. • The reduction of Eu 3+ ions to Eu 2+ ions is presented in this material. • The intensity of Ag + luminescence. • The introduction of Eu ions accelerated the reaction between Eu 2+ ions and silver ions inducing the silver clusters formation. - Abstract: Ag + doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410 nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag + decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu 3+ to Eu 2+ in our glass system, it revealed that Ag + has been reduced by the neighboring Eu 2+ which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag + /Ag aggregates to the Eu 3+ was investigated for the enhancement of Eu 3+ luminescence

  1. Studies on L-histidine capped Ag and Au nanoparticles for dopamine detection

    Energy Technology Data Exchange (ETDEWEB)

    Nivedhini Iswarya, Chandrasekaran; Kiruba Daniel, S.C.G. [Division of Nanoscience and Technology, Anna University-BIT Campus, Tiruchirappalli 620024 (India); Sivakumar, Muthusamy, E-mail: muthusiva@gmail.com [Division of Nanoscience and Technology, Anna University-BIT Campus, Tiruchirappalli 620024 (India); Department of Chemistry, Anna University-BIT Campus, Tiruchirappalli 620024 (India)

    2017-06-01

    This work demonstrates the effective surface functionalization of Ag, Au and bimetallic Ag-Au nanoparticles using L-histidine for colorimetric detection of dopamine (DA) which plays majorly in recognizing the neurological disorder. L-Histidine (L-His) capped Ag, Au, and bimetallic Ag-Au nanoparticles are characterized using physico-chemical techniques. The optical behaviour of nanoparticles has been analysed at various time intervals using UV–Vis absorption spectroscopy. FT-IR results provide the evidence of chemical bonding between L-histidine and metal nanoparticles. Its structure with the capping of L-His was clearly shown in HR-TEM images. The average size of nanoparticles has calculated from TEM image fringes are 11 nm, 5 nm and 6.5 nm respectively, matches with crystals size calculated from X-ray diffraction pattern. Enhanced optical nature of nanoparticles provides the best platform to develop a colorimetric-based biosensor for DA detection. After addition of DA, a rapid colour change has been noted in colloids of nanoparticles. The substantial changes in absorbance and λ{sub max} in metal nanoparticles respect to DA concentration have been observed and formulated. This is one of the successive methods for trace level determination of DA and will be going to a significant material for designing biosensor to determine DA in real extracellular body fluids. - Highlights: • L-His functionalized Ag, Au and bimetallic Ag-Au nanoparticles were prepared and its properties were studied. • L-His based Ag, Au, Ag-Au nanoparticles have characterized by spectroscopy, XRD and microscopic studies. • Enhanced optical nature of nanoparticles delivers the best platform to develop a biosensor for DA detection. • For qualitative determination of dopamine, SPR of metal nanoparticles plays a major role in dopamine determination. • This basic finding can be utilized for further identification of imbalanced DA concentration in body fluids.

  2. Radiochemical synthesis of {sup 105g}Ag-labelled silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ichedef, C., E-mail: cigdem_ch@yahoo.com; Simonelli, F.; Holzwarth, U. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy); Bagaria, J. Piella; Puntes, V. F. [Institut Català de Nanotecnologia (ICN2) (Spain); Cotogno, G.; Gilliland, D.; Gibson, N. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy)

    2013-11-15

    A method for synthesis of radiolabelled silver nanoparticles is reported. The method is based on proton activation of silver metal powder, enriched in {sup 107}Ag, with a 30.7 MeV proton beam. At this proton energy {sup 105g}Ag is efficiently created, mainly via the {sup 107}Ag(p,3n){sup 105}Cd → {sup 105g}Ag reaction. {sup 105g}Ag has a half-life of 41.29 days and emits easily detectable gamma radiation on decay to {sup 105}Pd. This makes it very useful as a tracing radionuclide for experiments over several weeks or months. Following activation and a period to allow short-lived radionuclides to decay, the powder was dissolved in concentrated nitric acid in order to form silver nitrate (AgNO{sub 3}), which was used to synthesise radiolabelled silver nanoparticles via the process of sodium borohydride reduction. For comparison, non-radioactive silver nanoparticles were synthesised using commercially supplied AgNO{sub 3} in order to check if the use of irradiated Ag powder as a starting material would alter in any way the final nanoparticle characteristics. Both nanoparticle types were characterised using dynamic light scattering, zeta-potential and X-ray diffraction measurements, while additionally the non-radioactive samples were analysed by transmission electron microscopy and UV–Vis spectrometry. A hydrodynamic diameter of about 16 nm was determined for both radiolabelled and non-radioactive nanoparticles, while the electron microscopy on the non-radioactive samples indicated that the physical size of the metal NPs was (7.3 ± 1.4) nm.

  3. Self-healing of cracks in Ag joining layer for die-attachment in power devices

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chuantong, E-mail: chenchuantong@sanken.osaka-u.ac.jp; Nagao, Shijo; Suganuma, Katsuaki; Jiu, Jinting; Zhang, Hao; Sugahara, Tohru [Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 (Japan); Iwashige, Tomohito; Sugiura, Kazuhiko; Tsuruta, Kazuhiro [Research Division 3, Denso Corporation, Komenoki-cho, Minamiyama 500-1, Nissin, Aichi 470-0111 (Japan)

    2016-08-29

    Sintered silver (Ag) joining has attracted significant interest in power devices modules for its ability to form stable joints with a porous interconnection layer. A function for the self-healing of cracks in sintered porous Ag interlayers at high temperatures is discovered and reported here. A crack which was prepared on a Ag joining layer was closed after heating at 200 °C in air. The tensile strength of pre-cracked Ag joining layer specimens recovers to the value of non-cracked specimens after heating treatment. Transmission electron microscopy (TEM) was used to probe the self-healing mechanism. TEM images and electron diffraction patterns show that a large quantity of Ag nanoparticles formed at the gap with the size less than 10 nm, which bridges the crack in the self-healing process. This discovery provides additional motivation for the application of Ag as an interconnection material for power devices at high temperature.

  4. Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

    Directory of Open Access Journals (Sweden)

    M. Vinod

    2014-12-01

    Full Text Available Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

  5. A study on synthesis and properties of Ag nanoparticles immobilized polyacrylamide hydrogel composites

    International Nuclear Information System (INIS)

    Saravanan, P.; Padmanabha Raju, M.; Alam, Sarfaraz

    2007-01-01

    Synthesis of Ag nanoparticles containing polyacrylamide (PAm) hydrogel composites was performed by free-radical cross-linking polymerization of acrylamide monomer in an aqueous medium containing Ag + ions. The Ag nanoparticle/PAm composites exhibit faint yellow colour and are found to stable under ambient conditions, without undergoing oxidation. TEM micrographs reveal the presence of nearly spherical and well-separated Ag nanoparticles with diameters in the range of 4-7 nm. UV-vis studies apparently show the characteristic surface plasmon band at ∼415 nm, for the existence of Ag nanoparticles within the hydrogel matrix. The effect of varying Ag + ion concentration within the PAm hydrogels on the amount of formation of Ag nanoparticles, as well as on the bulk properties of hydrogel nanocomposites such as equilibrium swelling, optical and electrical properties are studied. The Ag/PAm hydrogel nanocomposites have higher swelling ratio and lower electron transfer resistance than its corresponding conventional hydrogel

  6. Size and composition tunable Ag-Au alloy nanoparticles by replacement reactions

    International Nuclear Information System (INIS)

    Zhang Qingbo; Lee, J Y; Yang Jun; Boothroyd, Chris; Zhang Jixuan

    2007-01-01

    Ag-Au alloy nanoparticles with tunable size and composition were prepared by a replacement reaction between Ag nanoparticles and HAuCl 4 at elevated temperatures. The formation of homogeneous alloy nanoparticles was confirmed by selected-area energy-dispersive x-ray spectroscopy (SAEDX), UV-visible absorption spectroscopy, high resolution transmission electron microscopy (HRTEM) and electron diffraction. This method leverages upon the rapid interdiffusion of Ag and Au atoms in the reduced dimension of a nanoparticle, elevated temperatures and the large number of vacancy defects created in the replacement reaction. This method of preparation has several notable advantages: (1) independent tuning of the size and composition of alloy nanoparticles; (2) production of alloy nanoparticles in high concentrations; (3) general utility in the synthesis of alloy nanoparticles that cannot be obtained by the co-reduction method

  7. Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity

    Science.gov (United States)

    Shu, Zhan; Zhang, Yi; Yang, Qian; Yang, Huaming

    2017-02-01

    Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs) and silver (Ag) into zinc oxide (ZnO) nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs) and Ag nanoparticles (Ag NPs) with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

  8. Subsurface Synthesis and Characterization of Ag Nanoparticles Embedded in MgO

    Energy Technology Data Exchange (ETDEWEB)

    Vilayur Ganapathy, Subramanian; Devaraj, Arun; Colby, Robert J.; Pandey, Archana; Varga, Tamas; Shutthanandan, V.; Manandhar, Sandeep; El-Khoury, Patrick Z.; Kayani, Asghar N.; Hess, Wayne P.; Thevuthasan, Suntharampillai

    2013-03-08

    Metal nanoparticles exhibit localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the dielectric medium surrounding it. LSPR causes field enhancement near the surface of the nanoparticle making them interesting candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix form hotspots which are prime locations for LSPR spectroscopy and sensing. This study involves synthesizing partially buried Ag nanoparticles in MgO and investigating the characteristics of this material system. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 10000C for 10 and 30 hours. A detailed optical and structural characterization was carried out to understand the evolution of Ag nanoparticle microstructure and size distribution inside the MgO matrix. Micro x-ray diffraction (MicroXRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes as seen from aberration corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  9. The irradiation influence on the properties of silver sulfide (Ag2S) colloidal nanoparticles

    Science.gov (United States)

    Rempel, S. V.; Kuznetsova, Yu. V.; Gerasimov, E. Yu.; Rempel', A. A.

    2017-08-01

    The aqueous solutions of different stability containing silver sulfide (Ag2S) nanoparticles are studied. The stable, transparent, and turbid solutions have been subjected to daylight for 7 months, to ultraviolet and laser irradiation, as well as to an electron beam. Solar radiation is found to favor the Ag2S reduction to Ag and/or the formation of Ag2S/Ag hybrid nanoparticles in the solution. At a high amount of hybrid nanoparticles, the exciton-plasmon interaction causes asymmetry in the absorption spectra. The exposure of Ag2S particles precipitated from the solution with the electron beam leads to the reversible growth of Ag threads. The possible exciton-plasmon interplay mechanisms in Ag2S/Ag hybrid nanoparticles are considered. The physical mechanisms of the changing Ag2S stoichiometry, the formation of metallic Ag and Ag2S/Ag hybrid nanoparticles are the generation of hot carriers and the energy transfer (exciton-plasmon interaction) in a metal-semiconductor hybrid nanosystem are elucidated, as well.

  10. Avoidance of Ag nanoparticles by earthworms, Eisenia fetida

    DEFF Research Database (Denmark)

    Mariyadas, Jennifer; Mónica, Amorim; Scott-Fordsmand, Janeck James

    2013-01-01

    Earthworms are key sentinel organisms playing an important role in improving the soil structure. Here we tested the avoidance behaviour of earthworms, Eisenia fetida to silver nanoparticles (Ag NPs). Silver nanoparticles are widely used in a range of consumer products mainly as antibacterial agents....... The avoidance behaviour could not be explained by the release of silver ions in the soil-solution. Although, Ag-ions release (if any) may still have had an influence on behaviour. The present results suggests that the earthworms perceive the presence of actual nanoparticles in the soil. Our results suggest that...... and thus causes potential risk to the environment once these particles are released into the environment [1]. In our tests, we were able to show that the earthworms avoided commercially fabricated silver nanoparticles in a dose and time dependent manner. The earthworms were exposed to 3 nanoparticles: NM...

  11. Electrochemical Glucose Oxidation Using Glassy Carbon Electrodes Modified with Au-Ag Nanoparticles: Influence of Ag Content

    Directory of Open Access Journals (Sweden)

    Nancy Gabriela García-Morales

    2015-01-01

    Full Text Available This paper describes the application of glassy carbon modified electrodes bearing Aux-Agy nanoparticles to catalyze the electrochemical oxidation of glucose. In particular, the paper shows the influence of the Ag content on this oxidation process. A simple method was applied to prepare the nanoparticles, which were characterized by transmission electron microscopy, Ultraviolet-Visible spectroscopy, X-ray diffraction spectroscopy, and cyclic voltammetry. These nanoparticles were used to modify glassy carbon electrodes. The effectiveness of these electrodes for electrochemical glucose oxidation was evaluated. The modified glassy carbon electrodes are highly sensitive to glucose oxidation in alkaline media, which could be attributed to the presence of Aux-Agy nanoparticles on the electrode surface. The voltammetric results suggest that the glucose oxidation speed is controlled by the glucose diffusion to the electrode surface. These results also show that the catalytic activity of the electrodes depends on the Ag content of the nanoparticles. Best results were obtained for the Au80-Ag20 nanoparticles modified electrode. This electrode could be used for Gluconic acid (GA production.

  12. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

    Science.gov (United States)

    Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

    2013-03-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  13. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

    International Nuclear Information System (INIS)

    Vilayurganapathy, S; Devaraj, A; Colby, R; Pandey, A; Varga, T; Shutthanandan, V; Manandhar, S; Thevuthasan, S; El-Khoury, P Z; Hess, W P; Kayani, Asghar

    2013-01-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag + ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles. (paper)

  14. Growth of Ag micro/nanoparticles using stress migration from multilayered metallic structure

    International Nuclear Information System (INIS)

    Lu, Yebo; Li, Yuan; Saka, Masumi

    2015-01-01

    Highlights: • A multilayered metallic structure was proposed to fabricate Ag micro/nanoparticles via stress migration. • Both ductile Pt and brittle TiN films can be used as the passivation layer by providing pathways for atomic migration. • The diameter of the formed Ag particle can be controlled using different material for passivation layer and changing the heating temperature. - Abstract: A multilayered metallic structure, consisting of Cu foil and subsequently deposited Ag thin film covered with a passivation layer, was proposed to fabricate Ag micro/nanoparticles by stress migration. With employing a ductile Pt or brittle TiN thin film as passivation, Ag micro/nanoparticles were successfully fabricated by annealing the corresponding multilayered structure. The relationship between characteristics (average diameter, number and volume) of the formed Ag micro/nanoparticles and the annealing temperature was discussed. On this basis, the growth mechanism was developed, which indicates that the dimension of Ag particles was mainly dominated by the different pathways for the migration of diffused Ag atoms in the passivation layers of Pt and TiN and the annealing temperature

  15. Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Zhan Shu

    2017-02-01

    Full Text Available Abstract Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs and silver (Ag into zinc oxide (ZnO nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs and Ag nanoparticles (Ag NPs with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

  16. Antifungal mechanisms of ZnO and Ag nanoparticles to Sclerotinia homoeocarpa

    Science.gov (United States)

    Li, Junli; Sang, Hyunkyu; Guo, Huiyuan; Popko, James T.; He, Lili; White, Jason C.; Parkash Dhankher, Om; Jung, Geunhwa; Xing, Baoshan

    2017-04-01

    Fungicides have extensively been used to effectively combat fungal diseases on a range of plant species, but resistance to multiple active ingredients has developed in pathogens such as Sclerotinia homoeocarpa, the causal agent of dollar spot on cool-season turfgrasses. Recently, ZnO and Ag nanoparticles (NPs) have received increased attention due to their antimicrobial activities. In this study, the NPs’ toxicity and mechanisms of action were investigated as alternative antifungal agents against S. homoeocarpa isolates that varied in their resistance to demethylation inhibitor (DMI) fungicides. S. homoeocarpa isolates were treated with ZnO NPs and ZnCl2 (25-400 μg ml-1) and Ag NPs and AgNO3 (5-100 μg ml-1) to test antifungal activity of the NPs and ions. The mycelial growth of S. homoeocarpa isolates regardless of their DMI sensitivity was significantly inhibited on ZnO NPs (≥200 μg ml-1), Ag NPs (≥25 μg ml-1), Zn2+ ions (≥200 μg ml-1), and Ag+ ions (≥10 μg ml-1) amended media. Expression of stress response genes, glutathione S-transferase (Shgst1) and superoxide dismutase 2 (ShSOD2), was significantly induced in the isolates by exposure to the NPs and ions. In addition, a significant increase in the nucleic acid contents of fungal hyphae, which may be due to stress response, was observed upon treatment with Ag NPs using Raman spectroscopy. We further observed that a zinc transporter (Shzrt1) might play an important role in accumulating ZnO and Ag NPs into the cells of S. homoeocarpa due to overexpression of Shzrt1 significantly induced by ZnO or Ag NPs within 3 h of exposure. Yeast mutants complemented with Shzrt1 became more sensitive to ZnO and Ag NPs as well as Zn2+ and Ag+ ions than the control strain and resulted in increased Zn or Ag content after exposure. This is the first report of involvement of the zinc transporter in the accumulation of Zn and Ag from NP exposure in filamentous plant pathogenic fungi. Understanding the molecular

  17. Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

    Science.gov (United States)

    Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

    2016-01-01

    Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

  18. Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO2 NTs

    International Nuclear Information System (INIS)

    Wang Qingyao; Yang Xiuchun; Liu Dan; Zhao Jianfu

    2012-01-01

    Graphical abstract: The TiO 2 NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC–R–S). The –OH group on the surface of TiO 2 NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO 3 solution. After Ag + ions were reduced by NaBH 4 , Ag nanoparticles formed by nucleation and growth. Highlights: ► Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO 2 nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. ► Bi-functional mercaptoacetic acid linkers were used to bind TiO 2 nanotubes with Ag nanoparticles. ► Ag nanoparticles modification of TiO 2 NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO 2 nanotubes (TiO 2 NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO 2 NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO 2 NTs, the vapor-thermally treated TiO 2 NTs and the Ag nanoparticles decorated TiO 2 NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO 2 into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO 2 NTs. Ag nanoparticles are uniformly distributed in the TiO 2 NTs, and the SILAR process does not damage the ordered tubular structure. A possible formation mechanism of Ag/TiO 2 NTs has also been proposed. The

  19. Application of a new coordination compound for the preparation of AgI nanoparticles

    International Nuclear Information System (INIS)

    Mohandes, Fatemeh; Salavati-Niasari, Masoud

    2013-01-01

    Graphical abstract: Silver iodide nanoparticles have been sonochemically synthesized by using silver salicylate complex, [Ag(HSal)], as silver precursor. A series of control experiments were carried out to investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures. - Highlights: • Silver salicylate as a new precursor was applied to fabricate γ-AgI nanoparticles. • To further decrease the particle size of AgI, SDS was used as surfactant. • The effect of preparation parameters on the particle size of AgI was investigated. - Abstract: AgI nanoparticles have been sonochemically synthesized by using silver salicylate, [Ag(HSal)], as silver precursor. To investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures, several experiments were carried out. The products were characterized by SEM, TEM, XRD, TGA/DTA, UV–vis, and FT-IR. Based on the experimental findings in this research, it was found that the size of AgI nanoparticles was dramatically dependent on the silver precursor, sonochemical irradiation, and surfactant concentration. Sodium dodecyl sulfate (SDS) was applied as surfactant. When the concentration of SDS was 0.055 mM, very uniform sphere-like AgI nanoparticles with grain size of about 25–30 nm were obtained. These results indicated that the high concentration of SDS could prevent the aggregation between colloidal nanoparticles due to its steric hindrance effect

  20. Application of a new coordination compound for the preparation of AgI nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mohandes, Fatemeh [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of)

    2013-10-15

    Graphical abstract: Silver iodide nanoparticles have been sonochemically synthesized by using silver salicylate complex, [Ag(HSal)], as silver precursor. A series of control experiments were carried out to investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures. - Highlights: • Silver salicylate as a new precursor was applied to fabricate γ-AgI nanoparticles. • To further decrease the particle size of AgI, SDS was used as surfactant. • The effect of preparation parameters on the particle size of AgI was investigated. - Abstract: AgI nanoparticles have been sonochemically synthesized by using silver salicylate, [Ag(HSal)], as silver precursor. To investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures, several experiments were carried out. The products were characterized by SEM, TEM, XRD, TGA/DTA, UV–vis, and FT-IR. Based on the experimental findings in this research, it was found that the size of AgI nanoparticles was dramatically dependent on the silver precursor, sonochemical irradiation, and surfactant concentration. Sodium dodecyl sulfate (SDS) was applied as surfactant. When the concentration of SDS was 0.055 mM, very uniform sphere-like AgI nanoparticles with grain size of about 25–30 nm were obtained. These results indicated that the high concentration of SDS could prevent the aggregation between colloidal nanoparticles due to its steric hindrance effect.

  1. Synthesis, Antibacterial and Thermal Studies of Cellulose Nanocrystal Stabilized ZnO-Ag Heterostructure Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohd Zobir Hussein

    2013-05-01

    Full Text Available Synthesis of ZnO-Ag heterostructure nanoparticles was carried out by a precipitation method with cellulose nanocrystals (CNCs as a stabilizer for antimicrobial and thermal studies. ZnO-Ag nanoparticles were obtained from various weight percentages of added AgNO3 relative to Zn precursors for evaluating the best composition with enhanced functional properties. The ZnO-Ag/CNCs samples were characterized systematically by TEM, XRD, UV, TGA and DTG. From the TEM studies we observed that ZnO-Ag heterostructure nanoparticles have spherical shapes with size diameters in a 9–35 nm range. The antibacterial activities of samples were assessed against the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The CNC-stabilized ZnO-Ag exhibited greater bactericidal activity compared to cellulose-free ZnO-Ag heterostructure nanoparticles of the same particle size. The incorporation of ZnO-Ag hetreostructure nanoparticles significantly increased the thermal stability of cellulose nanocrystals.

  2. Chitosan/Carboxymethylcellulose/Ionic Liquid/Ag(0) Nanoparticles Form a Membrane with Antimicrobial Activity

    International Nuclear Information System (INIS)

    Quadros, C.; Faria, V.W.; Scheeren, C.W.; Klein, M.P.; Hertz, P.F.

    2013-01-01

    Silver metal nanoparticles were immobilized in chitosan/carboxymethylcellulose/BMI.BF4(1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid) (CS/CMC/IL) to form polymeric membrane with 20 μm thickness. The CS/CMC/IL polymeric membrane was prepared using a simple solution blending method. Irregularly shaped Ag(0) nanoparticles with monomodal size distributions of nm Ag(0) were immobilized in the membrane. The presence of small Ag(0) nanoparticles induced an augmentation in the CS/CMC/IL film surface areas. The CS/CMC/IL membrane containing Ag(0) showed increase antimicrobial activity the Ag(0) concentration increased up to saturation at 10 mg. CS/CMC/IL membrane that contains Ag(0) nanoparticles has enhanced durability of the membrane and exhibited stronger antimicrobial activity against Escherichia coli and Staphylococcus aureus.

  3. Shape-and size-controlled Ag nanoparticles stabilized by in situ generated secondary amines

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Meneses, E., E-mail: esther.ramirez@ibero.mx [Departamento de Ingeniería y Ciencias Químicas, Universidad Iberoamericana, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, Distrito Federal C.P. 01219 (Mexico); Montiel-Palma, V. [Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos C.P. 62209 (Mexico); Domínguez-Crespo, M.A.; Izaguirre-López, M.G. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada-IPN, Unidad Altamira. Km 14.5 Carretera Tampico-Puerto Industrial, 89600 Altamira, Tamaulipas (Mexico); Palacios-Gonzalez, E. [Laboratorio de Microscopia de Ultra alta Resolución, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas No. 152, C.P. 07730 México D.F. (Mexico); Dorantes-Rosales, H. [Departamento de Metalurgia, E.S.I.Q.I.E.-I.P.N., Unidad Profesional Adolfo López Mateos, Zacatenco, Delegación. Gustavo A. Madero, C.P. 07738 México D.F. (Mexico)

    2015-09-15

    Highlights: • Ag nanoparticles were generated from Ag amido complexes AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2}. • Ag nanoparticles were stabilized by in situ generated HN{sup i}Pr{sub 2} or HN(SiMe{sub 3}){sub 2}. • 1 or 5 equiv. of ethylenediamine as additional capping agent decreases the average size of the particles. • Ethylenediamine favor the formation of spherical particles. - Abstract: Silver amides such as AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2} have been employed successfully as precursors for the yield synthesis of silver nanoparticles under mild conditions of dihydrogen gas reduction (2 atm) in organic media. Transmission electron microscopy (TEM) showed the formation of silver nanoparticles with FCC structure, variously sized from 26 to 35 nm for AgN{sup i}Pr{sub 2} and from 14 to 86 nm for AgN(SiMe{sub 3}){sub 2}, the synthesis could take place in absence of added stabilizers due to the in situ formation of secondary amines from the reaction of dihydrogen gas with the amide ligands of the silver precursor. Indeed, the presence of HNR{sub 2} (R = iPr{sub 2}, N(SiMe{sub 3}){sub 2}) on the surface of the nanoparticle was confirmed by spectroscopic means. Finally, the addition of ethylenediamine as additional capping agent allowed not only the control of the structural characteristics of the resulting Ag nanoparticles (well-dispersed with spherical shape), but that regarding the nanoparticle size as it inhibited overgrowth, limiting it to ca. 25 nm.

  4. Strain Distribution of Au and Ag Nanoparticles Embedded in Al2O3 Thin Film

    Directory of Open Access Journals (Sweden)

    Honghua Huang

    2014-01-01

    Full Text Available Au and Ag nanoparticles embedded in amorphous Al2O3 matrix are fabricated by the pulsed laser deposition (PLD method and rapid thermal annealing (RTA technique, which are confirmed by the experimental high-resolution transmission electron microscope (HRTEM results, respectively. The strain distribution of Au and Ag nanoparticles embedded in the Al2O3 matrix is investigated by the finite-element (FE calculations. The simulation results clearly indicate that both the Au and Ag nanoparticles incur compressive strain by the Al2O3 matrix. However, the compressive strain existing on the Au nanoparticle is much weaker than that on the Ag nanoparticle. This phenomenon can be attributed to the reason that Young’s modulus of Au is larger than that of Ag. This different strain distribution of Au and Ag nanoparticles in the same host matrix may have a significant influence on the technological potential applications of the Au-Ag alloy nanoparticles.

  5. Ultraviolet photosensors fabricated with Ag nanowires coated with ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Guan-Hung [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Hong, Franklin Chau-Nan, E-mail: hong@mail.ncku.edu.tw [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan (China); NCKU Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2014-11-03

    We have developed a simple low temperature process to coat zinc oxide (ZnO) nanoparticles (NPs) on Ag nanowires (NWs) with well-controlled morphology. Triethanolamine (TEA) was employed to react with zinc acetate (Zn(CH{sub 3}COO){sub 2}) forming ZnO NPs. TEA was also found to enhance the nucleation and binding of ZnO NPs on the Ag nanowire surfaces facilitating a complete coverage of Ag nanowire surfaces with ZnO NPs. The effects of the process parameters including reaction time and reaction temperature were studied. The surfaces of 60 nm diameter Ag NWs could be completely covered with ZnO NPs with the final diameters of Ag-NWs@ZnO (core–shell NWs) turning into the range from 100 nm to 450 nm. The Ag-NWs@ZnO was characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray mapping analysis, X-ray diffraction, and photoluminescence spectra. Finally, ultraviolet (UV) photosensors were fabricated using Ag-NWs@ZnO. They were found to improve photosensitivity with greatly enhanced fast response by reducing the recovery time by 2 orders, in comparison with the UV-sensors using single-crystalline ZnO NWs. - Highlights: • Solution process to coat ZnO nanoparticles on Ag nanowires has been developed. • Ultraviolet photosensing of ZnO nanoparticles coated on the Ag nanowires was found. • High defect concentration of ZnO nanoparticles enhanced the photosensing properties.

  6. Activated Carbon Fibers "Thickly Overgrown" by Ag Nanohair Through Self-Assembly and Rapid Thermal Annealing

    Science.gov (United States)

    Yan, Xuefeng; Xu, Sijun; Wang, Qiang; Fan, Xuerong

    2017-11-01

    Anisotropic nanomaterial-modified carbon fibers attract increasing attention because of their superior properties over traditional ones. In this study, activated carbon fibers (ACFs) "thickly overgrown" by Ag nanohair were prepared through self-assembly and rapid thermal annealing. Viscose fibers with well-dispersed silver nanoparticles (AgNPs) on surfaces were first prepared through self-assembly of hyperbranched poly(amino-amine) (HBPAA)-capped AgNPs on viscose surfaces. HBPAA endowed the AgNP surfaces with negative charges and abundant amino groups, allowing AgNPs to monodispersively self-assemble to fiber surfaces. Ag nanohair-grown ACFs were prepared by sequential pre-oxidation and carbonization. Because the carbonization furnace was open-ended, ACFs are immediately transferrable to the outside of the furnace. Therefore, the Ag liquid adsorbed by ACF pores squeezed out to form Ag nanowires through thermal contraction. FESEM characterization indicated that Ag nanohairs stood on ACF surface and grew from ACF caps. XPS and XRD characterization showed that Ag successfully assembled to fiber surfaces and retained its metallic state even after high-temperature carbonization. TG analysis suggested that Ag nanohair-grown ACFs maintained their excellent thermal stabilities. Finally, the fabricated ACFs showed excellent and durable antibacterial activities, and the developed method may provide a potential strategy for preparing metal nanowire-grown ACFs.

  7. Facile synthesis of hollow dendritic Ag/Pt alloy nanoparticles for enhanced methanol oxidation efficiency.

    Science.gov (United States)

    Sui, Ning; Wang, Ke; Shan, Xinyao; Bai, Qiang; Wang, Lina; Xiao, Hailian; Liu, Manhong; Colvin, Vicki L; Yu, William W

    2017-11-14

    Hollow dendritic Ag/Pt alloy nanoparticles were synthesized by a double template method: Ag nanoparticles as the hard template to obtain hollow spheres by a galvanic replacement reaction between PtCl 6 2- and metallic Ag and surfactant micelles (Brij58) as the soft template to generate porous dendrites. The formation of a Ag/Pt alloy phase was confirmed by XRD and HRTEM. Elemental mapping and line scanning revealed the formation of the hollow architecture. We studied the effects of the Ag/Pt ratio, surfactant and reaction temperature on the morphology. In addition, we explored the formation process of hollow dendritic Ag/Pt nanoparticles by tracking the morphologies of the nanostructures formed at different stages. In order to improve the electrocatalytic property, we controlled the size of the nanoparticles and the thickness of the shell by adjusting the amount of the precursor. We found that these Ag/Pt alloy nanoparticles exhibited high activity (440 mA mg -1 ) and stability as an electrocatalyst for catalyzing methanol oxidation.

  8. Preparation and self-sterilizing properties of Ag@TiO{sub 2}–styrene–acrylic complex coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiang-dong; Chen, Feng; Yang, Jin-tao, E-mail: yangjt@zjut.edu.cn; Yan, Xiao-hui; Zhong, Ming-qiang, E-mail: zhongmingqiang@hotmail.com

    2013-04-01

    In this study, we report a simple and cost-effective method for self-sterilized complex coatings obtained by Ag@TiO{sub 2} particle incorporation into styrene–acrylic latex. The Ag@TiO{sub 2} particles were prepared via a coupling agent modification process. The composite latices characterized by transmission electron microscopy (TEM) study were highly homogeneous at the nanometric scale, and the Ag@TiO{sub 2} particles were well dispersed and exhibited an intimate contact between both the organic and inorganic components. The Ag@TiO{sub 2} nanoparticles significantly enhanced the absorption in the visible region and engendered a good heat-insulating effect of the complex coatings. Moreover, the Ag@TiO{sub 2} nanoparticle incorporation into this polymer matrix renders self-sterilized nanocomposite materials upon light excitation, which are tested against Escherichia coli and Staphylococcus aureus. The complex coatings display an impressive performance in the killing of all micro-organisms with a maximum for a Ag@TiO{sub 2} loading concentration of 2–5 wt.%. The weathering endurance of the complex coating was also measured. - Highlights: ► We prepared Ag@TiO{sub 2}–styrene–acrylic complex latex in one pot. ► Good antibacterial performances of complex coatings were observed. ► The complex coating was resistant to weathering after 48 h. ► The complex coating exhibits good heat-insulating effect.

  9. Effect of chemically and biologically synthesized Ag nanoparticles on the algae growth inhibition

    Science.gov (United States)

    Anna, Mražiková; Oksana, Velgosová; Jana, Kavuličová

    2017-12-01

    Over the past few years green methods for preparation of silver nanoparticles has become necessary due to its friendly influence on ecosystem. In the present work antimicrobial properties of biologically synthesized silver nanoparticles (Bio-AgNPs) using green algae extract and chemically synthesized silver nanoparticles (Chem-AgNPs) using sodium citrate against algae Parachlorella kessleri is investigated. Both used Bio-AgNPs and Chem-AgNPs exhibit long-term stability as demonstrated by UV-vis spectroscopy measurements. The results revealed stronger toxic effects of Bio-AgNPs on agar plates what was confirmed clear inhibition zone around wells impregnated with Bio-AgNPs. On the other hand Bio-AgNPs were confirmed to be less toxic in aquatic environments for the growths of green algae P. kessleri comparing to Chem-AgNPs.

  10. Self-assembly Ag nanoparticle monolayer film as SERS Substrate for pesticide detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li, E-mail: zhlisuzh@163.com [School of Chemistry and Life Science, Anhui Key Laboratory of Spin Electron and Nanomaterials (Cultivating Base), Suzhou University, SuZhou 234000 (China)

    2013-04-01

    A self-assembled protocol is introduced to provide effective platforms for the fabrication of ordered Ag nanosized monolayer film. The assembled Ag nanosized monolayer film was characterized using scanning electronic microscopy and surface-enhanced Raman scattering (SERS). The results show that the assembled SERS substrate own excellent Raman enhancement and reproducibility. The synthesized SERS-active substrate was further used to detect methyl-parathion, and the limitation of detection can reach 10{sup −7} M.

  11. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng, E-mail: wangfeng@shnu.edu.cn; Yang, Haifeng

    2017-01-15

    Highlights: • AgCl/PDA/AgNPs (polydopamine (PDA) adlayer covered cubic AgCl core inlaid with Ag nanoparticles (AgNPs)) was fabricated for in-situ SERS detection. • Such SERS substrate shows in-situ laser improving Raman scattering effect due to the generation of more AgNPs. • Enhancement factor could reach 10{sup 7}. • Such SERS substrate shows good reproducibility and long term stability. - Abstract: We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 10{sup 7}. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  12. In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles

    Science.gov (United States)

    San-Miguel, Miguel A.; da Silva, Edison Z.; Zannetti, Sonia M.; Cilense, Mario; Fabbro, Maria T.; Gracia, Lourdes; Andrés, Juan; Longo, Elson

    2016-06-01

    Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.

  13. Temperature stability of AgCu nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sopoušek, Jiří, E-mail: sopousek@mail.muni.cz; Zobač, Ondřej; Vykoukal, Vít [Masaryk University, Department of Chemistry, Faculty of Science (Czech Republic); Buršík, Jiří; Roupcová, Pavla [Institute of Physics of Materials ASCR (Czech Republic); Brož, Pavel; Pinkas, Jiří [Masaryk University, Department of Chemistry, Faculty of Science (Czech Republic); Vřešťál, Jan [Masaryk University, Central European Institute of Technology, CEITEC (Czech Republic)

    2015-12-15

    The colloidal solutions of the Ag–Cu nanoparticles (NPs, 10–32 nm) were prepared by solvothermal reactions. The samples of dried AgCu NPs and the resulting microstructures after heat treatment in air were investigated by various methods including electron microscopy (TEM, SEM) and high-temperature X-ray powder diffraction (HTXRD). The AgCu randomly mixed, Cu-rich, and Ag-rich face centred cubic crystal lattices were detected during the experiments. The temperature induced sintering was observed experimentally by HTXRD at 250 °C. The phase transformations at high temperatures were monitored by differential scanning calorimetry. The formation of the Ag-rich grains during heating in air and evolution of copper oxide microstructure were detected.Graphical abstract.

  14. Translocation, accumulation and distribution of 110mAg in carp

    International Nuclear Information System (INIS)

    Li Chuanzhao; Zhao Wenhu; Xu Shiming

    1995-01-01

    The experimental carp were raised in the water with 110m Ag specific activity of 3.7 x 10 2 Bq/L, 3.7 x 10 3 Bq/L, 3.7 x 10 4 Bq/L respectively. The carp were sampled after raising 1,2,3,5,7,9,12,15,18,21 and 23 days, and separated into scale, bone, muscle, gill, alimentary canal, heart and heptapancreas for measuring the radioactivity. The results showed that 110m Ag was absorbed rapidly by carp via gill and alimentary canal from water, and distributed into all parts of the body, mainly in soft tissue with blood circulation. 110m Ag accumulation of the body increased with the 110m Ag specific activity in the water in the same raising time. The accumulation of 110m Ag in gill, alimentary canal, heart, muscle and bone appeared mono-peak curves with raising time. There was a linear relationship between the specific activity of 110m Ag in heptapancreas and the carp's raising time in 110m Ag water. The concentration abilities for 110m Ag in all organs were in the order of heptapancreas>gill>alimentary>canal>heart>muscle>bone

  15. Effect of Ag nanoparticles on resistive switching of polyfluorene-based organic non-volatile memory devices

    International Nuclear Information System (INIS)

    Kim, Tae-Wook; Oh, Seung-Hwan; Choi, Hye-Jung; Wang, Gun-Uk; Kim, Dong-Yu; Hwang, Hyun-Sang; Lee, Tak-Hee

    2010-01-01

    The effects of Ag nanoparticles on the switching behavior of polyfluorene-based organic nonvolatile memory devices were investigated. Polyfluorene-derivatives (WPF-oxy-F) with and without Ag nanoparticles were synthesized, and the presence of Ag nanoparticles in Ag-WPF-oxy-F was identified by transmission electron microscopy and X-ray photoelectron spectroscopy analyses. The Ag-nanoparticles did not significantly affect the basic switching performances, such as the current-voltage characteristics, the distribution of on/off resistance, and the retention. The pulse switching time of Ag-WPF-oxy-F was faster than that of WPF-oxy-F. Ag-WPF-oxy-F memory devices showed an area dependence in the high resistance state, implying that formation of a Ag metallic channel for current conduction.

  16. Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles

    International Nuclear Information System (INIS)

    Whang, Thou-Jen; Hsieh, Mu-Tao; Chen, Huang-Han

    2012-01-01

    The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO 3 relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).

  17. Gamma-irradiation assisted seeded growth of Ag nanoparticles within PVA matrix

    International Nuclear Information System (INIS)

    Eisa, Wael H.; Abdel-Moneam, Yasser K.; Shaaban, Yasser; Abdel-Fattah, Atef A.; Abou Zeid, Amira M.

    2011-01-01

    Highlights: → Nucleation and growth must be two completely separated steps. → The amount of zerovalent nuclei can be controlled by varying the irradiation dose. → PVA act as physical barrier to inhibit aggregation or the growth of Ag nanoparticles. - Abstract: Polyvinyl alcohol (PVA)/Ag hybrid nanocomposites have been prepared from polymeric film of PVA and silver nitrate (AgNO 3 ). The silver nanoparticles were generated in PVA matrix by the reduction of silver ions with gamma-irradiation. UV-visible spectra showed a single peak at 422 nm, arising from the surface plasmon absorption of silver nanoparticles. The shifting of surface plasmon resonance peak after irradiation reveals that the gamma irradiation can be used as a size controlling agent for the preparation of silver nanoparticles embedded in PVA film. This result was in good agreement with the result obtained from TEM images. The TEM images showed the narrow size distribution of the obtained Ag nanoparticles with average particle size of 30 nm, which decreased to 17 nm with increasing irradiation dose. The X-ray diffraction analysis revealed that silver metal was present in face centered cubic (fcc) crystal structure. These results clearly indicate that monodispersed silver nanoparticles are embedded homogenously in PVA matrix.

  18. Photochemical generation of antimicrobial Ag-nanoparticles in intraocular lenses

    Science.gov (United States)

    Badur, Thorben; Kim, Hee-Cheol; Hampp, Norbert

    2017-02-01

    The antimicrobial properties of silver (Ag) nanoparticles (NP) have been investigated in depth during the last decades.[1] For cataract treatment minimal invasive surgery has become state-of-the-art. The physicians are still fighting against postoperative inflammations, such as endophthalmitis.[2] We present a novel approach to reduce these postoperative complications by equipping the hydrophilic intraocular lenses (IOL) with a Ag NP depot. As the Ag NP are completely entrapped inside the polymeric IOL no direct contact of the nanoparticles with epithelial cells may occur. Using 1-hydroxybenzotriazole (HOBt) or 7-hydroxycumarine (7HOCum) as photo reduction mediators (PRM) the formation of the Ag NP is accomplished in situ. PRM and Ag nitrate are diffused into the ready made IOL. By means of two-photon-absorption (TPA) photochemistry at λTPA = 532 nm the Ag NP generation is precisely controlled to occur inside the IOL only. At no point NP are directly exposed to the surface.[3] Interesting dependencies between the used PRM and the resulting particle size distribution or the effectiveness of the silver ion reduction inside the polymer matrix are reported. The Ag NP were prepared in the outer area of the IOL not to affect the optical properties of the ophthalmic implant. The amount of Ag ions released was determined and found to be sufficient to effectively reduce the counts of airborne germs. Besides HOBt and 7HOCum we also investigated the photo reductive properties of several other organic reagents, such as benzophenone (BP) and 4-hydroxybenzophenone (4HOBP) for the ability to produce even three-dimensional nanoparticle structures inside a polymer matrix.

  19. A simple approach for facile synthesis of Ag, anisotropic Au and bimetallic (Ag/Au) nanoparticles using cruciferous vegetable extracts

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Jasmine; Mukherjee, Tulsi; Kapoor, Sudhir, E-mail: sudhirk@barc.gov.in

    2012-10-01

    We present a simple and straightforward approach for the synthesis and stabilization of relatively monodisperse Ag, Au and bimetallic (Ag/Au) nanoparticles by using cruciferous vegetable (green/red) extracts by simply adjusting the pH environment in the aqueous medium. The vegetable extracts act both as reducing and capping agents. The monometallic and bimetallic nanoparticles of Ag and Au so obtained were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM). It is shown that red cabbage extract can be used for the preparation of anisotropic Au nanoparticles. The formation of Au anisotropic nanoparticles was found to depend on a number of environmental factors, such as the pH of the reaction medium, reaction time, and initial reactant concentrations. Additionally, it is shown that these extract-stabilized Au and Ag nanoparticles can be used as a seed for preparation of bimetallic Au/Ag nanoparticles. For bimetallic alloy nanoparticles the absorption peak was observed between the two maxima of the corresponding metallic particles. The surface plasmon absorption maxima for bimetallic nanoparticles changed linearly with increasing Au mole ratio content in various alloy compositions. It has been shown that the formation of hollow Au spheres depends on the experimental conditions. - Graphical abstract: TEM image of gold nanoparticles at pH 3.27 formed by red cabbage extract. Highlights: Black-Right-Pointing-Pointer First report on the reactivity of the extracts toward metal ions using a spectrophotometric technique. Black-Right-Pointing-Pointer Red cabbage extract has better reducing properties than green cabbage extract. Black-Right-Pointing-Pointer Red cabbage extract can reduce metal ions at any pH. Black-Right-Pointing-Pointer Reduction of metal ions can have important consequences in the study of soil chemistry.

  20. A simple approach for facile synthesis of Ag, anisotropic Au and bimetallic (Ag/Au) nanoparticles using cruciferous vegetable extracts

    International Nuclear Information System (INIS)

    Jacob, Jasmine; Mukherjee, Tulsi; Kapoor, Sudhir

    2012-01-01

    We present a simple and straightforward approach for the synthesis and stabilization of relatively monodisperse Ag, Au and bimetallic (Ag/Au) nanoparticles by using cruciferous vegetable (green/red) extracts by simply adjusting the pH environment in the aqueous medium. The vegetable extracts act both as reducing and capping agents. The monometallic and bimetallic nanoparticles of Ag and Au so obtained were characterized by UV–visible spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM). It is shown that red cabbage extract can be used for the preparation of anisotropic Au nanoparticles. The formation of Au anisotropic nanoparticles was found to depend on a number of environmental factors, such as the pH of the reaction medium, reaction time, and initial reactant concentrations. Additionally, it is shown that these extract-stabilized Au and Ag nanoparticles can be used as a seed for preparation of bimetallic Au/Ag nanoparticles. For bimetallic alloy nanoparticles the absorption peak was observed between the two maxima of the corresponding metallic particles. The surface plasmon absorption maxima for bimetallic nanoparticles changed linearly with increasing Au mole ratio content in various alloy compositions. It has been shown that the formation of hollow Au spheres depends on the experimental conditions. - Graphical abstract: TEM image of gold nanoparticles at pH 3.27 formed by red cabbage extract. Highlights: ► First report on the reactivity of the extracts toward metal ions using a spectrophotometric technique. ► Red cabbage extract has better reducing properties than green cabbage extract. ► Red cabbage extract can reduce metal ions at any pH. ► Reduction of metal ions can have important consequences in the study of soil chemistry.

  1. Noble silver nanoparticles (AgNPs) synthesis and characterization ...

    African Journals Online (AJOL)

    Nanotechnology is rapidly growing with nanoparticles produced and utilized in a wide range of pharmaceutical and commercial products throughout the world. In this study, fig (Ficus carica) leaf extracts were used for ecofriendly extracellular synthesis of stable silver nanoparticles (AgNPs) by treating an aqueous silver ...

  2. Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys

    International Nuclear Information System (INIS)

    Alonso, J; Fdez-Gubieda, M L; Sarmiento, G; Chaboy, J; Boada, R; García Prieto, A; Haskel, D; Laguna-Marco, M A; Lang, J C; Meneghini, C; Fernández Barquín, L; Neisius, T; Orue, I

    2012-01-01

    The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe 50 Ag 50 and Fe 55 Ag 45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe 50 Ag 50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L 2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling.

  3. Synergistic effect of Ag nanoparticle-decorated graphene oxide and carbon fiber on electrical actuation of polymeric shape memory nanocomposites

    International Nuclear Information System (INIS)

    Lu, Haibao; Leng, Jinsong; Du, Shanyi; Liang, Fei; Gou, Jihua

    2014-01-01

    This study reports an effective approach of significantly improving electrical properties and recovery performance of shape memory polymer (SMP) nanocomposite, of which its shape recovery was triggered by electrically resistive Joule heating. Reduced graphene oxide (GOs) self-assembled and grafted onto carbon fiber, were used to enhance the interfacial bonding with the SMP matrix via van der Waals force and covalent bond, respectively. A layer of Ag nanoparticles was synthesized from Ag + solution and chemically deposited onto GO assemblies. These Ag nanoparticles were expected to bridge the gap between GO and improve the electrical conductivity. The experimental results reveal that the electrical conductivity of the SMP nanocomposite was significantly improved via the synergistic effect between Ag nanoparticle-decorated GO and carbon fiber. Finally, the electrically induced shape memory effect of the SMP nanocomposite was achieved, and the temperature distribution in the SMP nanocomposites was recorded and monitored. An effective approach was demonstrated to produce the electro-activated SMP nanocomposites and the resistive Joule heating was viable at a low electrical voltage below 10 V. (paper)

  4. Application of the specific thermal properties of Ag nanoparticles to high-resolution metal patterning

    International Nuclear Information System (INIS)

    Son, Yong; Yeo, Junyeob; Ha, Cheol Woo; Lee, Jinhwan; Hong, Sukjoon; Nam, Koo Hyun; Yang, Dong-Yol; Ko, Seung Hwan

    2012-01-01

    Metal nanoparticles exhibit specific electronic, chemical and optical properties due to the thermodynamic size effect, which cannot be observed in bulk materials. Ag NPs show size dependent melting temperature depression phenomena. In this study, the thermal sintering behavior of the self-assembled monolayer protected Ag NPs has been observed using in situ transmission electron microscopy. The thermal characteristics of the Ag NPs have also been examined with a thermogravimetric analysis, a differential scanning calorimetry and a thermal conductivity measurement. These assessments have shown that the melting of the Ag NPs starts at 150 °C, which is much lower than the melting temperature of bulk silver (960 °C). The measured thermal conductivity of the Ag NPs (0.37 W/(m K)) is also lower than that of bulk silver (429 W/(m K)). These specific thermal properties of the Ag NPs can be applied to a low-temperature and a high-resolution direct-metal patterning process.

  5. Ag Nanoparticle-Based Triboelectric Nanogenerator To Scavenge Wind Energy for a Self-Charging Power Unit.

    Science.gov (United States)

    Jiang, Qiang; Chen, Bo; Zhang, Kewei; Yang, Ya

    2017-12-20

    Li-ion batteries are a green energy storage technology with advantages of high energy density, long lifetime, and sustainability, but they cannot generate electric energy by themselves. As a novel energy-harvesting technology, triboelectric nanogenerators (TENGs) are a promising power source for supplying electronic devices, however it is difficult to directly use their high output voltage and low output current. Here, we designed a Ag nanoparticle-based TENG for scavenging wind energy. After including a transformer and a power management circuit into the system, constant output voltages such as 3.6 V and a pulsed current of about 100 mA can be obtained, which can be used to directly light up a light-emitting diode. Furthermore, the produced electric energy can be effectively stored in a WO 3 /LiMn 2 O 4 electrode based Li-ion battery. Our present work provides a new approach to effectively scavenge wind energy and store the obtained electric energy, which is significant for exploring self-charging power units.

  6. Ablation and optical third-order nonlinearities in Ag nanoparticles

    Directory of Open Access Journals (Sweden)

    Carlos Torres-Torres

    2010-11-01

    Full Text Available Carlos Torres-Torres1, Néstor Peréa-López2, Jorge Alejandro Reyes-Esqueda3, Luis Rodríguez-Fernández3, Alejandro Crespo-Sosa3, Juan Carlos Cheang-Wong3, Alicia Oliver31Section of Graduate Studies and Research, School of Mechanical and Electrical Engineering, National Polytechnic Institute, Zacatenco, Distrito Federal, Mexico; 2Laboratory for Nanoscience and Nanotechnology Research and Advanced Materials Department, IPICYT, Camino a la Presa San Jose, San Luis Potosi, Mexico; 3Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, México, D.F. 01000, MéxicoAbstract: The optical damage associated with high intensity laser excitation of silver nanoparticles (NPs was studied. In order to investigate the mechanisms of optical nonlinearity of a nanocomposite and their relation with its ablation threshold, a high-purity silica sample implanted with Ag ions was exposed to different nanosecond and picosecond laser irradiations. The magnitude and sign of picosecond refractive and absorptive nonlinearities were measured near and far from the surface plasmon resonance (SPR of the Ag NPs with a self-diffraction technique. Saturable optical absorption and electronic polarization related to self-focusing were identified. Linear absorption is the main process involved in nanosecond laser ablation, but nonlinearities are important for ultrashort picosecond pulses when the absorptive process become significantly dependent on the irradiance. We estimated that near the resonance, picosecond intraband transitions allow an expanded distribution of energy among the NPs, in comparison to the energy distribution resulting in a case of far from resonance, when the most important absorption takes place in silica. We measured important differences in the ablation threshold and we estimated that the high selectiveness of the SPR of Ag NPs as well as their corresponding optical nonlinearities can be strongly significant for laser

  7. Fabrication, characterization and photocatalytic properties of Ag nanoparticles modified TiO{sub 2} NTs

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qingyao [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Yang Xiuchun, E-mail: yangxc@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Liu Dan; Zhao Jianfu [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)

    2012-06-25

    Graphical abstract: The TiO{sub 2} NTs were first treated with bi-functional mercaptoacetic acid linkers (HOOC-R-S). The -OH group on the surface of TiO{sub 2} NT provides a strong affinity with the carboxylate group in the linker molecules. The thiol functional group in the linker molecules facilitates the binding with Ag from AgNO{sub 3} solution. After Ag{sup +} ions were reduced by NaBH{sub 4}, Ag nanoparticles formed by nucleation and growth. Highlights: Black-Right-Pointing-Pointer Ag nanoparticles with an average diameter of 9.2 nm were filled in the TiO{sub 2} nanotubes by a successive ionic layer adsorption and reaction (SILAR) technique. Black-Right-Pointing-Pointer Bi-functional mercaptoacetic acid linkers were used to bind TiO{sub 2} nanotubes with Ag nanoparticles. Black-Right-Pointing-Pointer Ag nanoparticles modification of TiO{sub 2} NTs largely enhanced the photocatalytic degradation of methyl orange under ultraviolet light irradiation. - Abstract: Ordered anatase TiO{sub 2} nanotubes (TiO{sub 2} NTs) on Ti substrate were synthesized by electrochemical anodization and subsequently vapor-thermal treatment. Ag nanoparticles were decorated on TiO{sub 2} NTs by successive ionic layer adsorption and reaction (SILAR) technique. Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for the characterization of surface morphology, phase composition, and microstructure of the original TiO{sub 2} NTs, the vapor-thermally treated TiO{sub 2} NTs and the Ag nanoparticles decorated TiO{sub 2} NTs. The results indicate that vapor-thermal treatment favors to the transformation of amorphous TiO{sub 2} into anatase phase. Increasing the SILAR cycle times favors to increase the loaded amounts of Ag nanoparticles in TiO{sub 2} NTs. Ag nanoparticles are uniformly distributed in the TiO{sub 2} NTs, and

  8. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    Science.gov (United States)

    Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

    2017-06-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

  9. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    International Nuclear Information System (INIS)

    Gloria, E. Campillo; Ederley, Vélez; César, Hincapié; Gladis, Morales; Jaime, Osorio; Oscar, Arnache; José, Ignacio Uribe; Franklin, Jaramillo

    2017-01-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO 3 ) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) – Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV–visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λ max ∼ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated. (paper)

  10. Synthesis and extracellular accumulation of silver nanoparticles by employing radiation-resistant Deinococcus radiodurans, their characterization, and determination of bioactivity

    Directory of Open Access Journals (Sweden)

    Kulkarni RR

    2015-01-01

    Full Text Available Rasika R Kulkarni, Nayana S Shaiwale, Dileep N Deobagkar, Deepti D Deobagkar Molecular Biology Research Laboratory, Center of Advanced Studies, Department of Zoology, University of Pune, Pune, India Abstract: There has been rapid progress in exploring microorganisms for green synthesis of nanoparticles since microbes show extraordinary diversity in terms of species richness and niche localization. Microorganisms are easy to culture using relatively inexpensive and simple nutrients under varied conditions of temperature, pressure, pH, etc. In this work, Deinococcus radiodurans that possesses the ability to withstand extremely high radiation and desiccation stress has been employed for the synthesis of silver nanoparticles (AgNPs. D. radiodurans was able to accumulate AgNPs in medium under various conditions, and process optimization was carried out with respect to time, temperature, pH, and concentration of silver salt. AgNPs were characterized using UV/vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The microbially synthesized AgNPs exhibited good antimicrobial activity against both Gram-negative and Gram-positive organisms and anti-biofouling activity. Their ability to inhibit growth and proliferation of cancer cell line was also examined, and it could be seen that AgNPs synthesized using D. radiodurans exhibited excellent anticancer activity. Keywords: Deinococcus radiodurans, silver nanoparticles, anticancer, radiation resistance, antibacterial, anti-biofouling 

  11. Photoinduced formation of Ag nanoparticles on the surface of As2S3/Ag thin bilayer

    International Nuclear Information System (INIS)

    Binu, S; Khan, Pritam; Barik, A R; Sharma, Rituraj; Adarsh, K V; Golovchak, R; Jain, H

    2014-01-01

    In this article, we demonstrate the combined effect of photodoping and photoinduced-surface deposition in a bilayer of chalcogenide glass (ChG) and Ag as an alternative method to optically synthesize Ag nanoparticles (AgNP) on the surface of ChG. In our experiment, AgNP formation occurs through two distinct stages: In the first stage, Ag is transported through the As 2 S 3 layer as Ag + ions, and in the second stage Ag + ions are photo-deposited as AgNP. The ex situ x-ray photoelectron spectroscopy measurements and AFM observations show photoinduced Ag mass transport and the formation of AgNP. (paper)

  12. Biosynthesis of Ag nanoparticles using pedicellamide and its photocatalytic activity: an eco-friendly approach.

    Science.gov (United States)

    Tamuly, Chandan; Hazarika, Moushumi; Bordoloi, Manobjyoti; Bhattacharyya, Pradip Kr; Kar, Rahul

    2014-11-11

    The synthesis of silver (Ag) nanoparticles using by pedicellamide (A), isolated from Piper pedicellatum C.DC leaf is demonstrated here. TEM analysis revealed that the Ag nanoparticles predominantly form spherical in shape. The compound 'A' act as a reducing, stabilizing and capping agent. The reaction mechanism was established by using density functional theory (DFT). Photocatalytic property of the Ag nanoparticles is investigated by degradation of Methyl Red (MR) dye under UV light. The kinetic, reaction mechanism and rate constant of photocatalytic degradation of MR was evaluated. The results show that Ag nanoparticles have suitable photocatalytic activity for the degradation of MR dye. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Improving g-C3N4 photocatalysis for NOx removal by Ag nanoparticles decoration

    International Nuclear Information System (INIS)

    Sun, Yanjuan; Xiong, Ting; Ni, Zilin; Liu, Jie; Dong, Fan; Zhang, Wei; Ho, Wing-Kei

    2015-01-01

    Graphical abstract: Ag/g-C 3 N 4 nanocomposites were prepared via a facile method for enhanced photocatalytic NO x removal due to surface plasmon resonance of Ag. - Highlights: • The Ag/g-C 3 N 4 nanocomposites were prepared using urea as the precursor. • The Ag/g-C 3 N 4 nanocomposites were applied in removal of NO x in air. • The Ag nanoparticles enhanced the photocatalytic activity of g-C 3 N 4 . • The surface plasmon resonance of Ag played a key role in photocatalysis. - Abstract: In order to overcome the intrinsic drawback of pristine g-C 3 N 4 , we prepared g-C 3 N 4 nanosheets with enhanced photocatalytic performance by Ag nanoparticles decoration using urea as the precursor. It was revealed that the monodispersed Ag nanoparticles were deposited on the surface of g-C 3 N 4 nanosheets. The Ag/g-C 3 N 4 nanocomposites were applied in removal of NO x in air under visible light irradiation. The results showed that the decoration of Ag nanoparticles not only enhanced the photocatalytic activity of g-C 3 N 4 nanosheets, but also benefited the oxidation of NO to final products. The increased visible light absorption arising from the surface plasmon resonance of Ag and improved separation and transfer of photoinduced carriers over Ag/g-C 3 N 4 composites were demonstrated by the UV–vis diffuse reflectance spectra and photoluminescence spectra, respectively. It was therefore proposed that the enhanced photocatalytic activity of Ag/g-C 3 N 4 composites could be attributed to the extended light response range and enhanced charge separation due to the introduction of Ag nanoparticles.

  14. Synthesis of Ag-Cu and Ag-Cu{sub 2}O alloy nanoparticles using a seed-mediated polyol process, thermodynamic and kinetic aspects

    Energy Technology Data Exchange (ETDEWEB)

    Niknafs, Yasaman; Amirjani, Amirmostafa; Marashi, Pirooz, E-mail: pmarashi@aut.ac.ir; Fatmehsari, Davoud Haghshenas

    2017-03-01

    In this paper, Ag, Ag-Cu and Ag-Cu{sub 2}O nanoparticles were synthesized using a modified polyol method. Size, shape and composition of the obtained nanostructures were effectively controlled by adjusting the kinetic and thermodynamic conditions. Response surface methodology was employed to consider the interaction of parameters and to develop a polynomial equation for predicting the size of the silver nanoparticles. The precisely controlled silver nanoaprticles were used as the seeds for the formation of alloyed nanoparticles. By manipulating the involved parameters, both spherical and cubical Ag-Cu and Ag-Cu{sub 2}O nanostructures are obtainable in the size range of 90–100 nm. The morphological, optical and compositional characteristics of the obtained nanostructures were studied using SEM, FE-SEM, UV–Vis, EDS and XRD. - Highlights: • Synthesis of Ag, Ag-Cu and Ag-Cu{sub 2}O alloy nanostructures. • RSM was successfully employed for predicting the size of the AgNPs. • Size and composition tuning by adjusting the kinetic and thermodynamic conditions.

  15. Transparent Conducting Film Fabricated by Metal Mesh Method with Ag and Cu@Ag Mixture Nanoparticle Pastes

    Directory of Open Access Journals (Sweden)

    Hyun Min Nam

    2017-05-01

    Full Text Available Transparent conducting electrode film is highly desirable for application in touch screen panels (TSPs, flexible and wearable displays, sensors, and actuators. A sputtered film of indium tin oxide (ITO shows high transmittance (90% at low sheet resistance (50 Ω/cm2. However, ITO films lack mechanical flexibility, especially under bending stress, and have limitation in application to large-area TSPs (over 15 inches due to the trade-off in high transmittance and low sheet resistance properties. One promising solution is to use metal mesh-type transparent conducting film, especially for touch panel application. In this work, we investigated such inter-related issues as UV imprinting process to make a trench layer pattern, the synthesis of core-shell-type Ag and Cu@Ag composite nanoparticles and their paste formulation, the filling of Ag and Cu@Ag mixture nanoparticle paste to the trench layer, and touch panel fabrication processes.

  16. Facile synthesis of Ag nanoparticles supported on TiO2 inverse opal with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhao Yongxun; Yang Beifang; Xu Jiao; Fu Zhengping; Wu Min; Li Feng

    2012-01-01

    TiO 2 inverse opal films loaded with silver nanoparticles (ATIO) were synthesized on glass substrates. TiO 2 inverse opal (TIO) films were prepared via a sol–gel process using self-assembly of SiO 2 colloidal crystal template and a facile wet chemical route featuring an AgNO 3 precursor solution to fabricate silver nanoparticles on the TIO films. The inverse opal structure and Ag deposition physically and chemically modify titania, respectively. The catalysts were characterized by Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), UV–vis absorption spectra, X-ray photoelectron spectroscopy and photoluminescence spectroscopy. The HRTEM results show that Ag nanoparticles measuring 5–10 nm were evenly distributed on TIO. Both the UV- and visible-light photocatalytic activities of the samples were evaluated by analyzing the degradation of methylene blue (MB) in aqueous solution. The results reveal that the apparent reaction rate constant (k app ) of MB degradation of the sample ATIO under UV-light irradiation is approximately 1.5 times that of the conventional Ag-loaded TiO 2 film (ATF) without an ordered porous structure at an AgNO 3 concentration of 5 mM in the precursor solution. At an AgNO 3 concentration of 10 mM, the sample exhibits a k app value approximately 4.2 times that of ATF under visible-light irradiation. This enhanced visible-light photocatalytic performance can be attributed to the synergistic effect of optimized Ag nanoparticle deposition and an ordered macroporous TIO structure. Repeated cycling tests revealed that the samples showed stable photocatalytic activity, even after six repeated cycles. - Highlights: ►TiO 2 inverse opal films loaded with silver nanoparticles were synthesized. ►Physical and chemical modifications of TiO 2 were achieved simultaneously. ►The catalysts exhibited enhanced visible-light photocatalytic activity. ►The mechanism for enhanced

  17. Polypropylene fibers modified by plasma treatment for preparation of Ag nanoparticles.

    Science.gov (United States)

    Tseng, Chun-Hao; Wang, Cheng-Chien; Chen, Chuh-Yung

    2006-03-09

    A novel method for preparing poly(propylene-graft-2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester)-silver fibers (PPG-IAg fibers) by plasma-induced grafting polymerization is presented in this study. The chelating groups, -N(CH2COO-)2 (GMA-IDA), on the surface of the PPG-I fibers are the coordination sites for chelating silver ions. At these sites, Ag nanoparticles were grown first by reduction with UV light with a wavelength of 366 nm, and second, through immersion in a 24% formaldehyde solution with pH values set variously at 2, 5, 8, and 11. The characteristics of the PPG-I fibers with differing durations of plasma treatment were monitored by using a Fourier transform infrared (FT-IR) spectroscope. Scanning electronic microscopy (SEM) and elemental analysis show that the percentage of GMA-IDA grafted onto PP fiber reaches a maximum when the plasma treatment time is 3 min. Plasma treatment time beyond a certain length of time results in an abundance of free radicals and causes considerable cross-linking on the fiber surface which thus decreases the extent of grafting. Moreover, the crystalline phase of Ag nanoparticles is identified by using X-ray diffraction (XRD). When the PPG-I fibers are reduced by the UV light method, SEM and TEM microscopes reveal that the size of the Ag nanoparticles on the fiber surface decreases significantly with the increase of pH values in aqueous solutions. Notably, in the reduction of formaldehyde solution, the particle size of Ag nanoparticles reaches a minimum at the lowest pH value. The TEM observations show that Ag nanoparticles are distributed both in the exterior and interior of the grafting layer. In addition, under high pH values the distribution of the Ag nanoparticles permeate more deeply in the GMA-IDA grafting layer due to the swelling effect of the GMA-IDA polymer.

  18. DNA intercalation studies and antimicrobial activity of Ag@ZrO2 core–shell nanoparticles in vitro

    International Nuclear Information System (INIS)

    Dhanalekshmi, K.I.; Meena, K.S.

    2016-01-01

    Ag@ZrO 2 core–shell nanoparticles were prepared by one pot simultaneous reduction of AgNO 3 and hydrolysis of zirconium (IV) isopropoxide. The formation of core–shell nanoparticles was confirmed by absorption, XRD, and HR-TEM techniques. The antibacterial activity of Ag@ZrO 2 core–shell nanoparticles against Escherichia coli and Staphylococcus aureus and the antifungal properties against Candida albicans, Candida glabrata, Aspergillus niger and Aspergillus flavus were examined by the agar diffusion method. DNA intercalation studies were carried out in CT-DNA. As a result ZrO 2 supported on the surface of AgNPs not only prevented aggregation, but also proved to have enhanced antimicrobial activity and DNA intercalation than the Ag nanoparticles. - Highlights: • Ag@ZrO 2 core–shell nanoparticles were prepared by one pot synthesis. • The ZrO 2 coated AgNPs prevent aggregation and enhanced stability. • The surfaced modified AgNPs showed higher antimicrobial activity. • DNA intercalation studies show better binding affinity of core–shell NPs.

  19. Spectroscopic exploration of interaction between PEG-functionalized Ag2S nanoparticles with bovine serum albumin

    Science.gov (United States)

    Prasanth, S.; RitheshRaj, D.; Vineeshkumar, T. V.; Sudarsanakumar, C.

    2018-05-01

    The introduction of nanoparticles into biological fluids often leads to the formation of biocorona over the surface of nanoparticles. For the effective use of nanoparticles in biological applications it is very essential to understand their interactions with proteins. Herein, we investigated the interactions of Poly ethylene glycol capped Ag2S nanoparticles with Bovine Serum Albumin by spectroscopic techniques. By the addition of Ag2S nanoparticles, a ground state complex is formed. The CD spectroscopy reveals that the secondary structure of BSA is altered by complexation with PEG-Ag2S nanoparticles, while the overall tertiary structure remains closer to that of native BSA.

  20. Inbuilt potential of YEM medium and its constituents to generate Ag/Ag₂O nanoparticles.

    Directory of Open Access Journals (Sweden)

    G Yamal

    Full Text Available We discovered that Yeast Extract Mannitol (YEM medium possessed immense potential to generate silver nanoparticles from AgNO3 upon autoclaving, which was evident from (i alteration in color of the medium; (ii peak at ∼410 nm in UV-Vis spectrum due to surface plasmon resonance specific to silver nanoparticles; and (iii TEM investigations. TEM coupled with EDX confirmed that distinct nanoparticles were composed of silver. Yeast extract and mannitol were key components of YEM medium responsible for the formation of nanoparticles. PXRD analysis indicated crystalline geometry and Ag/Ag2O phases in nanoparticles generated with YEM medium, yeast extract and mannitol. Our investigations also revealed that both mannitol and yeast extract possessed potential to convert ∼80% of silver ions in 0.5 mM AgNO3 to nanoparticles, on autoclaving for 30 min at 121°C under a pressure of 1.06 kg/cm(2. Addition of filter sterilized AgNO3 under ambient conditions to pre-autoclaved YEM medium and yeast extract brought about color change due to the formation of silver nanoparticles, but required prolonged duration. In general, even after 72 h intensity of color was significantly less than that recorded following autoclaving. Silver nanoparticles formed at room temperature were more heterogeneous compared to that obtained upon autoclaving. In summary, our findings demonstrated that (i YEM medium and its constituents promote synthesis of silver nanoparticles; and (ii autoclaving enhances rapid synthesis of silver nanoparticles by YEM medium, yeast extract and mannitol.

  1. Large-scale synthesis of Ni-Ag core-shell nanoparticles with magnetic, optical and anti-oxidation properties

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chung-Che; Chen, Dong-Hwang [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Taiwan (China)

    2006-07-14

    The large-scale synthesis and characterization of Ni-core/Ag-shell (Ni at Ag) nanoparticles by the successive hydrazine reduction of nickel chloride and silver nitrate in ethylene glycol using polyethyleneimine (PEI) as a protective agent are described. The resultant Ni at Ag nanoparticles had a mean core diameter of 6.2 nm and a shell thickness of 0.85 nm, without significant change in the nickel concentration of 0.25-25 mM for the Ag coating. Also, both Ni cores and Ag nanoshells had an fcc structure and PEI was capped on the particle surface. X-ray photoelectron spectroscopy analysis confirmed that the Ni cores were fully covered by Ag nanoshells. In addition, the Ni at Ag nanoparticles exhibited a characteristic absorption band at 430 nm and were nearly superparamagnetic. Based on the weight of Ni cores, the saturation magnetization (M{sub s}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were obtained as 17.2 emu g{sup -1}, 4.0 emu g{sup -1} and 81 Oe, respectively. Furthermore, the resultant Ni at Ag nanoparticles exhibited better anti-oxidation properties than Ni nanoparticles did due to the protection of the Ag nanoshells.

  2. The effect of soil properties on the toxicity and bioaccumulation of Ag nanoparticles and Ag ions in Enchytraeus crypticus

    NARCIS (Netherlands)

    Topuz, Emel; van Gestel, Cornelis A.M.

    2017-01-01

    Standard natural Lufa soils (2.2, 2.3 and 5 M) with different organic carbon contents (0.67–1.61%) and pHCaCl2 (5.5–7.3) were spiked with ionic Ag (AgNO3) and polyvinyl pyrrolidone (AgNP-PVP) and citrate (AgNP-Cit) coated Ag nanoparticles (NPs). Enchytraeus crypticus were exposed for 21 days to

  3. Novel method for the preparation of core-shell nanoparticles with movable Ag core and polystyrene loop shell

    International Nuclear Information System (INIS)

    Liu Weijun; Zhang Zhicheng; He Weidong; Zheng Cheng; Ge Xuewu; Li, Jian; Liu Huarong; Jiang Hao

    2006-01-01

    Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag at PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: γ-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under γ-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe 2+ -EDTA-SFS) as the redox initiation pair. The resulted Ag at PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)

  4. Different growth regimes in InP nanowire growth mediated by Ag nanoparticles.

    Science.gov (United States)

    Oliveira, D S; Zavarize, M; Tizei, L H G; Walls, M; Ospina, C A; Iikawa, F; Ugarte, D; Cotta, M A

    2017-12-15

    We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

  5. Uptake, Accumulation and Toxicity of Silver Nanoparticle in Autotrophic Plants, and Heterotrophic Microbes: A Concentric Review

    Science.gov (United States)

    Tripathi, Durgesh K.; Tripathi, Ashutosh; Shweta; Singh, Swati; Singh, Yashwant; Vishwakarma, Kanchan; Yadav, Gaurav; Sharma, Shivesh; Singh, Vivek K.; Mishra, Rohit K.; Upadhyay, R. G.; Dubey, Nawal K.; Lee, Yonghoon; Chauhan, Devendra K.

    2017-01-01

    Nanotechnology is a cutting-edge field of science with the potential to revolutionize today’s technological advances including industrial applications. It is being utilized for the welfare of mankind; but at the same time, the unprecedented use and uncontrolled release of nanomaterials into the environment poses enormous threat to living organisms. Silver nanoparticles (AgNPs) are used in several industries and its continuous release may hamper many physiological and biochemical processes in the living organisms including autotrophs and heterotrophs. The present review gives a concentric know-how of the effects of AgNPs on the lower and higher autotrophic plants as well as on heterotrophic microbes so as to have better understanding of the differences in effects among these two groups. It also focuses on the mechanism of uptake, translocation, accumulation in the plants and microbes, and resulting toxicity as well as tolerance mechanisms by which these microorganisms are able to survive and reduce the effects of AgNPs. This review differentiates the impact of silver nanoparticles at various levels between autotrophs and heterotrophs and signifies the prevailing tolerance mechanisms. With this background, a comprehensive idea can be made with respect to the influence of AgNPs on lower and higher autotrophic plants together with heterotrophic microbes and new insights can be generated for the researchers to understand the toxicity and tolerance mechanisms of AgNPs in plants and microbes. PMID:28184215

  6. Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures

    Science.gov (United States)

    Liu, Ruoyu; Hu, Peiguang; Chen, Shaowei

    2012-10-01

    Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.

  7. W18O49 nanorods decorated with Ag/AgCl nanoparticles as highly-sensitive gas-sensing material and visible-light-driven photocatalyst

    International Nuclear Information System (INIS)

    Sun Shibin; Chang Xueting; Dong Lihua; Zhang Yidong; Li Zhenjiang; Qiu Yanyan

    2011-01-01

    A novel gas-sensing material and photocatalyst was successfully obtained by decorating Ag/AgCl nanoparticles on the W 18 O 49 nanorods through a clean photochemical route. The as-prepared samples were characterized using combined techniques of X-ray diffractometry, electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. Gas-sensing measurements indicate that the Ag/AgCl/W 18 O 49 NRs sensors exhibit superior reducing gas-sensing properties to those of bare W 18 O 49 NRs, and they are highly selective and sensitive to NH 3 , acetone, and H 2 S with short response and recovery times. The Ag/AgCl/W 18 O 49 NRs photocatlysts also possess higher photocatalytic performance than bare W 18 O 49 NRs for degradation of methyl orange under simulated sunlight irradiation. Possible mechanisms concerning the enhancement of gas-sensing and photocatalytic activities of the Ag/AgCl/W 18 O 49 NRs composite were proposed. - Graphical Abstract: The Ag/AgCl nanoparticles adhered well to the W 18 O 49 nanorod. The Ag could act as transfer center of the photoexcited carriers, prohibiting their recombinations in both W 18 O 49 and AgCl. Highlights: → Ag/AgCl/W 18 O 49 NRs were successfully obtained via a clean photochemical route. → The Ag/AgCl nanoparticles decorated on the W 18 O 49 NRs possessed cladding structure. → The Ag/AgCl/W 18 O 49 NRs exhibited excellent gas-sensing and photocatalytic properties.

  8. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications.

    Science.gov (United States)

    Dong, Wenjun; Huang, Huandi; Zhu, Yanjun; Li, Xiaoyun; Wang, Xuebin; Li, Chaorong; Chen, Benyong; Wang, Ge; Shi, Zhan

    2012-10-26

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide-amine intermediate and Ag(+) at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO(3) nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag-MoO(3) nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature.

  9. Gamma radiation effects on nano composites of Ag nanoparticles in Zn O matrices

    International Nuclear Information System (INIS)

    Villasenor C, L. S.

    2015-01-01

    The study of gamma radiation effects in nano composites of silver nanoparticles in a Zn O matrix has been performed in this work. First, silver nanoparticles (AgNPs) were synthesized by colloidal methods, with two different mean average sizes, 48 nm and 24 nm respectively. These nanoparticles were characterized by transmission electron microscopy (Tem) and UV-Vis spectroscopy (UV-Vis). Then, with the synthesized AgNPs, nano composites in a matrix of Zn O were prepared. The first nano composite was prepared with the 48 nm AgNPs at 9.5 weight % of silver (Ag) and the second nano composite with the 24 nm nanoparticles at 1.0 weight % of Ag. Both nano composites were analyzed by scanning electron microscopy (Sem). The formation of the Zn O phase in the nano composite was corroborated through X-ray diffraction analysis. It was observed that the presence of AgNPs during the formation of the AgNPs/Zn O nano composite modified the size and morphology of the structures obtained compared to those of the pure Zn O without nanoparticles, however both exhibit a radial structure. Then, the nano composite at 9.5 weight % of Ag was irradiated with gamma rays at doses of 1, 20 and 50 kGy. Samples were analyzed by Sem and the Bet technique, before and after being irradiated, in order to determine the effect of gamma radiation in the morphology, porosity and surface area of the studied material. Even when there are changes in porosity and Surface area, this difference is not very significant for some applications, however it will have to be considered during the design of a specific application of the nano composites. On the other hand, no morphology modifications were identified on the samples irradiated at the studied doses, with the electron microscopy techniques used. (Author)

  10. Synthesis, characterization, and 3D-FDTD simulation of Ag@SiO2 nanoparticles for shell-isolated nanoparticle-enhanced Raman spectroscopy.

    Science.gov (United States)

    Uzayisenga, Viviane; Lin, Xiao-Dong; Li, Li-Mei; Anema, Jason R; Yang, Zhi-Lin; Huang, Yi-Fan; Lin, Hai-Xin; Li, Song-Bo; Li, Jian-Feng; Tian, Zhong-Qun

    2012-06-19

    Au-seed Ag-growth nanoparticles of controllable diameter (50-100 nm), and having an ultrathin SiO(2) shell of controllable thickness (2-3 nm), were prepared for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Their morphological, optical, and material properties were characterized; and their potential for use as a versatile Raman signal amplifier was investigated experimentally using pyridine as a probe molecule and theoretically by the three-dimensional finite-difference time-domain (3D-FDTD) method. We show that a SiO(2) shell as thin as 2 nm can be synthesized pinhole-free on the Ag surface of a nanoparticle, which then becomes the core. The dielectric SiO(2) shell serves to isolate the Raman-signal enhancing core and prevent it from interfering with the system under study. The SiO(2) shell also hinders oxidation of the Ag surface and nanoparticle aggregation. It significantly improves the stability and reproducibility of surface-enhanced Raman scattering (SERS) signal intensity, which is essential for SERS applications. Our 3D-FDTD simulations show that Ag-core SHINERS nanoparticles yield at least 2 orders of magnitude greater enhancement than Au-core ones when excited with green light on a smooth Ag surface, and thus add to the versatility of our SHINERS method.

  11. DNA intercalation studies and antimicrobial activity of Ag@ZrO{sub 2} core–shell nanoparticles in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Dhanalekshmi, K.I., E-mail: dhanamveni88@gmail.com; Meena, K.S.

    2016-02-01

    Ag@ZrO{sub 2} core–shell nanoparticles were prepared by one pot simultaneous reduction of AgNO{sub 3} and hydrolysis of zirconium (IV) isopropoxide. The formation of core–shell nanoparticles was confirmed by absorption, XRD, and HR-TEM techniques. The antibacterial activity of Ag@ZrO{sub 2} core–shell nanoparticles against Escherichia coli and Staphylococcus aureus and the antifungal properties against Candida albicans, Candida glabrata, Aspergillus niger and Aspergillus flavus were examined by the agar diffusion method. DNA intercalation studies were carried out in CT-DNA. As a result ZrO{sub 2} supported on the surface of AgNPs not only prevented aggregation, but also proved to have enhanced antimicrobial activity and DNA intercalation than the Ag nanoparticles. - Highlights: • Ag@ZrO{sub 2} core–shell nanoparticles were prepared by one pot synthesis. • The ZrO{sub 2} coated AgNPs prevent aggregation and enhanced stability. • The surfaced modified AgNPs showed higher antimicrobial activity. • DNA intercalation studies show better binding affinity of core–shell NPs.

  12. Pt@Ag and Pd@Ag core/shell nanoparticles for catalytic degradation of Congo red in aqueous solution

    Science.gov (United States)

    Salem, Mohamed A.; Bakr, Eman A.; El-Attar, Heba G.

    2018-01-01

    Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17 nm for Pt@Ag and 8.8 nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH4) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes.

  13. [Ag25(SR)18]¯: The ‘Golden’ Silver Nanoparticle

    KAUST Repository

    Joshi, Chakra Prasad

    2015-08-31

    Silver nanoparticles with an atomically precise molecular formula [Ag25(SR)18]¯ (‒SR: thiolate) are synthesized and their single-crystal structure is determined. This synthesized nanocluster is the only silver nanoparticle that has a virtually identical analogue in gold, i.e., [Au25(SR)18]¯, in terms of number of metal atoms, ligand count, super-atom electronic configuration, and atomic arrangement. Furthermore, both [Ag25(SR)18]¯ and its gold analogue share a number of features in their optical absorption spectra. This unprecedented molecular synthesis in silver to mimic gold offers the first model nanoparticle platform to investigate the centuries-old problem of understanding the fundamental differences between silver and gold in terms of nobility, catalytic activity, and optical property.

  14. [Ag25(SR)18]¯: The ‘Golden’ Silver Nanoparticle

    KAUST Repository

    Joshi, Chakra Prasad; Bootharaju, Megalamane Siddaramappa; Alhilaly, Mohammad J.; Bakr, Osman

    2015-01-01

    Silver nanoparticles with an atomically precise molecular formula [Ag25(SR)18]¯ (‒SR: thiolate) are synthesized and their single-crystal structure is determined. This synthesized nanocluster is the only silver nanoparticle that has a virtually identical analogue in gold, i.e., [Au25(SR)18]¯, in terms of number of metal atoms, ligand count, super-atom electronic configuration, and atomic arrangement. Furthermore, both [Ag25(SR)18]¯ and its gold analogue share a number of features in their optical absorption spectra. This unprecedented molecular synthesis in silver to mimic gold offers the first model nanoparticle platform to investigate the centuries-old problem of understanding the fundamental differences between silver and gold in terms of nobility, catalytic activity, and optical property.

  15. Characterization and electrocatalytic properties of sonochemical synthesized PdAg nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Godinez-Garcia, Andres, E-mail: agodinez@qro.cinvestav.mx [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Perez-Robles, Juan Francisco [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Martinez-Tejada, Hader Vladimir [Grupo de Energia y Termodinamica, Universidad Pontificia Bolivariana, Medellin, Antioquia C.P. 050031 (Colombia); Solorza-Feria, Omar [Depto. Quimica, CINVESTAV-IPN, Av. IPN 2508, A. P. 14-740, 07360 D.F. Mexico (Mexico)

    2012-06-15

    High intensity ultrasound was used in the synthesis of PdAg nanoparticles. PdAg nanoparticles were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). Catalytic properties for oxygen reduction reaction (ORR) were determined by electrochemical techniques of cyclic voltammetry (CV) and thin-film rotating disk electrode (TF-RDE). Finally the electrocatalyst was tested as a cathode in a single polymer electrolyte membrane fuel cell (PEMFC). Sonochemical synthesis (SS) decreased the overpotential required for the ORR and increased the double-layer capacitance (DLC) respect to the sodium borohydride reduction method due to a better distribution on vulcan carbon support. The electrocatalytic activity of the nanometric bimetallic electrocatalyst for the ORR in acid media showed a favorable multielectron charge transfer process (n = 4e{sup -}) to water formation. The performance of the membrane electrode assembly (MEA) prepared with dispersed PdAg/C as a cathode catalyst in a single PEMFC is lower in comparison to platinum. - Highlights: Black-Right-Pointing-Pointer Sonochemical synthesized PdAg nanoparticles supported on carbon were produced. Black-Right-Pointing-Pointer The material showed catalytic properties for the oxygen reduction reaction (ORR). Black-Right-Pointing-Pointer The ORR favored the pathway to water formation.

  16. Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 solar cells

    International Nuclear Information System (INIS)

    Yin, Guanchao; Steigert, Alexander; Andrae, Patrick; Goebelt, Manuela; Latzel, Michael; Manley, Phillip; Lauermann, Iver; Christiansen, Silke; Schmid, Martina

    2015-01-01

    Graphical abstract: Plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells are investigated. Ag diffusion is successfully passivated by reducing the substrate temperature and introducing a 50 nm atomic layer deposition (ALD) prepared Al_2O_3 film. This clears the thermal obstacle in incorporating Ag nanoparticles in CIGSe solar cells. Simulations show that Ag nanoparticles have the potential to greatly enhance the light absorption in ultra-thin CIGSe solar cells. - Highlights: • Ag nanoparticles are able to diffuse through ITO substrate into CIGSe absorber even at a low substrate temperature of 440 °C. • The direction (inserting a dielectric passivation layer) to thermally block the Ag diffusion and the requirements for the passivation layer are indicated and generalized. • An atomic layer deposited Al_2O_3 layer is experimentally proved to be able to thermally passivate the Ag nanoparticles, which clears the thermal obstacle in using Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. • It is theoretically proved that the Ag nanoparticles as a back reflector have the potential to effectively enhance the absorption in ultra-thin CIGSe solar cells. - Abstract: Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells is investigated. X-ray photoelectron spectroscopy results show that Ag nanoparticles underneath a Sn:In_2O_3 back contact could not be thermally passivated even at a low substrate temperature of 440 °C during CIGSe deposition. It is shown that a 50 nm thick Al_2O_3 film prepared by atomic layer deposition is able to block the diffusion of Ag, clearing the thermal obstacle in utilizing Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. Via 3-D finite element optical simulation, it is proved that the Ag nanoparticles show the potential to contribute the effective absorption in CIGSe solar cells.

  17. Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

    Science.gov (United States)

    Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

    2013-06-21

    A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

  18. Collagen-chitosan scaffold modified with Au and Ag nanoparticles: Synthesis and structure

    International Nuclear Information System (INIS)

    Rubina, M.S.; Kamitov, E.E.; Zubavichus, Ya. V.; Peters, G.S.; Naumkin, A.V.; Suzer, S.; Vasil’kov, A.Yu.

    2016-01-01

    Graphical abstract: - Highlights: • Biocompatible collagen-chitosan scaffolds were modified by Au and Ag nanoparticles via the metal-vapor synthesis. • Structural and morphological parameters of the nanocomposites were assessed using a set of modern instrumental techniques, including electron microscopy, X-ray diffraction, small-angle X-ray scattering, EXAFS, XPS. • Potential application of the nanocomposites are envisaged. - Abstract: Nowadays, the dermal biomimetic scaffolds are widely used in regenerative medicine. Collagen-chitosan scaffold one of these materials possesses antibacterial activity, good compatibility with living tissues and has been already used as a wound-healing material. In this article, collagen-chitosan scaffolds modified with Ag and Au nanoparticles have been synthesized using novel method - the metal-vapor synthesis. The nanocomposite materials are characterized by XPS, TEM, SEM and synchrotron radiation-based X-ray techniques. According to XRD data, the mean size of the nanoparticles (NPs) is 10.5 nm and 20.2 nm in Au-Collagen-Chitosan (Au-CollCh) and Ag-Collagen-Chitosan (Ag-CollCh) scaffolds, respectively in fair agreement with the TEM data. SAXS analysis of the composites reveals an asymmetric size distribution peaked at 10 nm for Au-CollCh and 25 nm for Ag-CollCh indicative of particle's aggregation. According to SEM data, the metal-carrying scaffolds have layered structure and the nanoparticles are rather uniformly distributed on the surface material. XPS data indicate that the metallic nanoparticles are in their unoxidized/neutral states and dominantly stabilized within the chitosan-rich domains.

  19. Collagen-chitosan scaffold modified with Au and Ag nanoparticles: Synthesis and structure

    Energy Technology Data Exchange (ETDEWEB)

    Rubina, M.S.; Kamitov, E.E. [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, 119991 Russian Federation (Russian Federation); Zubavichus, Ya. V.; Peters, G.S. [National Research center «Kurchatov Institute», Moscow, 123182 Russian Federation (Russian Federation); Naumkin, A.V. [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, 119991 Russian Federation (Russian Federation); Suzer, S. [Department of Chemistry, Bilkent University, Ankara, 06800 Turkey (Turkey); Vasil’kov, A.Yu., E-mail: alexandervasilkov@yandex.ru [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow, 119991 Russian Federation (Russian Federation)

    2016-03-15

    Graphical abstract: - Highlights: • Biocompatible collagen-chitosan scaffolds were modified by Au and Ag nanoparticles via the metal-vapor synthesis. • Structural and morphological parameters of the nanocomposites were assessed using a set of modern instrumental techniques, including electron microscopy, X-ray diffraction, small-angle X-ray scattering, EXAFS, XPS. • Potential application of the nanocomposites are envisaged. - Abstract: Nowadays, the dermal biomimetic scaffolds are widely used in regenerative medicine. Collagen-chitosan scaffold one of these materials possesses antibacterial activity, good compatibility with living tissues and has been already used as a wound-healing material. In this article, collagen-chitosan scaffolds modified with Ag and Au nanoparticles have been synthesized using novel method - the metal-vapor synthesis. The nanocomposite materials are characterized by XPS, TEM, SEM and synchrotron radiation-based X-ray techniques. According to XRD data, the mean size of the nanoparticles (NPs) is 10.5 nm and 20.2 nm in Au-Collagen-Chitosan (Au-CollCh) and Ag-Collagen-Chitosan (Ag-CollCh) scaffolds, respectively in fair agreement with the TEM data. SAXS analysis of the composites reveals an asymmetric size distribution peaked at 10 nm for Au-CollCh and 25 nm for Ag-CollCh indicative of particle's aggregation. According to SEM data, the metal-carrying scaffolds have layered structure and the nanoparticles are rather uniformly distributed on the surface material. XPS data indicate that the metallic nanoparticles are in their unoxidized/neutral states and dominantly stabilized within the chitosan-rich domains.

  20. Hydroxyapatite supported Ag3PO4 nanoparticles with higher visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Hong Xiaoting; Wu Xiaohui; Zhang Qiuyun; Xiao Mingfeng; Yang Gelin; Qiu Meirong; Han Guocheng

    2012-01-01

    Hydroxyapatite supported Ag 3 PO 4 nanocomposites have been synthesized by a wet impregnation process. UV-vis absorption spectra show a red shift of the absorption edges for the composite systems compared to pure hydroxyapatite support. The surface structure and morphology of the nanocomposites were characterized by Brunauer-Emmett-Teller (BET) apparatus, X-ray diffraction (XRD), transmission electron microscopy (TEM). The results suggest that Ag 3 PO 4 nanoparticles (6-17 nm in diameter) are well dispersed on the hydroxyapatite support and Ag 3 PO 4 nanoparticles density is larger for the higher Ag + loading sample. The as-prepared nanocomposite photocatalysts showed a pronounced photocatalytic activity upon decomposition of methylene blue dye in aqueous solution under both visible light (wavelength > 400 nm) and UV-vis light irradiation. A synergic mechanism of inherent photocatalytic capability of Ag 3 PO 4 and the accelerated electron/hole separation resulting from the photoinduced electrons captured by the slow-released Ag + at the interface of Ag 3 PO 4 and hydroxyapatite is proposed for the nanocomposites on the enhancement of photocatalytic performance in comparison to that of pure Ag 3 PO 4 nanoparticles. The support of hydroxyapatite may also act as an absorbent which favors the mass transfer in heterogeneous photocatalysis reaction.

  1. In vitro studies on oxidative stress-independent, Ag nanoparticles-induced cell toxicity of Candida albicans, an opportunistic pathogen

    Directory of Open Access Journals (Sweden)

    Radhakrishnan VS

    2018-03-01

    Full Text Available Venkatraman Srinivasan Radhakrishnan,1 Surya Prakash Dwivedi,2 Mohammed Haris Siddiqui,3 Tulika Prasad1 1Advanced Instrumentation Research Facility (AIRF, Jawaharlal Nehru University, New Delhi, 2School of Biotechnology, IFTM University, Moradabad, 3Department of Bioengineering, Integral University, Lucknow, Uttar Pradesh, India Abstract: Silver nanoparticles (AgNps have attracted maximal attention among all metal nanoparticles, and the study of their biological properties has gained impetus for further medical adoption. This study evaluated the cellular and molecular mechanisms associated with the action of AgNps against an opportunistic pathogen, Candida albicans. Spherical, stable AgNp (average size 21.6 nm prepared by a chemical reduction method showed minimum inhibitory concentration (required to inhibit the growth of 90% of organisms at 40 µg/mL. AgNps have been reported to induce oxidative stress-mediated programmed cell death through the accumulation of intracellular reactive oxygen species (ROS. However, this study demonstrated that intracellular levels of AgNp-induced ROS could be reversed by using antioxidant ascorbic acid, but the sensitivity of AgNp-treated Candida cells could not be completely reversed. Moreover, in addition to the generation of ROS, the AgNps were found to affect other cellular targets resulting in altered membrane fluidity, membrane microenvironment, ergosterol content, cellular morphology, and ultrastructure. Thus, the generation of ROS does not seem to be the sole major cause of AgNp-mediated cell toxicity in Candida. Rather, the multitargeted action of AgNps, generation of ROS, alterations in ergosterol content, and membrane fluidity together seem to have potentiated anti-Candida action. Thus, this “nano-based drug therapy” is likely to favor broad-spectrum activity, multiple cellular targets, and minimum host toxicity. AgNps, therefore, appear to have the potential to address the challenges in multidrug

  2. Core/shell AgNi/PtAgNi nanoparticles as methanol-tolerant oxygen reduction electrocatalysts

    International Nuclear Information System (INIS)

    Wu, Dengfeng; Cheng, Daojian

    2015-01-01

    A core/shell AgNi/PtAgNi nanoparticle (NP) was synthesized via a new seed-mediated growth method in organic solvent medium. The as-synthesized AgNi/PtAgNiNP exhibits an AgNi core coated with PtAgNi shell, which was confirmed by transmission electron microscopy (TEM), ultraviolet–visible absorption spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The AgNi/PtAgNiNPs/C catalyst possesses higher oxygen reduction reaction (ORR) activity and better durability compared with the commercial Pt/C catalyst. It is found that the ORR polarization curve of the AgNi/PtAgNiNPs/C catalyst shows an onset potential of 0.91 V vs. RHE, which is superior to the commercial Pt/C (0.88 V vs. RHE). In addition, the AgNi/PtAgNiNPs/C catalyst shows much better durability than the commercial Pt/C catalyst. More interestingly, the AgNi/PtAgNiNPs/C catalyst displays much higher methanol tolerance than the commercial Pt/C catalyst in 0.1 M KOH solution in the presence of 0.5 M methanol. Our results show that core/shell AgNi/PtAgNiNPs possess selective activity for ORR even in the presence of methanol, showing potential application as methanol-tolerant cathode catalysts in direct methanol fuel cells.

  3. Halloysite nanotube supported Ag nanoparticles heteroarchitectures as catalysts for polymerization of alkylsilanes to superhydrophobic silanol/siloxane composite microspheres.

    Science.gov (United States)

    Li, Cuiping; Li, Xueyuan; Duan, Xuelan; Li, Guangjie; Wang, Jiaqiang

    2014-12-15

    Halloysite nanotube supported Ag nanoparticles heteroarchitectures have been prepared through a very simple electroless plating method. Robust Ag nanocrystals can be reproducibly fabricated by soaking halloysite nanotubes in ethanolic solutions of AgNO3 and butylamine. By simply adjusting the molar ratio of AgNO3 and butylamine, Ag nanoparticles with tunable size and quantity on halloysite nanotube are achieved. It reveals that the Ag nanoparticles are well-dispersed on the surface of halloysite nanotubes. The halloysite nanotube supported Ag nanoparticles heteroarchitectures can serve as active catalysts for the polymerization of an alkylsilane C18H37SiH3 with water to form silanol/siloxane composite microspheres and exhibit interesting superhydrophobicity ascribed to the micro/nanobinary structure. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Green Synthesis Methods of CoFe_2O_4 and Ag-CoFe_2O_4 Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential

    International Nuclear Information System (INIS)

    Gingasu, D.; Mindru, I.; Patron, L.; Caleron-Moreno, J.M.; Mocioiu, O.C.; Preda, S.; Stanica, N.; Nita, S.; Dobre, N.; Popa, M.; Gradisteanu, G.; Chifiriuc, M. C.

    2016-01-01

    The cobalt ferrite (CoFe_2O_4) and silver-cobalt ferrite (Ag-CoFe_2O_4) nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe_2O_4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031-0.062 mg/ml) against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

  5. Green Synthesis Methods of CoFe2O4 and Ag-CoFe2O4 Nanoparticles Using Hibiscus Extracts and Their Antimicrobial Potential

    Directory of Open Access Journals (Sweden)

    Dana Gingasu

    2016-01-01

    Full Text Available The cobalt ferrite (CoFe2O4 and silver-cobalt ferrite (Ag-CoFe2O4 nanoparticles were obtained through self-combustion and wet ferritization methods using aqueous extracts of Hibiscus rosa-sinensis flower and leaf. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and magnetic measurements were used for the characterization of the obtained oxide powders. The antimicrobial activity of the cobalt ferrite and silver-cobalt ferrite nanoparticles against Gram-positive and Gram-negative bacteria, as well as fungal strains, was investigated by qualitative and quantitative assays. The most active proved to be the Ag-CoFe2O4 nanoparticles, particularly those obtained through self-combustion using hibiscus leaf extract, which exhibited very low minimal inhibitory concentration values (0.031–0.062 mg/mL against all tested microbial strains, suggesting their potential for the development of novel antimicrobial agents.

  6. In vivo evaluation of the biodistribution of intravenously administered naked and functionalised silver nanoparticles in rabbit

    KAUST Repository

    Ashraf, Ayesha; Sharif, Rehana; Ahmad, Munir; Masood, Misbah; Shahid, Abubakar; Anjum, Dalaver H.; Rafique, Muhammad Shahid; Ghani, Sheeba

    2015-01-01

    Water-based suspension of silver nanoparticles (AgNPs) and dextran coated AgNPs (dextran-AgNPs) are fabricated and characterised for intravenous administration. A simple method for radiolabelling of nanoparticles with 99mTc was used. Labelling efficiency for AgNPs and dextran-AgNPs was found to be more than 80 and 88%, respectively. In vivo tissue uptake of nanoparticles during dynamic phase, after systematic administration by biodistribution analysis with single-photon emission computed tomography imaging has been evaluated. Biodistribution analysis revealed that 99mTc-AgNPs and 99mTc-dextran-AgNPs are mainly accumulated in liver/spleen region but 99mTc-dextran-AgNPs delayed recognition and uptake by liver. Results indicate that dextran-AgNPs are able to evade reticuloendothelum system with enhanced blood retention time. Accumulation of nanoparticles in liver/spleen region implicates the utilisation of AgNPs for liver cancer treatment. © 2015 The Institution of Engineering and Technology.

  7. In vivo evaluation of the biodistribution of intravenously administered naked and functionalised silver nanoparticles in rabbit

    KAUST Repository

    Ashraf, Ayesha

    2015-12-01

    Water-based suspension of silver nanoparticles (AgNPs) and dextran coated AgNPs (dextran-AgNPs) are fabricated and characterised for intravenous administration. A simple method for radiolabelling of nanoparticles with 99mTc was used. Labelling efficiency for AgNPs and dextran-AgNPs was found to be more than 80 and 88%, respectively. In vivo tissue uptake of nanoparticles during dynamic phase, after systematic administration by biodistribution analysis with single-photon emission computed tomography imaging has been evaluated. Biodistribution analysis revealed that 99mTc-AgNPs and 99mTc-dextran-AgNPs are mainly accumulated in liver/spleen region but 99mTc-dextran-AgNPs delayed recognition and uptake by liver. Results indicate that dextran-AgNPs are able to evade reticuloendothelum system with enhanced blood retention time. Accumulation of nanoparticles in liver/spleen region implicates the utilisation of AgNPs for liver cancer treatment. © 2015 The Institution of Engineering and Technology.

  8. Bioaccumulation of Zn and Ag Nanoparticles in the Earthworms (Eisenia fetida)

    Science.gov (United States)

    Ha, Lee Seung; Sung-Dae, Kim; Yi, Yang Song; Byeong-Gweon, Lee

    2014-05-01

    Many studies are carried out to evaluate environmental effects of engineered nanoparticles (ENPs). Most of the previous studies primarily focused on the effects of nanoparticles into the aquatic environment and human. Model studies predict that ENPs released into environment would transferred primarily to the soil of the terrestrial environment. Despite this prediction, biogeochemical behavior of ENPs in soil environment as well as bioavailability of ENPs to soil-dwelling organisms such as earthworm, springtail, isopod and nematodes are poorly understood. The main goal of this study was to compare the bioaccumulation factor (BAFs) and subcellular partitioning of nanoparticles in the soil-dwelling earthworm (Eisenia fetida) from ENP (ZnO and Ag nanoparticles) or ionic metal (Zn2+, Ag+) contaminated soil. And the sequential extraction was also used to determine the mobility of metals in soil which could be used as to predict bioavailability and compare that with bioaccumulation factor. The radiotracer method was employed to trace the transfer of ENPs and ionic metal among different environmental media and animals. Radiolabeled 65ZnO, 110mAgNPs coated with PVP or citrate were synthesized in the laboratory and their chemical and biological behavior was compared to ionic 65Zn and 110mAg. The BAFs of Zn and Ag in the earthworms were determined after animals exposed to the contaminated soils. After the 7 days of elimination phase, subcellular partitioning of metals were also obtained. BAF for ZnO(0.06) was 31 times lower than that for Zn ion (1.86), suggesting that ZnO was less bioavailable than its ionic form from contaminated soil. On the other hands, BAFs for AgNPs coated with PVP (0.12) or with citrate (0.11) were comparable to those for Ag ion (0.17), indicating that Ag from contaminated soil was bioavailable in a similar rate regardless of chemical forms. The subcellular partitioning results showed that bioaccumulated Zn from Zn ion and ZnO contaminated soil were

  9. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications

    International Nuclear Information System (INIS)

    Dong Wenjun; Huang Huandi; Zhu Yanjun; Li Xiaoyun; Wang Xuebin; Li Chaorong; Chen Benyong; Wang Ge; Shi Zhan

    2012-01-01

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide–amine intermediate and Ag + at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO 3 nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag–MoO 3 nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature. (paper)

  10. Thermal conductivity enhancements and viscosity properties of water based Nanofluid containing carbon nanotubes decorated with ag nanoparticles

    Science.gov (United States)

    Gu, Yanni; Xu, Sheng; Wu, Xiaoshan

    2018-06-01

    The water based nanofluid containing carbon nanotube (CNT) decorated with Ag nanoparticles (Ag/CNT) is prepared. Its thermal conductivity ( k) enhancement increases with the thermal filler loading and the decoration quantity of Ag nanoparticles. The low absolute CNT content will decrease the tangles or aggregations among the CNTs, and it will be good at the Brownian motion of CNTs in the water. It has positive effects on the thermal conductivity of nanofluid. With the increase of Ag loading, the average size of Ag nanoparticles increased, and further results in the decrease of dispersing amount of Ag/CNT as the weight of Ag/CNT is fixed. Little dispersing quantity of Ag/CNT makes it possible that the Ag/CNT particles disperse well in the fluid. So it is not easy for CNTs to form aggregation. The high intrinsic k of CNT and the effective thermal conductive networks forming by CNTs and Ag nanoparticles are good at the k enhancement. With temperature increase the k of Ag/CNT nanofluid appears improvement. The study results make it possible to develop high-efficiency nanofluid for advanced thermal management regions.

  11. Thermal conductivity enhancements and viscosity properties of water based Nanofluid containing carbon nanotubes decorated with ag nanoparticles

    Science.gov (United States)

    Gu, Yanni; Xu, Sheng; Wu, Xiaoshan

    2018-01-01

    The water based nanofluid containing carbon nanotube (CNT) decorated with Ag nanoparticles (Ag/CNT) is prepared. Its thermal conductivity (k) enhancement increases with the thermal filler loading and the decoration quantity of Ag nanoparticles. The low absolute CNT content will decrease the tangles or aggregations among the CNTs, and it will be good at the Brownian motion of CNTs in the water. It has positive effects on the thermal conductivity of nanofluid. With the increase of Ag loading, the average size of Ag nanoparticles increased, and further results in the decrease of dispersing amount of Ag/CNT as the weight of Ag/CNT is fixed. Little dispersing quantity of Ag/CNT makes it possible that the Ag/CNT particles disperse well in the fluid. So it is not easy for CNTs to form aggregation. The high intrinsic k of CNT and the effective thermal conductive networks forming by CNTs and Ag nanoparticles are good at the k enhancement. With temperature increase the k of Ag/CNT nanofluid appears improvement. The study results make it possible to develop high-efficiency nanofluid for advanced thermal management regions.

  12. The impact of Ag nanoparticles on the parameters of DSS- cells sensitized by Z907

    International Nuclear Information System (INIS)

    Ibrayev, N Kh; Aimukhanov, A K; Zeinidenov, A K

    2016-01-01

    Research of influence of Ag nanoparticles are in-process undertaken on absorption and on parameters CVC DSS-cells sensitized Z907. It is set that with the height of concentration Ag nanoparticles in tape to the concentration of 0.3% wt%. the absorbance of Z907 in a short-wave stripe grew to the value 1,6. It is set that under reaching the concentration of Ag nanoparticles in the cell of value the 0.3% wt%. efficiency of cell increased to 2.2%. (paper)

  13. Large third-order optical nonlinearity in vertically oriented mesoporous silica thin films embedded with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Min; Liu, Qiming, E-mail: qmliu@whu.edu.cn [Wuhan University, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology (China)

    2016-12-15

    Taking advantage of the channel confinement of mesoporous films to prevent the agglomeration of Ag nanoparticles to achieve large third-order optical nonlinearity in amorphous materials, Ag-loaded composite mesoporous silica film was prepared by the electrochemical deposition method on ITO substrate. Ag ions were firstly transported into the channels of mesoporous film by the diffusion and binding force of channels, which were reduced to nanoparticles by applying suitable voltage. The existence and uniform distribution of Ag nanoparticles ranging in 1–10 nm in the mesoporous silica thin films were exhibited by UV spectrophotometer, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. The third-order optical nonlinearity induced by Ag nanoparticles was studied by the Z-scan technique. Due to the local field surface plasmon resonance, the maximum third-order nonlinear optical susceptibility of Ag-loaded composite mesoporous silica film is 1.53×10{sup −10} esu, which is 1000 times larger than that of the Ag-contained chalcogenide glasses which showed large nonlinearity in amorphous materials.

  14. Using Ag-embedded TiO{sub 2} nanotubes array as recyclable SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Zhuo, Yuqing; Huang, Liang [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Mao, Duolu [School of Physical and Electronic Information Engineering, Qinghai Nationalities University, Xining, Qinghai 810007 (China)

    2016-12-01

    Highlights: • Ag embedded nanoparticles inside nanotube have better SERS enhancement than surface cap. • Ag NPs reconstruction via self-migration with UV and humidity control. • Self-cleaning effects both on organic molecule photo-oxidation as well as Ag ions photo-reduction. - Abstract: A simple strategy for synthesizing Ag-loaded TiO{sub 2} nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO{sub 2} nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

  15. Core–shell Au/Ag nanoparticles embedded in silicate sol–gel ...

    Indian Academy of Sciences (India)

    Administrator

    Dedicated to the memory of the late Professor S K Rangarajan. *For correspondence. Core–shell Au/Ag nanoparticles embedded in silicate sol–gel network for sensor .... An immediate colour change was observed for the mixed solution, indicating the dis- persion of metal nanoparticles in the MTMOS sol– gel matrix.

  16. Enhanced electrochromic coloration in Ag nanoparticle decorated WO3 thin films

    International Nuclear Information System (INIS)

    Kharade, Rohini R.; Mali, Sawanta S.; Patil, Satish P.; Patil, Kashinath R.; Gang, Myong G.; Patil, Pramod S.; Kim, Jin H.; Bhosale, Popatrao N.

    2013-01-01

    Highlights: • Electrochromic WO 3 /Ag nanocomposites prepared by hybrid physico-chemical route. • XRD and XPS results confirm formation of Ag 8 W 4 O 16 phase. • WO 3 /Ag thin films showed good optical transmittance change and coloration efficiency. • SPR enhanced coloration and bleaching mechanism is well explained for electrochromism. • Color stimuli are quantified using CIE chromaticity principles. -- Abstract: WO 3 /Ag composite thin films were prepared by microwave assisted sol–gel synthesis (MW-SGS) of WO 3 followed by vacuum evaporation of Ag nanoparticles and their enhanced electrochromic coloration was investigated. The composition and morphology of WO 3 thin films with different thickness of Ag layer obtained by vacuum evaporation were investigated. Distinct plasmon absorption bands of Ag nanoparticle thin films were obtained. The optical band gap energy of WO 3 /Ag films decreased with increasing the Ag layer thickness. The surface of these films has been examined using X-ray photoelectron spectroscopy (XPS) to gain information about the chemical states of species present at surfaces. Experimental results indicated that the conductivity of the films increased after surface modification by Ag layer. To investigate the origin of enhanced electrochromic absorption in optical properties, working electrode consisting of WO 3 /Ag thin film was used and observed the optical properties during electrochemical reaction. It was found that composite electrode shows enhancement in electrochromic properties in terms of optical modulation (ΔOD) and coloration efficiency (η)

  17. Nanoscale coupling of photons to vibrational excitation of Ag nanoparticle 2D array studied by scanning tunneling microscope light emission spectroscopy.

    Science.gov (United States)

    Katano, Satoshi; Toma, Koji; Toma, Mana; Tamada, Kaoru; Uehara, Yoichi

    2010-11-28

    Scanning tunneling microscope light emission (STM-LE) spectroscopy has been utilized to elucidate the luminescence phenomena of Ag nanoparticles capped with myristate (myristate-capped AgNP) and 2-methyl-1-propanethiolate (C(4)S-capped AgNP) on the dodecanethiol-precovered Au substrate. The STM imaging revealed that myristate-capped AgNPs form an ordered hexagonal array whereas C(4)S-capped AgNPs show imperfect ordering, indicating that a shorter alkyl chain of C(4)S-capped AgNP is not sufficient to form rigid interdigitation. It should be noted that such a nanoparticle ordering affects the luminescence properties of the Ag nanoparticle. We found that the STM-LE is only detected from the Ag nanoparticles forming the two-dimensional superlattice. This indicates that the STM-LE of the Ag nanoparticle is radiated via the collective excitation of the local surface plasmon resonance (LSPR) spread over the Ag nanoparticles. Note that the STM-LE spectra of the Ag nanoparticles exhibit spike-like peaks superimposed on the broad light emission peak. Using Raman spectroscopy, we concluded that the spike-like structure appearing in the STM-LE spectra is associated with the vibrational excitation of the molecule embedded between Ag nanoparticles.

  18. Photovoltaic Properties and Ultrafast Plasmon Relaxation Dynamics of Diamond-Like Carbon Nanocomposite Films with Embedded Ag Nanoparticles.

    Science.gov (United States)

    Meškinis, Šarūnas; Peckus, Domantas; Vasiliauskas, Andrius; Čiegis, Arvydas; Gudaitis, Rimantas; Tamulevičius, Tomas; Yaremchuk, Iryna; Tamulevičius, Sigitas

    2017-12-01

    Ultrafast relaxation dynamics of diamond-like carbon (DLC) films with embedded Ag nanoparticles (DLC:Ag) and photovoltaic properties of heterojunctions consisting of DLC:Ag and crystalline silicon (DLC:Ag/Si) were investigated by means of transient absorption (TAS) spectroscopy and photovoltaic measurements. The heterojunctions using both p type and n type silicon were studied. It was found that TAS spectra of DLC:Ag films were dependent on the used excitation wavelength. At wavelengths where Ag nanoparticles absorbed light most intensively, only DLC signal was registered. This result is in good accordance with an increase of the DLC:Ag/Si heterojunction short circuit current and open circuit voltage with the excitation wavelength in the photovoltaic measurements. The dependence of the TAS spectra of DLC:Ag films and photovoltaic properties of DLC:Ag/Si heterostructures on the excitation wavelength was explained as a result of trapping of the photoexcited hot charge carriers in DLC matrix. The negative photovoltaic effect was observed for DLC:Ag/p-Si heterostructures and positive ("conventional") for DLC:Ag/n-Si ones. It was explained by the excitation of hot plasmonic holes in the Ag nanoparticles embedded into DLC matrix. Some decrease of DLC:Ag/Si heterostructures photovoltage as well as photocurrent with DLC:Ag film thickness was observed, indicating role of the interface in the charge transfer process of photocarriers excited in Ag nanoparticles.

  19. On-the-fly green generation and dispersion of AgI nanoparticles for cloud seeding nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiuli; Zhou, Wenbo; Wang, Xizheng; Wu, Tao; Delisio, Jeffery B.; Zachariah, Michael R., E-mail: mrz@umd.edu [University of Maryland, Department of Chemical and Biomolecular Engineering (United States)

    2016-07-15

    This study reports on an on-the-fly green synthesis/dispersion of silver iodide (AgI) nanoparticles from the combustion of AgIO{sub 3}/carbon black (CB)/nitrocellulose (NC) composites, which could be used as a candidate for a cloud-seeding pyrotechnic. Films were formed by direct electrospray deposition of a mixture of synthesized silver iodate with CB and NC. The decomposition pathways of AgIO{sub 3}/CB and AgIO{sub 3}/CB/NC were evaluated by temperature jump time of flight mass spectrometry (T-jump TOFMS) and XRD, showing that AgI particles and CO{sub 2} are released from the reaction between AgIO{sub 3} and CB without other toxic residuals. The flame propagation velocity of AgIO{sub 3}/CB/NC films increases with the increasing of particle mass loading of AgIO{sub 3} and CB and peaks at 40 wt%, which is much higher than that of an AgI/AP/NC film. The mean diameter of the resultant AgI nanoparticles is from 51 to 97 nm. The mass loading of AgIO{sub 3} and CB was found to play a major role in size control of the AgI nanoparticles.

  20. Spontaneous Ag-Nanoparticle Growth at Single-Walled Carbon Nanotube Defect Sites: A Tool for In Situ Generation of SERS Substrate

    Directory of Open Access Journals (Sweden)

    Jason Maley

    2011-01-01

    Full Text Available Silver nanoparticles were spontaneously formed on pristine and oxidized single-wall nanotubes. Nanoparticles were observed on carbon nanotubes with AFM, and the presence of Ag nanoparticles were confirmed by ESR experiments. Raman spectroscopy of the Ag-treated carbon nanotubes had a 4–10X enhancement of intensity compared to untreated carbon nanotubes. Ag nanoparticles formed at defect sites on the CNT surface, where free electrons located at the defect sites reduced Ag+ to Ag. A mechanism for the propagation of the nanoparticles is through a continual negative charge generation on the nanoparticle by electron transfer from doublet oxygen (O2−.

  1. In situ Raman scattering study on a controllable plasmon-driven surface catalysis reaction on Ag nanoparticle arrays

    International Nuclear Information System (INIS)

    Dai, Z G; Xiao, X H; Zhang, Y P; Ren, F; Wu, W; Zhang, S F; Zhou, J; Jiang, C Z; Mei, F

    2012-01-01

    Control of the plasmon-driven chemical reaction for the transformation of 4-nitrobenzenethiol to p,p′-dimercaptoazobenzene by Ag nanoparticle arrays was studied. The Ag nanoparticle arrays were fabricated by means of nanosphere lithography. By changing the PS particle size, the localized surface plasmon resonance (LSPR) peaks of the Ag nanoparticle arrays can be tailored from 460 to 560 nm. The controlled reaction process was monitored by in situ surface-enhanced Raman scattering. The reaction can be dramatically influenced by varying the duration of laser exposure, Ag nanoparticle size, laser power and laser excitation wavelength. The maximum reaction speed was achieved when the LSPR wavelength of the Ag nanoparticle arrays matched the laser excitation wavelength. The experimental results reveal that the strong LSPR can effectively drive the transfer of the ‘hot’ electrons that decay from the plasmon to the reactants. The experimental results were confirmed by theoretical calculations. (paper)

  2. Biofabrication of Ag nanoparticles using Moringa oleifera leaf extract and their antimicrobial activity

    Science.gov (United States)

    Prasad, TNVKV; Elumalai, EK

    2011-01-01

    Objective To formulate a simple rapid procedure for bioreduction of silver nanoparticles using aqueous leaves extract of Moringa oleifera (M. oleifera). Methods 10 mL of leaf extract was mixed to 90 mL of 1 mM aqueous of AgNO3 and was heated at 60 - 80 °C for 20 min. A change from brown to reddish color was observed. Characterization using UV-Vis spectrophotometry, Transmission Electron Microscopy (TEM) was performed. Results TEM showed the formation of silver nanoparticles with an average size of 57 nm. Conclusions M. oleifera demonstrates strong potential for synthesis of silver nanoparticles by rapid reduction of silver ions (Ag+ to Ag0). Biological methods are good competents for the chemical procedures, which are eco-friendly and convenient. PMID:23569809

  3. Fabrication of Ag/ZnO heterostructure and the role of surface coverage of ZnO microrods by Ag nanoparticles on the photophysical and photocatalytic properties of the metal-semiconductor system

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Bikash; Sarma, Bimal K., E-mail: sarmabimal@gmail.com

    2017-07-15

    Highlights: • Fabrication of Ag/ZnO heterostructure by facile chemical processes. • Decoration of plasmonic Ag nanoparticles on ZnO microrods through direct attachment. • Quenching of photoluminescence is observed in Ag/ZnO heterostructure. • Extent of surface coverage governs photophysical and photochemical properties. - Abstract: This report presents findings on microstructural, photophysical, and photocatalytic properties of Ag/ZnO heterostructure grown on flexible and silicon substrates. ZnO microrods are prepared by thermal decomposition method for different solute concentrations and Ag/ZnO heterostructure are fabricated by photo-deposition of Ag nanoparticles on ZnO microrods. X-ray diffraction and electron microscopy studies confirm that ZnO microrods belong to the hexagonal wurtzite structure and grown along [001] direction with random alignment showing that majority microrods are aligned with (100) face parallel to the sample surface. Plasmonic Ag nanoparticles are attached to different faces of ZnO. In the optical reflection spectra of Ag/ZnO heterostructure, the surface plasmon resonance peak due to Ag nanoparticles appears at 445 nm. Due to the oxygen vacancies the band gaps of ZnO microrods turn out to be narrower compared to that of bulk ZnO. The presence of Ag nanoparticles decreases the photoluminescence intensity which might be attributed to the non-radiative energy and direct electron transfer in the plasmon–exciton system. The quenching of photoluminescence in Ag/ZnO heterostructure at different growth conditions depend on the extent of surface coverage of ZnO by plasmonic Ag nanoparticles. Photocatalytic degradation efficiency of Ag/ZnO heterostructure is higher than that of ZnO microrods. The extent of surface coverage of ZnO microrods by Ag nanoparticles is crucial for the observed changes in photophysical and photochemical properties.

  4. Transformation of AgCl nanoparticles in a sewer system — A field study

    Energy Technology Data Exchange (ETDEWEB)

    Kaegi, Ralf, E-mail: ralf.kaegi@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf (Switzerland); Voegelin, Andreas; Sinnet, Brian [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf (Switzerland); Zuleeg, Steffen [KUSTER + HAGER Group, Oberstrasse 222, 9014 St. Gallen (Switzerland); Siegrist, Hansruedi [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf (Switzerland); Burkhardt, Michael [HSR University of Applied Sciences, Institute of Environmental and Process Engineering (UMTEC), Oberseestrasse 10, 8640 Rapperswil (Switzerland)

    2015-12-01

    Silver nanoparticles (Ag-NP) are increasingly used in consumer products and their release during the use phase may negatively affect aquatic ecosystems. Research efforts, so far, have mainly addressed the application and use of metallic Ag(0)-NP. However, as shown by recent studies on the release of Ag from textiles, other forms of Ag, especially silver chloride (AgCl), are released in much larger quantities than metallic Ag(0). In this field study, we report the release of AgCl-NP from a point source (industrial laundry that applied AgCl-NP during a piloting phase over a period of several months to protect textiles from bacterial regrowth) to the public sewer system and investigate the transformation of Ag during its transport in the sewer system and in the municipal wastewater treatment plant (WWTP). During the study period, the laundry discharged ~ 85 g of Ag per day, which dominated the Ag loads in the sewer system from the respective catchment (72–95%) and the Ag in the digested WWTP sludge (67%). Combined results from electron microscopy and X-ray absorption spectroscopy revealed that the Ag discharged from the laundry to the sewer consisted of about one third AgCl and two thirds Ag{sub 2}S, both forms primarily occurring as nanoparticles with diameters < 100 nm. During the 800 m transport in the sewer channel to the nearby WWTP, corresponding to a travel time of ~ 30 min, the remaining AgCl was transformed into nanoparticulate Ag{sub 2}S. Ag{sub 2}S-NP also dominated the Ag speciation in the digested sludge. In line with results from earlier studies, the very low Ag concentrations measured in the effluent of the WWTP (< 0.5 μg L{sup −1}) confirmed the very high removal efficiency of Ag from the wastewater stream (> 95%). - Highlights: • First field study on the transformation of AgCl nanoparticles released from a point source into the municipal sewer system. • Transformation of AgCl-NP into Ag{sub 2}S already occurred during 30-min transport in the

  5. Antifungal Effects of Silver Nanoparticles (AgNPs) against Various Plant Pathogenic Fungi.

    Science.gov (United States)

    Kim, Sang Woo; Jung, Jin Hee; Lamsal, Kabir; Kim, Yun Seok; Min, Ji Seon; Lee, Youn Su

    2012-03-01

    This research is concerned with the fungicidal properties of nano-size silver colloidal solution used as an agent for antifungal treatment of various plant pathogens. We used WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R silver nanoparticles (AgNPs) at concentrations of 10, 25, 50, and 100 ppm. Eighteen different plant pathogenic fungi were treated with these AgNPs on potato dextrose agar (PDA), malt extract agar, and corn meal agar plates. We calculated fungal inhibition in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. The results indicated that AgNPs possess antifungal properties against these plant pathogens at various levels. Treatment with WA-CV-WB13R AgNPs resulted in maximum inhibition of most fungi. Results also showed that the most significant inhibition of plant pathogenic fungi was observed on PDA and 100 ppm of AgNPs.

  6. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    International Nuclear Information System (INIS)

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-01-01

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity

  7. Localized Surface Plasmon-Enhanced Electroluminescence in OLEDs by Self-Assembly Ag Nanoparticle Film

    Science.gov (United States)

    He, Xiaoxiao; Wang, Wenjun; Li, Shuhong; Wang, Qingru; Zheng, Wanquan; Shi, Qiang; Liu, Yunlong

    2015-12-01

    We fabricated Ag nanoparticle (NP) film in organic light emission diodes (OLEDs), and a 23 times increase in electroluminescence (EL) at 518 nm was probed by time-resolved EL measurement. The luminance and relative external quantum efficiency (REQE) were increased by 5.4 and 3.7 times, respectively. There comes a new energy transport way that localized surface plasmons (LSPs) would absorb energy that corresponds to the electron-hole pair before recombination, promoting the formation of electron-hole pair and exciting local surface plasmon resonance (LSPR). The extended lifetime of Alq3 indicates the existence of strong interaction between LSPR and exciton, which decreases the nonradiative decay rate of OLEDs.

  8. Ag@ZnO core-shell nanoparticles study by first principle: The structural, magnetic and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Hai-Xia [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Xiao-Xu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Computing Center, Beijing 100094 (China); Hu, Yao-Wen [Department of Physics, Tsinghua University, Beijing 100084 (China); Song, Hong-Quan; Huo, Jin-Rong; Li, Lu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Qian, Ping, E-mail: ustbqianp@163.com [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Song, Yu-Jun [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-12-15

    Ag@ZnO core-shell nanoparticles of around 72 atoms have been investigated by the density functional theory, revealing proving for the first time that the core-shell structure exhibits a shrinkage phenomenon from outer shell in agreement with the other studies in literatures. Our calculations predict that the Ag@ZnO core-shell structure is a ferromagnetic spin polarized state, and the magnetism mainly stems from the spin splitting of 2p electrons of O atoms. In addition, the total and partial DOS of Ag@ZnO indicate that the nanostructure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. Furthermore, the optical properties calculations show that the absorption edge of Ag@ZnO have a red shift and good photocatalysis compare to that of the bulk ZnO. These results of the Ag@ZnO core-shell structure obtain a well agreement with the experimental measurement. - Graphical abstract: Geometric structure of (a) Ag@ZnO core-shell nanostructure; (b) the core of Ag; (c) the shell of ZnO The core-shell nanoparticle Ag@ZnO contains Ag inner core of radius of 4 Å and ZnO outer shell with thickness of 2 Å. Ag@ZnO core-shell nanoparticles of around 72 atoms have been proved for the first time that the core-shell structure exhibit a shrinkage phenomenon from outer shell. Our calculations predict that the Ag@ZnO core-shell structure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. The absorption edge of Ag@ZnO have a red shift and get good photo-catalysis compare to that of the bulk ZnO.

  9. Revelation of susceptibility differences due to Hg(II) accumulation in Streptococcus pyogenes against CX-AgNPs and Cefixime by atomic force microscopy.

    Science.gov (United States)

    Rasheed, Wasia; Shah, Muhammad Raza; Perveen, Samina; Ahmed, Shakil; Uzzaman, Sami

    2018-01-01

    Solution based method for the formation of chemically modified silver nanoparticles (CX-AgNPs) using Cefixime as stabilizing and reducing agent was developed. The CX-AgNPs were characterized by AFM, UV-visible, FT-IR and MALDI-TOF MS. Bactericidal efficiency of CX-AgNPs and Cefixime against Streptococcus pyogenes was evaluated. Afterwards, susceptibility differences of Streptococcus pyogenes due to accumulation of Hg(II) against CX-AgNPs and Cefixime were estimated and validated through Atomic force microscopy. Selectivity and sensitivity of CX-AgNPs against Hg(II) was evaluated in a systematic manner. The CX-AgNPs was titrated against optically silent Hg(II) which induced enhancement in the SPR band of CX-AgNPs. The increase in intensity of SPR band of CX-AgNPs was determined to be proportionate to the concentration of Hg(II) in the range of 33.3-700µM obeying linear regression equation of y = 0.125x + 8.962 with the detection limit of 0.10µM and the coefficient of determination equals to 0.985 (n = 3). The association constant Ka of CX-AgNPs-Hg(II) was found to be 386.0095mol -1 dm 3 by using the Benesi Hildebrand plot. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Preparation of Au and Ag nanoparticles using Artemisia annua and their in vitro antibacterial and tyrosinase inhibitory activities

    Energy Technology Data Exchange (ETDEWEB)

    Basavegowda, Nagaraj; Idhayadhulla, Akber; Lee, Yong Rok, E-mail: yrlee@yu.ac.kr

    2014-10-01

    This work describes a plant-mediated approach to the preparation of metal nanoparticles using leaf extract of Artemisia annua (A. annua), an ethno-medicinal plant widely found in Asia, which was used as reducing and stabilizing agent. A. annua is used in traditional Chinese medicine to alleviate fever. Au and Ag nanoparticles were prepared using a one-step aqueous method at room temperature without any toxic chemicals. The formation of Au and Ag nanoparticles was monitored by UV–vis spectroscopy. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). TEM analysis of Au nanoparticles showed that they had triangular and spherical shapes with sizes ranging from 15 to 40 nm. The silver nanoparticles were predominantly spherical and uniformly sized (30–50 nm). The Au and Ag nanoparticles produced showed significant tyrosinase inhibitory and antibacterial effects. These results suggest that the synthesized nanoparticles provide good alternatives in varied medical and industrial applications. - Highlights: • Au and Ag nanoparticles were synthesized using Artemisia annua leaf aqueous extract. • Nanoparticles were characterized by UV–vis spectroscopy, FT-IR, TEM, EDX, XRD, and TGA. • Au and Ag nanoparticles were of size 25 and 30 nm respectively, in spherical forms. • Nanoparticles showed significant tyrosinase inhibitory and antibacterial activities.

  11. Preparation of Au and Ag nanoparticles using Artemisia annua and their in vitro antibacterial and tyrosinase inhibitory activities

    International Nuclear Information System (INIS)

    Basavegowda, Nagaraj; Idhayadhulla, Akber; Lee, Yong Rok

    2014-01-01

    This work describes a plant-mediated approach to the preparation of metal nanoparticles using leaf extract of Artemisia annua (A. annua), an ethno-medicinal plant widely found in Asia, which was used as reducing and stabilizing agent. A. annua is used in traditional Chinese medicine to alleviate fever. Au and Ag nanoparticles were prepared using a one-step aqueous method at room temperature without any toxic chemicals. The formation of Au and Ag nanoparticles was monitored by UV–vis spectroscopy. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). TEM analysis of Au nanoparticles showed that they had triangular and spherical shapes with sizes ranging from 15 to 40 nm. The silver nanoparticles were predominantly spherical and uniformly sized (30–50 nm). The Au and Ag nanoparticles produced showed significant tyrosinase inhibitory and antibacterial effects. These results suggest that the synthesized nanoparticles provide good alternatives in varied medical and industrial applications. - Highlights: • Au and Ag nanoparticles were synthesized using Artemisia annua leaf aqueous extract. • Nanoparticles were characterized by UV–vis spectroscopy, FT-IR, TEM, EDX, XRD, and TGA. • Au and Ag nanoparticles were of size 25 and 30 nm respectively, in spherical forms. • Nanoparticles showed significant tyrosinase inhibitory and antibacterial activities

  12. Ag/Pd core-shell nanoparticles by a successive method: Pulsed laser ablation of Ag in water and reduction reaction of PdCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mottaghi, N. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Farrokhpour, H. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Khoshouei, M. [Max Planck Institute of Biochemistry, Department of Molecular Structural Biology, Am Klopferspitz 18, Martinsried 82152 (Germany); Khoshouei, A.; Kameli, P.; Salamati, H. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Tabrizchi, M. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Jalilian-Nosrati, M. [Physics department, Central Azad University, Tehran 14676-86831 (Iran, Islamic Republic of)

    2014-02-15

    In this study Ag/Pd nanoparticles (NPs) have been fabricated by a successive method; first, colloids of Ag nanoparticles (NPs) have been prepared in water by pulsed laser ablation in liquid (PLAL) method. Then PdCl{sub 2} solution (up to 0.2 g/l) were added to the as-prepared or aged colloidal Ag NPs. Characterizations were done using UV–vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmissions electron microscopy (TEM) techniques. Spectroscopy data showed that surface plasmon resonance (SPR) peaks of as-prepared Ag NPs at about λ = 400 nm were completely extinguished after addition of PdCl{sub 2} solution while this effect was not observed when aged Ag NPs are used. XRD and XPS results revealed that by addition of the PdCl{sub 2} solution into the as-prepared Ag NPs, metallic palladium, and silver chloride composition products are generated. TEM images revealed that as a result of this reaction, single and core-shell nanoparticles are obtained and their average sizes are 2.4 nm (Ag) and 3.2 nm (Ag/Pd). The calculated d-spacing values form XRD data with observations on high magnification TEM images were able to explain the chemical nature of different parts of Ag/Pd NPs.

  13. Photoinduced absorption of Ag nanoparticles deposited on ITO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ozga, K., E-mail: cate.ozga@wp.pl [Chair of Public Health, Czestochowa University of Technology, Al. Armii Krajowej 36B, 42-200 Czestochowa (Poland); Oyama, M. [Department of Material Chemisrty, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520 (Japan); Szota, M. [Institute of Materials Science and Engineering, Technical University of Czestochowa, al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Nabialek, M. [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland); Kityk, I.V. [Electrical Engineering Department, Czestochowa University of Technology, Al. Armii Krajowej 17/19, 42-200 Czestochowa (Poland); Slezak, A. [Chair of Public Health, Czestochowa University of Technology, Al. Armii Krajowej 36B, 42-200 Czestochowa (Poland); Umar, A.A. [Institute of Micronegineering and Nanoelectronics Universiti Kebangsaan Malaysia 43600 UKM bangi, Selangor D.E. (Malaysia); Nouneh, K. [INANOTECH, Institute of Nanomaterials and Nanotechnology, MAScIR (Moroccan Advanced Science, Innovation and Research Foundation), ENSET, Av. Armee Royale, 10100, Rabat (Morocco)

    2011-06-15

    Research highlights: > We study photoinduced absorption for two Ag NP deposited on the ITO. > The higher resistance eof the NP favors larger photoinduced changes. > Principal role is played by nanointerfaces. - Abstract: Substantial changes of absorption after illumination by 300 mW continuous wave green laser at 532 nm were observed. The effect of indium tin oxide (ITO) substrate was explored versus Ag nanoparticles (AgNPs) size, their regularity and surface plasmon resonance. The ITO substrate features play a crucial role for the formation of homogenous AgNPs. The attachments of AgNPs on ITO surface as well as their homogeneity are significantly changed under the influence of the laser treatment. We study the Ag NP deposited on the two different substrates which play a crucial role in the photoinduced absorption. The dependence of the photoinduced absorption versus the time of optical treatment is explained within a framework of the photopolarization of the particular trapping levels on the borders between the ITO substrate and the Ag NP.

  14. Generation and oxidation of aerosol deposited PdAg nanoparticles

    Science.gov (United States)

    Blomberg, S.; Gustafson, J.; Martin, N. M.; Messing, M. E.; Deppert, K.; Liu, Z.; Chang, R.; Fernandes, V. R.; Borg, A.; Grönbeck, H.; Lundgren, E.

    2013-10-01

    PdAg nanoparticles with a diameter of 10 nm have been generated by an aerosol particle method, and supported on a silica substrate. By using a combination of X-ray Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy it is shown that the size distribution of the particles is narrow and that the two metals form an alloy with a mixture of 75% Pd and 25% Ag. Under oxidizing conditions, Pd is found to segregate to the surface and a thin PdO like oxide is formed similar to the surface oxide previously reported on extended PdAg and pure Pd surfaces.

  15. Effects of silver nanoparticle (Ag NP on oxidative stress biomarkers in rat

    Directory of Open Access Journals (Sweden)

    Akram Ranjbar

    2014-04-01

    Full Text Available Objective(s: Nanotechnology and nanoparticles are increasingly recognized for their potential applications in aerospace engineering, nanoelectronics, and environmental remediation, medicine and consumer products. More importantly is the potential for the application of silver nanoparticles (Ag NPs in the treatment of diseases that require maintenance of circulating drug concentration or targeting of specific cells or organs the aim of this study was to investigate the possible protective role of Ag NP antioxidative biomarkers in rats. Ag NPs are used to investigate the potential risks for the environment and health. Materials and Methods: Rats received Ag NP, 5, 50, 250 and 500 mg/kg/day IP. After two week of treatment, the activity of enzymatic scavengers such as glutathione peroxidase (GPx, superoxide dismutase (SOD and total antioxidant capacity (TAC of blood samples were measured. Results: Ag NP in 5, 50, 250 and 500 mg/kg reduced activities of CAT, SOD and increased TAC in plasma. Conclusion: In this study, Ag NP with 500mg/kg induced activities of CAT, SOD and decreased TAC. It is concluded that antioxidative properties of Ag NP is dose dependent.

  16. The fabrication and photocatalytic performances of flower-like Ag nanoparticles/ZnO nanosheets-assembled microspheres

    International Nuclear Information System (INIS)

    Deng, Quan; Tang, Haibin; Liu, Gang; Song, Xiaoping; Xu, Guoping; Li, Qian; Ng, Dickon H.L.; Wang, Guozhong

    2015-01-01

    Graphical abstract: - Highlights: • ZnO nanosheets-assembled microspheres (ZnOs) were prepared. • Ag nanoparticles (Ag-NPs) were decorated onto the whole surface of the ZnOs. • The Ag-NPs/ZnOs composite showed enhanced photocatalytic performance to MB and MO. • Cyclic voltammetry and impedance spectra revealed enhanced charge transportation. - Abstract: A new micro/nanostructure photocatalyst, Ag nanoparticles decorated ZnO nanosheets-assembled microspheres (Ag-NPs/ZnOs), was synthesised by a two-step method. The flower-like micron-sized ZnO spheres assembled with ∼25 nm thick ZnO nanosheets were initially fabricated via a facile solvothermal method. Then, highly dispersed Ag nanoparticles (Ag-NPs) with dimension ranging from 15 to 50 nm were anchored onto the surface of the each ZnO nanosheet by the Sn(II) ion activation method. The as-prepared Ag-NPs/ZnOs demonstrated enhanced photocatalytic performance in eliminating methylene blue and methyl orange aqueous solutions under UV irradiation, showing twice faster reaction rate than the bare ZnOs. The enhanced photocatalytic activity was due to the suppression of electron/hole pair recombination and the acceleration of surface charge transfer induced by the highly dispersive Ag-NPs, which was further demonstrated by the cyclic voltammetry and impedance spectra measurements

  17. Behavior of Ag nanoparticles in soil: Effects of particle surface coating, aging and sewage sludge amendment

    International Nuclear Information System (INIS)

    Whitley, Annie R.; Levard, Clément; Oostveen, Emily; Bertsch, Paul M.; Matocha, Chris J.; Kammer, Frank von der; Unrine, Jason M.

    2013-01-01

    This study addressed the relative importance of particle coating, sewage sludge amendment, and aging on aggregation and dissolution of manufactured Ag nanoparticles (Ag MNPs) in soil pore water. Ag MNPs with citrate (CIT) or polyvinylpyrrolidone (PVP) coatings were incubated with soil or municipal sewage sludge which was then amended to soil (1% or 3% sludge (w/w)). Pore waters were extracted after 1 week and 2 and 6 months and analyzed for chemical speciation, aggregation state and dissolution. Ag MNP coating had profound effects on aggregation state and partitioning to pore water in the absence of sewage sludge, but pre-incubation with sewage sludge negated these effects. This suggests that Ag MNP coating does not need to be taken into account to understand fate of AgMNPs applied to soil through biosolids amendment. Aging of soil also had profound effects that depended on Ag MNP coating and sludge amendment. -- Highlights: •Silver nanoparticle coating affects fate in unamended soils. •Citrated coated silver nanoparticles could be found in pore water for up to six months. •Pre-incubation of silver nanoparticles in sewage sludge negated effects of surface coating. •Weathered or reprecipitated particles found in pore water for up to two months in sludge amended soils. •Particle surface coating, sewage sludge amendment and aging all have important impacts. -- Behavior of manufactured silver nanoparticles in soil depends on surface coating, contact with sewage sludge, and aging

  18. Ag nanoparticles hosted in monolithic mesoporous silica by thermal decomposition method

    International Nuclear Information System (INIS)

    Chen Wei; Zhang Junying

    2003-01-01

    Ag nanoparticles were obtained by thermal decomposition of silver nitrate within pores of mesoporous silica. Microstructure of this composite was examined by X-ray diffraction and high-resolution transmission electron microscopy. Optical measurements for the nanocomposite show that Ag particle doping leads to a large red shift of the absorption edge

  19. Formation of nanoparticles and nanorods via UV irradiation of AgNO3 solutions

    International Nuclear Information System (INIS)

    Szymanska-Chargot, M.; Gruszecka, A.; Smolira, A.; Bederski, K.; Gluch, K.; Cytawa, J.; Michalak, L.

    2009-01-01

    The synthesis of silver nanoparticles via UV irradiation of AgNO 3 solutions was controlled by using UV-vis absorption spectra and TEM (transmission electron microscope) images. The UV-vis absorption method is good enough for the general control of synthesis process, and TEM images give us information about size of formed species. For investigated solutions of silver nitrate in ethanol and water, we observed formation of large nanoparticles (size about 100 nm) and nanorods (100 nm in length). Moreover, there was effort to confirm evidence of formation of these particles by using TOF mass spectrometer. Due to laser desorption/ionization process there is only evidence of small silver nanoparticles Ag x , x ≤ 4 (clusters), and variety of silver compounds Ag x N y O z (x ≤ 5, y ≤ 2, z ≤ 3).

  20. Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays.

    Science.gov (United States)

    Liu, Jing; Chen, Chaoyang; Yang, Guangsong; Chen, Yushan; Yang, Cheng-Fu

    2017-04-03

    The nanosphere lithography (NSL) method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single-layer NSL mask was formed by using self-assembly nano-scale polystyrene (PS) nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single-layer NSL mask. From the observations of scanning electronic microscopy (SEM), we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single-layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e-gun deposition, were used to

  1. Synthesis and characterization of TiO2/Ag/polymer ternary nanoparticles via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Park, Jung Tae; Koh, Joo Hwan; Seo, Jin Ah; Cho, Yong Soo; Kim, Jong Hak

    2011-01-01

    We report on the novel ternary hybrid materials consisting of semiconductor (TiO 2 ), metal (Ag) and polymer (poly(oxyethylene methacrylate) (POEM)). First, a hydrophilic polymer, i.e. POEM, was grafted from TiO 2 nanoparticles via the surface-initiated atom transfer radical polymerization (ATRP) technique. These TiO 2 -POEM brush nanoparticles were used to template the formation of Ag nanoparticles by introduction of a AgCF 3 SO 3 precursor and a NaBH 4 aqueous solution for reduction process. Successful grafting of polymeric chains from the surface of TiO 2 nanoparticles and the in situ formation of Ag nanoparticles within the polymeric chains were confirmed using transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FT-IR spectroscopy also revealed the specific interaction of Ag nanoparticles with the C=O groups of POEM brushes. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the semiconductor, producing ternary hybrid inorganic-organic nanomaterials.

  2. Synthesis and characterization of Ag-Ni bimetallic nanoparticles by laser-induced plasma

    International Nuclear Information System (INIS)

    Xiao Qingmei; Yao Zhi; Liu Jiahong; Hai Ran; Oderji, Hassan Yousefi; Ding Hongbin

    2011-01-01

    We present an approach in which laser ablation deposition is used to synthesize silver-nickel bimetallic nanoparticles. A variety of techniques, including scanning electron microscopy, energy disperse spectroscopy and X-ray photoelectron spectroscopy have been used to characterize the morphology, composition and construction of synthesized bimetallic nanoparticles, respectively. The formation mechanism of bimetallic nanoparticles has been discussed. The Raman spectra of silver-nickel bimetallic nanoparticles have been analyzed. Time-of-flight mass spectrometry has been applied to directly measure intermediate species. The results indicate that diatomic AgNi is the most abundant species and suggest that the AgNi is the most stable intermediate which may play an important role in the synthesis process. Emission spectra demonstrate that the electron temperature is in the range of 6000-10000 K during the ablation process and increases with the laser power density.

  3. Ag/AgCl nanoparticles-modified CdSnO3·3H2O nanocubes photocatalyst for the degradation of methyl orange and antibiotics under visible light irradiation.

    Science.gov (United States)

    Yang, Shi-Feng; Niu, Cheng-Gang; Huang, Da-Wei; Zhang, Huan; Zeng, Guang-Ming

    2017-11-01

    CdSnO 3 ·3H 2 O (CSH) nanocubes modified with Ag/AgCl nanoparticles were constructed via the ultrasonic-assisted precipitation-photoreduction method. The obtained samples were characterized using various analytical techniques. Methyl orange (MO), tetracycline (TC), and oxytetracycline hydrochloride (OTC-HCl) were degraded as target pollutants under visible light irradiation to evaluate the photocatalytic activity of the as-prepared samples. Compared with pure CSH and Ag/AgCl nanoparticles, the developed composite of which 5mL of AgNO 3 was added on the synthesis, labelled as 5-Ag/AgCl/CSH, occupied the best photocatalytic activity. The corresponding degradation rate for MO was 94% within 40min. 94% of TC and 90% of OTC-HCl were also degraded by 5-Ag/AgCl/CSH catalyst within 60min, respectively. The enhanced photocatalytic activity might arise from the surface plasmon resonance effect of Ag/AgCl nanoparticles and efficient separation of photogenerated electron-hole pairs. Meanwhile, a possible photocatalytic mechanism over 5-Ag/AgCl/CSH sample was proposed based on the experiment and theoretical analysis. Copyright © 2017. Published by Elsevier Inc.

  4. Passive accumulation of Au nanoparticles in tumours in mice

    International Nuclear Information System (INIS)

    Kempson, I.M.; Wang, C.H.; Lai, S.F.; Cai, X.; Hwu, Y.; Yang, C.S.; Margaritondo, G.

    2011-01-01

    Full text: Enhance biocompatibility and passive accumulation of gold nanoparticles into tumours in vivo. Improved biocompatible nanoparticles synthesized by radical synthesis in solution by X-ray irradiation (5,000 Gy/sec). As an alternative to the use of chemical reducing agents, irradiation solutions can cause the reduction of dissolved ions to form nuclei form in sub-second times and growth is easily controlled by physically the X-ray intensity. The intensity can be used to manipulate growth rates for different applications and in the information of spherical and rod-structures. Size is easily controlled by exposure time and capping agents and provides high reproducibility with small size distributions. Resulting body burden in subcutaneous tumour mouse models was determined in various organs with ICP-MS. Cellular distributions were analysed with transmission x-ray Microscopy and conventional histology. The resulting nanoparticle sols were highly concentrated. naturally sterile, have high temperature stability and synthesised with fewer chemical reactants; providing greater chemical and biological adaptability. The results demonstrated that a passivated biocompatible surface, minimizing physiological clearance from the animal allows non-specific accumulation of large concentrations of nanoparticles into tumour tissues and significant penetration and circumnavigation of the binding site barrier effect. Concentrations of gold reached ∼ 25 times greater than surrounding muscle tissue and were retained for many hours. Physicochemical properties of nanoparticles impart significant influence on their ability to penetrate and accumulate in tumour tissues. Effective synthesis enables high concentrations of gold nanoparticles to accumulate in tumour tissues which could be applied to development in radiation oncology applications.

  5. SERS-active Ag, Au and Ag–Au alloy nanoparticles obtained by laser ablation in liquids for sensing methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Olea-Mejía, Oscar, E-mail: oleaoscar@yahoo.com.mx [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Universidad Autónoma del Estado de México, km 14.5 Carretera Toluca-Atlacomulco, San Cayetano 50200, México (Mexico); Fernández-Mondragón, Mariana; Rodríguez-de la Concha, Gabriela [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Universidad Autónoma del Estado de México, km 14.5 Carretera Toluca-Atlacomulco, San Cayetano 50200, México (Mexico); Camacho-López, Marco [Laboratorio de Investigación y Desarrollo de Materiales Avanzados, Universidad Autónoma del Estado de México, Km 14.5 Carretera Toluca-Atlacomulco, San Cayetano 50925, México (Mexico)

    2015-09-01

    Highlights: • We synthesized Ag/Au nanoparticles by laser ablation in liquids. • We characterized such particles by UV–vis, TEM and EDS/STEM. • The SERS effect was studied for the obtained nanoparticles. • Pure silver nanoparticles showed the highest SERS signals. • We can sense methylene blue at a concentration of 10{sup −10} mole/L. - Abstract: We have synthesized Ag–Au nanoparticles by laser ablation in liquids using five different targets: 100% Ag, 80%Ag/20%Au, 50%Ag/50%Au, 20%Ag/80%Au and 100% Au (weight percentages). We used ethanol and methylene blue solutions in ethanol as the liquid media. The nanoparticles were mostly spherical with diameters 15, 19, 18, 23 and 11 nm, respectively. When alloyed targets were used, the resulting nanoparticles were completely alloyed forming solid solutions as evidenced by UV–vis Spectroscopy and Scanning Transmission Electron Microscopy. The obtained nanoparticles were employed to study the SERS effect of the methylene blue molecule. All the samples showed good SERS activity, however the ones composed of pure silver showed the greatest Raman signal enhancement. Finally, pure Ag nanoparticles were used for sensing methylene blue at different concentrations. While almost no signal can be discerned from the Raman spectrum when no particles are used at a concentration of methylene blue of 1 × 10{sup −2} M (∼3000 ppm), when Ag nanoparticles are used one can observe the characteristic peak of the molecule at concentrations as low as 1 × 10{sup −10} M (∼3 × 10{sup −5} ppm)

  6. Photoinduced absorption of Ag nanoparticles deposited on ITO substrate

    International Nuclear Information System (INIS)

    Ozga, K.; Oyama, M.; Szota, M.; Nabialek, M.; Kityk, I.V.; Slezak, A.; Umar, A.A.; Nouneh, K.

    2011-01-01

    Research highlights: → We study photoinduced absorption for two Ag NP deposited on the ITO. → The higher resistance eof the NP favors larger photoinduced changes. → Principal role is played by nanointerfaces. - Abstract: Substantial changes of absorption after illumination by 300 mW continuous wave green laser at 532 nm were observed. The effect of indium tin oxide (ITO) substrate was explored versus Ag nanoparticles (AgNPs) size, their regularity and surface plasmon resonance. The ITO substrate features play a crucial role for the formation of homogenous AgNPs. The attachments of AgNPs on ITO surface as well as their homogeneity are significantly changed under the influence of the laser treatment. We study the Ag NP deposited on the two different substrates which play a crucial role in the photoinduced absorption. The dependence of the photoinduced absorption versus the time of optical treatment is explained within a framework of the photopolarization of the particular trapping levels on the borders between the ITO substrate and the Ag NP.

  7. Self-catalytic stabilized Ag-Cu nanoparticles with tailored SERS response for plasmonic photocatalysis

    Science.gov (United States)

    He, Lili; Liu, Changqing; Tang, Jia; Zhou, Youchen; Yang, Hui; Liu, Ruiyu; Hu, Jiugang

    2018-03-01

    In-situ SERS monitoring of direct plasmon-driven photocatalysis was achieved using relatively earth-abundant Cu NPs following their decoration with tiny amounts of silver, which promoted excellent SERS and high catalytic activity. The SERS and catalytic performance of the Ag-Cu NPs can be tuned by changing their composition. In particular, it was found that the surface oxidation state of copper could be switched to its metallic state via self-plasmon catalysis under laser irradiation, highlighting the potential of air-unstable copper NPs as stable plasmonic catalysts. These dual functional Ag-Cu NPs were used for SERS real-time monitoring of plasmon-driven photocatalysis reactions involving the degradation of Rhodamine 6G and the dimerization of 4-nitrothiophenol. The corresponding catalytic reaction mechanisms were discussed.

  8. Pulsed magneto-motive ultrasound imaging to detect intracellular accumulation of magnetic nanoparticles

    International Nuclear Information System (INIS)

    Mehrmohammadi, Mohammad; Qu Min; Sokolov, Konstantin V; Emelianov, Stanislav Y; Ma, Li L; Johnston, Keith P; Romanovicz, Dwight K

    2011-01-01

    As applications of nanoparticles in medical imaging and biomedicine rapidly expand, the interactions of nanoparticles with living cells have become an area of active interest. For example, intracellular accumulation of nanoparticles-an important part of cell-nanoparticle interaction-has been well studied using plasmonic nanoparticles and optical or optics-based techniques due to the change in optical properties of the nanoparticle aggregates. However, magnetic nanoparticles, despite their wide range of clinical applications, do not exhibit plasmonic-resonant properties and therefore their intracellular aggregation cannot be detected by optics-based imaging techniques. In this study, we investigated the feasibility of a novel imaging technique-pulsed magneto-motive ultrasound (pMMUS)-to identify intracellular accumulation of endocytosed magnetic nanoparticles. In pMMUS imaging a focused, high intensity, pulsed magnetic field is used to excite the cells labeled with magnetic nanoparticles, and ultrasound imaging is then used to monitor the mechanical response of the tissue. We demonstrated previously that clusters of magnetic nanoparticles amplify the pMMUS signal in comparison to the signal from individual nanoparticles. Here we further demonstrate that pMMUS imaging can identify interaction between magnetic nanoparticles and living cells, i.e. intracellular accumulation of nanoparticles within the cells. The results of our study suggest that pMMUS imaging can not only detect the presence of magnetic nanoparticles but also provides information about their intracellular accumulation non-invasively and in real-time.

  9. Magnetic and optical properties of Ag@SiO{sub 2}-FITC-Fe{sub 3}O{sub 4} hybrid nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Ning [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France); College of Material Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Monnier, Virginie, E-mail: virginie.monnier@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France); Salvia, Marie-Virginie; Chevolot, Yann; Souteyrand, Eliane [Université de Lyon, Institut des Nanotechnologies de Lyon–INL, UMR CNRS 5270, Site Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully Cedex (France)

    2014-03-15

    Highlights: • New magnetic/fluorescent nanoparticles were synthesized. • The silver core led to a maximum 4-fold enhanced fluorescence of fluorophore. • Maximum enhancement factor was obtained when metal-fluorophore distance is 5 nm. • Magnetism and fluorescence appeared simultaneously for nanoparticles in solution. -- Abstract: Nanoparticles composed of a silver core coated with a silica shell (Ag@SiO{sub 2}) were prepared. A dye, fluorescein isothiocyanate (FITC), was further encapsulated during the growth of a second silica shell onto Ag@SiO{sub 2} nanoparticles. The proximity of silver nanoparticles led to a 4-fold maximal enhancement in the fluorescence of FITC when the first silica shell thickness was set at 5 nm. After amino-functionalization of Ag@SiO{sub 2}-FITC nanoparticles, iron oxide nanoparticles were bonded to their surface. The magnetic and metal-enhanced fluorescence properties appeared simultaneously when Ag@SiO{sub 2}-FITC-Fe{sub 3}O{sub 4} hybrid nanoparticles were dispersed in a solution.

  10. Improving g-C{sub 3}N{sub 4} photocatalysis for NO{sub x} removal by Ag nanoparticles decoration

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yanjuan [Air Environmental Modelling and Pollution Controlling Key Laboratory of Sichuan Higher Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225 (China); Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067 (China); Xiong, Ting; Ni, Zilin [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067 (China); Liu, Jie [Air Environmental Modelling and Pollution Controlling Key Laboratory of Sichuan Higher Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225 (China); Dong, Fan, E-mail: dfctbu@126.com [Air Environmental Modelling and Pollution Controlling Key Laboratory of Sichuan Higher Education Institutes, College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225 (China); Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067 (China); Zhang, Wei, E-mail: andyzhangwei@163.com [Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Ho, Wing-Kei [Department of Science and Environmental Studies, The Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Hong Kong (China)

    2015-12-15

    Graphical abstract: Ag/g-C{sub 3}N{sub 4} nanocomposites were prepared via a facile method for enhanced photocatalytic NO{sub x} removal due to surface plasmon resonance of Ag. - Highlights: • The Ag/g-C{sub 3}N{sub 4} nanocomposites were prepared using urea as the precursor. • The Ag/g-C{sub 3}N{sub 4} nanocomposites were applied in removal of NO{sub x} in air. • The Ag nanoparticles enhanced the photocatalytic activity of g-C{sub 3}N{sub 4}. • The surface plasmon resonance of Ag played a key role in photocatalysis. - Abstract: In order to overcome the intrinsic drawback of pristine g-C{sub 3}N{sub 4}, we prepared g-C{sub 3}N{sub 4} nanosheets with enhanced photocatalytic performance by Ag nanoparticles decoration using urea as the precursor. It was revealed that the monodispersed Ag nanoparticles were deposited on the surface of g-C{sub 3}N{sub 4} nanosheets. The Ag/g-C{sub 3}N{sub 4} nanocomposites were applied in removal of NO{sub x} in air under visible light irradiation. The results showed that the decoration of Ag nanoparticles not only enhanced the photocatalytic activity of g-C{sub 3}N{sub 4} nanosheets, but also benefited the oxidation of NO to final products. The increased visible light absorption arising from the surface plasmon resonance of Ag and improved separation and transfer of photoinduced carriers over Ag/g-C{sub 3}N{sub 4} composites were demonstrated by the UV–vis diffuse reflectance spectra and photoluminescence spectra, respectively. It was therefore proposed that the enhanced photocatalytic activity of Ag/g-C{sub 3}N{sub 4} composites could be attributed to the extended light response range and enhanced charge separation due to the introduction of Ag nanoparticles.

  11. EUROPIUM ION INFLUENCE ON THE FORMATION OF Ag-NANOPARTICLES IN FLUORINE PHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    R. O. Pysh'ev

    2015-05-01

    Full Text Available The paper deals with research of formation characteristics of silver nanoparticles in fluorophosphate glasses 0.25 Na2O - 0.5 P2O5 - 0.10 Ga2O3 - 0.075 AlF3 - 0.025 NaF - 0.05 ZnF2 doped with EuF3 (0.8 and 4 wt.% and without them. The synthesis was carried out in closed glassy carbon crucibles in argon atmosphere. Nanoparticles were formed after a low temperature process of Ag+ → Na+ ion-exchange (320 °C and subsequent heat treatment. It was shown that in the initial glasses doped with EuF3, rare earth ions exist in two valence forms (Eu2+ and Eu3+ in dynamic equilibrium and the concentration of Eu2+ increases proportionally to the total concentration of fluoride. It was shown that sizes of molecular clusters or metal nanoparticles depend on the concentration of europium fluoride and duration of ion exchange. The metallic Ag-nanoparticles sizes were defined for different times of heat treatment and ion exchange. The possibility of the stimulating growth of nanoparticles through the introduction of additional EuF3 in the glass was proved. The possibility of obtaining nanoparticles without the heat treatment in glasses with a high concentration of EuF3 was shown. Chemical mechanism for the formation of Ag-nanoparticles during the ion exchange was suggested.

  12. Protective agent-free synthesis of Ni-Ag core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.-H. [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)]. E-mail: chendh@mail.ncku.edu.tw; Wang, S.-R. [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2006-12-10

    Ni-Ag core-shell nanoparticles have been prepared by successive hydrazine reduction in ethylene glycol in the absence of protective agents. TEM analysis indicated the product was very fine and the thickness of Ag nanoshells could be controlled by the added silver nitrate concentration. The analyses of electron diffraction pattern and XRD revealed that both Ni cores and Ag shells had a fcc structure. The surface composition analysis by XPS indicated that Ni cores were fully covered by Ag nanoshells. Because of the absence of protective agent, the appropriate nickel concentration for the coating of Ag nanoshells should be less than 1.0 mM to avoid particle agglomeration. The product possessed the surface character of Ag and the magnetic property of Ni, and may have many potential applications in optical, magnetic, catalytic, biochemical, and biomedical fields.

  13. Synthesis, Characterizations of Superparamagnetic Fe3O4-Ag Hybrid Nanoparticles and Their Application for Highly Effective Bacteria Inactivation.

    Science.gov (United States)

    Tung, Le Minh; Cong, Nguyen Xuan; Huy, Le Thanh; Lan, Nguyen Thi; Phan, Vu Ngoc; Hoa, Nguyen Quang; Vinh, Le Khanh; Thinh, Nguyen Viet; Tai, Le Thanh; Ngo, Duc-The; Mølhave, Kristian; Huy, Tran Quang; Le, Anh-Tuan

    2016-06-01

    In recent years, outbreaks of infectious diseases caused by pathogenic micro-organisms pose a serious threat to public health. In this work, Fe3O4-Ag hybrid nanoparticles were synthesized by simple chemistry method and these prepared nanoparticles were used to investigate their antibacterial properties and mechanism against methicilline-resistant Staphylococcus aureus (MRSA) pathogen. The formation of dimer-like nanostructure of Fe3O4-Ag hybrid NPs was confirmed by X-ray diffraction and High-resolution Transmission Electron Microscopy. Our biological analysis revealed that the Fe3O4-Ag hybrid NPs showed more noticeable bactericidal activity than that of plain Fe3O4 NPs and Ag-NPs. We suggest that the enhancement in bactericidal activity of Fe3O4-Ag hybrid NPs might be likely from main factors such as: (i) enhanced surface area property of hybrid nanoparticles; (ii) the high catalytic activity of Ag-NPs with good dispersion and aggregation stability due to the iron oxide magnetic carrier, and (iii) large direct physical contacts between the bacterial cell membrane and the hybrid nanoparticles. The superparamagnetic hybrid nanoparticles of iron oxide magnetic nanoparticles decorated with silver nanoparticles can be a potential candidate to effectively treat infectious MRSA pathogen with recyclable capability, targeted bactericidal delivery and minimum release into environment.

  14. Phase transitions during formation of Ag nanoparticles on In{sub 2}S{sub 3} precursor layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: yang.liu@helmholtz-berlin.de; Fu, Yanpeng; Dittrich, Thomas; Sáez-Araoz, Rodrigo; Schmid, Martina; Hinrichs, Volker; Lux-Steiner, Martha Ch.; Fischer, Christian-Herbert

    2015-09-01

    Phase transitions have been investigated for silver deposition onto In{sub 2}S{sub 3} precursor layers by spray chemical vapor deposition from a trimethylphosphine (hexafluoroacetylacetonato) silver (Ag(hfacac)(PMe{sub 3})) solution. The formation of Ag nanoparticles (Ag NPs) on top of the semiconductor layer set on concomitant with the formation of AgIn{sub 5}S{sub 8}. The increase of the diameter of Ag NPs was accompanied by the evolution of orthorhombic AgInS{sub 2}. The formation of Ag{sub 2}S at the interface between Ag NPs and the semiconductor layer was observed. Surface photovoltage spectroscopy indicated charge separation and electronic transitions in the ranges of corresponding band gaps. The phase transition approach is aimed to be applied for the formation of plasmonic nanostructures on top of extremely thin semiconducting layers. - Highlights: • Silver nanoparticles were deposited onto In{sub 2}S{sub 3} precursor layer by spray pyrolysis. • The silver nanoparticle size and density could be controlled by deposition time. • Phase transitions during deposition and material properties were investigated. • The layers still show semiconducting properties after phase transitions. • Plasmonic absorption enhancement has been demonstrated.

  15. Anchoring of Ag-Au alloy nanoparticles on reduced graphene oxide sheets for the reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Hareesh, K., E-mail: appi.2907@gmail.com [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Joshi, R.P. [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Sunitha, D.V. [School of Physics, Reva University, Bangalore 560064 (India); Bhoraskar, V.N. [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-12-15

    Highlights: • Ag-Au-rGO nanocomposite was synthesized by gamma radiation assisted method. • Ag-Au nanoparticles of size (5–19) nm were decorated on rGO. • Ag-Au-rGO showed enhanced catalytic activity for reduction of 4-Nitrophenol. - Abstract: One-step gamma radiation assisted method has been used for the synthesis of Silver-Gold (Ag-Au) alloy nanoparticles with simultaneous reduction of graphene oxide (GO). UV–vis spectroscopic results along with X-ray diffraction analysis, X-ray Photoelectron spectroscopy and Transmission electron microscopy confirmed the decoration face centered cubic structured Ag-Au nanoparticles of size (5–19) nm on reduced graphene oxide (rGO) sheets. The increase in disorder parameter in Raman spectroscopy indicates the formation of more number of small sp{sup 2} domains. The synthesized Ag-Au-rGO nanocomposite showed enhanced catalytic activity towards the reduction of 4-Nitrophenol compared to individual Ag-Au and rGO components.

  16. Fabrication of graphene oxide enwrapped Z-scheme Ag{sub 2}SO{sub 3}/AgBr nanoparticles with enhanced visible-light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Yujuan; Liang, Chunyan; Xia, Yue, E-mail: xiayue_chem@126.com; Huang, Wei; Li, Zelin

    2017-02-28

    Highlights: • A novel GO/Ag{sub 2}SO{sub 3}/AgBr composite was prepared via a solution method. • It showed enhanced photocatalytic performance to degrade dyes under visible light irradiation. • Its photocatalytic ability was effectively maintained for 4 cycles without sacrificial reagents. - Abstract: A novel graphene oxide (GO) enwrapped Ag{sub 2}SO{sub 3}/AgBr (GO/Ag{sub 2}SO{sub 3}/AgBr) composite was fabricated through a facile solution approach via electrostatic interaction and precipitation transformation reaction for the first time. The results of XRD, Raman, SEM, TEM and XPS confirmed the structure, morphology and composition of the GO/Ag{sub 2}SO{sub 3}/AgBr composite very well. The Ag{sub 2}SO{sub 3}/AgBr nanoparticles were found to be encapsulated by GO sheets. The photocatalytic activity of the composite was investigated by the degradation of methyl orange (MO), rhodamine B (RhB) and methylene blue (MB) in water under visible light. The incorporation of GO sheets not only significantly enhanced the photocatalytic activity but also improved the reusability of Ag{sub 2}SO{sub 3}/AgBr nanoparticles. The photocatalytic ability of GO/Ag{sub 2}SO{sub 3}/AgBr can be maintained at a high level for 4 times cycle experiments. The trapping experiments confirmed that holes and superoxide ion radicals were the main active species responsible for the degradation reaction. A plasmonic Z-scheme photocatalytic mechanism was proposed to illustrate the possible transferred and separated behavior of electron-hole pairs among Ag, Ag{sub 2}SO{sub 3}, AgBr and GO quaternary system under visible light irradiation.

  17. Limitations and possibilities of green synthesis and long-term stability of colloidal Ag nanoparticles

    Science.gov (United States)

    Velgosová, Oksana; Mražíková, Anna

    2017-12-01

    In this paper the influence of algae life cycle and the solutions pH on the green synthesis of colloidal Ag nanoparticles (AgNPs) as well as effect of different storage conditions on AgNPs long-term stability was investigated. Silver nanoparticles were biologically synthesized using extracts of Parachlorella kessleri algae cultivated 1, 2, 3 and 4 weeks. The formation of AgNPs was monitored using a UV-vis spectrophotometer and verified by TEM observation. The results confirmed formation of polyhedron and/or near polyhedron AgNPs, ranging between 5 and 60 nm in diameter. The age of algae influenced the synthesis rate and an amount of AgNPs in solution. The best results were obtained using tree weeks old algae. UV-vis analysis and TEM observation also revealed that the size and the stability of AgNPs depend on the pH of solution. AgNPs formed in solutions of higher pH (8 and 10) are polyhedron, fine, with narrow size interval and stabile. Nanoparticles formed in solutions of low pH (2, 4 and 6) started to lose their stability on 10th day of experiment, and the particle size interval was wide. The long-term stability of AgNPs can be influenced by light and temperature conditions. The most significant stability loss was observed at day light and room temperature (21°C). After 200-days significant amount of agglomerated particles settled on the bottom of the Erlenmeyer flask. AgNPs stored at dark and room temperature showed better long-term stability, weak particles agglomeration was observed. AgNPs stored at dark and at temperature 5°C showed the best long-term stability. Such AgNPs remained spherical, fine (5-20 nm), with narrow size interval and stable (no agglomeration) even after more than six months.

  18. Breathing Raman modes in Ag{sub 2}S nanoparticles obtained from F9 zeolite matrix

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Beleño, Y. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Cortez-Valadez, M., E-mail: jose.cortez@unison.mx [CONACYT Research Fellow, Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Martinez-Nuñez, C.E.; Britto Hurtado, R.; Alvarez, Ramón A.B.; Rocha-Rocha, O.; Arizpe-Chávez, H.; Perez-Rodríguez, A.; Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico)

    2015-12-16

    Highlights: • Raman breathing modes in small silver sulfide nanoparticles. • Low energy (AgS){sub n} clusters. • Vibrational spectra predicted by DFT. • Zeolite synthesis for small nanoparticles. - Abstract: Ag{sub 2}S nanoparticles were synthesized with a combination of synthetic F9, silver nitrate (AgNO{sub 3}) and monohydrated sodium sulfide (Na{sub 2}S{sub 9}H{sub 2}O). An ionic exchange was achieved via hydrothermal reaction. Nanoparticles with a predominant size ranging from 2 to 3 nm were obtained through Transmission Electron Microscopy (TEM). The nanoparticles feature a phase P21/n (14) monoclinic structure. A Raman band can be observed at around 250 cm{sup −1} in the nanoparticles. Furthermore, the vibrational properties and stability parameters of the clusters (AgS){sub n}, (with n = 2–9) were studied by the Density Functional Theory (DFT). The approximation levels used with DFT were: Local Spin Density Approximation (LSDA) and Becke’s three-parameter and the gradient corrected functional of Lee, Yang and Puar (B3LYP) in combination with the basis set LANL2DZ (the effective core potentials and associated double-zeta valence). The Radial Breathing Mode (RBM) for B3LYP was found between 227 and 295 cm{sup −1} as well as in longer wavelengths for LSDA.

  19. Solvent and stabilizer free growth of Ag and Pd nanoparticles using metallic salts/cyclotriphosphazenes mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Díaz Valenzuela, C. [Departamento de Química, Facultad de Química, Universidad de Chile, La Palmeras 3425, Nuñoa, Casilla 653, Santiago de Chile (Chile); Valenzuela, M.L., E-mail: mlvalenzuela@unab.cl [Universidad Andres Bello, Departamento de Ciencias Química, Facultad de Ciencias Exactas, Av. Republica 275, Santiago (Chile); Caceres, S.; Diaz, R. [Departamento de Química, Facultad de Química, Universidad de Chile, La Palmeras 3425, Nuñoa, Casilla 653, Santiago de Chile (Chile); O' Dwyer, C. [Applied Nanoscience Group, Department of Chemistry, University College Cork, Cork (Ireland); Micro and Nanoelectronics Centre, Tyndall National Institute, Lee Maltings, Cork (Ireland)

    2013-12-16

    Cyclotriphosphazene is used as a sacrificial solid-state template to synthesize a range of Ag and Pd nanoparticles with diverse geometries by thermal treatment using MLn/N{sub 3}P{sub 3}(O{sub 2}C{sub 12}H{sub 8}){sub 3} mixtures. The Pd and Ag nanoparticles are synthesized by solid-state pyrolysis of AgPPh{sub 3}[CF{sub 3}SO{sub 3}]/N{sub 3}P{sub 3}(O{sub 2}C{sub 12}H{sub 8}){sub 3} and PdCl{sub 2}/N{sub 3}P{sub 3}(O{sub 2}C{sub 12}H{sub 8}){sub 3} mixtures with molar relationships of 1:1, 1:5 and 1:10 respectively, in air and at 800 °C. The morphology of the as-prepared nanoparticles is found to depend on the molar ratio of the precursor mixture, the preparation method and of the nature of the metal. Ag and Pd, microcrystals were thermally grown on Si from the respective 1:1 precursors while that metal foams were grown from 1:5 ratios precursors on SiO{sub 2} wafers. High resolution transmission electron microscopy investigations reveal in most cases small crystals of Pd. HRSTEM measurements indicate that the formation of the Pd and Ag nanoparticles occurs through a phase demixing and dewetting mechanism. This approach has potential to be a useful and facile method to prepare metallic nanoparticles without requiring solutions or surfactants for application in electronic, catalytic and sensor materials and devices. - Highlights: • Pyrolysis MLn/N{sub 3}P{sub 3}(O{sub 2}C{sub 12}H{sub 8}){sub 3} mixtures under air, give Pd and Ag nanoparticles. • AgPPh{sub 3}[CF{sub 3}SO{sub 3}] and PdCl{sub 2} in molar ratios 1:1 and 1:5 were used. • Metal foams were obtained from 1:5 ratios when deposited on SiO{sub 2.} • Using crucible supporting in 1:1 metal/trimer <2 nm Pd nanoparticles were obtained. • The probable mechanism involves a dewetting, nucleation and ripening crystallization.

  20. Antimicrobial activity of tantalum oxide coatings decorated with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huiliang, E-mail: hlc@mail.sic.ac.cn; Meng, Fanhao; Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2016-07-15

    Silver plasma immersion ion implantation was used to decorate silver nanoparticles (Ag NPs) on tantalum oxide (TO) coatings. The coatings acted against bacterial cells (Staphylococcus epidermidis) in the dark by disrupting their integrity. The action was independent of silver release and likely driven by the electron storage capability of the Schottky barriers established at the interfaces between Ag NPs and the TO support. Moreover, no apparent side effect on the adhesion and differentiation of rat bone mesenchymal stem cells was detected when using Ag NPs-modified TO coatings. These results demonstrate that decoration of tantalum oxide using Ag NPs could be a promising procedure for improving the antibacterial properties for orthopedic and dental implants.

  1. Embedded layer of Ag nanoparticles prepared by a combined PECVD/PVD process producing SiOxCy-Ag nanocomposite thin films.

    Science.gov (United States)

    Bedel, Laurent; Cayron, Cyril; Jouve, Michel; Maury, Francis

    2012-01-13

    Structural properties of SiO(x)C(y)-Ag nanocomposite thin films prepared by a dual process PVD-PECVD in the same reactor have been investigated. The experimental results have demonstrated the influence of a PECVD process carried out at room temperature for the growth of a dielectric matrix on the size and the distribution density of Ag nanoparticles (NPs) deposited beforehand by magnetron sputtering. The plasma during the growth of the encapsulation SiO(x)C(y) layer caused a diffusion of silver from NPs through the SiO(x)C(y) matrix associated with a decrease in the average size of nanoparticles and an increase of their distribution density. Silver diffusion is blocked at a barrier interface to form a buried layer of individual Ag NPs which, for instance, can find plasmonic applications. Silver also diffuses toward the outer surface inducing antibacterial properties. In both cases initial Ag NPs act as reservoirs for multifunctional properties of advanced nanostructured films.

  2. Sensors based on Ag-loaded hematite (α-Fe2O3 nanoparticles for methyl mercaptan detection at room temperature

    Directory of Open Access Journals (Sweden)

    Daniel Garcia

    2017-06-01

    Full Text Available Sensors based on Ag/α-Fe2O3 nanoparticles have been prepared by the coprecipitation method for sensing methyl mercaptan at room temperature. X-ray diffraction patterns of samples matched perfectly with characteristic peaks of hematite with no peaks assigned to Ag even at the highest concentration. STEM images and EDX analysis revealed the presence of Ag nanoparticles (from 2 to 5 nm which were highly dispersed onto α-Fe2O3 surface with an Ag/Fe ratio from 0.014 to 0.099. The Ag nanoparticles were deposited on the hematite surface. Sensing tests of Ag-loaded hematite nanoparticles showed much higher response signal than the unmodified sensor. Hematite loaded with 3%(Wt Ag showed the highest response with a linear dependence from 20 to 80 ppm. The sensor also depicted a good selectivity and stability during 4 days with short recovery time. The high dispersion of reduced Ag evaluated by XPS analysis played an important chemical role in the sensing mechanism that favored the contact of CH3SH with oxygen.

  3. Phytotoxicity, uptake, and accumulation of silver with different particle sizes and chemical forms

    Energy Technology Data Exchange (ETDEWEB)

    Quah, Bryan [Southern Illinois University Carbondale, Department of Civil and Environmental Engineering (United States); Musante, Craig; White, Jason C. [The Connecticut Agricultural Experiment Station, Department of Analytical Chemistry (United States); Ma, Xingmao, E-mail: xma@civil.tamu.edu [Texas A& M University, Zachry Department of Civil Engineering (United States)

    2015-06-15

    The antimicrobial property of silver nanoparticles (AgNPs) makes it one of the most commonly encountered nanomaterials in commercial products. Consequently, its detection in the environment is highly likely and its potential toxicity has been heavily investigated. While it is now generally agreed that AgNP itself exerts unique toxicity to plants in addition to that of dissolved silver ion, the accumulation and fate of different forms of silver in plant tissues are unknown. This study investigates the phytotoxicity, accumulation, and transport of Ag with different physical and chemical characteristics (e.g., ionic, nanoparticles, and bulk) in two agricultural crop species: Glycine max (soybean) and Triticum aestivum (wheat). The results showed that different forms of Ag demonstrated differential toxicity in these two species, with the Ag{sup +} at the same nominal concentration displaying the strongest effect on plant growth. Exposure to 5 mg/L of elemental Ag in different forms all resulted in significant deposition on the root surface but its morphology and distribution patterns varied considerably. The Ag transport efficiency from roots to shoots differed with both Ag type and plant species. Notably, the upward transport of AgNPs (20–50 nm) was considerably more substantial than that of bulk Ag (1–3 µm). Cell fractionation studies confirmed that all types of Ag were internalized, with the plant cell wall as the predominant place for element accumulation. The findings demonstrate that Ag toxicity and in planta fate vary with particle type and that such considerations are likely necessary to adequately assess food safety concerns upon NP exposure.

  4. The effects of silver nanoparticles on mouse embryonic stem cell self-renewal and proliferation

    Directory of Open Access Journals (Sweden)

    Pavan Rajanahalli

    2015-01-01

    Full Text Available Silver nanoparticles (AgNPs are gaining rapid popularity in many commonly used medical and commercial products for their unique anti-bacterial properties. The molecular mechanisms of effects of AgNPs on stem cell self-renewal and proliferation have not yet been well understood. The aim of the work is to use mouse embryonic stem cells (mESCs as a cellular model to evaluate the toxicity of AgNPs. mESC is a very special cell type which has self-renewal and differentiation properties. The objective of this project is to determine the effects of AgNPs with different surface chemical compositions on the self-renewal and cell cycle of mESCs. Two different surface chemical compositions of AgNPs, polysaccharide-coated and hydrocarbon-coated, were used to test their toxic effects on self-renewal and proliferation of mESCs. The results indicated that both polysaccharide-coated and hydrocarbon-coated AgNPs changed the cell morphology of mESCs. Cell cycle analysis indicated that AgNPs induced mESCs cell cycle arrest at G1 and S phases through inhibition of the hyperphosphorylation of Retinoblastoma (Rb protein. Furthermore, AgNPs exposure reduced Oct4A isoform expression which is responsible for the pluripotency of mESCs, and induced the expression of several isoforms OCT4B-265, OCT4B-190, OCT4B-164 which were suggested involved in stem cell stresses responses. In addition, the evidence of reactive oxygen species (ROS production with two different surface chemical compositions of AgNPs supported our hypothesis that the toxic effect AgNPs exposure is due to overproduction of ROS which altered the gene expression and protein modifications. Polysaccharide coating reduced ROS production, and thus reduced the AgNPs toxicity.

  5. A New Smart Surface-Enhanced Raman Scattering Sensor Based on pH-Responsive Polyacryloyl Hydrazine Capped Ag Nanoparticles.

    Science.gov (United States)

    Yuan, Shuai; Ge, Fengyan; Zhou, Man; Cai, Zaisheng; Guang, Shanyi

    2017-08-14

    A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10 -12  M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors.

  6. A New Smart Surface-Enhanced Raman Scattering Sensor Based on pH-Responsive Polyacryloyl Hydrazine Capped Ag Nanoparticles

    Science.gov (United States)

    Yuan, Shuai; Ge, Fengyan; Zhou, Man; Cai, Zaisheng; Guang, Shanyi

    2017-08-01

    A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10-12 M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors.

  7. Synthesis of polymer-stabilized monometallic Cu and bimetallic Cu/Ag nanoparticles and their surface-enhanced Raman scattering properties

    Science.gov (United States)

    Zhang, Danhui; Liu, Xiaoheng

    2013-03-01

    The present study demonstrates a facile process for the production of spherical-shaped Cu and Ag nanoparticles synthesized and stabilized by hydrazine and gelatin, respectively. Advantages of the synthetic method include its production of water dispersible copper and copper/silver nanoparticles at room temperature under no inert atmosphere. The resulting nanoparticles (copper or copper/silver) are investigated by X-ray diffraction (XRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The nanometallic dispersions were characterized by surface plasmon absorbance measuring at 420 and 572 nm for Ag and Cu nanoparticles, respectively. Transmission electron microscopy showed the formation of nanoparticles in the range of ˜10 nm (silver), and ˜30 nm (copper). The results also demonstrate that the reducing order of Cu2+/Ag+ is important for the formation of the bimetallic nanoparticles. The surface-enhanced Raman scattering effects of copper and copper/silver nanoparticles were also displayed. It was found that the enhancement ability of copper/silver nanoparticles was little higher than the copper nanoparticles.

  8. Synergetic scattering of SiO2 and Ag nanoparticles for light-trapping enhancement in organic bulk heterojunction

    Science.gov (United States)

    Yang, Huan; Ding, Qiuyu; Li, Ben Q.; Jiang, Xinbing; Zhang, Manman

    2018-02-01

    Though noble metal nanoparticles have been explored to enhance the performance of the organic solar cell, effect of dielectric nanoparticles, and coupled effect of dielectric and metal nanoparticles, have rarely been reported, if at all, on organic solar cell. This work reports an experimental study on synergetic scattering of SiO2 and Ag nanoparticles in a bulk organic heterojunction for the broadband light absorption enhancement. The wavelength scale SiO2 particles were arranged as a monolayer on the surface of the solar cell to guide incident light into the active layer and prolong the effective optical length of the entered energy. This is achieved by the excitation of whispering gallery modes in SiO2 nanoparticles and by leaky mode radiation. When small size Ag particles were incorporated into the transport layer of the solar cell, synergetic scattering of SiO2 and Ag nanoparticles is formed by coupling of the whispering gallery mode of closely arranged SiO2 particles atop and collaborative localized surface plasma resonance scattering of Ag nanoparticles dispersed in the transport layer. As a result, the performance of the organic solar cell is greatly enhanced and the short-circuit current density has an improvement of 42.47%. Therefore, the organic solar cell incorporated with SiO2 and Ag particles presents a meaningful strategy to achieve high energy-harvesting performance. [Figure not available: see fulltext.

  9. The effect of Ni pre-implantation on surface morphology and optical absorption properties of Ag nanoparticles embedded in SiO2

    International Nuclear Information System (INIS)

    Shen, Yanyan; Qi, Ting; Qiao, Yu; Yu, Shengwang; Hei, Hongjun; He, Zhiyong

    2016-01-01

    Graphical abstract: - Highlights: • Ag concentration increased significantly due to the Ni pre-implantation. • Deposition and accumulation process of Ag atoms depends on Ni fluences. • The incorporation of Ni elements in Ag NPs can damp SPR absorption intensity. • AgNi alloy NPs embedded in SiO 2 have been created by sequentially implantation. • Unique SPR absorption with dual peaks centered at 406 nm and 563 nm was observed. - Abstract: The effect of Ni ion fluence on Ag nucleation and particle growth was investigated by sequentially implantation of 60 keV Ni ions at fluences of 1 × 10 16 , 5 × 10 16 , 1 × 10 17 ions/cm 2 and 70 keV Ag ions at a fluence of 5 × 10 16 ions/cm 2 . Due to the modification of the deposition and accumulation process of Ag implants caused by Ni pre-implantation, the surface morphology, structures, and optical absorption properties of the Ag nanoparticles (NPs) depends strongly on the Ni fluences. UV–vis absorption spectroscopy study showed that the introducing of Ni atoms lead to intensity decrease in the Ag SPR band. Remarkable local concentration increase of Ag profiles appeared for the sample pre-implanted by Ni ions of 5.0 × 10 16 ions/cm 2 . In particular, the AgNi alloy NPs with dual absorption peaks centered at 406 nm and 563 nm have been formed after 600 °C annealing in Ar atmosphere. However, at a low fluence of 1.0 × 10 16 ions/cm 2 , only small increase of the local Ag concentration than the Ag ions singly implanted sample can be observed. At a high fluence of 1.0 × 10 17 ions/cm 2 , lots Ag atoms are trapped close to the surface, which result in heavy sputtering loss of Ag atoms and the sublimation of Ag atoms after 600 °C annealing.

  10. Ag and CdS nanoparticles co-sensitized TiO2 nanotubes for enhancing visible photoelectrochemical performance

    International Nuclear Information System (INIS)

    Wang Qingyao; Yang Xiuchun; Liu Dan; Chi Lina; Hou Junwei

    2012-01-01

    Highlights: ► Ag and CdS nanoparticles co-sensitized TiO 2 nanotubes were fabricated by the SILAR method. ► The co-sensitization expands the photoresponse range of TiO 2 NTs to 668.7 nm. ► Visible light photocurrents and photocatalytic activities of CdS–Ag/TiO 2 NTs were studied. ► The electron transfer mechanism of CdS–Ag/TiO 2 NTs was proposed. - Abstract: The Ag and CdS nanoparticles co-sensitization of TiO 2 nanotubes (CdS–Ag/TiO 2 NTs) were prepared by successive ionic layer adsorption and reaction (SILAR) technique. The phase composition, morphology and optical property were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffusion reflection spectroscopy (DRS). The co-modification of Ag and CdS nanoparticles expanded the photoresponse range of TiO 2 NTs from ultraviolet region to 668.7 nm, and the CdS–Ag/TiO 2 NTs prepared by SILAR deposition of 5 cycles exhibited higher visible photocurrent and stability against photocorrosion. The detailed electrons transfer mechanism of CdS–Ag/TiO 2 NTs was proposed, and photocatalytic activity toward degradation of methyl orange (MO) under visible-light irradiation was also investigated.

  11. Influence of plasmon coupling on the photoluminescence of ZnS/Ag nanoparticles obtained by laser irradiation in liquid

    Science.gov (United States)

    Moos, Rafaela; Graff, Ismael L.; de Oliveira, Vinicius S.; Schreiner, Wido H.; Bezerra, Arandi G.

    2017-10-01

    We investigate the photoluminescence, optical absorption and structural properties of ZnS submitted to laser irradiation in water and isopropyl alcohol. Nanoparticles were produced by irradiating micro-sized ZnS particles dispersed in both liquids, with and without the addition of Ag nanoparticles, taking advantage of the laser-assisted fragmentation effect. When ZnS microparticles are irradiated either in pure water or isopropyl alcohol a considerable size reduction is achieved (from micra to few nanometers). The photoluminescence of these nanoparticles mainly occurs in the UV, centered at 350 nm, and with smaller intensity in the visible, centered at 600 nm. Irradiation of ZnS microparticles dispersed in colloidal silver triggers a reaction between both materials, modifying its optical absorption and photoluminescent properties. After irradiation of ZnS in alcohol containing Ag nanoparticles, a giant increase of the UV photoluminescence is observed. Interestingly, when the irradiation is performed in aqueous Ag nanoparticles colloids, the photoluminescence suffers a red-shift towards the violet-blue. The data show that core-shell (Ag-ZnO) nanostructures are formed after irradiation and the visible emission likely originates from the ZnO shell grown around silver nanoparticles. The presence of Ag nanoparticles in the liquid medium promotes a stronger absorption of the laser beam during irradiation due to the coupling with the surface plasmon resonance, fostering intense reactions among ZnS, Ag nanoparticles, and the liquid medium. Our study shows that with a simple change of the liquid medium wherein the irradiation is conducted the photoluminescence can be tuned from UV to visible and core-shell nanostructures can be obtained.

  12. Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

    Science.gov (United States)

    Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

    2015-11-18

    Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles.

  13. Fabrication, characterization and screen printing of conductive ink based on carbon@Ag core-shell nanoparticles.

    Science.gov (United States)

    Wu, Wei; Yang, Shuanglei; Zhang, Shaofeng; Zhang, Hongbo; Jiang, Changzhong

    2014-08-01

    The large-scale synthesis and characterization of carbon-core/Ag-shell (C@Ag) nanoparticles by the successive reduction of silver ammonia are described. The resultant C@Ag nanoparticles had a mean core diameter of 360 nm and a controllable shell thickness from 10 to 40 nm by simple adjustments of repeat coating times. Various analysis techniques confirmed that the carbon cores were fully covered by Ag nanoshells. The results also show that C/Ag composite nanomaterials-based conductive inks, which can be easily produced on a large scale and possess outstanding electronic properties, have great potential for the convenient fabrication of flexible and low-cost carbon-based electronic devices and replace the traditional pure silver paste, by using a simple screen printing technique. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Film Formation of Ag Nanoparticles at the Organic-Aqueous Liquid Interface

    Science.gov (United States)

    Vigorita, John

    2005-03-01

    A wet-chemical method to make films by spontaneous assembly of passivated Ag nanoparticles at the organic-aqueous liquid interface is presented. The interfacial films exhibit a blue opalescence, or in other cases a silvery color, and are characterized with transmission electron microscopy and UV-visible spectrophotometry. Measurements indicate that nanoparticles in the interfacial film can form superlattices and in some cases nanostructures.

  15. Impact of Ag and Al2O3 nanoparticles on soil organisms: In vitro and soil experiments

    International Nuclear Information System (INIS)

    Fajardo, C.; Saccà, M.L.; Costa, G.; Nande, M.; Martin, M.

    2014-01-01

    In vitro analyses were conducted to assess the impact of Al 2 O 3 and Ag nanoparticles on two common soil bacteria, Bacillus cereus and Pseudomonas stutzeri. Al 2 O 3 nanoparticles did not show significant toxicity at any dose or time assayed, whereas exposure to 5 mg L −1 Ag nanoparticles for 48 h caused bactericidal effects. Moreover, alterations at the morphological level were observed by transmission electron microscopy (TEM); Ag but not Al 2 O 3 nanoparticles evoked the entrance of B. cereus cells in an early sporulation stage and both nanoparticles penetrated P. stutzeri cells. At the molecular level, a dramatic increase (8.2-fold) in katB gene expression was found in P. stutzeri following Al 2 O 3 nanoparticles exposure, indicative of an oxidative stress-defence system enhancement in this bacterium. In the microcosm experiment, using two different natural soils, Al 2 O 3 or Ag nanoparticles did not affect the Caenorhabditis elegans toxicity endpoints growth, survival, or reproduction. However, differences in microbial phylogenetic compositions were detected by fluorescence in situ hybridization (FISH). The use of katB- and pykA-based sequences showed that the microbial transcriptional response to nanoparticle exposure decreased, suggesting a decrease in cellular activity. These changes were attributable to both the nanoparticles treatment and soil characteristics, highlighting the importance of considering the soil matrix on a case by case basis. - Highlights: • Al 2 O 3 or Ag NPs impact on bacteria was assessed at phenotypic and molecular level. • katB gene involved in oxidative-stress response was overexpressed in P. stutzeri following Al 2 O 3 NPs exposure. • A decrease in bacterial transcriptional response was detected in NPs-treated soils. • A soil-dependent response to specific NP treatment was observed. • In NPs-treated soils no acute toxic effects on C. elegans were found

  16. Effects of concentration of Ag nanoparticles on surface structure and in vitro biological responses of oxide layer on pure titanium via plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ki Ryong; Kim, Yeon Sung; Kim, Gye Won [Department of Materials Science and Engineering, Hanyang University, Ansan 425-791 (Korea, Republic of); Yang, Hae Woong [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ko, Young Gun, E-mail: younggun@ynu.ac.kr [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Shin, Dong Hyuk, E-mail: dhshin@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, Ansan 425-791 (Korea, Republic of)

    2015-08-30

    Highlights: • Ag nanoparticles were embedded into the oxide surface without any compositional changes. • Oxide layer from the electrolyte with 0.1 g/l Ag nanoparticles could disinfect all bacteria. • With increasing Ag nanoparticles, bone-forming ability and cell proliferation rate decrease. - Abstract: This study was to investigate how Ag nanoparticles with various concentrations affect the surface structure and in vitro biological properties of oxide layers on the pure titanium produced by a plasma electrolytic oxidation (PEO) process. For this aim, PEO processes were carried out at an AC current density of 100 mA/cm{sup 2} for 300 s in potassium pyrophosphate (K{sub 4}P{sub 2}O{sub 7}) electrolytes containing 0, 0.1, 0.3 and 0.5 g/l Ag nanoparticles. Structural investigations using scanning electron microscopy evidenced that the oxide layers showed the successful incorporation of Ag nanoparticles, and the topographical deformation of the porous surface was found when the concentration of Ag nanoparticles was more than 0.1 g/l. Based on the anti-bacterial activity of all oxide layers, the Ag nanoparticles uniformly spread were of considerable importance in triggering the disinfection of E. coli bacteria. The bone forming abilities and cell (MC3T3-E1) proliferation rates of oxide layers produced in electrolytes containing 0 and 0.1 g/l Ag nanoparticles were higher than those containing 0.3 and 0.5 g/l Ag nanoparticles. Consequently, the oxide layer on pure titanium via PEO process in the electrolyte with 0.1 g/l Ag nanoparticles exhibited better the bioactivity accompanying the anti-bacterial activity.

  17. Photoelectrochemical Performances and Potential Applications of TiO2 Nanotube Arrays Modified with Ag and Pt Nanoparticles

    International Nuclear Information System (INIS)

    Xu, Guangqing; Liu, Haipeng; Wang, Jinwen; Lv, Jun; Zheng, Zhixiang; Wu, Yucheng

    2014-01-01

    TiO 2 nanotube arrays (NTAs) modified with Ag (Ag/TiO 2 ) and Pt (Pt/TiO 2 ) nanoparticles were fabricated by anodic oxidation combined with photoreduction and hydrothermal methods, respectively. Structures, element components and morphologies of TiO 2 , Ag/TiO 2 and Pt/TiO 2 NTAs were measured by X-ray diffraction diffractometer, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The photoeletrochemical performances of TiO 2 , Pt/TiO 2 and Ag/TiO 2 NTAs were characterized by cyclic voltammetry and amperometry in phosphate buffer solution in absence and presence of glucose. Modifications of Ag and Pt nanoparticles play different roles in the photoelectrochemical process and have different potential applications. Ag nanoparticles decrease the photocurrent in buffer solution but increase the photocurrent response to organic compounds, which is fit for electrochemical detection of organic compounds due to the low background photocurrent and high photocurrent response. Ag/TiO 2 NTAs achieve the best detection performance with sensitivity of 0.152 μA/μM and detection limit of 0.53 μM. On the contrary, Pt nanoparticles can enhance the photocurrent of TiO 2 NTAs in buffer solution but decrease the photocurrent response to organic compounds, which are benefit for photocatalytic water splitting but not for photoelectrochemical detection

  18. Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4-Ag core-shell nanoparticles: Characterization and application

    International Nuclear Information System (INIS)

    Tahmasebi, Elham; Yamini, Yadollah

    2012-01-01

    Graphical abstract: Self assembling of bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid on Fe 3 O 4 -Ag core-shell nanoparticles and application of it for solid phase extraction of PAHs. Highlights: ► A novel sorbent for magnetic solid-phase extraction of PAHs was introduced. ► Silver was coated on Fe 3 O 4 nanoparticles (MNPs) by reduction of AgNO 3 with NaBH 4 . ► Bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid self-assembled on silver coated MNPs. ► Size, morphology, composition and properties of the nanoparticles were characterized. ► Extraction efficiency of the sorbent was investigated by extraction of five PAHs. - Abstract: A novel sorbent for magnetic solid-phase extraction by self-assembling of organosulfur compound, (bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid), onto the silver-coated Fe 3 O 4 nanoparticles was introduced. Due to the formation of covalent bond of S-Ag, the new coating on the silver surface was very stable and showed high thermal stability (up to 320 °C). The size, morphology, composition, and properties of the prepared nanoparticles have also been characterized and determined using scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), dynamic light scattering (DLS), Fourier transform-infrared (FT-IR) spectroscopy, and thermal gravimetric analysis (TGA). Extraction efficiency of the new sorbent was investigated by extraction of five polycyclic aromatic hydrocarbons (PAHs) as model compounds. The optimum extraction conditions for PAHs were obtained as of extraction time, 20 min; 50 mg sorbent from 100 mL of the sample solution, and elution with 100 μL of 1-propanol under fierce vortex for 2 min. Under the optimal conditions, the calibration curves were obtained in the range of 0.05–100 μg L −1 (R 2 > 0.9980) and the LODs (S/N = 3) were obtained in the range of 0.02–0.10 μg L −1 . Relative standard deviations (RSDs) for intra- and inter-day precision were 2.6–4.2% and 3.6–8

  19. Soil type influence on Ag Nanoparticles by earthworms, Eisenia fetida

    DEFF Research Database (Denmark)

    Mariyadas, Jennifer; Mónica, Amorim; Scott-Fordsmand, Janeck James

    2014-01-01

    Earthworms are key sentinel organisms playing an important role in improving the soil structure. Here we tested the importance of soil type on the toxicity to silver nanoparticles (Ag NPs) to earthworms, Eisenia fetida. Silver nanoparticles are widely used in a range of consumer products mainly...... as antibacterial agents and thus causes potential risk to the environment once these particles are released into the environment [1]. In our tests, we were able to show that the earthworm toxicity was strongly dependent on the soil type, with strongest effect in low organic matter soil. Studies on the organic...... matter content, clay and cation exchange capacity along with the metal solution activity will provide insight into the bioavailability of metals in different soils, hence For each of the soil type the fate of the AgNPs was also measured....

  20. Ag/C:F Antibacterial and hydrophobic nanocomposite coatings

    Science.gov (United States)

    Kylián, Ondřej; Kratochvíl, Jiří; Petr, Martin; Kuzminova, Anna; Slavínská, Danka; Biederman, Hynek; Beranová, Jana

    Silver-based nanomaterials that exhibit antibacterial character are intensively studied as they represent promising weapon against multi-drug resistant bacteria. Equally important class of materials represent coatings that have highly water repellent nature. Such materials may be used for fabrication of anti-fogging or self-cleaning surfaces. The aim of this study is to combine both of these valuable material characteristics. Antibacterial and highly hydrophobic Ag/C:F nanocomposite films were fabricated by means of gas aggregation source of Ag nanoparticles and sputter deposition of C:F matrix. The nanocomposite coatings had three-layer structure C:F base layer/Ag nanoparticles/C:F top layer. It is shown that the increasing number of Ag nanoparticles in produced coatings leads not only in enhancement of their antibacterial activity, but also causes substantial increase of their hydrophobicity. Under optimized conditions, the coatings are super-hydrophobic with water contact angle equal to 165∘ and are capable to induce 6-log reduction of bacteria presented in solution within 4h.

  1. Tribological behavior of in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films

    International Nuclear Information System (INIS)

    Guo Yanbao; Wang Deguo; Liu Shuhai

    2010-01-01

    Multilayer polyelectrolyte films containing silver ions were obtained by molecular deposition method on a glass plate or a quartz substrate. The in situ Ag nanoparticles were synthesized in the multilayer polyelectrolyte films which were put into fresh NaBH 4 aqueous solution. The structure and surface morphology of composite molecular deposition films were observed by UV-vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Tribological characteristic was investigated by AFM and micro-tribometer. It was found that the in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films have lower coefficient of friction and higher anti-wear life than pure polyelectrolyte molecular deposition films.

  2. Synthesis of Gold Nanoparticle-Embedded Silver Cubic Mesh Nanostructures Using AgCl Nanocubes for Plasmonic Photocatalysis.

    Science.gov (United States)

    Joo, Jang Ho; Kim, Byung-Ho; Lee, Jae-Seung

    2017-11-01

    A novel room-temperature aqueous synthesis for gold nanoparticle-embedded silver cubic mesh nanostructures using AgCl templates via a template-assisted coreduction method is developed. The cubic AgCl templates are coreduced in the presence of AuCl 4 - and Ag + , resulting in the reduction of AuCl 4 - into gold nanoparticles on the outer region of AgCl templates, followed by the reduction of AgCl and Ag + into silver cubic mesh nanostructures. Removal of the template clearly demonstrates the delicately designed silver mesh nanostructures embedded with gold nanoparticles. The synthetic mechanism, structural properties, and surface functionalization are spectroscopically investigated. The plasmonic photocatalysis of the cubic mesh nanostructures for the degradation of organic pollutants and removal of highly toxic metal ions is investigated; the photocatalytic activity of the cubic mesh nanostructures is superior to those of conventional TiO 2 catalysts and they are catalytically functional even in natural water, owing to their high surface area and excellent chemical stability. The synthetic development presented in this study can be exploited for the highly elaborate, yet, facile design of nanomaterials with outstanding properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

    Science.gov (United States)

    Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

    2015-07-21

    Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

  4. Synthesis of unidirectional structures of SiO2-Ag using Au nanoparticles as nucleation centers

    International Nuclear Information System (INIS)

    Villa S, G.; Mendoza A, D.; Gutierrez W, C.; Perez H, R.

    2008-01-01

    This paper reports a method to synthesize Ag unidirectional structures covered with SiO 2 by sol-gel technique using Au nanoparticles as nucleation centers of the unidirectional structures. In the first phase unidirectional structures of SiO 2 -Ag CI are obtained by sol-gel, using TEOS as a precursor of metallic structures (Ag) and the incorporation of Au nanoparticles as nucleation centers for growth of unidirectional structures. In the second stage, one-way systems are subjected to thermal treatment in H 2 atmosphere for obtain AG 0 particles through mechanisms that diffusion and coalescence of silver to form structures that have a thin cover of SiO 2 . Analysis by scanning electron microscopy, transmission and atomic force microscopy allowed to determine the chemical composition and microstructural properties of unidirectional systems SiO 2 -Ag. (Author)

  5. Synthesis of novel cellulose- based antibacterial composites of Ag nanoparticles@ metal-organic frameworks@ carboxymethylated fibers.

    Science.gov (United States)

    Duan, Chao; Meng, Jingru; Wang, Xinqi; Meng, Xin; Sun, Xiaole; Xu, Yongjian; Zhao, Wei; Ni, Yonghao

    2018-08-01

    A novel cellulose-based antibacterial material, namely silver nanoparticles@ metal-organic frameworks@ carboxymethylated fibers composites (Ag NPs@ HKUST-1@ CFs), was synthesized. The results showed that the metal-organic frameworks (HKUST-1) were uniformly anchored on the fiber's surfaces by virtue of complexation between copper ions in HKUST-1 and carboxyl groups on the carboxymethylated fibers (CFs). The silver nanoparticles (Ag NPs) were immobilized and well-dispersed into the pores and/or onto the surfaces of HKUST-1 via in situ microwave reduction, resulting in the formation of novel Ag NPs@ HKUST-1@ CFs composites. The antibacterial assays showed that the as-prepared composites exhibited a much higher antibacterial activity than Ag NPs@ CFs or HKUST-1@ CFs samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Modification of Ag nanoparticles on the surface of SrTiO3 particles and resultant influence on photoreduction of CO2

    Science.gov (United States)

    Shao, Kunjuan; Wang, Yanjie; Iqbal, Muzaffar; Lin, Lin; Wang, Kai; Zhang, Xuehua; He, Meng; He, Tao

    2018-03-01

    Modification of a wide-bandgap semiconductor with noble metals that can exhibit surface plasmon effect is an effective approach to make it responsive to the visible light. In this work, a series of cubic and all-edge-truncated SrTiO3 with and without thermal pretreatment in air are modified by Ag nanoparticles via photodeposition method. The crystal structure, morphology, loading amount of Ag nanoparticles, and optical properties of the obtained Ag-SrTiO3 nanomaterials are well characterized by powder X-ray diffraction, scanning microscope, transmission electron microscope, energy disperse X-ray spectroscopy, ICP-MS and UV-vis diffuse-reflection spectroscopy. The loading amount and size of the Ag nanoparticles can be controlled to some extent by tuning the photodeposition time via growth-dissolution mechanism. The Ag nanoparticles are inclined to deposit on different locations on the surface of cubic and truncated SrTiO3 with and without thermal pretreatment. The resultant SrTiO3 modified by Ag nanoparticles exhibits visible light activity for photocatalytic reduction of CO2, which is closely related to the oxygen vacancy induced by thermal pretreatment, size and amount of Ag nanoparticles. Accordingly, there is an optimized photodeposition time for the synthesis of the photocatalyst that exhibits the highest photocatalytic activity.

  7. Immobilization of Ag nanoparticles/FGF-2 on a modified titanium implant surface and improved human gingival fibroblasts behavior.

    Science.gov (United States)

    Ma, Qianli; Mei, Shenglin; Ji, Kun; Zhang, Yumei; Chu, Paul K

    2011-08-01

    The objective of this study was to form a rapid and firm soft tissue sealing around dental implants that resists bacterial invasion. We present a novel approach to modify Ti surface by immobilizing Ag nanoparticles/FGF-2 compound bioactive factors onto a titania nanotubular surface. The titanium samples were anodized to form vertically organized TiO(2) nanotube arrays and Ag nanoparticles were electrodeposited onto the nanotubular surface, on which FGF-2 was immobilized with repeated lyophilization. A uniform distribution of Ag nanoparticles/FGF-2 was observed on the TiO(2) nanotubular surface. The L929 cell line was used for cytotoxicity assessment. Human gingival fibroblasts (HGFs) were cultured on the modified surface for cytocompatibility determination. The Ag/FGF-2 immobilized samples displayed excellent cytocompatibility, negligible cytotoxicity, and enhanced HGF functions such as cell attachment, proliferation, and ECM-related gene expression. The Ag nanoparticles also exhibit some bioactivity. In conclusion, this modified TiO(2) nanotubular surface has a large potential for use in dental implant abutment. Copyright © 2011 Wiley Periodicals, Inc.

  8. Synthesis and characterization of bracelet-like magnetic nanorings consisting of Ag-Fe3O4 bi-component nanoparticles.

    Science.gov (United States)

    Zhou, Shuai; Chen, Qianwang

    2011-09-14

    Stable bracelet-like magnetic nanorings, formed by Ag-Fe(3)O(4) nanoparticles with an average size around 40 nm, have been successfully prepared in large scale by means of reducing Ag(+) and Fe(3+) simultaneously under mild conditions. In the reaction, tiny grains of silver are used as seeds to prompt small Fe(3)O(4) nanoparticles to grow larger, which is essential to enhance the magnetic dipole-dipole interactions, while only superparamagnetic Fe(3)O(4) nanoparticles (about 10 nm in size) can be obtained in the absence of Ag seeds. The XRD, TEM, SAED and the EDS line scan data reveal that these nanoparticles are in the core-shell structure. These magnetic Ag-Fe(3)O(4) nanoparticles assembled into nanorings by magnetic dipole-dipole interactions with a diameter of 100-200 nm. The saturation magnetization of the nanorings is 39.5 emu g(-1) at room temperature. The MRI images indicate that these kind of nanorings have the potential application in diagnostics as a T(2) MRI contrast agent. This journal is © The Royal Society of Chemistry 2011

  9. The negative temperature coefficient resistivities of Ag2S-Ag core–shell structures

    International Nuclear Information System (INIS)

    Yu, Mingming; Liu, Dongzhi; Li, Wei; Zhou, Xueqin

    2014-01-01

    In this paper, the conductivity of silver nanoparticle films protected by 3-mercaptopropionic acid (Ag/MPA) has been investigated. When the nanoparticles were annealed in air at 200 °C, they converted to stable Ag 2 S-Ag core–shell structures. The mechanism for the formation of the Ag 2 S-Ag core–shell structures along with the compositional changes and the microstructural evolution of the Ag/MPA nanoparticles during the annealing process are discussed. It is proposed that the Ag 2 S-Ag core–shell structure was formed through a solid-state reduction reaction, in which the Ag + ions coming from Ag 2 S were reduced by sulfonate species and sulfur ions. The final Ag 2 S-Ag films display an exponentially decreased resistivity with increasing temperature from 25 to 170 °C. The negative temperature coefficient resistivity of Ag 2 S-Ag films can be adjusted by changing the S/Ag molar ratio used for the synthesis of the Ag/MPA nanoparticles, paving the way for the preparation of negative temperature-coefficient thermistors via printing technology for use in the electronics.

  10. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    Science.gov (United States)

    Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

    2016-02-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

  11. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    International Nuclear Information System (INIS)

    Martínez-Bernett, D; Silva-Granados, A; Herrera, A; Correa-Torres, S N

    2016-01-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO 3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution. (paper)

  12. One-pot synthesis of Ag-SiO2-Ag sandwich nanostructures

    International Nuclear Information System (INIS)

    Li Chaorong; Mei Jie; Li Shuwen; Lu Nianpeng; Wang Lina; Chen Benyong; Dong Wenjun

    2010-01-01

    Ag-SiO 2 -Ag sandwich nanostructures were prepared by a facile one-pot synthesis method. The Ag core, SiO 2 shell and Ag nanoparticle shell were all synthesized with polyvinylpyrrolidone, catalysed by ammonia, in the one-pot reaction. The polyvinylpyrrolidone, acting as a smart reducing agent, reduced the Ag + to Ag cores and Ag shells separately. Furthermore, the polyvinylpyrrolidone served as a protective agent to prevent the silver cores from aggregating. The SiO 2 shell and outer layer Ag nanoparticles were obtained when tetraethyl orthosilicate and ammonia were added to the silver core solution. Ammonia, acting as the catalyst, accelerated the hydrolysis of the tetraethyl orthosilicate to SiO 2 , which coated the silver cores. Furthermore, Ag(NH 3 ) 2 + ions were formed when aqueous ammonia was added to the solution, which increased the reduction capability. Then the polyvinylpyrrolidone reduced the Ag(NH 3 ) 2 + ions to small Ag nanoparticles on the surface of the Ag-SiO 2 and formed Ag-SiO 2 -Ag sandwich structures with a standard deviation of less than 4%. This structure effectively prevented the Ag nanoparticles on the silica surface from aggregating. Furthermore, the Ag-SiO 2 -Ag sandwich structures showed good catalysis properties due to the large surface area/volume value and activity of surface atoms of Ag particles.

  13. Soft-lithographic patterning of room temperaturesintering Ag nanoparticles on foil

    NARCIS (Netherlands)

    Moonen,P.F.; Bat,E.; Voorthuijzen, W.P.; Huskens, J.

    2013-01-01

    Room temperature-sintering, poly(acrylic acid)-capped silver nanoparticles (Ag-PAA NPs) were used in a wide range of nanofabrication methods to form metallic silver microstructures on flexible poly(ethylene terephthalate) (PET) substrates. Silver wires on top of PET foil were patterned by

  14. Transfer Study of Silver Nanoparticles in Poultry Production

    NARCIS (Netherlands)

    Gallocchio, F.; Biancotto, G.; Cibin, V.; Losasso, C.; Belluco, S.; Peters, R.; Bemmel, G. van; Cascio, C.; Weigel, S.; Tromp, P.; Gobbo, F.; Catania, S.; Ricci, A.

    2017-01-01

    Silver nanoparticles (AgNPs) are of interest due to their antimicrobial activity and are seen as potential candidates to replace antibiotics in animal husbandry. A few studies have focused on this new application, but they lack any considerations about residual accumulation of AgNPs in edible animal

  15. Transfer Study of Silver Nanoparticles in Poultry Production

    NARCIS (Netherlands)

    Gallocchio, Federica; Biancotto, Giancarlo; Cibin, Veronica; Losasso, Carmen; Belluco, Simone; Peters, Ruud; Bemmel, van Greet; Cascio, Claudia; Weigel, Stefan; Tromp, Peter C.; Gobbo, Federica; Catania, Salvatore; Ricci, Antonia

    2017-01-01

    Silver nanoparticles (AgNPs) are of interest due to their antimicrobial activity and are seen as potential candidates to replace antibiotics in animal husbandry. A few studies have focused on this new application, but they lack any considerations about residual accumulation of AgNPs in edible

  16. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    International Nuclear Information System (INIS)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    Graphical abstract: - Highlights: • A novel Ag-loading and TiO 2 -coating technique was used to prepare samples. • The photocatalytic activity of the product was evaluated by removing of Rh B. • The as-synthesized samples showed an excellent photocatalytic activity. - Abstract: A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5–10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO 2 nanocrystals

  17. Synthesis of spindle-shaped AgI/TiO{sub 2} nanoparticles with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liu; Gao, Minggang; Dai, Bin; Guo, Xuhong; Liu, Zhiyong; Peng, Banghua, E-mail: banghuapeng@hotmail.com

    2016-11-15

    Highlights: • Nanoporous spindle-shaped AgI/TiO{sub 2} was synthesized by the solvothermal approach. • The spindle-shaped TiO{sub 2} was an excellent support for loading nanoparticles, such as AgI, transferring electrons quickly from AgI, which is beneficial for stabilizing the AgI. • AgI/TiO{sub 2} nanoparticles showed enhanced absorption intensity in the visible region and exhibited excellent photocatalytic activity. - Abstract: A novel synthetic route has been developed to prepare silver iodide (AgI) loaded spindle-shaped TiO{sub 2} nanoparticles (NPs). The morphology and crystallinity characterization revealed that small AgI NPs, with an average diameter of 15 nm were dispersed on the surface and interior of nanoporous anatase TiO{sub 2} support. High-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) surface area, Raman and X-ray photoelectron spectroscopy (XPS) were used to identify the nanoporous structure of TiO{sub 2} and the existence of AgI NPs. Diffuse reflectance spectra (DRS) showed that AgI/TiO{sub 2} composite exhibited a remarkable enhancement of visible light absorption, which is ascribed to the addition of AgI. For illustrating the superior property of this hybrid as photocatalyst, the degradation experiments were carried out for processing rhodamine B (RhB) solution under visible light irradiation and it was found that the photocatalytic activity was dramatically improved for AgI/TiO{sub 2} compared with nanoporous TiO{sub 2} and commercial P25 TiO{sub 2}. The enhanced photocatalytic properties could be attributed to the large surface area of porous TiO{sub 2}, good stability of AgI particles, and the effective charge separation due to the synergetic effect between AgI and TiO{sub 2} that can facilitate the separation of electron-hole pairs. Our novel composite based on nanoporous spindle-shaped TiO{sub 2} represents a promising new pathway for the design of high-performance photocatalysts for environmental

  18. Cytotoxicity of serum protein-adsorbed visible-light photocatalytic Ag/AgBr/TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Seo, Ji Hye; Jeon, Won Il; Dembereldorj, Uuriintuya; Lee, So Yeong; Joo, Sang-Woo

    2011-01-01

    Highlights: ► Photocytotoxicity of visible-light catalytic NPs was examined in vitro. ► Ag/AgBr/TiO 2 NPs were well internalized in cells after adsorption of serum proteins. ► Cell viability was decreased by 40–60% using ∼8 ppm NPs and 60 W/cm 2 visible light within 5 h. ► Mitochondria activity test indicated the reactive oxygen species for photo-destruction of cells. ► Ag/AgBr/TiO 2 NPs were found to eliminate xenograft tumors significantly in vivo. - Abstract: Photocytotoxicity of visible-light catalytic Ag/AgBr/TiO 2 nanoparticles (NPs) was examined both in vitro and in vivo. The Ag/AgBr/TiO 2 NPs were prepared by the deposition–precipitation method. Their crystalline structures, atomic compositions, and light absorption property were examined by X-ray diffraction (XRD) patterns, X-ray photoelectron (XPS) intensities, and ultraviolet-visible (UV–vis) diffuse reflectance spectroscopic tools. The Ag/AgBr/TiO 2 NPs appeared to be well internalized in human carcinoma cells as evidenced by transmission electron microscopy (TEM). The cytotoxicity of cetylmethylammonium bromide (CTAB) appeared to be significantly reduced by adsorption of serum proteins in the cellular medium on the NP surfaces. Two types of human cervical HeLa and skin A431 cancer cells were tested to check their viability after the cellular uptake of the Ag/AgBr/TiO 2 NPs and subsequent exposure to an illumination of visible light from a 60 W/cm 2 halogen lamp. Fluorescence images taken to label mitochondria activity suggest that the reactive oxygen species should trigger the photo-destruction of cancer cells. After applying the halogen light illumination for 50–250 min and ∼8 ppm (μg/mL) of photocatalytic Ag/AgBr/TiO 2 NPs, we observed a 40–60% selective decrease of cell viability. Ag/AgBr/TiO 2 NPs were found to eliminate xenograft tumors significantly by irradiating visible light in vivo for 10 min.

  19. Influence of temperature and precursor concentration on the synthesis of HDA-capped Ag{sub 2}Se nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mlambo, M. [Department of Chemistry, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits 2050 (South Africa); Moloto, M.J., E-mail: makwenam@vut.ac.za [Department of Chemistry, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Moloto, N. [Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits 2050 (South Africa); Mdluli, P.S. [Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 (South Africa)

    2013-06-01

    Graphical abstract: The temperature effect on the growth and size of silver selenide nanoparticles with the size distribution and XRD patterns. Highlights: ► The HDA-capped Ag{sub 2}Se nanoparticles were synthesized via the colloidal route. ► Temperature and monomer concentration of the reaction were varied. ► The concentration as a factor influenced particles with a decrease observed as the amount of Ag{sup +} ion source is increased. ► Temperature has expected influence on the growth of particles resulting in increase as the temperature is increased. ► TEM images shows spherical particles and their orthorhombic phase from structural analysis by XRD. - Abstract: The size dependent of temperature and precursor concentration on the synthesis of hexadecylamine capped Ag{sub 2}Se nanoparticles via the colloidal route were studied using the combination of optical and structural analysis. The as-prepared Ag{sub 2}Se nanoparticles showed the quantum confinement with all the obtained absorption band edges blue-shifted from the bulk and their corresponding emission maxima displaying a red-shift from band edges characterised by UV–vis absorption and photoluminescence spectroscopy. The particle sizes were obtained from transmission electron microscopy analysis. The increase in precursor concentration resulted in a decrease in nanoparticle sizes. The increase in reaction temperature showed an increase in the nanoparticle sizes, when the critical temperature at 160 °C was reached, the nanoparticle sizes decreased.

  20. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    Science.gov (United States)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

  1. Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

    Science.gov (United States)

    Chen, Limei; Deming, Christopher P.; Peng, Yi; Hu, Peiguang; Stofan, Jake; Chen, Shaowei

    2016-07-01

    Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold

  2. Ag-Cu Colloid Synthesis: Bimetallic Nanoparticle Characterisation and Thermal Treatment

    Czech Academy of Sciences Publication Activity Database

    Sopoušek, J.; Pinkas, J.; Brož, P.; Buršík, Jiří; Vykoukal, V.; Škoda, D.; Stýskalík, A.; Zobač, O.; Vřešťál, J.; Hrdlička, A.; Šimbera, J.

    2014-01-01

    Roč. 2014, ID 638964 (2014), s. 1-13 ISSN 1687-4110 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Ag-Cu nanoparticles * DSC * TEM Subject RIV: BJ - Thermodynamics Impact factor: 1.644, year: 2014

  3. Continuous Synthesis of Ag/TiO2 Nanoparticles with Enhanced Photocatalytic Activity by Pulsed Laser Ablation

    Directory of Open Access Journals (Sweden)

    Rui Zhou

    2017-01-01

    Full Text Available A facile and environmental friendly synthesis strategy based on pulsed laser ablation has been developed for potential mass production of Ag-loaded TiO2 (Ag/TiO2 nanoparticles. By sequentially irradiating titanium and silver target substrates, respectively, with the same 1064 nm 100 ns fiber laser, Ag/TiO2 particles can be fabricated. A postannealing process leads to the crystallization of TiO2 to anatase phase with high photocatalytic activity. The phase composition, microstructure, and surface state of the elaborated Ag/TiO2 are characterized by X-ray diffraction (XRD, energy dispersive X-ray (EDX, field emission scanning electron microscope (FESEM, transmission electron microscope (TEM, and X-ray photoelectron spectroscopy (XPS techniques. The results suggest that the presence of silver clusters deposited on the surface of TiO2 nanoparticles. The nanostructure is formed through laser interaction with materials. Photocatalytic activity evaluation shows that silver clusters could significantly enhance the photocatalytic activity of TiO2 in degradation of methylene blue (MB under UV light irradiation, which is attributed to the efficient electron traps by Ag clusters. Our developed Ag/TiO2 nanoparticles synthesized via a straightforward, continuous, and green pathway could have great potential applications in photocatalysis.

  4. Microstructure evolution during 300 °C storage of sintered Ag nanoparticles on Ag and Au substrates

    Energy Technology Data Exchange (ETDEWEB)

    Paknejad, S.A. [King’s College London, Physics Department, Strand, London WC2R 2LS (United Kingdom); Dumas, G. [Eltek Semiconductors Ltd, Nelson Road Industrial Estate, Dartmouth, Devon TQ6 9LA (United Kingdom); West, G. [Loughborough University, Materials Department, Loughborough LE11 3TU (United Kingdom); Lewis, G. [Eltek Semiconductors Ltd, Nelson Road Industrial Estate, Dartmouth, Devon TQ6 9LA (United Kingdom); Mannan, S.H., E-mail: samjid.mannan@kcl.ac.uk [King’s College London, Physics Department, Strand, London WC2R 2LS (United Kingdom)

    2014-12-25

    Highlights: • Shear strength of pressure-free sintered Ag found to increase during ageing at 300 °C on Ag substrate. • Rapid collapse of void number density after 24 h ageing in the sintered Ag layer. • Higher porosity at edge of joint compared to the middle. • Shear strength of pressure-free sintered Ag decreases during ageing at 300 °C due to high porosity layer growth. • Void free layer and high porosity layer growth explained in terms of atomic diffusion and grain boundary migration. - Abstract: A silver nanoparticle based die attach material was used in a pressure free process to bond 2.5 mm square Ag plated Si die to Ag and Au plated substrates. The assemblies were stored at 300 °C for up to 500 h and the morphology of the sintered Ag and the shear strength were monitored as a function of time. On Ag substrate it was found that die shear strength increased and that the Ag grains grew in size and porosity decreased over time. There was also a clear difference in morphology between sintered Ag at the die edge and centre. On Au substrate, it was observed that the initially high die shear strength decreased with storage time and that voids migrated away from the Ag/Au interface and into the Ag joint. This has led to the formation of a void free layer at the interface followed by a high porosity region, which weakened the joint. The microstructure reveals a high density of grain and twin boundaries which facilitate the Ag and Au atomic diffusion responsible. The grain structure of the plated Au led to diffusion of Au into the Ag via high-angle tilt grain boundaries, and grain boundary migration further dispersed the Au into the Ag layer.

  5. Chalcone dendrimer stabilized core-shell nanoparticles—a comparative study on Co@TiO2, Ag@TiO2 and Co@AgCl nanoparticles for antibacterial and antifungal activity

    Science.gov (United States)

    Vanathi Vijayalakshmi, R.; Praveen Kumar, P.; Selvarani, S.; Rajakumar, P.; Ravichandran, K.

    2017-10-01

    A series of core@shell nanoparticles (Co@TiO2, Ag@TiO2 and Co@AgCl) stabilized with zeroth generation triazolylchalcone dendrimer was synthesized using reduction transmetalation method. The coordination of chalcone dendrimer with silver ions was confirmed by UV-vis spectroscopy. The NMR spectrum ensures the number of protons and carbon signals in the chalcone dendrimer. The prepared samples were structurally characterized by XRD, FESEM and HRTEM analysis. The SAED and XRD analyses exhibited the cubic structure with d hkl   =  2.2 Å, 1.9 Å and 1.38 Å. The antibacterial and antifungal activities of the dendrimer stabilized core@shell nanoparticles (DSCSNPs) were tested against the pathogens Bacillus subtilis, Proteus mirabilis, Candida albicans and Aspergillus nigir from which it is identified that the dendrimer stabilized core shell nanoparticles with silver ions at the shell (Co@AgCl) shows effectively high activity against the tested pathogen following the other core@shell nanoparticles viz Ag@TiO2 and Co@TiO2.

  6. Gamma radiation effects on nano composites of Ag nanoparticles in Zn O matrices; Efectos de la radiacion gamma en nanocompositos de nanoparticulas de Ag en matrices de ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Villasenor C, L. S.

    2015-07-01

    The study of gamma radiation effects in nano composites of silver nanoparticles in a Zn O matrix has been performed in this work. First, silver nanoparticles (AgNPs) were synthesized by colloidal methods, with two different mean average sizes, 48 nm and 24 nm respectively. These nanoparticles were characterized by transmission electron microscopy (Tem) and UV-Vis spectroscopy (UV-Vis). Then, with the synthesized AgNPs, nano composites in a matrix of Zn O were prepared. The first nano composite was prepared with the 48 nm AgNPs at 9.5 weight % of silver (Ag) and the second nano composite with the 24 nm nanoparticles at 1.0 weight % of Ag. Both nano composites were analyzed by scanning electron microscopy (Sem). The formation of the Zn O phase in the nano composite was corroborated through X-ray diffraction analysis. It was observed that the presence of AgNPs during the formation of the AgNPs/Zn O nano composite modified the size and morphology of the structures obtained compared to those of the pure Zn O without nanoparticles, however both exhibit a radial structure. Then, the nano composite at 9.5 weight % of Ag was irradiated with gamma rays at doses of 1, 20 and 50 kGy. Samples were analyzed by Sem and the Bet technique, before and after being irradiated, in order to determine the effect of gamma radiation in the morphology, porosity and surface area of the studied material. Even when there are changes in porosity and Surface area, this difference is not very significant for some applications, however it will have to be considered during the design of a specific application of the nano composites. On the other hand, no morphology modifications were identified on the samples irradiated at the studied doses, with the electron microscopy techniques used. (Author)

  7. On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

    Science.gov (United States)

    Mikhlin, Yuri L.; Vorobyev, Sergey A.; Saikova, Svetlana V.; Vishnyakova, Elena A.; Romanchenko, Alexander S.; Zharkov, Sergey M.; Larichev, Yurii V.

    2018-01-01

    Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

  8. Cellulose nanocrystals as templates for cetyltrimethylammonium bromide mediated synthesis of Ag nanoparticles and their novel use in PLA films.

    Science.gov (United States)

    Yalcinkaya, E E; Puglia, D; Fortunati, E; Bertoglio, F; Bruni, G; Visai, L; Kenny, J M

    2017-02-10

    In the present paper, we reported how cellulose nanocrystals (CNC) from microcrystalline cellulose have the capacity to assist in the synthesis of metallic nanoparticles chains. A cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used as modifier for CNC surface. Silver nanoparticles were synthesized on CNC, and nanoparticle density and size were optimized by varying concentrations of nitrate and reducing agents, and the reduction time. The experimental conditions were optimized for the synthesis and the resulting Ag grafted CNC (Ag-g-CNC) were characterized by means of TGA, SEM, FTIR and XRD, and then introduced in PLA matrix. PLA nanocomposite containing silver grafted cellulose nanocrystals (PLA/0.5Ag-g-1CNC) was characterized by optical and thermal analyses and the obtained data were compared with results from PLA nanocomposites containing 1% wt. of CNC (PLA/1CNC), 0.5% wt. of silver nanoparticles (PLA/0.5Ag) and hybrid system containing CNC and silver in the same amount (PLA/1CNC/0.5Ag). The results demonstrated that grafting of silver nanoparticles on CNC positively affected the thermal degradation process and cold crystallization processes of PLA matrix. Finally, the antibacterial activity of the different systems was studied at various incubation times and temperatures, showing the best performance for PLA/1CNC/0.5Ag based nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Visualization of silver-decorated poly (DL-lactide-co-glycolide) nanoparticles and their efficacy against Staphylococcus epidermidis

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Chisato, E-mail: chisato@dpc.agu.ac.jp [Pharmaceutical Engineering, School of Pharmacy, Aichi Gakuin University, 1-100, Kusumoto-cho, Chikusa-ku, Nagoya 464-8650 (Japan); Matsubara, Nobuhiro; Akachi, Yuki; Ogawa, Noriko [Pharmaceutical Engineering, School of Pharmacy, Aichi Gakuin University, 1-100, Kusumoto-cho, Chikusa-ku, Nagoya 464-8650 (Japan); Kalita, Golap [Department of Frontier Materials, Nagoya Institute of Technology, Gokisocho, Showa-ku, Nagoya 466-8555 (Japan); Asaka, Toru [Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokisocho, Showa-ku, Nagoya 466-8555 (Japan); Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokisocho, Showa-ku, Nagoya 466-8555 (Japan); Kawashima, Yoshiaki; Yamamoto, Hiromitsu [Pharmaceutical Engineering, School of Pharmacy, Aichi Gakuin University, 1-100, Kusumoto-cho, Chikusa-ku, Nagoya 464-8650 (Japan)

    2017-03-01

    Understanding of self-protection activity of the bacteria and interaction with drug substances has significant importance for designing of effective drug delivery system for treatment of biofilm infections. Recently silver nanoparticle has attracted attention as antibacterial substance for drug delivery system because of its high antibacterial activity. Here, efflux of silver nanoparticles obtained from within the prepared silver-decorated poly (DL-lactide-co-glycolide) (Ag PLGA) nanoparticles derived from Staphylococcus epidermidis bacterial cell was successfully visualized using scanning transmission electron microscopy (STEM). We also revealed the interaction between prepared Ag PLGA nanoparticles and the bacterial cells at the nanoscale level using field emission scanning electron microscopy and STEM, after a pretreatment process by an ionic liquid. This finding is significant to understand a fundamental function of S. epidermidis bacterial cells, which is not explored previously. The results suggest that Ag PLGA nanoparticles could demonstrate high efficacy against biofilm infections. - Highlights: • Ag PLGA nanoparticles with high efficacy against biofilm infections were prepared. • Self-protection activity of bacteria against Ag nanoparticles was visualized by STEM. • Antibacterial mechanism of Ag PLGA nanoparticles against biofilm was proposed.

  10. Synthesis, characterization and catalytic property of CuO and Ag/CuO nanoparticles for the epoxidation of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Lashanizadegan, Maryam; Erfaninia, Nasrin [Alzahra University, Tehran (Iran, Islamic Republic of)

    2013-11-15

    CuO nanorodes, CuO nanoplates and Ag/CuO nanoparticles were synthesized in the presence of polyethylene glycol by depositional in alkaline environment. Oxide nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared absorption spectra (FT-IR). CuO and Ag/CuO nanoparticles show high catalytic activity for the selective epoxidation of styrene to styrene oxide by TBHP. Under the optimized reaction condition, the oxidation of styrene catalyzed by CuO nanorods gave 100% conversion with 60 and 35% styrene oxide and benzaldehyde, respectively. Ag/CuO gave 99% conversion and styrene oxide (71%) and benzaldehyde (12%) being the major product.

  11. The effect of biologically and chemically synthesized silver nanoparticles (AgNPs) on biofilm formation

    Science.gov (United States)

    Chojniak, Joanna; Biedroń, Izabela; Mendrek, Barbara; Płaza, Grażyna

    2017-11-01

    Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental-friendly technology for synthesis of nanomaterials. Different types of nanomaterials like copper, zinc, titanium, magnesium, gold, and silver have applied in the various industries but silver nanoparticles have proved to be most effective against bacteria, viruses and eukaryotic microorganisms. The antimicrobial property of silver nanoparticles are widely known. Due to strong antibacterial property silver nanoparticles are used, e.g. in clothing, food industry, sunscreens, cosmetics and many household and environmental appliances. The aim of the study was to compare the effect of silver nanoparticles (AgNPs) synthesized biologically and chemically on the biofilm formation. The biofilm was formed by the bacteria isolated from the water supply network. The commonly used crystal violet assay (CV) was applied for biofilm analysis. In this study effect of biologically synthesized Ag-NPs on the biofilm formation was evaluated.

  12. Formation of Ag nanoparticles in percolative Ag–PbTiO3 composite thin films through lead-rich Ag–Pb alloy particles formed as transitional phase

    International Nuclear Information System (INIS)

    Hu, Tao; Wang, Zongrong; Su, Yanbo; Tang, Liwen; Shen, Ge; Song, Chenlu; Han, Gaorong; Weng, Wenjian; Ma, Ning; Du, Piyi

    2012-01-01

    The Ag nanoparticle dispersed percolative PbTiO 3 ceramic thin film was prepared in situ by sol–gel method with excess lead introduced into a sol precursor. The influence of excess lead and the heat treatment time on the formation of Ag nanoparticles was investigated by energy dispersive X-ray spectra, scanning electron microscopy, X-ray diffraction, and ultraviolet–visible absorption spectra. Results showed that the excess lead introduced into the sol precursor was in favor of the crystallization of the thin film and in favor of formation of the perovskite phase without the pyrochlore phase. Lead-rich Ag–Pb alloy particles first formed in the thin films and then decomposed to become large numbers of Ag nanoparticles of about 3 nm in size in the thin films when the heat treatment time was longer than 2 min. The content of the Ag nanoparticles increased with increasing the heat treatment time. The percolative behavior appears typically in the Ag nanoparticle dispersed thin films. The dielectric constant of the thin film was about 3 times of that without Ag nanoparticles. - Highlights: ► The Ag nanoparticles formed in the PbTiO 3 percolative ceramic thin film. ► The Ag–Pb alloy particles formed as transitional phase during thin film preparation. ► The lead-rich Ag–Pb alloy particles decomposed to form Ag nanoparticles in the film. ► Permittivity of the thin film is 3 times higher than that without Ag nanoparticles.

  13. Improving the oxidation resistance and stability of Ag nanoparticles by coating with multilayered reduced graphene oxide

    Science.gov (United States)

    Li, Yahui; Zhang, Huayu; Wu, Bowen; Guo, Zhuo

    2017-12-01

    A kind of coating nanostructure, Ag nanoparticles coated with multilayered reduced graphene oxide (RGO), is fabricated by employing a three-step reduction method in an orderly manner, which is significantly different from the conventional structures that are simply depositing or doping with Ag nanoparticles on RGO via chemical reduction. The as-prepared nanostructure is investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electronic diffraction (SEAD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that the obtained Ag/RGO nanostructure is observed to be a perfect coating structure with well dispersed Ag particles, which is responsible for the remarkable oxidation resistance. The results of XPS spectra indicate the content of metallic Ag is far greater than that of Ag oxides despite of prolonged exposure to the air, which fully demonstrate the excellent stability of thus coating nanostructure.

  14. Structure and effects of silver nanoparticles on the surface of α-Ag{sub 2}-xWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Gollino, Felipe; Silva, Alberico Borges Ferreira da, E-mail: felipe.gollino@gmail.com [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Longo, Elson [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2016-07-01

    Full text: This work has the aim to study the effects of nanoparticles in the interface of microstructures of silver tungstate and silver tungstate with Ag nanoparticles trying to understand the influence of them in the material. The rods of α-Ag{sub 2}WO{sub 4} were synthesized using a microwave assisted hydrothermal (MAH) method, the samples was divided in two groups, the first one was irradiated by an electron beam, promoting the Ag{sup +} ions inside of the crystal to the surface of the material as nanoparticles of Ag{sup 0}, this growth could be accompanied in situ by MEV-FEG. The other one was submitted by a thermal treatment with intention to oxidize the surface of material. The materials were characterized structurally by Raman and infrared spectroscopies, which give the information on the atomic bonds, showing the same pattern. The phase of the material, the atomic positions and the structure distortions were confirmed by DRX pattern with Rietveld refinement. The electronic behavior was study by UV-Vis-NIR spectroscopy by determining the bandgap, and in the absorption measures, they were exhibited plasmon bands feature of metallic nanoparticles. In EFM images can be seen that the nanoparticles created does not present greater electric potential related by the matrix of Ag{sub 2}WO{sub 4}, what induces that each nanoparticle do not change their charge carriers with the crystal. The XPS measurements were performed to analyze the composition, and can be notice that the peaks had different shifts for the matrix and the nanoparticle, but in the thermally treated did not show that, this behavior could be interpreted by an independent behavior. (author)

  15. Glutamate decarboxylase-derived IDDM autoantigens displayed on self-assembled protein nanoparticles

    International Nuclear Information System (INIS)

    Choi, Hyoung; Ahn, Ji-Young; Sim, Sang Jun; Lee, Jeewon

    2005-01-01

    The recombinant ferritin heavy chain (FTN-H) formed self-assembled spherical nanoparticles with the size comparable to native one. We tried to express the GAD65 COOH-terminal fragments, i.e., 448-585 (GAD65 448-585 ), 487-585 (GAD65 487-585 ), and 512-585 (GAD65 512-585 ) amino acid fragments, using FTN-H as N-terminus fusion expression partner in Escherichia coli. All of recombinant fusion proteins (FTN-H::GAD65 448-585 , FTN-H::GAD65 487-585 , and FTN-H::GAD65 512-585 ) also formed spherical nanoparticles due probably to the self-assembly function of the fused ferritin heavy chain. The antigenic epitopes within GAD65 448-585 , GAD65 487-585 , and GAD65 512-585 against insulin-dependent diabetes mellitus (IDDM) marker (autoantibodies against GAD65) were localized at the surface of the spherical protein nanoparticles so that anti-GAD65 Ab could recognize them. Protein nanoparticles like FTN-H seem to provide distinct advantages over other inorganic nanoparticles (e.g., Au, Ag, CdSe, etc.) in that through the bacterial synthesis, the active capture probes can be located at the nanoparticle surface with constant orientation/conformation via covalent cross-linking without complex chemistry. Also it is possible for the protein nanoparticles to have uniform particle size, which is rarely achieved in the chemical synthesis of inorganic nanoparticles. Thus, the recombinant ferritin particles can be used as a three-dimensional (spherical) and nanometer-scale probe structure that is a key component in ultra-sensitive protein chip for detecting protein-small molecule interactions and protein-protein interactions

  16. Ag nanoparticle effects on the thermoluminescent properties of monoclinic ZrO2 exposed to ultraviolet and gamma radiation

    International Nuclear Information System (INIS)

    Villa-Sanchez, G; Mendoza-Anaya, D; Gutierrez-Wing, C; Perez-Hernandez, R; Gonzalez-MartInez, P R; Angeles-Chavez, C

    2007-01-01

    The goal of this work was to analyse ZrO 2 in the pure state and when doped with Ag nanoparticles, by electron microscopy, x-ray diffraction and thermoluminescence methods. According to the results obtained, Ag nanoparticles did not modify the morphology or the crystalline structure of the ZrO 2 . The thermoluminescent (TL) response of pure ZrO 2 showed two peaks, one at 334 K and the other at 417 K, when it was exposed to ultraviolet (UV) radiation, and at 342 and 397 K when gamma radiation was used. For ZrO 2 impregnated with Ag nanoparticles a diminished TL intensity due to nanoparticle shielding was observed, but the glow curve shape was similar. However, when Ag nanoparticles were added during the ZrO 2 synthesis, a shift of the TL peaks towards higher temperature values with reference to pure ZrO 2 was observed. A linear dependence of the integrated TL signal as a function of the irradiation dose was observed in all analysed samples. It was possible to determine some kinetic parameters, such as activation energy, kinetic order and frequency factor, using the sequential quadratic programming glow curve deconvolution; it was found that these values are highly dependent on the type of radiation used. Ag nanoparticles present in ZrO 2 also modified the kinetic parameters, mainly when they were added during the synthesis of ZrO 2 . Our results reinforce the possibilities of using pure and doped ZrO 2 as an appropriate dosimetric material in radiation physics

  17. Detection of Single Pt Nanoparticle Collisions by Open-Circuit Potential Changes at Ag Ultramicroelectrode

    International Nuclear Information System (INIS)

    Mun, Seon Kyu; Shin, Changhwan; Kwon, Seong Jung

    2016-01-01

    Single platinum (Pt) nanoparticle (NP) collisions were investigated with open-circuit potential (OCP) using a silver (Ag) ultramicroelectrode (UME). The Ag UME showed higher sensitivity to single Pt NP detection by the OCP method than gold (Au) UME. The detection of ⁓2 nm radius Pt NP collisions was carried out successfully using Ag UME. The magnitude of the potential step and collision frequency for the single Pt NP collision on Ag UME was investigated and compared with those of the previous work done on Au UME.

  18. Preparation of Ag/TiO{sub 2}/SiO{sub 2} films via photo-assisted deposition and adsorptive self-assembly for catalytic bactericidal application

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Baojuan, E-mail: baojuanxi@gmail.com [Department of Electrical and Computer Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Chu, Xiaona; Hu, Jiangyong [Department of Civil and Environmental Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo [Department of Electrical and Computer Engineering, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

    2014-08-30

    Highlights: • We prepared controlledly the silver nanoparticles on TiO{sub 2}/SiO{sub 2} film by the facile photoreduction under the aid of structure-directing agents. • We studied the effect of silver loading on the antibactierial behavior of TiO{sub 2} film and optimized the content of silver. • We extended the route to fabricate other metals on substrates. - Abstract: The deterioration of water supply quality due to the waterborne bacteria is an environmental problem requiring the urgent attention. Due to the excellent and synergic antimicrobial capability, Ag-loaded TiO{sub 2} photocatalyst emerges as a feasible measure to guard the water. In our work, Ag nanoparticles have been prepared by the photoassisted reduction of AgNO{sub 3} on the TiO{sub 2} film fabricated by solution-based adsorptive self-assembly approach. The role of surfactant on the growth rate and size controlling of particles is also studied. In this connection, different kinds of surfactants, such as PVP, Tween-20, Tween-40 and so on, are applied in the system to investigate the formation of Ag nanoparticles. The surface profile and elemental analysis of Ag/TiO{sub 2}/SiO{sub 2} films are examined by scanning electron microscopy and attached energy-dispersive X-ray spectroscopy, respectively. In the anti-bacteria detection, Ag nanoparticles are found to enhance the bactericidal efficiency strongly comparing with the pure TiO{sub 2} film under the same condition. In addition, by comparison with Ag/TiO{sub 2}/SiO{sub 2} film in the dark environment as the reference experiment, UV–visible light plays a vital role in the improved bactericidal behavior, demonstrating the more efficient charge separation induced by metal silver. Because of the versatility of the method, the present photoreductive route is also exploited for the synthesis of Au nanoparticles on TiO{sub 2}/SiO{sub 2} films. The corresponding photocatalytical detection results demonstrate the loading of Au nanoparticles can

  19. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

    Directory of Open Access Journals (Sweden)

    Yang Yongkun

    2012-10-01

    Full Text Available Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs to encapsulate gold nanoparticles. The protein nanoparticles are formed upon self-assembly of a protein chain that is composed of a pentameric coiled-coil domain at the N-terminus and trimeric coiled-coil domain at the C-terminus. The self-assembling protein nanoparticles form a central cavity of about 10 nm in size, which is ideal for the encapsulation of gold nanoparticles with similar sizes. Results We have used SAPNs to encapsulate several commercially available gold nanoparticles. The hydrodynamic size and the surface coating of gold nanoparticles are two important factors influencing successful encapsulation by the SAPNs. Gold nanoparticles with a hydrodynamic size of less than 15 nm can successfully be encapsulated. Gold nanoparticles with citrate coating appear to have stronger interactions with the proteins, which can interfere with the formation of regular protein nanoparticles. Upon encapsulation gold nanoparticles with polymer coating interfere less strongly with the ability of the SAPNs to assemble into nanoparticles. Although the central cavity of the SAPNs carries an overall charge, the electrostatic interaction appears to be less critical for the efficient encapsulation of gold nanoparticles into the protein nanoparticles. Conclusions The SAPNs can be used to encapsulate gold nanoparticles. The SAPNs can be further functionalized by engineering functional peptides or proteins to either their N- or C-termini. Therefore encapsulation of gold

  20. Silica-covered star-shaped Au-Ag nanoparticles as new electromagnetic nanoresonators for Raman characterisation of surfaces

    Science.gov (United States)

    Krajczewski, Jan; Kołątaj, Karol; Pietrasik, Sylwia; Kudelski, Andrzej

    2018-03-01

    One of the tools used for determining the composition of surfaces of various materials is shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). SHINERS is a modification of "standard" surface-enhanced Raman spectroscopy (SERS), in which, before Raman spectra are recorded, the surfaces analysed are covered with a layer of plasmonic nanoparticles protected by a very thin layer of a transparent dielectric. The plasmonic cores of the core-shell nanoparticles used in SHINERS measurements generate a local enhancement of the electric field of the incident electromagnetic radiation, whereas the transparent coatings prevent the metal cores from coming into direct contact with the material being analysed. In this contribution, we propose a new type of SHINERS nanoresonators that contain spiky, star-shaped metal cores (produced from a gold/silver alloy). These spiky, star-shaped Au-Ag nanoparticles have been covered by a layer of silica. The small radii of the ends of the tips of the spikes of these plasmonic nanostructures make it possible to generate a very large enhancement of the electromagnetic field there, with the result that such SHINERS nanoresonators are significantly more efficient than the standard semi-spherical nanostructures. The Au-Ag alloy nanoparticles were synthesised by the reduction of a solution containing silver nitrate and chloroauric acid by ascorbic acid. The final geometry of the nanostructures thus formed was controlled by changing the ratio between the concentrations of AuCl4- and Ag+ ions. The shape of the synthesised star-shaped Au-Ag nanoparticles does not change significantly during the two standard procedures for depositing a layer of silica (by the decomposition of sodium silicate or the decomposition of tetraethyl orthosilicate).

  1. In situ transmission electron microscopy and scanning transmission electron microscopy studies of sintering of Ag and Pt nanoparticles

    International Nuclear Information System (INIS)

    Asoro, M.A.; Ferreira, P.J.; Kovar, D.

    2014-01-01

    Transmission electron microscopy and scanning transmission electron microscopy studies were conducted in situ on 2–5 nm Pt and 10–40 nm Ag nanoparticles to study mechanisms for sintering and to measure relevant sintering kinetics in nanoscale particles. Sintering between two separated particles was observed to initiate by either (1) diffusion of the particles on the sample support or (2) diffusion of atoms or small clusters of atoms to the neck region between the two particles. After particle contact, the rate of sintering was controlled by atomic surface diffusivity. The surface diffusivity was determined as a function of particle size and temperature from experimental measurements of the rate of neck growth of the particles. The surface diffusivities did not show a strong size effect for the range of particle sizes that were studied. The surface diffusivity for Pt nanoparticles exhibited the expected Arrhenius temperature dependence and did not appear to be sensitive to the presence of surface contaminants. In contrast, the surface diffusivity for Ag nanoparticles was affected by the presence of impurities such as carbon. The diffusivities for Ag nanoparticles were consistent with previous measurements of bulk surface diffusivities for Ag in the presence of C, but were significantly slower than those obtained from pristine Ag

  2. Investigation of widely used nanomaterials (TiO{sub 2}, Ag) and gold nanoparticles in standardized ecotoxicological tests

    Energy Technology Data Exchange (ETDEWEB)

    Hund-Rinke, Kerstin; Klawonn, Thorsten [Fraunhofer-Institut fuer Molekularbiologie und Angewandte Oekologie (IME), Schmallenberg (Germany)

    2013-04-15

    At the nanoscale level, the physical, chemical, and biological properties of materials differ in fundamental, and often valuable, ways from the properties of individual atoms and molecules, or bulk matter. Research and development in nanotechnology is directed towards creating im-proved materials, devices, and systems that exploit the new properties. The specific properties of nanoparticles proved to be very useful for an increasing number of commercial applications, such as protective coatings, light-weight materials or self-cleaning clothing, for example. As a consequence of their specific properties, nanoparticles differ from conventional chemicals with respect to their impact on human health and the environment. Therefore, traditional testing and assessment methods typically used to determine the safety of conventional chemicals are not necessarily (fully) applicable to nanoparticles. In November 2007, OECD's Working Party on Manufactured Nanomaterials (WPMN) launched a Sponsorship Programme involving OECD member countries as well as non-member econo-mies and other stakeholders to pool available expertise and to fund the safety testing of specific Manufactured Nanomaterials (MNs). In launching the Sponsorship Programme, the WPMN agreed on a priority list of 13 MNs selected for testing from a pool of nanomaterials that are in, or close to, commerce. The WPMN also agreed upon a list of endpoints for which the selected materials should be tested. Much valuable information on the safety of MNs can be derived by testing this representative set of nanomaterials with respect to human health and environmental safety. As a sponsor country supporting research into TiO{sub 2} and a co-sponsor for Ag research, Germany, among others, is involved in assessing the potential effects of TiO{sub 2} and Ag nanoparticles with respect to human health and the environment. Several months after starting the present project, the work programme was extended to include the

  3. Effect of the Fabrication Parameters of the Nanosphere Lithography Method on the Properties of the Deposited Au-Ag Nanoparticle Arrays

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2017-04-01

    Full Text Available The nanosphere lithography (NSL method can be developed to deposit the Au-Ag triangle hexagonal nanoparticle arrays for the generation of localized surface plasmon resonance. Previously, we have found that the parameters used to form the NSL masks and the physical methods required to deposit the Au-Ag thin films had large effects on the geometry properties of the nanoparticle arrays. Considering this, the different parameters used to grow the Au-Ag triangle hexagonal nanoparticle arrays were investigated. A single‐layer NSL mask was formed by using self‐assembly nano-scale polystyrene (PS nanospheres with an average radius of 265 nm. At first, the concentration of the nano-scale PS nanospheres in the solution was set at 6 wt %. Two coating methods, drop-coating and spin-coating, were used to coat the nano-scale PS nanospheres as a single‐layer NSL mask. From the observations of scanning electronic microscopy (SEM, we found that the matrixes of the PS nanosphere masks fabricated by using the drop-coating method were more uniform and exhibited a smaller gap than those fabricated by the spin-coating method. Next, the drop-coating method was used to form the single‐layer NSL mask and the concentration of nano-scale PS nanospheres in a solution that was changed from 4 to 10 wt %, for further study. The SEM images showed that when the concentrations of PS nanospheres in the solution were 6 and 8 wt %, the matrixes of the PS nanosphere masks were more uniform than those of 4 and 10 wt %. The effects of the one-side lifting angle of substrates and the vaporization temperature for the solvent of one-layer self-assembly PS nanosphere thin films, were also investigated. Finally, the concentration of the nano-scale PS nanospheres in the solution was set at 8 wt % to form the PS nanosphere masks by the drop-coating method. Three different physical deposition methods, including thermal evaporation, radio-frequency magnetron sputtering, and e

  4. Soft-lithographic patterning of room termperature-sintering Ag Nanoparticles on foil

    NARCIS (Netherlands)

    Moonen, P.; Bat, E.; Voorthuijzen, W. Pim; Huskens, Jurriaan

    2013-01-01

    Room temperature-sintering, poly(acrylic acid)-capped silver nanoparticles (Ag-PAA NPs) were used in a wide range of nanofabrication methods to form metallic silver microstructures on flexible poly(ethylene terephthalate) (PET) substrates. Silver wires on top of PET foil were patterned by

  5. Preparation and characterization of Ag-doped In2O3 nanoparticles gas sensor

    Science.gov (United States)

    Anand, Kanica; Kaur, Jasmeet; Singh, Ravi Chand; Thangaraj, Rengasamy

    2017-08-01

    Pure and Ag-doped In2O3 nanoparticles are synthesized by the co-precipitation method and are characterized by X-ray diffraction, transmission electron microscopy and photoluminescence spectroscopy. Gas sensing properties of the sensors has been investigated towards methanol, ethanol, acetone and LPG at different operating temperatures. It is found that the sensor response magnitude of the 3% Ag-doped In2O3 nanoparticles sensors is higher to 50 ppm of ethanol at 300 °C, to acetone at 350 °C and to LPG at 400 °C. This is mainly attributed to the large number of oxygen vacancies and defects in doped sensors as corroborated by the photoluminescence studies.

  6. A biodynamic understanding of dietborne and waterborne Ag uptake from Ag NPs in the sediment-dwelling oligochaete, Tubifex tubifex

    Science.gov (United States)

    Tangaa, Stine Rosendal; Winther-Nielsen, Margrethe; Selck, Henriette; Croteau, Marie-Noele

    2018-01-01

    Metal nanoparticles (Me-NPs) are increasingly used in various products, such as inks and cosmetics, enhancing the likelihood of their release into aquatic environments. An understanding of the mechanisms controlling their bioaccumulation and ecotoxicity in aquatic biota will help support environmental risk assessment. Here we characterized unidirectional parameters for uptake and elimination of silver (Ag) in the sediment-dwelling oligochaete Tubifex tubifex after waterborne (0.01–47 nmol Ag/L) and dietborne (0.4–482 nmol Ag/g dw sed.) exposures to Ag NPs and AgNO3, respectively. Worms accumulated Ag from AgNO3more efficiently than from Ag NPs during waterborne exposure. The Ag uptake rate constants from water were 8.2 L/g/d for AgNO3 and 0.34 L/g/d for Ag NPs. Silver accumulated from both forms was efficiently retained in tissues, as no significant loss of Ag was detected after up to 20 days of depuration in clean media. High mortality (~50%) during depuration (i.e. after 17 days) was only observed for worms exposed to waterborne AgNO3 (3 nmol/L). Sediment exposures to both Ag forms resulted in low accumulation, i.e., the uptake rate constants were 0.002 and 0.005 g/g/d for AgNO3 and Ag NPs, respectively. Avoidance was only observed for worms exposed to sediment amended with AgNO3. Incorporation of the estimated rate constants into a biodynamic model predicted that sediment is likely the most important route of uptake for Ag in both forms in ecologically relevant aquatic environments. However, inference of bioavailability from our estimations of Ag assimilation efficiencies (AE) suggests that Ag (AE: 3–12% for AgNO3 and 0.1–0.8% for Ag NPs) is weakly bioavailable from sediment for this species. Thus, Ag amended to sediment as NPs might not pose greater problems than 'conventional' Ag for benthic organisms such as T. tubifex.

  7. Antibacterial Activity Of ternary semiconductor compounds AgInSe2 Nanoparticles Synthesized by Simple Chemical Method

    Science.gov (United States)

    Shehab, A. A.; Fadaam, S. A.; Abd, A. N.; Mustafa, M. H.

    2018-05-01

    In this objective AgInSe2Nanoparticles (AgInSe2 NPs) were prepared by a simple chemical method (SCM). The optica structural l and morphological properties of the synthesized AgInSe2 NPs swere investigated by using UVVI absorption atomic force microscopy AFMmf, Fourier Transform Infrared Spectroscopy and x-ray diffraction. The resistance of bacteria represents a trouble and the outlook for the use of antibiotics in the future until now uncertain. Measures must be taken to decrease this problem. Antibacterial activity of the AgInSe2 nanoparticles were exposed against several pathogenic bacteriaa including Klebsiella pneumonia KPa, Staphylococcus aureus, Bacillus subtili, Enterobacter Cloacae and Esherichia Coliby. Using a good spread method the results showed that AgInSe2 NPs had inhibitory effect versus some pathogenic bacteria with suppression area 18, 14 and 17 mm for SAgInSe2 NPs had an inhibitory effect against S Bacillus Subtilis 11 mm K EnterobactercCloacae 12 mm.

  8. Speciation of silver nanoparticles and Ag(I) species using cloud point extraction followed by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2014-01-01

    Silver nanoparticles in the presence of Triton-X114 were extracted into a micellar phase obtained after incubation at 40 °C for 10 min followed by centrifugation. After injection of an aliquot (30 μL) of the surfactant-rich phase into the electrothermal atomizer, the enrichment effect due to cloud point extraction allowed a detection limit of 2 ng L −1 silver to be achieved. The preconcentration factor was 242, and the repeatability for ten measurements at a 50 ng L −1 silver level was 4.6%. Ag(I) species were adsorbed onto the silver nanoparticles and were also extracted in the micellar phase. The incorporation of 0.01 mol L −1 ammonium thiocyanate to the sample solution prevented the extraction of Ag(I) species. Speciation was carried out using two extractions, one in the absence and the other in the presence of thiocyanate, the concentration of Ag(I) species being obtained by difference. The procedure was applied to the determination of silver nanoparticles and Ag(I) species in waters and in lixiviates obtained from sticking plasters and cleaning cloths. - Highlights: • Silver nanoparticles and Ag(I) species are separated into a surfactant-rich phase. • The Ag(I) species are not extracted in the presence of thiocyanate. • The cloud point extraction of two aliquots allows speciation to be carried out. • Extreme sensitivity (detection limit 2 ng L −1 ) is achieved

  9. Speciation of silver nanoparticles and Ag(I) species using cloud point extraction followed by electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel, E-mail: hcordoba@um.es

    2014-11-01

    Silver nanoparticles in the presence of Triton-X114 were extracted into a micellar phase obtained after incubation at 40 °C for 10 min followed by centrifugation. After injection of an aliquot (30 μL) of the surfactant-rich phase into the electrothermal atomizer, the enrichment effect due to cloud point extraction allowed a detection limit of 2 ng L{sup −1} silver to be achieved. The preconcentration factor was 242, and the repeatability for ten measurements at a 50 ng L{sup −1} silver level was 4.6%. Ag(I) species were adsorbed onto the silver nanoparticles and were also extracted in the micellar phase. The incorporation of 0.01 mol L{sup −1} ammonium thiocyanate to the sample solution prevented the extraction of Ag(I) species. Speciation was carried out using two extractions, one in the absence and the other in the presence of thiocyanate, the concentration of Ag(I) species being obtained by difference. The procedure was applied to the determination of silver nanoparticles and Ag(I) species in waters and in lixiviates obtained from sticking plasters and cleaning cloths. - Highlights: • Silver nanoparticles and Ag(I) species are separated into a surfactant-rich phase. • The Ag(I) species are not extracted in the presence of thiocyanate. • The cloud point extraction of two aliquots allows speciation to be carried out. • Extreme sensitivity (detection limit 2 ng L{sup −1}) is achieved.

  10. Self-oriented Ag-based polycrystalline cubic nanostructures through polymer stabilization

    Science.gov (United States)

    Alonso, Amanda; Vigués, Núria; Rodríguez-Rodríguez, Rosalía; Borrisé, Xavier; Muñoz, María; Muraviev, Dmitri N.; Mas, Jordi; Muñoz-Berbel, Xavier

    2016-10-01

    This paper presents the study of the dynamics of the formation of polymer-assisted highly-orientated polycrystalline cubic structures (CS) by a fractal-mediated mechanism. This mechanism involves the formation of seed Ag@Co nanoparticles by InterMatrix Synthesis and subsequent overgrowth after incubation at a low temperature in chloride and phosphate solutions. These ions promote the dissolution and recrystallization in an ordered configuration of pre-synthetized nanoparticles initially embedded in negatively-charged polymeric matrices. During recrystallization, silver ions aggregate in AgCl@Co fractal-like structures, then evolve into regular polycrystalline solid nanostructures (e.g. CS) in a single crystallization step on specific regions of the ion exchange resin (IER) which maintain the integrity of polycrystalline nanocubes. Here, we study the essential role of the IER in the formation of these CS for the maintenance of their integrity and stability. Thus, this synthesis protocol may be easily expanded to the composition of other nanoparticles providing an interesting, cheap and simple alternative for cubic structure formation and isolation.

  11. Glycosylation of the self-recognizing Escherichia coli Ag43 autotransporter protein

    DEFF Research Database (Denmark)

    Sherlock, O.; Dobrindt, U.; Jensen, J.B.

    2006-01-01

    a novel member to this exclusive group, namely, antigen 43 (Ag43), a self-recognizing autotransporter protein. By mass spectrometry Ag43 was demonstrated to be glycosylated by addition of heptose residues at several positions in the passenger domain. Glycosylation of Ag43 by the action of the Aah and Tib......C glycosyltransferases was observed in laboratory strains. Importantly, Ag43 was also found to be glycosylated in a wild-type strain, suggesting that Ag43-glycosylation may be a widespread phenomenon. Glycosylation of Ag43 does not seem to interfere with its self-associating properties. However, the glycosylated form...

  12. Self-reduction and size controlled synthesis of silver nanoparticles on carbon nanospheres by grafting triazine-based molecular layer for conductivity improvement

    Science.gov (United States)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-02-01

    A facile, self-reduction and size controlled synthesis method has been explored to fabricate silver nanoparticles (Ag NPs) on carbon nanosphere (CNs) under mild conditions. Without using predeposition of seed metals and reducing agent, a uniform and complete layer of Ag NPs was formed through grafting a molecular layer on CNs surfaces under UV irradiation. The size and thickness of Ag NPs were effectively tuned by adjusting the UV irradiation time. This direct formation of Ag NPs was attributed to self seed in aqueous Ag(NH3)2+ complex solution through a triazine-based silane coupling agent molecular layer, even at 25 °C. Scanning electron microscopy (SEM), Transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the Ag NPs' properties. A substantial conductivity improvement of prepared Ag NPs on carbon nanosphere was demonstrated. The presented method is simple and environmentally friendly and thus should be of significant value for the industrial fabrication of Ag NPs on carbon nanosphere in conduct electricity paint and coating applications.

  13. Improved diode performance of Ag nanoparticle dispersed Er doped In2O3 film

    Science.gov (United States)

    Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Mondal, Aniruddha

    2018-04-01

    Ag nanoparticle(NP) dispersedEr doped In2O3 film was prepared by sol-gel method followed by thermal evaporation cum glancing angle deposition technique. The Schottky contact based devicecontaining Ag NPs shows ideality factor of ˜180 at 10 K and ˜5 at 300 K, which is lesser as compared to the device that does not contain Ag NPs. The lower ideality factor value all over the temperature range makes the diode more reliable.

  14. Synergistic bactericidal effect by combined exposure to Ag nanoparticles and UVA

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaoxu; Toyooka, Tatsushi; Ibuki, Yuko, E-mail: ibuki@u-shizuoka-ken.ac.jp

    2013-08-01

    Broad and strong antimicrobial properties of silver (Ag) have been used for biomedical applications, water treatment, etc. In this study, a synergistic antibacterial effect between Ag nanoparticles (AgNPs) and ultraviolet (UV) light was examined. AgNPs (< 0.1 μm) with subsequent exposure to UVA (320–400 nm) showed pronounced toxicity in Escherichia coli, but micro-sized Ag particles (> 1 μm) with UVA and AgNPs with UVB (280–325 nm) did not. As significant bactericidal activity was also exhibited by hydrogen peroxide-treated AgNPs, the surface oxidation of AgNPs caused by UVA irradiation was considered to contribute to the enhanced antibacterial effect. Although no difference in NP-incorporation rates was observed with or without the surface oxidation of AgNPs, a particle size of less than 0.1 μm was a factor for AgNPs uptake and an essential requirement for the antimicrobial function of Ag particles. Incorporated AgNPs oxidized by UVA irradiation released larger amounts of Ag ion inside cells than reduced AgNPs, which reacted with intercellular molecules having –SH groups such as glutathione. The synergistic use of AgNPs and UVA could become a powerful tool with broad antimicrobial applications. Highlights: • Combined treatment with AgNPs and UV achieved a remarkable antibacterial effect in E. coli. • For the antibacterial effect, it is necessary to satisfy the following requirements: • 1) Translocation of nano-sized Ag particles inside E. coli. • 2) Oxidation of AgNPs by UVA, and extensive and persistent release of Ag{sup +} inside E. coli. • Ag{sup +} released inside cells reacted with intercellular molecules having –SH groups such as GSH.

  15. Optical studies of CdSe/HgSe and CdSe/Ag2Se core/shell nanoparticles embedded in gelatin

    International Nuclear Information System (INIS)

    Azhniuk, Yu M; Dzhagan, V M; Valakh, M Ya; Raevskaya, A E; Stroyuk, A L; Kuchmiy, S Ya; Zahn, D R T

    2008-01-01

    CdSe/HgSe and CdSe/Ag 2 Se core-shell nanoparticles are obtained by colloidal synthesis from aqueous solutions in the presence of gelatin. Optical absorption, luminescence, and Raman spectra of the nanoparticles obtained are measured. The variation of the optical spectra of CdSe/HgSe and CdSe/Ag 2 Se core-shell nanoparticles with the shell thickness is discussed. Sharp non-monotonous variation of the photoluminescence spectra at low shell coverage is observed.

  16. Enhanced and tunable optical quantum efficiencies from plasmon bandwidth engineering in bimetallic CoAg nanoparticles

    Directory of Open Access Journals (Sweden)

    A. Malasi

    2016-10-01

    Full Text Available Plasmonic nanoparticles are amongst the most effective ways to resonantly couple optical energy into and out of nanometer sized volumes. However, controlling and/or tuning the transfer of this incident energy to the surrounding near and far field is one of the most interesting challenges in this area. Due to the dielectric properties of metallic silver (Ag, its nanoparticles have amongst the highest radiative quantum efficiencies (η, i.e., the ability to radiatively transfer the incident energy to the surrounding. Here we report the discovery that bimetallic nanoparticles of Ag made with immiscible and plasmonically weak Co metal can show comparable and/or even higher η values. The enhancement is a result of the narrowing of the plasmon bandwidth from these bimetal systems. The phenomenological explanation of this effect based on the dipolar approximation points to the reduction in radiative losses within the Ag nanoparticles when in contact with cobalt. This is also supported by a model of coupling between poor and good conductors based on the surface to volume ratio. This study presents a new type of bandwidth engineering, one based on using bimetal nanostructures, to tune and/or enhance the quality factor and quantum efficiency for near and far-field plasmonic applications.

  17. The effect of soil properties on the toxicity and bioaccumulation of Ag nanoparticles and Ag ions in Enchytraeus crypticus.

    Science.gov (United States)

    Topuz, Emel; van Gestel, Cornelis A M

    2017-10-01

    Standard natural Lufa soils (2.2, 2.3 and 5M) with different organic carbon contents (0.67-1.61%) and pH CaCl2 (5.5-7.3) were spiked with ionic Ag (AgNO 3 ) and polyvinyl pyrrolidone (AgNP-PVP) and citrate (AgNP-Cit) coated Ag nanoparticles (NPs). Enchytraeus crypticus were exposed for 21 days to assess effects on survival and reproduction. Soil, pore water and animals were analyzed for Ag. AgNP-Cit had a strong increasing effect on soil pH, leading to high enchytraeid mortality at concentrations higher than 60-100mg Ag/kg dry soil which made it impossible to determine the influence of soil properties on its toxicity. LC50s were lower for AgNO 3 than for AgNP-PVP (92-112 and 335-425mg Ag/kg dry soil, respectively) and were not affected by soil properties. AgNO 3 and AgNP-PVP had comparable reproductive toxicity with EC50s of 26.9-75.2 and 28.2-92.3mg Ag/kg dry soil, respectively; toxicity linearly increased with decreasing organic carbon content of the soils but did not show a clear effect of soil pH. Ag uptake in the enchytraeids was higher at higher organic carbon content, but could not explain differences in toxicity between soils. This study indicates that the bioavailability of both ionic and nanoparticulate Ag is mainly affected by soil organic carbon, with little effect of soil pH. Copyright © 2017. Published by Elsevier Inc.

  18. Synthesis of triangular Au core-Ag shell nanoparticles

    International Nuclear Information System (INIS)

    Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali

    2007-01-01

    In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules

  19. Silica-covered star-shaped Au-Ag nanoparticles as new electromagnetic nanoresonators for Raman characterisation of surfaces.

    Science.gov (United States)

    Krajczewski, Jan; Kołątaj, Karol; Pietrasik, Sylwia; Kudelski, Andrzej

    2018-03-15

    One of the tools used for determining the composition of surfaces of various materials is shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). SHINERS is a modification of "standard" surface-enhanced Raman spectroscopy (SERS), in which, before Raman spectra are recorded, the surfaces analysed are covered with a layer of plasmonic nanoparticles protected by a very thin layer of a transparent dielectric. The plasmonic cores of the core-shell nanoparticles used in SHINERS measurements generate a local enhancement of the electric field of the incident electromagnetic radiation, whereas the transparent coatings prevent the metal cores from coming into direct contact with the material being analysed. In this contribution, we propose a new type of SHINERS nanoresonators that contain spiky, star-shaped metal cores (produced from a gold/silver alloy). These spiky, star-shaped Au-Ag nanoparticles have been covered by a layer of silica. The small radii of the ends of the tips of the spikes of these plasmonic nanostructures make it possible to generate a very large enhancement of the electromagnetic field there, with the result that such SHINERS nanoresonators are significantly more efficient than the standard semi-spherical nanostructures. The Au-Ag alloy nanoparticles were synthesised by the reduction of a solution containing silver nitrate and chloroauric acid by ascorbic acid. The final geometry of the nanostructures thus formed was controlled by changing the ratio between the concentrations of AuCl 4 - and Ag + ions. The shape of the synthesised star-shaped Au-Ag nanoparticles does not change significantly during the two standard procedures for depositing a layer of silica (by the decomposition of sodium silicate or the decomposition of tetraethyl orthosilicate). Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Isotopically modified silver nanoparticles to assess nanosilver bioavailability and toxicity at environmentally relevant exposures

    Science.gov (United States)

    Croteau, Marie-Noële; Dybowska, Agnieszka D.; Luoma, Samuel N.; Misra, Superb K.; Valsami-Jones, Eugenia

    2014-01-01

    A major challenge in understanding the environmental implications of nanotechnology lies in studying nanoparticle uptake in organisms at environmentally realistic exposure concentrations. Typically, high exposure concentrations are needed to trigger measurable effects and to detect accumulation above background. But application of tracer techniques can overcome these limitations. Here we synthesised, for the first time, citrate-coated Ag nanoparticles using Ag that was 99.7 % 109Ag. In addition to conducting reactivity and dissolution studies, we assessed the bioavailability and toxicity of these isotopically modified Ag nanoparticles (109Ag NPs) to a freshwater snail under conditions typical of nature. We showed that accumulation of 109Ag from 109Ag NPs is detectable in the tissues of Lymnaea stagnalis after 24-h exposure to aqueous concentrations as low as 6 ng L–1 as well as after 3 h of dietary exposure to concentrations as low as 0.07 μg g–1. Silver uptake from unlabelled Ag NPs would not have been detected under similar exposure conditions. Uptake rates of 109Ag from 109Ag NPs mixed with food or dispersed in water were largely linear over a wide range of concentrations. Particle dissolution was most important at low waterborne concentrations. We estimated that 70 % of the bioaccumulated 109Ag concentration in L. stagnalis at exposures –1 originated from the newly solubilised Ag. Above this concentration, we predicted that 80 % of the bioaccumulated 109Ag concentration originated from the 109Ag NPs. It was not clear if agglomeration had a major influence on uptake rates.

  1. Impact of Ag and Al{sub 2}O{sub 3} nanoparticles on soil organisms: In vitro and soil experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, C., E-mail: carmen.fajardo@vet.ucm.es [Facultad de Veterinaria, Universidad Complutense, 28040 Madrid (Spain); Saccà, M.L., E-mail: marialudovicasacca@pdi.ucm.es [Facultad de Veterinaria, Universidad Complutense, 28040 Madrid (Spain); Campus de Excelencia Internacional de Moncloa, 28040 Madrid (Spain); Costa, G., E-mail: costag@vet.ucm.es [Facultad de Veterinaria, Universidad Complutense, 28040 Madrid (Spain); Nande, M., E-mail: mnande@vet.ucm.es [Facultad de Veterinaria, Universidad Complutense, 28040 Madrid (Spain); Martin, M., E-mail: margamar@vet.ucm.es [Facultad de Veterinaria, Universidad Complutense, 28040 Madrid (Spain)

    2014-03-01

    In vitro analyses were conducted to assess the impact of Al{sub 2}O{sub 3} and Ag nanoparticles on two common soil bacteria, Bacillus cereus and Pseudomonas stutzeri. Al{sub 2}O{sub 3} nanoparticles did not show significant toxicity at any dose or time assayed, whereas exposure to 5 mg L{sup −1} Ag nanoparticles for 48 h caused bactericidal effects. Moreover, alterations at the morphological level were observed by transmission electron microscopy (TEM); Ag but not Al{sub 2}O{sub 3} nanoparticles evoked the entrance of B. cereus cells in an early sporulation stage and both nanoparticles penetrated P. stutzeri cells. At the molecular level, a dramatic increase (8.2-fold) in katB gene expression was found in P. stutzeri following Al{sub 2}O{sub 3} nanoparticles exposure, indicative of an oxidative stress-defence system enhancement in this bacterium. In the microcosm experiment, using two different natural soils, Al{sub 2}O{sub 3} or Ag nanoparticles did not affect the Caenorhabditis elegans toxicity endpoints growth, survival, or reproduction. However, differences in microbial phylogenetic compositions were detected by fluorescence in situ hybridization (FISH). The use of katB- and pykA-based sequences showed that the microbial transcriptional response to nanoparticle exposure decreased, suggesting a decrease in cellular activity. These changes were attributable to both the nanoparticles treatment and soil characteristics, highlighting the importance of considering the soil matrix on a case by case basis. - Highlights: • Al{sub 2}O{sub 3} or Ag NPs impact on bacteria was assessed at phenotypic and molecular level. • katB gene involved in oxidative-stress response was overexpressed in P. stutzeri following Al{sub 2}O{sub 3} NPs exposure. • A decrease in bacterial transcriptional response was detected in NPs-treated soils. • A soil-dependent response to specific NP treatment was observed. • In NPs-treated soils no acute toxic effects on C. elegans were found.

  2. Biosynthesis of Cu, ZVI, and Ag nanoparticles using Dodonaea viscosa extract for antibacterial activity against human pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Kiruba Daniel, S. C. G.; Vinothini, G. [Anna University of Technology, Tiruchirappalli, Department of Nanoscience and Technology (India); Subramanian, N. [Anna University of Technology, Tiruchirappalli, Department of Pharmaceutical Technology (India); Nehru, K. [Anna University of Technology, Tiruchirappalli, Department of Chemistry (India); Sivakumar, M., E-mail: muthusiva@gmail.com [Anna University of Technology, Tiruchirappalli, Department of Nanoscience and Technology (India)

    2013-01-15

    Biosynthesis of copper, zero-valent iron (ZVI), and silver nanoparticles using leaf extract of Dodonaea viscosa has been investigated in this report. There are no additional surfactants/polymers used as capping or reducing agents for these syntheses. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, atomic force microscopy, and high-resolution transmission electron microscopy. The phase analysis was performed using selected area electron diffraction. The pH dependence of surface plasmon resonance and subsequent size variation has been determined. The synthesized nanoparticles showed spherical morphology and the average size of 29, 27, and 16 nm for Cu, ZVI, and Ag nanoparticles, respectively. Finally, biosynthesized Cu, ZVI, and Ag nanoparticles were tested against human pathogens viz. Gram-negative Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens and Gram-positive Staphylococcus aureus and Bacillus subtilis, and showed good antimicrobial activity.

  3. Biosynthesis of Cu, ZVI, and Ag nanoparticles using Dodonaea viscosa extract for antibacterial activity against human pathogens

    International Nuclear Information System (INIS)

    Kiruba Daniel, S. C. G.; Vinothini, G.; Subramanian, N.; Nehru, K.; Sivakumar, M.

    2013-01-01

    Biosynthesis of copper, zero-valent iron (ZVI), and silver nanoparticles using leaf extract of Dodonaea viscosa has been investigated in this report. There are no additional surfactants/polymers used as capping or reducing agents for these syntheses. The synthesized nanoparticles were characterized by UV–Vis spectroscopy, X-ray diffraction, atomic force microscopy, and high-resolution transmission electron microscopy. The phase analysis was performed using selected area electron diffraction. The pH dependence of surface plasmon resonance and subsequent size variation has been determined. The synthesized nanoparticles showed spherical morphology and the average size of 29, 27, and 16 nm for Cu, ZVI, and Ag nanoparticles, respectively. Finally, biosynthesized Cu, ZVI, and Ag nanoparticles were tested against human pathogens viz. Gram-negative Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens and Gram-positive Staphylococcus aureus and Bacillus subtilis, and showed good antimicrobial activity.

  4. Fabrication of Poly(styrene-co-maleic anhydride)@Ag Spheres with High Surface Charge Intensity and their Self-Assembly into Photonic Crystal Films.

    Science.gov (United States)

    Bi, Jiajie; Fan, Genrui; Wu, Suli; Su, Xin; Xia, Hongbo; Zhang, Shu-Fen

    2017-10-01

    Herein, we developed a method to prepare monodisperse poly(styrene-co-maleic anhydride)@Ag (PSMA@Ag) core-shell microspheres with high surface charge intensity by using an in situ reduction method. In this method, ethylenediamine tetraacetic acid tetrasodium salt (Na 4 EDTA) was used as a reducing agent to promote the growth of Ag, and at the same time endowed the PSMA@Ag spheres with a surface charge. The monodispersity of PSMA and PSMA@Ag and the ordered array of the photonic crystal films were characterized by using SEM. The formation of Ag nanoparticles was confirmed by using TEM, HR-TEM, and XRD characterizations. Due to the existence of surface charges, the obtained PSMA@Ag microspheres easily self-assembled to form photonic crystal structures. In addition, the surface-enhanced Raman scattering (SERS) activity of the PSMA@Ag photonic crystal films was evaluated by detecting the signal from Raman probe molecules, 4-aminothiophenol (4-ATP). The PSMA@Ag photonic crystal films exhibited a high SERS effect, a low detection limit of up to 10 -8 for 4-ATP, good uniformity, and reproducibility.

  5. Improved Catalysis of Green-Synthesized Pd-Ag Alloy-Nanoparticles for Anodic Oxidation of Methanol in Alkali

    International Nuclear Information System (INIS)

    Roy Chowdhury, Sreya; Ghosh, Srabanti; Bhattachrya, Swapan Kumar

    2017-01-01

    Highlights: • Pd and Pd x Ag y nanoalloys are synthesised by simple green synthetic method without using any capping agent. • Increased electrochemical surface area and roughness factor in case of Pd x Ag y alloy generates enhanced catalytically active sites which help methanol oxidation reaction. • By analysing the products of MOR reaction by CV, FTIR and HPLC plausible mechanism of the reaction is proposed. • Among different compositions Pd 4 Ag and Pd are the best electrodes for oxidation of methanol and formate respectively in alkali. - Abstract: Monometallic Pd, Ag and bimetallic Pd x Ag y alloy nanoparticles were synthesized in a single pot using a green synthetic protocol in absence of any capping agent. X-ray, electron diffraction, microscopic and spectroscopic studies of synthesized material demonstrate the formation of nanoballs with radius of 10–20 nm of face centred cubic metals and alloys. The electrochemical studies of as-synthesized materials loaded on carbon support reveal that the Pd 4 Ag nanoparticles exhibit the best and synergistic electro-catalytic activity in reference to oxidation of methanol in alkali. The most active Pd 4 Ag nanoparticles show higher peak current (201 mA mg −1 ) in comparison to that (133 mA mg −1 ) of Pd in cyclic voltammetric study. The electrode shows the highest exchange current density (1.95 × 10 −2 mA mg −1 of Pd) for methanol oxidation reaction (MOR) and higher catalytic activity for oxidation of possible intermediates like formaldehyde and sodium formate of MOR. Ex-situ infrared spectrometry and chromatographic studies of reaction products reveal that Ag accelerates the formation of formate rather than carbonate elucidating the plausible mechanism of the reaction. These findings have important implications for further fine-tuning of the Pd nano alloys toward highly active and selective catalysts for alcohol fuel cells.

  6. Picosecond laser fabricated Ag, Au and Ag-Au nanoparticles for detecting ammonium perchlorate using a portable Raman spectrometer

    Science.gov (United States)

    Byram, Chandu; Moram, Sree Sathya Bharathi; Soma, Venugopal Rao

    2018-04-01

    In this paper, we present the results from fabrication studies of Ag, Au, and Ag-Au alloy nanoparticles (NPs) using picosecond laser ablation technique in the presence of liquid media. The alloy formation in the NPs was confirmed from UV-Visible measurements. The shape and crystallinity of NPs were investigated by using high resolution transmission electron microscopy (HRTEM), selected area diffraction pattern (SAED) and energy dispersive spectroscopy (EDS). The SERS effect of fabricated NPs was tested with methylene blue and an explosive molecule (ammonium perchlorate) using a portable Raman spectrometer and achieved EFs of ˜106.

  7. Tailoring the light absorption of Ag-PZT thin films by controlling the growth of hexagonal- and cubic-phase Ag nanoparticles

    Science.gov (United States)

    Hu, Tao; Wang, Zongrong; Ma, Ning; Du, Piyi

    2017-12-01

    PbZr0.52Ti0.48O3 thin films containing hexagonal and cubic Ag nanoparticles (Ag NPs) of various sizes were prepared using the sol-gel technique. During the aging process, Ag ions were photo-reduced to form hexagonal Ag NPs. These NPs were uniform in size, and their uniformity was maintained in the thin films during the heat treatment process. Both the total volume and average size of the hexagonal Ag NPs increased with an increasing Ag ion concentration from 0.02 to 0.08 mol l-1. Meanwhile, the remaining Ag ions were reduced to form unstable Ag-Pb alloy particles with Pb ions during the early heating stage. During subsequent heat treatment, these alloys decomposed to form cubic Ag NPs in the thin films. The absorption range of the thin films, quantified as the full width at half maximum in the ultraviolet-visible absorption spectrum, expanded from 6.3 × 1013 Hz (390-425 nm) to 8.4 × 1013 Hz (383-429 nm) as the Ag NPs/PZT ratio increased from 0.2 to 0.8. This work provides an effective way to broaden the absorption range and enhance the optical properties of such films.

  8. Tailoring the light absorption of Ag-PZT thin films by controlling the growth of hexagonal- and cubic-phase Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Tao; Wang, Zongrong; Ma, Ning; Du, Piyi [Zhejiang University, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Hangzhou (China)

    2017-12-15

    PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} thin films containing hexagonal and cubic Ag nanoparticles (Ag NPs) of various sizes were prepared using the sol-gel technique. During the aging process, Ag ions were photo-reduced to form hexagonal Ag NPs. These NPs were uniform in size, and their uniformity was maintained in the thin films during the heat treatment process. Both the total volume and average size of the hexagonal Ag NPs increased with an increasing Ag ion concentration from 0.02 to 0.08 mol l{sup -1}. Meanwhile, the remaining Ag ions were reduced to form unstable Ag-Pb alloy particles with Pb ions during the early heating stage. During subsequent heat treatment, these alloys decomposed to form cubic Ag NPs in the thin films. The absorption range of the thin films, quantified as the full width at half maximum in the ultraviolet-visible absorption spectrum, expanded from 6.3 x 10{sup 13} Hz (390-425 nm) to 8.4 x 10{sup 13} Hz (383-429 nm) as the Ag NPs/PZT ratio increased from 0.2 to 0.8. This work provides an effective way to broaden the absorption range and enhance the optical properties of such films. (orig.)

  9. Sonochemically synthesized Ag nanoparticles as a SERS active substrate and effect of surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Dar, Nitzan, E-mail: n58987012@mail.ncku.edu.tw [Department of Material Science and Engineering, National Cheng Kung University, Tainan 70101 Taiwan (China); Chen, Kuang-Yu [Department of Material Science and Engineering, National Cheng Kung University, Tainan 70101 Taiwan (China); Nien, Yung-Tang, E-mail: ytnien@nfu.edu.tw [Department of Materials Science and Engineering, National Formosa University, Huwei, Yunlin 63201, Taiwan (China); Perkas, Nina [Institute of nanotechnology and advanced materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002 (Israel); Gedanken, Aharon, E-mail: Aharon.Gedanken@biu.ac.il [Institute of nanotechnology and advanced materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002 (Israel); Chen, In-Gann, E-mail: ingann@mail.ncku.edu.tw [Department of Material Science and Engineering, National Cheng Kung University, Tainan 70101 Taiwan (China)

    2015-03-15

    Highlights: • Solid state Ag SERS active substrates were sonochemically synthesized. • High intensity SERS spectra of both crystal violet and rhodamine 6G were observed. • We discovered that PVP aided synthesized substrates showed higher SERS intensity. - Abstract: Surface enhanced Raman scattering (SERS) enables the detection of substances at low concentrations using silver or gold nanostructure. The SERS technique has many applications, such as environmental detection and biosensing. Sonochemistry is an excellent and cheap deposition technique for coating substrates in a form of nanostructure at ambient temperature. It can also be utilized to prepare large SERS substrates. Here, we used the advantages of sonochemistry to deposit solid SERS substrates immobilized on GaN nanostructure. Morphology was studied by scanning electron microscopy. The elemental composition and the spatial distribution were examined by energy dispersive X-ray spectroscopy. The crystal structure and atomic presence was confirmed by X-ray diffraction. SERS substrates were examined with the analytes crystal violet (10{sup −5} M) and rhodamine 6G (10{sup −6} M), they showed prominent characteristic peaks. We discovered that the SERS intensity of poly-vinyl-pyrrolidinone aided sonochemical deposition of Ag nanoparticles was increased. The reason for the effect is morphological changes of the Ag nanoparticles. Smaller nanoparticles were fabricated, which increase their SERS intensity.

  10. Room temperature nanojoining of Cu-Ag core-shell nanoparticles and nanowires

    International Nuclear Information System (INIS)

    Wang, Jiaqi; Shin, Seungha

    2017-01-01

    Room temperature (T room , 300 K) nanojoining of Ag has been widely employed in fabrication of microelectronic applications where the shapes and structures of microelectronic components must be maintained. In this research, the joining processes of pure Ag nanoparticles (NPs), Cu-Ag core-shell NPs, and nanowires (NWs) are studied using molecular dynamics simulations at T room . The evolution of densification, potential energy, and structural deformation during joining process are analyzed to identify joining mechanisms. Depending on geometry, different joining mechanisms including crystallization-amorphization, reorientation, Shockley partial dislocation are determined. A three-stage joining scenario is observed in both joining process of NPs and NWs. Besides, the Cu core does not participate in all joining processes, however, it enhances the mobility of Ag shell atoms, contributing to a higher densification and bonding strength at T room , compared with pure Ag nanomaterials. The tensile test shows that the nanojoint bears higher rupture strength than the core-shell NW itself. This study deepens understanding in the underlying joining mechanisms and thus nanojoint with desirable thermal, electrical, and mechanical properties could be potentially achieved.

  11. Self-learning kinetic Monte Carlo simulations of self-diffusion of small Ag islands on the Ag(111) surface

    International Nuclear Information System (INIS)

    Shah, Syed Islamuddin; Nandipati, Giridhar; Rahman, Talat S; Karim, Altaf

    2016-01-01

    We studied self-diffusion of small two-dimensional Ag islands, containing up to ten atoms, on the Ag(111) surface using self-learning kinetic Monte Carlo (SLKMC) simulations. Activation barriers are calculated using the semi-empirical embedded atom method (EAM) potential. We find that two- to seven-atom islands primarily diffuse via concerted translation processes with small contributions from multi-atom and single-atom processes, while eight- to ten-atom islands diffuse via single-atom processes, especially edge diffusion, corner rounding and kink detachment, along with a minimal contribution from concerted processes. For each island size, we give a detailed description of the important processes, and their activation barriers, responsible for its diffusion. (paper)

  12. Localized surface plasmon behavior of Ag-Cu alloy nanoparticles stabilized by rice-starch and gelatin

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manish Kumar; Mandal, R. K., E-mail: rkmandal.met@itbhu.ac.in [Department of Metallurgical Engineering, IIT (BHU), Varanasi and DST Unit on Nanoscience and Technology, BHU, Varanasi-221 005 (India); Manda, Premkumar; Singh, A. K. [DefenceMetallurgical Research Laboratory, KanchanBagh, Hyderabad-500058 (India)

    2015-10-15

    The purpose of this communication was to understand localized surface plasmon behavior of a series of Ag-Cu alloy nanoparticles capped by rice-starch and gelatin. The structures of dried powders were investigated with the help of X-ray diffraction. The analysis revealed Ag-rich and Cu-rich phases with maximum solid solubility of Cu ∼9 atom per cent; 8 atom per cent and Ag ∼ 16 atom per cent; 14 atom per cent in rice-starch and gelatin capped samples respectively. Transmission electron microscope was used for knowing the particle size as well as to supplement FCC phase formations of Ag-rich and Cu-rich solid phases arrived at based on X-ray diffraction studies. The UV-Vis spectra of sols were examined for the formation and stability of alloy nanoparticles. The temporal evolution of LSPR curves gave us to assert that the sol is stable for more than two months. Small angle X-ray scattering in the sol state was extensively utilized to understand nature of suspensions in terms of fractals. Such a study is important for having a correlation between LSPR behaviors with those of nanoparticle dispersion in aqueous media. It is believed that this work will be a contribution to the emerging field of plasmonics that include applications in the area of photophysical processes and photochemical reactions.

  13. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens

    Science.gov (United States)

    Sankar Boxi, Siddhartha; Mukherjee, Khushi; Paria, Santanu

    2016-02-01

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated •OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.

  14. Graphene oxide chemically decorated with hybrid Ag-Ru/chitosan nanoparticles: fabrication and properties

    OpenAIRE

    Veerapandian, Murugan; Neethirajan, Suresh

    2015-01-01

    Hybridization of distinct materials into a single nanoplatform is relevant to advance material’s properties for functional application such as biosensor platform. We report the synthesis and characterization of nanosheets of graphene oxide decorated with hybrid nanoparticles of silver-ruthenium bipyridine complex (Ag@[Ru(bpy)3]2+) core and chitosan shell. Hybrid nanoparticles were first obtained through a sequential wet-chemical approach using in situ reduction, electrostatic and coordination...

  15. Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

    KAUST Repository

    Chng, Ting Ting

    2011-05-03

    Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

  16. Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction as a highly efficient and stable visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Cao, Chenghao [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Xubiao [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2015-03-21

    Graphical abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction was fabricated by simple electrochemical method. The heterostructures exhibit high photocatalytic activity and excellent recycling performance. - Highlights: • Ag-bridged Ag{sub 2}O nanowire network self-stability structure. • Ag{sub 2}O nanowire network/TiO{sub 2} nanotube p–n heterojunction. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction (Ag–Ag{sub 2}O/TiO{sub 2} NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO{sub 2} NT and then were partly oxidized to Ag{sub 2}O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag{sub 2}O nanowire network. The Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag–Ag{sub 2}O self-stability structure and p–n heterojunction permitted high and stable photocatalytic activity of Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag–Ag{sub 2}O/TiO{sub 2} NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO{sub 2} NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag–Ag{sub 2}O/TiO{sub 2} NT remained highly stable photocatalytic activity.

  17. Preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles and their application in hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Mahmoudian, M.R.; Alias, Y.; Basirun, W.J.; Ebadi, M.

    2012-01-01

    Highlights: ► Ag nanoparticles-decorated ultra thin polypyrrole nanosheets were prepared. ► Higher surface area of the polymer increased interaction between the polymer and Ag + . ► The sensitivity was estimated to be 4.477 μA mM −1 for linear segment. ► The LOD and LOQ (S/N = 3) were estimated to be 0.57 μM and 1.93 μM, respectively. - Abstract: This study examines the preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles (Ag-UTPNSs) and their application in the enzyme-less detection of hydrogen peroxide (H 2 O 2 ) detection. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirmed that Ag nanoparticles (NPs) were deposited onto the surface of the UTPNSs. The increase of the H 2 O 2 reduction current peak to 120 μA in the presence of the Ag-UTPNS/glassy carbon electrode (GCE) as compared to the UTPNS/GCE indicates that the sensitivity of the electrode to H 2 O 2 is significant. This observation can be explained by the larger surface area of the UTPNSs, which can increase the interactions between the polymer and the AgNO 3 solution during the deposition of the Ag NPs, and by the small size of the deposited Ag NPs, which can produce a surface area of Ag that is suitable for the reaction with H 2 O 2 . The amperometric responses show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated to be 0.57 μM, 1.93 μM and 4.477 μA mM −1 , respectively, for the linear segment. The results of the reproducibility experiments show that the use of Ag-UTPNS/GCE is feasible for the quantitative detection of certain concentration ranges of H 2 O 2 .

  18. Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods.

    Science.gov (United States)

    Zhou, Wenwen; Zhao, Weiyun; Lu, Ziyang; Zhu, Jixin; Fan, Shufen; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

    2012-07-07

    In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.

  19. Accumulation of radioactive corrosion products on steel surfaces of VVER type nuclear reactors. I. 110mAg

    CSIR Research Space (South Africa)

    Hirschberg, G

    1999-03-01

    Full Text Available contaminants in the passive layer formed on austenitic stainless steel. In the first part of the series the accumulation of 110mAg has been investigated. Potential dependent sorption of Ag+. ions (cementation) is found to be the predominant process...

  20. Fabrication and size control of Ag nano particles

    International Nuclear Information System (INIS)

    Farbod, M.; Batvandi, M. R.

    2012-01-01

    The objective of this research was to fabricate Ag nanoparticles and control their sizes. Colloidal Ag nanoparticles with particle size of 30 nm were prepared by dissolving AgNO 3 in ethanol and through the chemical reduction of Ag + in alcohol solution. To control the nanoparticle size, different samples were fabricated by changing the AgNO 3 and stabilizer concentrations and the effects of different factors on the shape and size of nanoparticles were investigated. The samples were characterized using Scanning Electron Microscopy and EDX analysis. The results showed that by increasing the AgNO 3 concentration, the average size of nanoparticles increases and nanoparticles lose their spherical shape. Also, we found that by using the stabilizer, it is possible to produce stable nanoparticles but increasing the stabilizer concentration caused an increase in size of nanoparticles. Fabrication of nanoparticles without using stabilizer was achieved but the results showed the nanoparticles size had a growth of 125 nm/h in the alcoholic media.

  1. Direct in situ activation of Ag0 nanoparticles in synthesis of Ag/TiO2 and its photoactivity

    International Nuclear Information System (INIS)

    Jaafar, N.F.; Jalil, A.A.; Triwahyono, S.; Efendi, J.; Mukti, R.R.; Jusoh, R.; Jusoh, N.W.C.; Karim, A.H.; Salleh, N.F.M.; Suendo, V.

    2015-01-01

    Graphical abstract: - Highlights: • Ag 0 loaded on TiO 2 was prepared by a direct in situ electrochemical method. • 5 wt% Ag–TiO 2 demonstrated the best photocatalytic degradation of 2-CP. • Isomorphous substitution of Ag with Ti occurred to form Ti−O−Ag bonds. • Ag 0 and oxygen vacancies trapped electrons to enhance e–H + separation. • Substitution of Ag in the TiO 2 structure decreased the number of oxygen vacancies. - Abstract: Metallic Ag nanoparticles (Ag 0 ) were successfully activated using a direct in situ electrochemical method before being supported on TiO 2 . Catalytic testing showed that 5 wt% Ag–TiO 2 gave the highest photodegradation (94%) of 50 mg L −1 2-chlorophenol (2-CP) at pH 5 using 0.375 g L −1 catalyst within 6 h, while under similar conditions, 1 wt% and 10 wt% Ag–TiO 2 only gave 75% and 78% degradation, respectively. Characterization results illustrated that the photoactivity was affected by the amount of Ag 0 and oxygen vacancies which act as an electrons trap to enhance the electron–hole separation. While, the Ag−O−Ti bonds formation reduced the photoactivity. The degradation followed a pseudo-first order Langmuir–Hinshelwood model where adsorption was the controlling step. Study on the effect of scavengers showed that the hole (H + ) and hydroxyl radical (OH·) play important roles in the photodegradation. The regenerated photocatalyst was still stable after five cycling runs

  2. Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization

    Science.gov (United States)

    Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

    2016-02-01

    In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (106 ~ 109 Ω/◻).

  3. Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization.

    Science.gov (United States)

    Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

    2016-02-03

    In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (10(6)~ 10(9) Ω/◻).

  4. A Highly Active and Alcohol-Tolerant Cathode Electrocatalyst Containing Ag Nanoparticles Supported on Graphene

    International Nuclear Information System (INIS)

    Jiang, Rongzhong; Moton, Elizabeth; McClure, Joshua P.; Bowers, Zachary

    2014-01-01

    A highly active oxygen reduction reaction (ORR) catalyst was synthesized by supporting Ag nano-particles on graphene nano platelets (Ag/GNP) via ultrasound treatment. The Ag/GNP catalyzes the O 2 molecule through a 4-electron reduction to water in 0.1 M KOH electrolyte. The half-wave potential for the ORR on Ag/GNP is similar to a Pt black coated electrode (i.e -0.27 V at Ag/GNP, and -0.18 V at 40% Pt/C vs.SCE). The kinetic rate for the ORR on Ag/GNP is 3.16 × 10 −2 cm · s −1 at -0.4 V vs. SCE. The effect of alcohols and other impurities on the ORR catalytic activity for Ag/GNP was examined and found to be highly tolerant to methanol, ethanol and ethylene glycol. The Ag/GNP catalyst is also tolerant to tetraalkyl ammonium hydroxides; i.e. functional groups related to the chemical structure of common alkaline electrolyte membranes

  5. Sensitive determination of dopamine levels via surface-enhanced Raman scattering of Ag nanoparticle dimers.

    Science.gov (United States)

    Yu, Xiantong; He, XiaoXiao; Yang, Taiqun; Zhao, Litao; Chen, Qichen; Zhang, Sanjun; Chen, Jinquan; Xu, Jianhua

    2018-01-01

    Dopamine (DA) is an important neurotransmitter in the hypothalamus and pituitary gland, which can produce a direct influence on mammals' emotions in midbrain. Additionally, the level of DA is highly related with some important neurologic diseases such as schizophrenia, Parkinson, and Huntington's diseases, etc. In light of the important roles that DA plays in the disease modulation, it is of considerable significance to develop a sensitive and reproducible approach for monitoring DA. The objective of this study was to develop an efficient approach to quantitatively monitor the level of DA using Ag nanoparticle (NP) dimers and enhanced Raman spectroscopy. Ag NP dimers were synthesized for the sensitive detection of DA via surface-enhanced Raman scattering (SERS). Citrate was used as both the capping agent of NPs and sensing agent to DA, which is self-assembled on the surface of Ag NP dimers by reacting with the surface carboxyl group to form a stable amide bond. To improve accuracy and precision, the multiplicative effects model for surface-enhanced Raman spectroscopy was utilized to analyze the SERS assays. A low limits of detection (LOD) of 20 pM and a wide linear response range from 30 pM to 300 nM were obtained for DA quantitative detection. The SERS enhancement factor was theoretically valued at approximately 10 7 by discrete dipole approximation. DA was self-assembled on the citrate capped surface of Ag NPs dimers through the amide bond. The adsorption energy was estimated to be 256 KJ/mol using the Langmuir isotherm model. The density functional theory was used to simulate the spectral characteristics of SERS during the adsorption of DA on the surface of the Ag dimers. Furthermore, to improve the accuracy and precision of quantitative analysis of SERS assays with a multiplicative effects model for surface-enhanced Raman spectroscopy. A LOD of 20 pM DA-level was obtained, and the linear response ranged from 30 pM to 300 nM for quantitative DA detection. The

  6. A transparent conductive oxide electrode with highly enhanced flexibility achieved by controlled crystallinity by incorporating Ag nanoparticles on substrates

    Energy Technology Data Exchange (ETDEWEB)

    Triambulo, Ross E.; Cheong, Hahn-Gil [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of); Lee, Gun-Hwan [Advanced Thin Film Research Group, Korea Institute of Materials Science (KIMS), Changwon (Korea, Republic of); Yi, In-Sook [R and D Center, InkTec Co., Ltd., Ansan (Korea, Republic of); Park, Jin-Woo, E-mail: jwpark09@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)

    2015-01-25

    Highlights: • We developed a composite transparent electrode with Ag nanoparticles and indium-tin-oxide. • Transmittance of AgNPs was improved by formation of oxide layers by O{sub 2} plasma treatment. • Ag nanoparticles became crystalline seeds to grow strong ITO with a uniform growth orientation. • The hybrid electrode is highly more conductive and stable under bending than ITO. - Abstract: We report the synthesis of highly flexible indium tin oxide (ITO) on a polymer substrate whose surface was engineered by oxide-coated Ag nanoparticles (AgNPs) smaller than 20 nm in diameter. Polyimide (PI) substrates were spin coated with Ag ion ink and were subsequently heat treated to form AgNP coatings. The Ag oxide was formed by O{sub 2} plasma treatment to reduce the light absorbance by AgNPs. ITO was dc magnetron sputter-deposited atop the AgNPs. The ITO on the AgNPs was crystalline grown primarily with (2 2 2) growth orientation. This contrasts to the typical microstructure of ITO grown on the polymer, which is that growing c-ITO nucleates are embedded in an amorphous ITO (a-ITO) matrix like a particulate composite. The surface roughness of ITO on AgNPs was as small as the ITO on PI without AgNPs. The crystalline nature of the ITO on the AgNP-coated polymer resulted in the decrease of electric resistivity (ρ) by 65% compared to that of ITO on the bare PI. Furthermore, an electric resistivity change (Δρ) of the ITO on the AgNPs was only 8% at a bending radius (r{sub b}) down to 4 mm, whereas the ITO on the non-coated polymer became almost insulating at an r{sub b} of 10 mm, owing to a drastic increase in the number of cracks. To validate the potential application in the displays, flexible organic light emitting diodes (f-OLEDs) were fabricated on the ITO on AgNPs and the performances was compared with the f-OLED on ITO on the bare PI.

  7. A transparent conductive oxide electrode with highly enhanced flexibility achieved by controlled crystallinity by incorporating Ag nanoparticles on substrates

    International Nuclear Information System (INIS)

    Triambulo, Ross E.; Cheong, Hahn-Gil; Lee, Gun-Hwan; Yi, In-Sook; Park, Jin-Woo

    2015-01-01

    Highlights: • We developed a composite transparent electrode with Ag nanoparticles and indium-tin-oxide. • Transmittance of AgNPs was improved by formation of oxide layers by O 2 plasma treatment. • Ag nanoparticles became crystalline seeds to grow strong ITO with a uniform growth orientation. • The hybrid electrode is highly more conductive and stable under bending than ITO. - Abstract: We report the synthesis of highly flexible indium tin oxide (ITO) on a polymer substrate whose surface was engineered by oxide-coated Ag nanoparticles (AgNPs) smaller than 20 nm in diameter. Polyimide (PI) substrates were spin coated with Ag ion ink and were subsequently heat treated to form AgNP coatings. The Ag oxide was formed by O 2 plasma treatment to reduce the light absorbance by AgNPs. ITO was dc magnetron sputter-deposited atop the AgNPs. The ITO on the AgNPs was crystalline grown primarily with (2 2 2) growth orientation. This contrasts to the typical microstructure of ITO grown on the polymer, which is that growing c-ITO nucleates are embedded in an amorphous ITO (a-ITO) matrix like a particulate composite. The surface roughness of ITO on AgNPs was as small as the ITO on PI without AgNPs. The crystalline nature of the ITO on the AgNP-coated polymer resulted in the decrease of electric resistivity (ρ) by 65% compared to that of ITO on the bare PI. Furthermore, an electric resistivity change (Δρ) of the ITO on the AgNPs was only 8% at a bending radius (r b ) down to 4 mm, whereas the ITO on the non-coated polymer became almost insulating at an r b of 10 mm, owing to a drastic increase in the number of cracks. To validate the potential application in the displays, flexible organic light emitting diodes (f-OLEDs) were fabricated on the ITO on AgNPs and the performances was compared with the f-OLED on ITO on the bare PI

  8. Porphyrins as SERRS spectral probes of chemically functionalized Ag nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Šišková, Karolína; Vlčková, B.; Turpin, P. Y.; Thorel, A.; Grosjean, A.

    2008-01-01

    Roč. 48, č. 1 (2008), s. 44-52 ISSN 0924-2031. [International Conference on Advanced Vibrational Spectroscopy (ICAVS-4) /4./. Corfu, 10.06.2007-15.06.2007] R&D Projects: GA ČR GA203/07/0717 Institutional research plan: CEZ:AV0Z40500505 Keywords : SERRS * citrate-modified Ag nanoparticles * laser ablation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.810, year: 2008

  9. Influence of particle coating and matrix constituents on the cloud point extraction efficiency of silver nanoparticles (Ag-NPs) and application for monitoring the formation of Ag-NPs from Ag(+).

    Science.gov (United States)

    Hartmann, Georg; Baumgartner, Tanja; Schuster, Michael

    2014-01-07

    For the quantification of silver nanoparticles (Ag-NPs) in environmental samples using cloud point extraction (CPE) for selective enrichment, surface modification of the Ag-NPs and matrix effects can play a key role. In this work we validate CPE with respect to the influence of different coatings and naturally occurring matrix components. The Ag-NPs tested were functionalized with inorganic and organic compounds as well as with biomolecules. Commercially available NPs and NPs synthesized according to methods published in the literature were used. We found that CPE can extract almost all Ag-NPs tested with very good efficiencies (82-105%). Only Ag-NPs functionalized with BSA (bovine serum albumin), which is a protein with the function to keep colloids in solution, cannot be extracted. No or little effect of environmentally relevant salts, organic matter, and inorganic colloids on the CPE of AgNPs was found. Additionally we used CPE to observe the in situ formation of Ag-NPs produced by the reduction of Ag(+) with natural organic matter (NOM).

  10. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

    OpenAIRE

    Yang Yongkun; Burkhard Peter

    2012-01-01

    Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs...

  11. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    Science.gov (United States)

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-01

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  12. Particle deposition and deformation from high speed impaction of Ag nanoparticles

    International Nuclear Information System (INIS)

    Chitrakar, T.V.; Keto, J.W.; Becker, M.F.; Kovar, D.

    2017-01-01

    The impaction of a single Ag nanoparticle onto an (001) Ag substrate was studied as a function of particle diameter (2–9 nm) and impaction velocity (10–1500 m/sec) using molecular dynamics simulations. The final crystallographic structures were observed to transition from a polycrystalline to an epitaxial morphology as impaction velocity was increased and the velocity required to achieve epitaxy increased with particle size. To understand how the crystallographic structures evolved to their final state, the deformation mechanisms were then studied over a range of time scales, beginning immediately upon impaction. The observed mechanisms included disordering of the atoms and the initiation and propagation of partial dislocations. Deformation increased with impaction velocity due to increases in the degree of disordering and the partial dislocation density. At longer time scales, relaxation of the disordered particles produced epitaxial morphologies, whereas polycrystalline morphologies were observed following incomplete disordering. These results suggest that the microstructures of thick films produced by high speed impaction of nanoparticle aerosols are strongly influenced by processing parameters.

  13. Impact of water composition on association of Ag and CeO₂ nanoparticles with aquatic macrophyte Elodea canadensis.

    Science.gov (United States)

    Van Koetsem, Frederik; Xiao, Yi; Luo, Zhuanxi; Du Laing, Gijs

    2016-03-01

    In this study, the potential association of (citrate-stabilized) Ag (14.1 ± 1.0 nm) and CeO2 (6.7 ± 1.2 nm) engineered nanoparticles (ENPs), or their ionic counterparts, with the submerged aquatic plant Elodea canadensis, was examined and, in particular, parameters affecting the distribution of the nanoparticles (or metal ions) between plant biomass and the water phase were assessed using five distinct aqueous matrices (i.e. tap water, 10 % Hoagland's solution and three natural surface water samples). Individual plants were exposed to varying concentrations of Ag and CeO2 ENPs or Ag(+) and Ce(3+) ions during 72-h-lasting batch experiments. A dose-dependent increase of silver or cerium in plant biomass was observed for both the nanoparticles and the ions, whereby exposure to the latter systematically resulted in significantly higher biomass concentrations. Furthermore, the apparent plant uptake of CeO2 ENPs appeared to be higher than that for Ag ENPs when comparing similar exposure concentrations. These findings suggest that association with E. canadensis might be affected by particle characteristics such as size, composition, surface charge or surface coating. Moreover, the stability of the ENPs or ions in suspension/solution may be another important aspect affecting plant exposure and uptake. The association of the nanoparticles or ions with E. canadensis was affected by the physicochemical characteristics of the water sample. The silver biomass concentration was found to correlate significantly with the electrical conductivity (EC), dry residue (DR) and Cl(-), K, Na and Mg content in the case of Ag ENPs or with the EC, inorganic carbon (IC) and Cl(-), NO3 (-), Na and Mg content in the case of Ag(+) ions, whereas significant relationships between the cerium biomass concentration and the EC, DR, IC and Ca content or the pH, EC, DR, IC and Cl(-), Ca and Mg content were obtained for CeO2 ENPs or Ce(3+) ions, respectively. Results also indicated that the Ag

  14. In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

    Science.gov (United States)

    Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

    2014-02-15

    Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Size effects on the Kauzmann temperature and related thermodynamic parameters of Ag nanoparticles

    International Nuclear Information System (INIS)

    Ao, Z M; Zheng, W T; Jiang, Q

    2007-01-01

    Based on the Sutton-Chen many-body potential function, several thermodynamic parameters of Ag are simulated by molecular dynamics. The parameters simulated are size dependences of the Kauzmann temperature T K and melting temperature T m , and size and temperature dependences of melting enthalpy H m and melting entropy S m . The simulation results and the results of the thermodynamic theory models of T K and T m show good agreement, indicating that as the size of the Ag particles decreases, the T K and T m functions decrease. However, the ratio of T K and T m of Ag nanoparticles is size-independent

  16. ANTIMICROBIAL ACTIVITY OF Ag+, Cu2+, Zn2+, Mg2+ IONS DOPED CHITOSAN NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    Sukhodub LB

    2015-04-01

    Full Text Available Modification by polymers and inorganic ions of the bioactive materials for orthopedic implants with the purpose of initiating controlled reactions in tissues that surround the implant, is one of the modern approaches in medical materials. A key feature of functional polymers is their ability to form complexes with various metal ions in solution. Chitosan is natural biopolymer with pronounced affinity to transition metal ions. Some researches prove the higher antimicrobial activity of Chitosan-metal complexes compared with pure Chitosan. The purpose of this work was the study of antimicrobial activity of Chitosan nanoparticles modified by metal ions Ag+, Cu2+, Zn2+, Mg2+ against reference strains S. aureus 25923 ATSS, E. coli ATCC 25922, C. albicans ATCC 885653 for their further use as components of the composite biomaterials for medical purpose.Chitosan nanoparticles suspension was prepared by known method based on the ionotropic gelation between chitosan and sodium tripolyphosphate.To obtain Chitosan-metal nanoparticles to the Chitosan suspension were added the corresponding metal ions aqueous solutions in quantity to match the concentration of metal ions of 200 ppm . Antibacterial activities of Ag+, Cu2+, Zn2+, Mg2+ ions doped Chitosan nanoparticles, pure Chitosan nanoparticles, metal ions and 1% (v/v acetic acid solution (it was used as solvent for Chitosan against bacteria were evaluated by determination of minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC in vitro. Muller– Hinton (MH broth and MH agar (Russia were used as growth media. The bacteria suspension for further use was prepared with concentration that corresponded 0,5units by McFarland scale. The MIC was determined by a broth dilution method. The results were read after 24 hours of experimental tubes incubation at 37 oC as equivalent to the concentration of the tube without visible growth. To evaluate MBC, a sample of 0,1 ml was transferred from

  17. Reducing strength prevailing at root surface of plants promotes reduction of Ag+ and generation of Ag(0/Ag2O nanoparticles exogenously in aqueous phase.

    Directory of Open Access Journals (Sweden)

    Peddisetty Pardha-Saradhi

    Full Text Available Potential of root system of plants from wide range of families to effectively reduce membrane impermeable ferricyanide to ferrocyanide and blue coloured 2,6-dichlorophenol indophenol (DCPIP to colourless DCPIPH2 both under non-sterile and sterile conditions, revealed prevalence of immense reducing strength at root surface. As generation of silver nanoparticles (NPs from Ag+ involves reduction, present investigations were carried to evaluate if reducing strength prevailing at surface of root system can be exploited for reduction of Ag+ and exogenous generation of silver-NPs. Root system of intact plants of 16 species from 11 diverse families of angiosperms turned clear colorless AgNO3 solutions, turbid brown. Absorption spectra of these turbid brown solutions showed silver-NPs specific surface plasmon resonance peak. Transmission electron microscope coupled with energy dispersive X-ray confirmed the presence of distinct NPs in the range of 5-50 nm containing Ag. Selected area electron diffraction and powder X-ray diffraction patterns of the silver NPs showed Bragg reflections, characteristic of crystalline face-centered cubic structure of Ag(0 and cubic structure of Ag2O. Root system of intact plants raised under sterile conditions also generated Ag(0/Ag2O-NPs under strict sterile conditions in a manner similar to that recorded under non-sterile conditions. This revealed the inbuilt potential of root system to generate Ag(0/Ag2O-NPs independent of any microorganism. Roots of intact plants reduced triphenyltetrazolium to triphenylformazon and impermeable ferricyanide to ferrocyanide, suggesting involvement of plasma membrane bound dehydrogenases in reduction of Ag+ and formation of Ag(0/Ag2O-NPs. Root enzyme extract reduced triphenyltetrazolium to triphenylformazon and Ag+ to Ag(0 in presence of NADH, clearly establishing potential of dehydrogenases to reduce Ag+ to Ag(0, which generate Ag(0/Ag2O-NPs. Findings presented in this manuscript put

  18. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    Directory of Open Access Journals (Sweden)

    Mallikarjuna N. Nadagouda

    2008-01-01

    Full Text Available For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag and palladium (Pd, nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4 or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing agents. The average particle size of nanoprticle was found to be Ag (average size 6.1±0.1 nm and Pd (average size 4.1±0.1 nm nanoparticles in ethylene glycol and Ag (average size 5.9±0.1 nm, and average size 6.1±0.1 nanoparticles in acetic acid and NMP, respectively. The formation of noble multiple shape nanostructures and their self assembly were dependent on the solvent employed for the preparation. When water was used as solvent media, Ag and Pd nanoparticles started to self-assemble into rod-like structures and in isopropanol Ag and Pd nanoparticles yielded wire-like structures with a thickness in the range of 10 to 20 nm and several hundred microns in length. In acetone and acetonitrile medium, the Ag and Pd nanoparticles are self-assembled into a regular pattern making nanorod structures with thicknesses ranging from 100 to 200 nm and lengths of a few microns. The so-synthesized nanostructures were characterized using scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive X-ray (EDX analysis, and UV spectroscopy. The ensuing Ag and Pd nanoparticles catalyzed the reactions of aniline and pyrrole to generate polyaniline and polypyrrole nanofibers and may find various technological and biological applications. This single-step greener approach is general and can be extended to other noble metals and transition metal oxides.

  19. [Three-dimensional vertically aligned CNTs coated by Ag nanoparticles for surface-enhanced Raman scattering].

    Science.gov (United States)

    Zhang, Xiao-Lei; Zhang, Jie; Fan, Tuo; Ren, Wen-Jie; Lai, Chun-Hong

    2014-09-01

    In order to make surface-enhanced Raman scattering (SERS) substrates contained more "hot spots" in a three-dimensional (3D) focal volume, and can be adsorbed more probe molecules and metal nanoparticles, to obtain stronger Raman spectral signal, a new structure based on vertically aligned carbon nanotubes (CNTs) coated by Ag nanoparticles for surface Raman enhancement is presented. The vertically aligned CNTs are synthesized by chemical vapor deposition (CVD). A silver film is first deposited on the vertically aligned CNTs by magnetron sputtering. The samples are then annealed at different temperature to cause the different size silver nanoparticles to coat on the surface and sidewalls of vertically aligned CNTs. The result of scanning electron microscopy(SEM) shows that Ag nanoparticles are attached onto the sidewalls and tips of the vertically aligned CNTs, as the annealing temperature is different , pitch size, morphology and space between the silver nanoparticles is vary. Rhodamine 6G is served as the probe analyte. Raman spectrum measurement indicates that: the higher the concentration of R6G, the stronger the Raman intensity, but R6G concentration increase with the enhanced Raman intensity varies nonlinearly; when annealing temperature is 450 °C, the average size of silver nanoparticles is about 100 to 120 nm, while annealing temperature is 400 °C, the average size is about 70 nm, and the Raman intensity of 450 °C is superior to the annealing temperature that of 400 °C and 350 °C.

  20. Room temperature nanojoining of Cu-Ag core-shell nanoparticles and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiaqi; Shin, Seungha, E-mail: sshin@utk.edu [The University of Tennessee, Department of Mechanical, Aerospace and Biomedical Engineering (United States)

    2017-02-15

    Room temperature (T{sub room}, 300 K) nanojoining of Ag has been widely employed in fabrication of microelectronic applications where the shapes and structures of microelectronic components must be maintained. In this research, the joining processes of pure Ag nanoparticles (NPs), Cu-Ag core-shell NPs, and nanowires (NWs) are studied using molecular dynamics simulations at T{sub room}. The evolution of densification, potential energy, and structural deformation during joining process are analyzed to identify joining mechanisms. Depending on geometry, different joining mechanisms including crystallization-amorphization, reorientation, Shockley partial dislocation are determined. A three-stage joining scenario is observed in both joining process of NPs and NWs. Besides, the Cu core does not participate in all joining processes, however, it enhances the mobility of Ag shell atoms, contributing to a higher densification and bonding strength at T{sub room}, compared with pure Ag nanomaterials. The tensile test shows that the nanojoint bears higher rupture strength than the core-shell NW itself. This study deepens understanding in the underlying joining mechanisms and thus nanojoint with desirable thermal, electrical, and mechanical properties could be potentially achieved.

  1. Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

    Science.gov (United States)

    Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

    2018-04-01

    Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

  2. Drastic nickel ion removal from aqueous solution by curcumin-capped Ag nanoparticles

    Science.gov (United States)

    Bettini, S.; Pagano, R.; Valli, L.; Giancane, G.

    2014-08-01

    A completely green synthesis protocol has been adopted to obtain silver nanoaggregates capped by the natural compound (1E, 6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-diene), also known as curcumin. The synthesis has been monitored by infrared, Raman, visible and fluorescence spectroscopies. Characterization confirms that curcumin reduces and caps the nanoparticles, and such a procedure allows its solubility in water and drastically increases curcumin stability. Silver nanoparticles (AgNPs)/curcumin complex has been dispersed in a water solution containing a known nickel ion concentration. After three days, a grey precipitate is observed and nickel concentration in the solution is reduced by about 70%.A completely green synthesis protocol has been adopted to obtain silver nanoaggregates capped by the natural compound (1E, 6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-diene), also known as curcumin. The synthesis has been monitored by infrared, Raman, visible and fluorescence spectroscopies. Characterization confirms that curcumin reduces and caps the nanoparticles, and such a procedure allows its solubility in water and drastically increases curcumin stability. Silver nanoparticles (AgNPs)/curcumin complex has been dispersed in a water solution containing a known nickel ion concentration. After three days, a grey precipitate is observed and nickel concentration in the solution is reduced by about 70%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02583k

  3. Preparation of Ag{sub core}/Au{sub shell} bimetallic nanoparticles from physical mixtures of Au clusters and Ag ions under dark conditions and their catalytic activity for aerobic glucose oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haijun, E-mail: zhanghaijun@wust.edu.cn [College of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei Province 430081 (China); Toshima, Naoki; Takasaki, Kanako [Department of Applied Chemistry, Tokyo University of Science Yamaguchi, SanyoOnoda-shi, Yamaguchi 756-0884 (Japan); Okumura, Mitsutaka [Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-0043 (Japan)

    2014-02-15

    Graphical abstract: The synthesis, characterization and catalytic activities for glucose oxidation of AgAu bimetallic nanoparticles (BNPs) with size of less than 2 nm are reported. The catalytic activity of Ag{sub 10}Au{sub 90} BNPs was about two times higher than that of Au NPs, even the BNPs have a larger particle size than that of Au NPs. -- Highlights: • Ag{sub core}/Au{sub shell} BNPs with size of less than 2.0 nm were prepared. • No any reducing reagents and lights were used for the preparation of the BNPs. • The catalytic activity of the BNPs is about two times higher than that of Au NPs. -- Abstract: AgAu bimetallic nanoparticles (BNPs), one of the most extensively studied bimetallic systems in the literatures, could have various structures and compositions depending on their preparation conditions. In the present work, catalytically highly active PVP-protected Ag{sub core}/Au{sub shell} BNPs of about 2.5 nm in diameter were fabricated from physical mixtures of aqueous dispersions of Au nanoparticles and Ag{sup +} ions under dark conditions without using any reducing agents. The prepared Ag{sub core}/Au{sub shell} BNP colloidal catalysts, which possessed a high activity for aerobic glucose oxidation, were characterized by Ultraviolet–visible spectrophotometry (UV–Vis), Inductive coupled plasma emission spectrometer (ICP), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Energy disperse spectroscopy (EDS) in High-resolution scanning transmission electron microscopy (HR-STEM). The highest activity (11,360 mol-glucose h{sup −1} mol-metal{sup −1}) was observed for the BNPs with the Ag/Au atomic ratio of 1/9, the TOF value of which is about two times higher than that of Au nanoparticles with the particle size of 1.3 nm. The enhanced catalytic activity of the prepared Ag{sub core}/Au{sub shell} BNPs compared to Au NPs can be ascribed to the presence of negatively charged Au atoms resulted from electron donations

  4. Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays

    Directory of Open Access Journals (Sweden)

    Jing Liu

    2015-05-01

    Full Text Available In this study, the nanosphere lithography (NSL method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz and 1.68 (SF5 glass, the nanoparticle arrays would have better refractive index sensitivity (RIS and figure of merit (FOM. Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results.

  5. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

    International Nuclear Information System (INIS)

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Ronning, Carsten; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Bharuth-Ram, Krish; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Ridgway, Mark; Hasan, Shakeeb Bin; Rockstuhl, Carsten

    2016-01-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic "8"4Kr and "1"9"7Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm"−"1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles. (paper)

  6. Optical Property Characterization of Novel Graphene-X (X=Ag, Au and Cu Nanoparticle Hybrids

    Directory of Open Access Journals (Sweden)

    Sumit Ranjan Sahu

    2013-01-01

    Full Text Available The present investigation reports new results on optical properties of graphene-metal nanocomposites. These composites were prepared by a solution-based chemical approach. Graphene has been prepared by thermal reduction of graphene oxide (GO at 90°C by hydrazine hydrate in an ammoniacal medium. This ammoniacal solution acts as a solvent as well as a basic medium where agglomeration of graphene can be prevented. This graphene solution has further been used for functionalization with Ag, Au, and Cu nanoparticles (NPs. The samples were characterized by X-ray diffraction (XRD, Raman spectroscopy, UV-Vis spectroscopy, scanning electron microscopy (SEM, and transmission electron microscopy (TEM to reveal the nature and type of interaction of metal nanoparticles with graphene. The results indicate distinct shift of graphene bands both in Raman and UV-Vis spectroscopies due to the presence of the metal nanoparticles. Raman spectroscopic analysis indicates blue shift of D and G bands in Raman spectra of graphene due to the presence of metal nanoparticles except for the G band of Cu-G, which undergoes red shift, reflecting the charge transfer interaction between graphene sheets and metal nanoparticles. UV-Vis spectroscopic analysis also indicates blue shift of graphene absorption peak in the hybrids. The plasmon peak position undergoes blue shift in Ag-G, whereas red shift is observed in Au-G and Cu-G.

  7. Studying the morphological features of plasma treated silver and PEGylated silver nanoparticles: antibacterial activity

    Science.gov (United States)

    Waseem, M.; Awan, T.; Yasin, H. M.; Rehman, N. U.

    2018-03-01

    A strategy to treat the silver and PEGylated silver nanoparticles with plasma was being purposed. Oil in water (o/w) microemulsion method was used for the synthesis of Ag nanoparticles (AgNPs). Polyethylene glycol (PEG) having molecular weight 600 was used to coat the surface of AgNPs. Optical emission spectroscopy (OES) was used to characterize the plasma and it is noted that plasma treatment is useful to modify the structural characteristic of silver nanoparticles. The nanoparticles were treated with helium-oxygen mixture plasma, generated in plasma needle at atmospheric pressure. Both AgNPs and PEGylated AgNPs before and after plasma treatment were characterized by x-rays diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystallite size of silver nanoparticles after the treatment of plasma decreases from 71 nm to 27 nm. The SEM micrographs show that the size of Ag nanoparticles was nearly 118 nm whereas the thickness of the silver needle was around 135 nm. All the characteristics IR bands associated to the silver nanoparticles were detected. The FTIR spectrum also support the accumulation of OH radicals in the plasma treated samples. The samples before and after plasma treatment were screened against Gram positive (Bacillus Subtilis and Staphylococcus Aureus) and Gram negative (Escherichia Coli and Pseudomonas Aeruginosa) bacteria. The promising response was detected when plasma treated PEGylated AgNPs was tested against bacterial strains.

  8. Bioactive compound synthesis of Ag nanoparticles from leaves of Melia azedarach and its control for mosquito larvae.

    Science.gov (United States)

    Ramanibai, R; Velayutham, K

    2015-02-01

    Larvicidal activity of synthesized Ag nanoparticles using 2,7.bis[2-[diethylamino]-ethoxy]fluorence isolate from the Melia azedarach leaves against Aedes aegypti and Culex quinquefasciatus. Six fractions were collected and concentrated, fraction three showed a single spot on TLC which was found to be a pure compound. The structures were elucidated by analyses of UV, MS, and NMR spectral data. The maximum mortality was fluorence against A. aegypti and C. quinquefasciatus (LC50 = 7.94, LC90 = 23.82 ppm and LC50 = 13.58 and LC90 = 40.03 ppm). The synthesized nanoparticles were characterized and confirmed as Ag nanoparticles by using UV-visible spectroscopy, XRD and HRTEM analysis. The maximum activity was observed in synthesized AgNPs against A. aegypti and C. quinquefasciatus (LC50 = 4.27 and 3.43 µg/mL; LC90 = 12.61 and 10.29 µg/mL). Rephrase test was studied to analyze the toxicological effects of Mesocyclops pehpeiensis for 24 h at synthesized AgNPs. This method is considered as an innovative alternative approach that can be used to control mosquitoes. Copyright © 2014. Published by Elsevier Ltd.

  9. Magnetic and magnetotransport properties of Fe nanoparticles embedded in Ag matrix

    Energy Technology Data Exchange (ETDEWEB)

    Sarmiento, G. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Apartado 644, 48080 Bilbao (Spain); Garcia Prieto, A. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Apartado 644, 48080 Bilbao (Spain); Orue, I. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Apartado 644, 48080 Bilbao (Spain); Fdez-Gubieda, M.L. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Apartado 644, 48080 Bilbao (Spain)]. E-mail: malu@we.lc.ehu.es

    2005-04-15

    Fe{sub 20}Ag{sub 80} and Fe{sub 30}Ag{sub 70} granular thin films have been prepared by the pulsed laser deposition technique under different parameter conditions of pulse frequency and target angular speed. Their influence on the microstructure of the sample, through the analysis of the hysteresis loops, magnetotransport response and magnetooptical Kerr effect, has been investigated. The Fe{sub 20}Ag{sub 80} samples present a superparamagnetic phase, composed of spherical Fe clusters with a mean diameter of 3nm. The number of Fe nanoparticles increases as both laser pulse frequency and target angular speed increase, thus enhancing their giant magnetoresistance response. The Fe{sub 30}Ag{sub 70} thin films have anisotropic magnetic behaviour and their magnetotransport measurements show giant magnetoresistance and extraordinary Hall effect. These anisotropies suggest the presence of Fe planar particles, which give rise to shape magnetic anisotropy that increases with increasing the target angular speed for a given laser pulse frequency. The planar shape of the Fe particles could be in the origin of the dominant extraordinary Hall effect.

  10. Magnetic and magnetotransport properties of Fe nanoparticles embedded in Ag matrix

    International Nuclear Information System (INIS)

    Sarmiento, G.; Garcia Prieto, A.; Orue, I.; Fdez-Gubieda, M.L.

    2005-01-01

    Fe 20 Ag 80 and Fe 30 Ag 70 granular thin films have been prepared by the pulsed laser deposition technique under different parameter conditions of pulse frequency and target angular speed. Their influence on the microstructure of the sample, through the analysis of the hysteresis loops, magnetotransport response and magnetooptical Kerr effect, has been investigated. The Fe 20 Ag 80 samples present a superparamagnetic phase, composed of spherical Fe clusters with a mean diameter of 3nm. The number of Fe nanoparticles increases as both laser pulse frequency and target angular speed increase, thus enhancing their giant magnetoresistance response. The Fe 30 Ag 70 thin films have anisotropic magnetic behaviour and their magnetotransport measurements show giant magnetoresistance and extraordinary Hall effect. These anisotropies suggest the presence of Fe planar particles, which give rise to shape magnetic anisotropy that increases with increasing the target angular speed for a given laser pulse frequency. The planar shape of the Fe particles could be in the origin of the dominant extraordinary Hall effect

  11. Study on the effect of nanoparticle bimetallic coreshell Au-Ag for sensitivity enhancement of biosensor based on surface plasmon resonance

    International Nuclear Information System (INIS)

    Widayanti; Abraha, K

    2016-01-01

    Bimetallic Au-Ag core-shell, a type of composite spherical nanoparticle consisting of a spherical Au core covered by Ag shell, have been used as active material for biomolecular analyte detection based on surface plasmon resonance (SPR) spectroscopy. SPR technology evolved into a key technology for characterization of biomolecular interaction. In this paper, we want to show the influence of nanoparticle bimettalic Au-Ag coreshell for optic respon of LSPR biosensor through attenuated total reflection (ATR) spectrum. The method consist of several steps begin from make a model LSPR system with Kretschmann configuration, dielectric function determination of composite bimetallic coreshell nanoparticle using effective medium theory approximation and the last is reflectivity calculation for size variation of core and shell bimetallic nanoparticle. Our result show that, by varying the radius of core and shell thickness, the peak of the reflectivity (ATR spectrum) shifted to the different angle of incident light and the addition of coreshell in SPR biosensor leads to enhancement the sensitivity. (paper)

  12. Ag2WO4 nanorods decorated with AgI nanoparticles: Novel and efficient visible-light-driven photocatalysts for the degradation of water pollutants

    Directory of Open Access Journals (Sweden)

    Shijie Li

    2018-04-01

    Full Text Available To develop efficient and stable visible-light-driven (VLD photocatalysts for pollutant degradation, we synthesized novel heterojunction photocatalysts comprised of AgI nanoparticle-decorated Ag2WO4 nanorods via a facile method. Various characterization techniques, including XRD, SEM, TEM, EDX, and UV–vis DRS were used to investigate the morphology and optical properties of the as-prepared AgI/Ag2WO4 catalyst. With AgI acting as the cocatalyst, the resulting AgI/Ag2WO4 heterostructure shows excellent performance in degrading toxic, stable pollutants such as rhodamine B (RhB, methyl orange (MO and para-chlorophenol (4-CP. The high performance is attributed to the enhanced visible-light absorption properties and the promoted separation efficiency of charge carriers through the formation of the heterojunction between AgI and Ag2WO4. Additionally, AgI/Ag2WO4 exhibits durable stability. The active species trapping experiment reveals that active species (O2•− and h+ dominantly contribute to RhB degradation. The AgI/Ag2WO4 heterojunction photocatalyst characterized in this work holds great potential for remedying environmental issues due to its simple preparation method and excellent photocatalytic performance.

  13. Safety evaluation of green synthesized Cola nitida pod, seed and seed shell extract-mediated silver nanoparticles (AgNPs using an Allium cepa assay

    Directory of Open Access Journals (Sweden)

    Taofeek A. Yekeen

    2017-11-01

    Full Text Available The increase in the use of nanoparticles in various fields of human endeavours calls for the need to understand the toxic potential of green synthesized nanoparticles. Cytogenotoxic potentials of green synthesized Cola pod (Cp-AgNPs, seed (Cs-AgNPs and seed shell (Css-AgNPs silver nanoparticles and silver nitrate salts (Ags were evaluated using an A. cepa assay. Twenty onion bulbs were exposed to 0.01, 0.10, 1.0, 10.0, and 100.0 μg/ml AgNPs and Ags solutions. Microscopic evaluation was performed at 24, 48 and 72 h with 5000 cells per concentration scored for chromosomal aberrations, while the effects on the root growth were evaluated at 72 h. The observed dividing cells and mitotic inhibition were dose-dependent for the three AgNPs and Ags at 24, 48 and 72 h. Mitotic index obtained for 1.0, 10 and 100 μg/mL at all times of evaluation were less than half the value of the negative control, while cell arrest was only observed at 72 h at a concentration of 100 μg/mL for the three AgNPs. The chromosomal aberrations observed were c-mitosis, a chromosome bridge, a vagrant chromosome, and a sticky chromosome, which indicate the potential of AgNPs for genotoxicity. The mean root length of A. cepa treated with AgNPs showed a dose-dependent significant decrease compared to the control, indicating their inhibitory potential, but the mean root lengths were found to be lower at all concentrations compared to those treated with Ags, thus showing the attenuation of growth inhibition. The EC50 values revealed the order of growth inhibition as Ags>Cp-AgNPs>Css-AgNPs>Cs-AgNPs. The cytogenotoxic potential of the AgNPs suggests that caution should be exercised in their usage to prevent environmental pollution. Keywords: Green synthesis, Nanoparticles, Silver, Aberration, Allium cepa, Cola nitida

  14. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Directory of Open Access Journals (Sweden)

    Peng Xia

    2017-11-01

    Full Text Available A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF state to low resistance (ON state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  15. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Science.gov (United States)

    Xia, Peng; Li, Luman; Wang, Pengfei; Gan, Ying; Xu, Wei

    2017-11-01

    A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM) Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF) state to low resistance (ON) state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  16. In-situ fabrication of hybrid polyoxometalate nanoparticles composite films

    International Nuclear Information System (INIS)

    Lan Yang; Mao Baodong; Wang Enbo; Song Yonghai; Kang Zhenhui; Wang Chunlei; Tian Chungui; Zhang Chao; Xu Lin; Li Zhuang

    2007-01-01

    Inorganic-organic hybrid nanoparticles multilayer films were fabricated by extending the method of nucleation and growth of particles in polymer assemblies. The polyelectrolyte matrix was constructed by layer-by-layer self-assembly method. Synthesis of polyoxometalate nanoparticles was achieved by alternately dipping the precursor polyelectrolyte matrix into AgNO 3 and H 4 SiW 12 O 40 aqueous solutions. Repeating the above synthesis process, Ag 4 SiW 12 O 40 nanoparticles with controllable diameters of 20 to 77 nm were synthesized in the multilayer films in-situ. UV-vis absorption spectra indicate that the nanoparticles grew gradually in the synthesis process. Transmission electron microscopy was used to observe the size and morphology of the nanoparticles

  17. Biochar alleviates the toxicity of imidacloprid and silver nanoparticles (AgNPs) to Enchytraeus albidus (Oligochaeta).

    Science.gov (United States)

    Nyoka, Ngitheni Winnie-Kate; Kanyile, Sthandiwe Nomthandazo; Bredenhand, Emile; Prinsloo, Godfried Jacob; Voua Otomo, Patricks

    2018-04-01

    The present study investigated the use of biochar for the alleviation of the toxic effects of a nanosilver colloidal dispersion and a chloronicotinyl insecticide. The survival and reproduction of the potworm Enchytraeus albidus were assessed after exposure to imidacloprid and silver nanoparticles (AgNPs). E. albidus was exposed to 0, 25, 50, 100, 200, and 400 mg imidacloprid/kg and 0, 5, 25, 125, and 625 mg Ag/kg for 21 days in 10% biochar amended and non-biochar amended OECD artificial soil. In both exposure substrates, the effects of imidacloprid on survival were significant in the two highest treatments (p imidacloprid. In the case of AgNPs, significant mortality was only observed in the highest AgNP treatments in both the amended and non-amended soils (p imidacloprid/kg in the non-amended soil and a higher EC 50  = 46.23 mg imidacloprid/kg in the biochar-amended soil. This indicated a 2-fold decrease in imidacloprid toxicity due to biochar amendment. A similar observation was made in the case of AgNPs where a reproduction EC 50  = 166.70 mg Ag/kg soil in the non-amended soil increased to an EC 50  > 625 mg Ag/kg soil (the highest AgNP treatment) in the amended soil. This indicated at least a 3.7-fold decrease in AgNPs toxicity due to biochar amendment. Although more studies may be needed to optimize the easing effects of biochar on the toxicity of these chemicals, the present results show that biochar could be useful for the alleviation of the toxic effects of imidacloprid and silver nanoparticles in the soil.

  18. Preparation and characterization of sub-20 nm Cu{sub X}@Ag{sub 1} core-shell nanoparticles by changing concentration of silver precursor

    Energy Technology Data Exchange (ETDEWEB)

    Chee, Sang-Soo; Lee, Jong-Hyun, E-mail: pljh@snut.ac.kr

    2017-01-01

    Ultrafine Ag-coated Cu (Cu@Ag) nanoparticles (NPs) less than 20 nm in diameter were prepared. After synthesizing ultrafine Cu NPs using a solvothermal method to serve as the core particles, Cu@Ag NPs were fabricated with different initial Ag precursor concentrations, resulting in different thicknesses, densities, and uniformities of Ag shells. The average thickness and density of the Ag shell increased with increasing initial Ag precursor concentration in a Cu:Ag atomic ratio from 6:1 to 1:1. However, excessive Ag precursor concentrations induced homogeneous nucleation and growth of surplus fine pure NPs. Ag dewetting behavior and Cu oxidation in the Cu{sub 4}@Ag{sub 1} NPs were observed, they occurred during heating at 200 and 250 °C, respectively. The electrical resistivities of sintered Cu{sub 4}@Ag{sub 1} films decreased with increasing temperature from 200 to 240 °C. The resistivity after washing the OA and sintering for 60 min at 240 °C in air was measured to be 4.96 × 10{sup −3} Ω cm. The film was sintered in nitrogen using the ink containing non-washed Cu{sub 4}@Ag{sub 1} NPs indicated the lower resistivity of 2.70 × 10{sup −3} Ω cm owing to the non-oxidation atmosphere, although the chemically capped oleylamine in the core-shell NPs hindered the sintering behavior. - Highlights: • Ultrafine Ag-coated Cu nanoparticles less than 20 nm in diameter were fabricated. • Different Ag precursor concentrations influenced thickness and density of Ag shell. • Excessive Ag precursor concentrations induced formation of surplus fine pure NPs. • Ag dewetting behavior and Cu oxidation in Cu{sub 4}@Ag{sub 1} nanoparticles were observed. • Electrical resistivities of sintered Cu{sub 4}@Ag{sub 1} films were 2.70–4.96 × 10{sup −3} Ω cm.

  19. Photocatalytic performances and activities of Ag-doped CuFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhengru, E-mail: zhengruzhu@gmail.com [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China); State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Xinyong; Zhao, Qidong [State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Yonghua; Sun, Caizhi; Cao, Yongqiang [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China)

    2013-08-01

    Graphical abstract: - Highlights: • CuFe{sub 2}O{sub 4} nanocrystals were synthesized by a co-precipitation method. • Ag/CuFe{sub 2}O{sub 4} catalyst was prepared by the wetness impregnation strategy. • The structural properties of Ag/CuFe{sub 2}O{sub 4} were investigated by XRD, TEM, DRS, and XPS techniques. • Ag/CuFe{sub 2}O{sub 4} has higher photocatalytic activity. - Abstract: In this work, CuFe{sub 2}O{sub 4} nanoparticles were synthesized by a chemical co-precipitation route. The Ag/CuFe{sub 2}O{sub 4} catalyst was prepared based on the CuFe{sub 2}O{sub 4} nanoparticles by the incipient wetness impregnation strategy, which showed excellent photoelectric property and catalytic activity. The structural properties of these samples were systematically investigated by X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) techniques. The photo-induced charge separation in the samples was demonstrated by surface photovoltage (SPV) measurement. The photocatalytic degradation of 4-CP by the Ag/CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4} samples were comparatively studied under xenon lamp irradiation. The results indicate that the Ag/CuFe{sub 2}O{sub 4} sample exhibited the higher efficiency for the degradation of 4-CP.

  20. Direct detection of cysteine using functionalized BaTiO3 nanoparticles film based self-powered biosensor.

    Science.gov (United States)

    Selvarajan, Sophia; Alluri, Nagamalleswara Rao; Chandrasekhar, Arunkumar; Kim, Sang-Jae

    2017-05-15

    Simple, novel, and direct detection of clinically important biomolecules have continuous demand among scientific community as well as in market. Here, we report the first direct detection and facile fabrication of a cysteine-responsive, film-based, self-powered device. NH 2 functionalized BaTiO 3 nanoparticles (BT-NH 2 NPs) suspended in a three-dimensional matrix of an agarose (Ag) film, were used for cysteine detection. BaTiO 3 nanoparticles (BT NPs) semiconducting as well as piezoelectric properties were harnessed in this study. The changes in surface charge properties of the film with respect to cysteine concentrations were determined using a current-voltage (I-V) technique. The current response increased with cysteine concentration (linear concentration range=10µM-1mM). Based on the properties of the composite (BT/Ag), we created a self-powered cysteine sensor in which the output voltage from a piezoelectric nanogenerator was used to drive the sensor. The potential drop across the sensor was measured as a function of cysteine concentrations. Real-time analysis of sensor performance was carried out on urine samples by non-invasive method. This novel sensor demonstrated good selectivity, linear concentration range and detection limit of 10µM; acceptable for routine analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime.

    Science.gov (United States)

    Chu, Ming-Wen; Sharma, Pradeep; Chang, Ching-Pin; Liou, Sz Chian; Tsai, Kun-Tong; Wang, Juen-Kai; Wang, Yuh-Lin; Chen, Cheng Hsuan

    2009-06-10

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (approximately 30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at approximately 3.5 eV (approximately 355 nm) and approximately 7.0 eV (approximately 177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  2. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime

    International Nuclear Information System (INIS)

    Chu, M-W; Chang, C-P; Liou, S C; Wang, J-K; Chen, C H; Sharma, Pradeep; Tsai, K-T; Wang, Y-L

    2009-01-01

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (∼30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at ∼3.5 eV (∼355 nm) and ∼7.0 eV (∼177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  3. Facile synthesis, structure, and properties of Ag{sub 2}S/Ag heteronanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, S. I., E-mail: sadovnikov@ihim.uran.ru; Gusev, A. I. [Ural Branch of the Russian Academy of Sciences, Institute of Solid State Chemistry (Russian Federation)

    2016-09-15

    Ag{sub 2}S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag{sub 2}S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag{sub 2}S and Ag nanoparticles is 45–50 and 15–20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag{sub 2}S acanthite transforms into superionic β-Ag{sub 2}S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag{sub 2}S/Ag heteronanostructure is proposed. The UV–Vis optical absorption spectra of colloidal solutions of Ag{sub 2}S/Ag heteronanostructures have been studied.Graphical Abstract.

  4. Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core–shell nanoparticles

    International Nuclear Information System (INIS)

    Kang, Fei; Xu, Kun; Hou, Xiangshu

    2015-01-01

    Glucose is a key energy substance in diverse biology and closely related to the life activities of the organism. To develop a simple and sensitive method for glucose detection is extremely urgent but still remains a key challenge. Herein, we report a colorimetric glucose sensor in a homogeneous system based on DNA-embedded core–shell Au@Ag nanoparticles. In this assay, a glucose substrate was first catalytically oxidized by glucose oxidase to produce H 2 O 2 which would further oxidize and gradually etch the outer silver shell of Au@Ag nanoparticles. Afterwards, the solution color changed from yellow to red and the surface plasmon resonance (SPR) band of Au@Ag nanoparticles declined and red-shifted from 430 to 516 nm. Compared with previous silver-based glucose colorimetric detection strategies, the distinctive SPR band change is superior to the color variation, which is critical to the high sensitivity of this assay. Benefiting from the outstanding optical property, robust stability and well-dispersion of the core–shell Au@AgNPs hybrid, this colorimetric assay obtained a detection limit of glucose as low as 10 nM, which is at least a 10-fold improvement over other AgNPs-based procedures. Moreover, this optical biosensor was successfully employed to the determination of glucose in fetal bovine serum. (paper)

  5. Third-order nonlinear optical response of Ag-CdSe/PVA hybrid nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K.; Kaur, Ramneek; Kaur, Jaspreet; Sharma, Mamta [Panjab University, Department of Physics, Center of Advanced Study in Physics, Chandigarh (India)

    2015-09-15

    Hybrid nanocomposites of II-VI semiconductor nanoparticles are gaining great interest in nonlinear optoelectronic devices. Present work includes the characterization of CdSe polymer nanocomposite prepared by chemical in situ technique. From X-ray diffraction, the hexagonal wurtzite structure of nanoparticles has been confirmed with spherical morphology from transmission electron microscopy. Ag-CdSe hybrid polymer nanocomposite has been prepared chemically at different Ag concentrations. The presence of Ag in hybrid nanocomposite has been confirmed with energy-dispersive X-ray spectroscopy. The effect of varying Ag concentration on the linear and nonlinear optical properties of the nanocomposites has been studied. In linear optical parameters, the linear absorption coefficient, refractive index, extinction coefficient and optical conductivity have been calculated. The third-order nonlinear optical properties have been observed with open- and closed-aperture Z-scan technique. The large nonlinear refractive index ∝10{sup -5} cm{sup 2}/W with self-focusing behaviour is due to the combined effect of quantum confinement and thermo-optical effects. The enhanced nonlinearity with increasing Ag content is due to the surface plasmon resonance, which enhances the local electric field near the nanoparticle surface. Thus, Ag-CdSe hybrid polymer nanocomposite has favourable nonlinear optical properties for various optoelectronic applications. (orig.)

  6. Third-order nonlinear optical response of Ag-CdSe/PVA hybrid nanocomposite

    International Nuclear Information System (INIS)

    Tripathi, S.K.; Kaur, Ramneek; Kaur, Jaspreet; Sharma, Mamta

    2015-01-01

    Hybrid nanocomposites of II-VI semiconductor nanoparticles are gaining great interest in nonlinear optoelectronic devices. Present work includes the characterization of CdSe polymer nanocomposite prepared by chemical in situ technique. From X-ray diffraction, the hexagonal wurtzite structure of nanoparticles has been confirmed with spherical morphology from transmission electron microscopy. Ag-CdSe hybrid polymer nanocomposite has been prepared chemically at different Ag concentrations. The presence of Ag in hybrid nanocomposite has been confirmed with energy-dispersive X-ray spectroscopy. The effect of varying Ag concentration on the linear and nonlinear optical properties of the nanocomposites has been studied. In linear optical parameters, the linear absorption coefficient, refractive index, extinction coefficient and optical conductivity have been calculated. The third-order nonlinear optical properties have been observed with open- and closed-aperture Z-scan technique. The large nonlinear refractive index ∝10 -5 cm 2 /W with self-focusing behaviour is due to the combined effect of quantum confinement and thermo-optical effects. The enhanced nonlinearity with increasing Ag content is due to the surface plasmon resonance, which enhances the local electric field near the nanoparticle surface. Thus, Ag-CdSe hybrid polymer nanocomposite has favourable nonlinear optical properties for various optoelectronic applications. (orig.)

  7. Determining the effects of green chemistry synthesized Ag-nisin nanoparticle on macrophage cells.

    Science.gov (United States)

    Moein, Masood; Imani Fooladi, Abbas Ali; Mahmoodzadeh Hosseini, Hamideh

    2018-01-01

    Bacteriocins are low molecular weight substances produced through post transcriptional changes. These molecules are easily degraded in mammalian gut by proteolytic enzymes especially protease. Nisin is a peptide with 34 aa and its structure contains a pentacyclic lanthionine and 4 beta metyllanthionine residues. Different formulations have been designed for nisin. Since "green synthesis" is a progressive method to prepare anti-microbial and anti-cancer compounds, this study aimed at green synthesis of nisin metal compounds to be used lower concentration still exerting nisin effects. For this purpose, a 1 mg/ml nisin solution was added to a 1 mM silver nitrate solution and incubated to synthesis nano Ag-nisin, then the optical density of new solution was detected using UV spectroscopy. To determine biomolecules in the Ag-nisin solution, the FTIR method was employed. The size and morphology of Ag-nisin was measured by TEM. The toxicity, inflammatory cytokines production, and intracellular ROS quantity was evaluated using MTT, ELISA and flow-cytometry. XRD pattern indicated the silver crystals in Ag-nisin solution. In addition, FTRI findings showed that the carbonyl groups of amino acid are potently able to bind to metal nanoparticles, cover, and prevent them from particle agglomeration. Treating macrophage cells with 10, 25, 50 and 100 μg/ml of Ag-nisin had no significant effect on the cell viability and intracellular ROS quantity compared to the control group. In addition, different concentrations of Ag-nisin had no effect on the IL-10 and TNF-α levels but caused an increased level of IL-12 in comparison with the control group. In the current study, for the first time, green synthesize was used to prepare Ag-nisin particles. The synthesized nanoparticle is able to induce inflammatory activity via increasing IL-12 without any change in the TNF-α level in macrophage cells. Copyright © 2017. Published by Elsevier Ltd.

  8. Ultrafine luminescent structures through nanoparticle self-assembly

    International Nuclear Information System (INIS)

    Prabhakaran, K; Goetzinger, S; Shafi, K V P M; Mazzei, A; Schietinger, S; Benson, O

    2006-01-01

    We report the fabrication of ultrafine structures consisting of regular arrays of nanoemitters through the self-assembly of luminescent nanoparticles on a silicon wafer. Nanoparticles of yttrium aluminium garnet (YAG) doped with Eu 3+ ions were synthesized by a sonochemical technique. These particles, suspended in ethanol, are introduced onto a pre-patterned silicon wafer, covered with a thin oxide layer. On annealing the sample in an ultrahigh-vacuum chamber, the nanoparticles self-assemble along the pattern. We demonstrate this 'chemical lithography' by assembling the nanoparticles along a variety of patterns. We believe that such self-organized nanopatterning of functional structures is important for the realization of nanodevices

  9. Polarization-driven self-organization of silver nanoparticles in 1D and 2D subwavelength gratings for plasmonic photocatalysis

    Science.gov (United States)

    Baraldi, G.; Bakhti, S.; Liu, Z.; Reynaud, S.; Lefkir, Y.; Vocanson, F.; Destouches, N.

    2017-01-01

    One of the main challenges in plasmonics is to conceive large-scale, low-cost techniques suitable for the fabrication of metal nanoparticle patterns showing precise spatial organization. Here, we introduce a simple method based on continuous-wave laser illumination to induce the self-organization of silver nanoparticles within high-index thin films. We show that highly regular and homogeneous nanoparticle gratings can be produced on large areas using laser-controlled self-organization processes. This very versatile technique can provide 1D and 2D patterns at a subwavelength scale with tunable features. It does not need any stabilization or expensive devices, such as those required by optical or electron lithography, and is rapid to implement. Accurate in-plane and in-depth characterizations provide valuable information to explain the mechanisms that lead to pattern formation and especially how 2D self-organization can fall into place with successive laser scans. The regular and homogeneous 2D self-organization of metallic NPs with a single laser scan is also reported for the first time in this article. As the reported nanostructures are embedded in porous TiO2, we also theoretically explore the interesting potential of organization on the photocatalytic activity of Ag-NP-containing TiO2 porous films, which is one of the most promising materials for self-cleaning or remediation applications. Realistic electromagnetic simulations demonstrate that the periodic organization of silver nanoparticles can increase the light intensity within the film more than ten times that produced with randomly distributed nanoparticles, leading as expected to enhanced photocatalytic efficiency.

  10. Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition

    NARCIS (Netherlands)

    Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.

    2014-01-01

    A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ?100 nm were

  11. Facile synthesis of dispersed Ag nanoparticles on chitosan-TiO2 composites as recyclable nanocatalysts for 4-nitrophenol reduction

    Science.gov (United States)

    Xiao, Gang; Zhao, Yilin; Li, Linghui; Pratt, Jonathan O.; Su, Haijia; Tan, Tianwei

    2018-04-01

    This paper presents a facile, rapid, and controllable procedure for the recovery of trace Ag+ ions and in situ assembly of well dispersed Ag nanoparticles on chitosan-TiO2 composites through bioaffinity adsorption followed by photocatalytic reduction. The prepared Ag nanoparticles are proven to be efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. Well dispersed quasi-spherical Ag NPs are synthesized in 20 min in the designed inner-irradiated photocatalytic system under a wide range of Ag+ concentrations (50-200 mg l-1), temperatures (10 °C-25 °C) conditions, and UV or visible light irradiation. The synthesized Ag NPs can catalyze the reduction of 4-nitrophenol by NaBH4 at 100% conversion in 120 min and preserve the catalytic activity in five successive cycles. This procedure for trace Ag+ ions recovery and Ag NPs assembly has the potential to be scaled up for the mass production of recyclable Ag nanocatalysts. The present work provides a green and efficient procedure for the conversion of hazardous 4-nitrophenol to industrially important 4-aminophenol and also sheds a light on designing scaled-up procedures for treating high volumes of wastewater with dilute heavy metals to produce recyclable metallic nanocatalysts in aqueous systems.

  12. Improved antifouling potential of polyether sulfone polymeric membrane containing silver nanoparticles: self-cleaning membranes.

    Science.gov (United States)

    Rana, Sidra; Nazar, Umair; Ali, Jafar; Ali, Qurat Ul Ain; Ahmad, Nasir M; Sarwar, Fiza; Waseem, Hassan; Jamil, Syed Umair Ullah

    2018-06-01

    A new strategy to enhance the antifouling potential of polyether sulfone (PES) membrane is presented. Chemically synthesized silver nanoparticles (AgNPs) were used to prepare a mixed-matrix PES membrane by the phase inversion technique. Primarily, AgNPs synthesis was confirmed by surface plasmon resonance at 410-430 nm using UV-Visible spectroscopy. X-ray diffraction analysis revealed that AgNPs were crystalline with a diameter of 21 ± 2 nm. Furthermore, PES membranes were characterized by energy dispersive X-ray spectroscopy to confirm the incorporation of AgNPs in membranes. Hydrophilicity of the membranes was enhanced, whereas roughness, mechanical strength and biofouling were relatively reduced after embedding the AgNPs. Antibacterial potential of AgNPs was evaluated for E. coli in the disc diffusion and colony-forming unit (CFU) count method. All of the membranes were assessed for antifouling activity by filtering a control dilution (10 6  CFU/ml) of E. coli and by counting CFU. Anti-biofouling activity of the membrane was observed with different concentrations of AgNPs. Maximum reduction (66%) was observed in membrane containing 1.5% of AgNPs. The addition of antibiotic ceftriaxone enhanced the antibacterial effect of AgNPs in PES membranes. Our practicable antifouling strategy may be applied to other polymeric membranes which may pave the new way to achieve sustainable and self-cleaning membrane reactors on large scale.

  13. Laser-induced atomic assembling of periodic layered nanostructures of silver nanoparticles in fluoro-polymer film matrix

    International Nuclear Information System (INIS)

    Bagratashvili, V N; Minaev, N V; Timashev, P S; Yusupov, V I; Rybaltovsky, A O; Firsov, V V

    2010-01-01

    Fluorinated acrylic polymer (FAP) films have been impregnated with silver precursor (Ag(hfac)COD) by supercritical fluid technique and next irradiated with laser (λ = 532 nm). Laser-chemically reduced Ag atoms have been assembled into massifs of Ag nanoparticles (3 – 8 nm) in FAP/Ag(hfac)COD films matrix in the form of periodic layered nanostructures (horizontal to film surface) with unexpectedly short period (90 – 180 nm). The wavelet analysis of TEM images reveals the existence of even shorter-period structures in such films. Photolysis with non-coherent light or pyrolysis of FAP/Ag(hfac)COD film results in formation of Ag nanoparticles massifs but free of any periodic nanoparticle assemblies. Our interpretation of the observed effect of laser formation of short-period nano-sized Ag nanoparticle assemblies is based on self-enhanced interference process in the course of modification of optical properties of film

  14. The effect of Fe segregation on the photocatalytic growth of Ag nanoparticles on rutile TiO{sub 2}(001)

    Energy Technology Data Exchange (ETDEWEB)

    Busiakiewicz, Adam, E-mail: adambus@uni.lodz.pl [University of Lodz, Faculty of Physics and Applied Informatics, Department of Solid State Physics, Pomorska 149/153, 90-236, Łódź (Poland); Kisielewska, Aneta; Piwoński, Ireneusz [University of Lodz, Faculty of Chemistry, Department of Materials Technology and Chemistry, Pomorska 163, 90-236, Łódź (Poland); Batory, Damian [Lodz University of Technology, Institute of Materials Science and Engineering, Stefanowskiego 1/15, 90-924, Łódź (Poland)

    2017-04-15

    Highlights: • Ag nanoparticles are grown photochemically on TiO{sub 2}(001). • Pristine TiO{sub 2}(001) and Fe/TiO{sub 2}(001) are compared. • The presence of segregated Fe strongly affects the growth Ag nanoparticles. • Abundant amount of Fe suppresses photocatalytic synthesis of AgNPs on TiO{sub 2}(001). - Abstract: The photocatalytic growth of silver nanoparticles (AgNPs) on rutile TiO{sub 2}(001) and Fe-modified rutile TiO{sub 2}(001) monocrystals was investigated. Various amount of Fe was segregated in a controlled way from the doped TiO{sub 2} substrates in ultra-high vacuum conditions resulting in low- medium- and high- content of Fe on TiO{sub 2} substrates. AgNPs were grown on pristine TiO{sub 2} and substrates containing Fe by photoreduction of Ag{sup +} ions under UV illumination. It was found that the size of AgNPs was larger on Fe/TiO{sub 2} than on TiO{sub 2} while the surface density exhibited the opposite behavior – a large number of AgNPs were present on the TiO{sub 2} surface but only a few AgNPs were visible on the Fe/TiO{sub 2} substrates. The reason for the differences in size and number of AgNPs on TiO{sub 2} and Fe/TiO{sub 2} is the limited access of Ag{sup +} to the TiO{sub 2} surface caused by the large number of Fe grains segregated onto the TiO{sub 2} surface. Another possible reason for the various AgNPs morphologies is alteration in the mechanism of Ag{sup +} photoreduction caused by iron present as Fe{sup 3+} ions and by newly formed AgNPs playing the role of electron traps. The surface elemental analysis of the investigated materials was performed with the use of X-ray photoelectron spectroscopy (XPS) and confirmed the composition of AgNPs/Fe/TiO{sub 2} systems. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed sizes, morphology and distribution of the nanostructures.

  15. Flexible Textile-Based Organic Transistors Using Graphene/Ag Nanoparticle Electrode

    Science.gov (United States)

    Kim, Youn; Kwon, Yeon Ju; Lee, Kang Eun; Oh, Youngseok; Um, Moon-Kwang; Seong, Dong Gi; Lee, Jea Uk

    2016-01-01

    Highly flexible and electrically-conductive multifunctional textiles are desirable for use in wearable electronic applications. In this study, we fabricated multifunctional textile composites by vacuum filtration and wet-transfer of graphene oxide films on a flexible polyethylene terephthalate (PET) textile in association with embedding Ag nanoparticles (AgNPs) to improve the electrical conductivity. A flexible organic transistor can be developed by direct transfer of a dielectric/semiconducting double layer on the graphene/AgNP textile composite, where the textile composite was used as both flexible substrate and conductive gate electrode. The thermal treatment of a textile-based transistor enhanced the electrical performance (mobility = 7.2 cm2·V−1·s−1, on/off current ratio = 4 × 105, and threshold voltage = −1.1 V) due to the improvement of interfacial properties between the conductive textile electrode and the ion-gel dielectric layer. Furthermore, the textile transistors exhibited highly stable device performance under extended bending conditions (with a bending radius down to 3 mm and repeated tests over 1000 cycles). We believe that our simple methods for the fabrication of graphene/AgNP textile composite for use in textile-type transistors can potentially be applied to the development of flexible large-area electronic clothes. PMID:28335276

  16. Fabrication of Carbon Nanotube/SiO2and Carbon Nanotube/SiO2/Ag Nanoparticles Hybrids by Using Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Li Haiqing

    2009-01-01

    Full Text Available Abstract Based on plasma-treated single wall carbon nanotubes (SWCNTs, SWCNT/SiO2and thiol groups-functionalized SWCNT/SiO2hybrids have been fabricated through a sol–gel process. By means of thiol groups, Ag nanoparticles have been in situ synthesized and bonded onto the SiO2shell of SWCNT/SiO2in the absence of external reducing agent, resulting in the stable carbon nanotube/SiO2/Ag nanoparticles hybrids. This strategy provides a facile, low–cost, and green methodology for the creation of carbon nanotube/inorganic oxides-metal nanoparticles hybrids.

  17. Locally formation of Ag nanoparticles in chalcogenide phase change thin films induced by nanosecond laser pulses

    International Nuclear Information System (INIS)

    Huang, Huan; Zhang, Lei; Wang, Yang; Han, Xiaodong; Wu, Yiqun; Zhang, Ze; Gan, Fuxi

    2012-01-01

    A simple method to optically synthesize Ag nanoparticles in Ge 2 Sb 2 Te 5 phase change matrix is described. The fine structures of the locally formed phase change chalcogenide nanocomposite are characterized by high-resolution transmission electron microscopy. The formation mechanism of the nanocomposite is discussed with temperature evolution and distribution simulations. This easy-prepared metal nano-particle-embedded phase change microstructure will have great potential in nanophotonics applications, such as for plasmonic functional structures. This also provides a generalized approach to the preparation of well-dispersed nanoparticle-embedded composite thin films in principle. -- Highlights: ► We describe a method to prepare chalcogenide microstructures with Ag nanoparticles. ► We give the fine structural images of phase change nanocomposites. ► We discuss the laser-induced fusion mechanism by temperature simulation. ► This microstructure will have great potential in nanophotonics applications.

  18. Intracellular uptake: a possible mechanism for silver engineered nanoparticle toxicity to a freshwater alga Ochromonas danica.

    Directory of Open Access Journals (Sweden)

    Ai-Jun Miao

    2010-12-01

    Full Text Available The behavior and toxicity of silver engineered nanoparticles (Ag-ENs to the mixotrophic freshwater alga Ochromonas danica were examined in the present study to determine whether any other mechanisms are involved in their algal toxicity besides Ag(+ liberation outside the cells. Despite their good dispersability, the Ag-ENs were found to continuously aggregate and dissolve rapidly. When the initial nanoparticle concentration was lower than 10 µM, the total dissolved Ag(+ concentration ([Ag(+](T in the suspending media reached its maximum after 1 d and then decreased suggesting that Ag(+ release might be limited by the nanoparticle surface area under these conditions. Furthermore, Ag-EN dissolution extent remarkably increased in the presence of glutathione. In the Ag-EN toxicity experiment, glutathione was also used to eliminate the indirect effects of Ag(+ that was released. However, remarkable toxicity was still observed although the free Ag(+ concentration in the media was orders of magnitude lower than the non-observed effect concentration of Ag(+ itself. Such inhibitive effects were mitigated when more glutathione was added, but could never be completely eliminated. Most importantly, we demonstrate, for the first time, that Ag-ENs can be taken in and accumulated inside the algal cells, where they exerted their toxic effects. Therefore, nanoparticle internalization may be an alternative pathway through which algal growth can be influenced.

  19. Combined use of vancomycin-modified Ag-coated magnetic nanoparticles and secondary enhanced nanoparticles for rapid surface-enhanced Raman scattering detection of bacteria.

    Science.gov (United States)

    Wang, Chongwen; Gu, Bing; Liu, Qiqi; Pang, Yuanfeng; Xiao, Rui; Wang, Shengqi

    2018-01-01

    Pathogenic bacteria have always been a significant threat to human health. The detection of pathogens needs to be rapid, accurate, and convenient. We present a sensitive surface-enhanced Raman scattering (SERS) biosensor based on the combination of vancomycin-modified Ag-coated magnetic nanoparticles (Fe 3 O 4 @Ag-Van MNPs) and Au@Ag nanoparticles (NPs) that can effectively capture and discriminate bacterial pathogens from solution. The high-performance Fe 3 O 4 @Ag MNPs were modified with vancomycin and used as bacteria capturer for magnetic separation and enrichment. The modified MNPS were found to exhibit strong affinity with a broad range of Gram-positive and Gram-negative bacteria. After separating and rinsing bacteria, Fe 3 O 4 @Ag-Van MNPs and Au@Ag NPs were synergistically used to construct a very large number of hot spots on bacteria cells, leading to ultrasensitive SERS detection. The dominant merits of our dual enhanced strategy included high bacterial-capture efficiency (>65%) within a wide pH range (pH 3.0-11.0), a short assay time (<30 min), and a low detection limit (5×10 2 cells/mL). Moreover, the spiked tests show that this method is still valid in milk and blood samples. Owing to these capabilities, the combined system enabled the sensitive and specific discrimination of different pathogens in complex solution, as verified by its detection of Gram-positive bacterium Escherichia coli , Gram-positive bacterium Staphylococcus aureus , and methicillin-resistant S. aureus . This method has great potential for field applications in food safety, environmental monitoring, and infectious disease diagnosis.

  20. Rich Ground State Chemical Ordering in Nanoparticles: Exact Solution of a Model for Ag-Au Clusters

    DEFF Research Database (Denmark)

    Larsen, Peter Mahler; Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2018-01-01

    We show that nanoparticles can have very rich ground state chemical order. This is illustrated by determining the chemical ordering of Ag-Au 309-atom Mackay icosahedral nanoparticles. The energy of the nanoparticles is described using a cluster expansion model, and a Mixed Integer Programming (MIP......) approach is used to find the exact ground state configurations for all stoichiometries. The chemical ordering varies widely between the different stoichiometries, and display a rich zoo of structures with non-trivial ordering....

  1. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei, E-mail: xuzhiwei@tjpu.edu.cn; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-05-01

    Highlights: • Graphene oxide sheets supported Ag nanoparticles composites are successfully prepared via γ-irradiation without surfactant or functional agent. • Ag nanoparticles exhibit single crystalline structure and parabolic distribution on the surface of graphene oxide sheets. • Proposing a view that the growth of intercellular AgNPs can be limited by graphite oxide. - Abstract: This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 10{sup 6} and detection limit of 1.0 × 10{sup −7} M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  2. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    International Nuclear Information System (INIS)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-01-01

    Highlights: • Graphene oxide sheets supported Ag nanoparticles composites are successfully prepared via γ-irradiation without surfactant or functional agent. • Ag nanoparticles exhibit single crystalline structure and parabolic distribution on the surface of graphene oxide sheets. • Proposing a view that the growth of intercellular AgNPs can be limited by graphite oxide. - Abstract: This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 10"6 and detection limit of 1.0 × 10"−"7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  3. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ravi Kant, E-mail: rkupadhyay85@gmail.com [Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India); Soin, Navneet, E-mail: n.soin@bolton.ac.uk [Knowledge Centre for Materials Chemistry (KCMC), Institute for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3 5AB (United Kingdom); Saha, Susmita, E-mail: ssaha@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Barman, Anjan, E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Sinha Roy, Susanta, E-mail: susanta.roy@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India)

    2015-04-15

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W{sub 0}), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W{sub 0}), with the lowest value of W{sub 0} (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH{sub 4}) as reducing agent. The effects of NaBH{sub 4} concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W{sub 0}). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH{sub 4}.

  4. Self-supported silver nanoparticles containing bacterial cellulose membranes

    International Nuclear Information System (INIS)

    Barud, Hernane S.; Barrios, Celina; Regiani, Thais; Marques, Rodrigo F.C.; Verelst, Marc; Dexpert-Ghys, Jeannette; Messaddeq, Younes; Ribeiro, Sidney J.L.

    2008-01-01

    Hydrated bacterial cellulose (BC) membranes obtained from cultures of Acetobacter xylinum were used in the preparation of silver nanoparticles containing cellulose membranes. In situ preparation of Ag nanoparticles was achieved from the hydrolytic decomposition of silver triethanolamine (TEA) complexes. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns both lead to the observation of spherical metallic silver particles with mean diameter of 8 nm well adsorbed onto the BC fibriles

  5. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    International Nuclear Information System (INIS)

    Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

    2016-01-01

    Highlights: • TiO 2 nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core (Ag) -shell (Cu) form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO 2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag core -Cu shell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  6. Synthesis and characterizations of AgSCN nanospheres using AgCl as the precursor

    International Nuclear Information System (INIS)

    Yang Ming; Ma Jing

    2009-01-01

    Nanospheres of AgSCN with an average radius of 30-80 nm have been prepared by a simple reaction between AgCl suspension and KSCN in the presence of gelatin. Gelatin played a decisive role as an inhibitor of the direct attack of SCN - ions to AgCl surfaces and coagulation of the growing AgSCN in producing the spherical AgSCN nanoparticles. The products were characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectra techniques. The electrical conductivity of thin films of as-prepared AgSCN nanoparticles and polyethylene oxide (PEO) at room temperature was measured. The maximum value of electrical conductivity of as-prepared AgSCN-PEO was 1.53 x 10 -5 S cm -1 .

  7. High surface enhanced Raman scattering activity of BN nanosheets–Ag nanoparticles hybrids

    International Nuclear Information System (INIS)

    Yang, Shanshan; Zhang, Zhaochun; Zhao, Jun; Zheng, Houli

    2014-01-01

    Highlights: • Boron nitride–silver nanohybrid was acquired through a liquid-phase reducing route. • The composite shown a high-quality SERS activity. • 2-Mercaptobenzimidazole was chemisorbed on silver surface in vertical orientation. -- Abstract: A facile liquid-phase reducing route was developed to modify boron nitride (BN) nanosheets with silver nanoparticles (AgNPs) in order to fabricate BN–AgNPs hybrids with high surface enhanced Raman scattering (SERS) activity. The layered structure and morphology of BN–AgNPs nanohybrids were characterized by transmission electron microscopy and atomic force microscopy, meanwhile, Fourier transform infrared spectroscopy and ultraviolet–visible were used for studying optical properties and surface plasmon resonance applied to the optical sensor. The SERS of adsorbed 2-mercaptobenzimidazole (MBI) molecule was investigated which shown that the BN–AgNPs substrate exhibited a very strong SERS activity, offering a great potential application in molecular probe sensor. On the basis of the analysis of SERS and the Raman surface selection rules, we could draw a conclusion that the MBI molecule was adsorbed upright on the AgNPs surface through the sulphur and nitrogen atoms. What is more, the cyclic voltammetry experiment indicated the electrochemically irreversible behavior of BN–AgNPs nanohybrids in KCl solution

  8. Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

    International Nuclear Information System (INIS)

    Fabbro, Maria T.; Gracia, Lourdes; Silva, Gabriela S.; Santos, Luís P.S.; Andrés, Juan; Cordoncillo, Eloisa; Longo, E.

    2016-01-01

    Ag 2 CrO 4 microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag 2 CrO 4 microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of the optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO 6 ] and [AgO 4 ] clusters, generating ideal conditions for the growth of Ag nanoparticles. - Graphical abstract: Theoretical representation of the Ag 2 CrO 4 orthorhombic structure. Display Omitted - Highlights: • The Ag 2 CrO 4 microcrystals indicate an orthorhombic structure. • The formation of Ag 0 promotes Ag-nanoparticle growth on the surface of the Ag 2 CrO 4 . • Electron irradiation of the material induces the formation of Ag vacancies.

  9. Reversible conversion between AgCl and Ag in AgCl-doped RSiO{sub 3/2}-TiO{sub 2} films prepared by a sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Go, E-mail: gokawamura@ee.tut.ac.jp [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Tsurumi, Yuuki [Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Muto, Hiroyuki [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Sakai, Mototsugu; Inoue, Mitsuteru [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Matsuda, Atsunori [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan)

    2011-10-17

    Highlights: {center_dot} The reversible redox behavior between AgCl and Ag in RSiO{sub 3/2}-TiO{sub 2} film is studied. {center_dot} TiO{sub 2} component induces Cl to remain in the film after conversion of AgCl to Ag. {center_dot} The survival of Cl is essential for reconversion of Ag to AgCl. {center_dot} The film shows potential to be applied as rewritable holographic material. - Abstract: The reversible redox behavior exhibited by AgCl-doped organosilsesquioxane-titania gel films is studied. Films prepared by the sol-gel method show reversible color changes with blue laser irradiation and subsequent heat treatment, which is based on the formation of Ag and AgCl nanoparticles, respectively. Two-beam interference exposure experiments reveal that the films have potential to be applied as rewritable holographic materials. A large titania content is essential for the conversion of Ag to AgCl because it induces the Cl to remain near the Ag nanoparticles during blue laser irradiation, allowing the Cl to react with neighboring Ag nanoparticles to reform AgCl upon subsequent heat treatment.

  10. Structural and optical properties of antimony-germanate-borate glass and glass fiber co-doped Eu3+ and Ag nanoparticles.

    Science.gov (United States)

    Zmojda, Jacek; Kochanowicz, Marcin; Miluski, Piotr; Baranowska, Agata; Pisarski, Wojciech A; Pisarska, Joanna; Jadach, Renata; Sitarz, Maciej; Dorosz, Dominik

    2018-08-05

    In the paper analysis of structural and luminescent properties of antimony-germanate-borate glasses and glass fiber co-doped with 0.6AgNO 3 /0.2Eu 2 O 3 are presented. Heat treatment of the fabricated glass and optical fiber (400 °C, 12 h) enabled to obtain Ag nanoparticles (NPs) with average size 30-50 nm on their surface. It has been proofed that silver ions migrate to the glass surface, where they are reduced to Ag 0 nanoparticles. Simultaneously, FTIR analysis showed that heat treatment of the glass and optical fiber increases the local symmetry of the Eu 3+ site. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. A Metal Bump Bonding Method Using Ag Nanoparticles as Intermediate Layer

    Science.gov (United States)

    Fu, Weixin; Nimura, Masatsugu; Kasahara, Takashi; Mimatsu, Hayata; Okada, Akiko; Shoji, Shuichi; Ishizuka, Shugo; Mizuno, Jun

    2015-11-01

    The future development of low-temperature and low-pressure bonding technology is necessary for fine-pitch bump application. We propose a bump structure using Ag nanoparticles as an intermediate layer coated on a fine-pitch Cu pillar bump. The intermediate layer is prepared using an efficient and cost-saving squeegee-coating method followed by a 100°C baking process. This bump structure can be easily flattened before the bonding process, and the low-temperature sinterability of the nanoparticles is retained. The bonding experiment was successfully performed at 250°C and 39.8 MPa and the bonding strength was comparable to that achieved via other bonding technology utilizing metal particles or porous material as bump materials.

  12. E-beam deposited Ag-nanoparticles plasmonic organic solar cell and its absorption enhancement analysis using FDTD-based cylindrical nano-particle optical model.

    Science.gov (United States)

    Kim, Richard S; Zhu, Jinfeng; Park, Jeung Hun; Li, Lu; Yu, Zhibin; Shen, Huajun; Xue, Mei; Wang, Kang L; Park, Gyechoon; Anderson, Timothy J; Pei, Qibing

    2012-06-04

    We report the plasmon-assisted photocurrent enhancement in Ag-nanoparticles (Ag-NPs) embedded PEDOT:PSS/P3HT:PCBM organic solar cells, and systematically investigate the causes of the improved optical absorption based on a cylindrical Ag-NPs optical model which is simulated with a 3-Dimensional finite difference time domain (FDTD) method. The proposed cylindrical Ag-NPs optical model is able to explain the optical absorption enhancement by the localized surface plasmon resonance (LSPR) modes, and to provide a further understanding of Ag-NPs shape parameters which play an important role to determine the broadband absorption phenomena in plasmonic organic solar cells. A significant increase in the power conversion efficiency (PCE) of the plasmonic solar cell was experimentally observed and compared with that of the solar cells without Ag-NPs. Finally, our conclusion was made after briefly discussing the electrical effects of the fabricated plasmonic organic solar cells.

  13. Generation of Hybrid Peptide-Silver Nanoparticles for Antibacterial and Antifouling Applications

    KAUST Repository

    Seferji, Kholoud

    2018-01-01

    and antifouling agents. Our innovative antibacterial agents are hybrid peptide silver nanoparticles (CH-01-AgNPs) that are created de novo and in situ from a silver nitrate solution (AgNO3) in the presence of ultrashort self-assembling peptides compounds

  14. A Simple Method for the Preparation of TiO2 /Ag-AgCl@Polypyrrole Composite and Its Enhanced Visible-Light Photocatalytic Activity.

    Science.gov (United States)

    Yao, Tongjie; Shi, Lei; Wang, Hao; Wang, Fangxiao; Wu, Jie; Zhang, Xiao; Sun, Jianmin; Cui, Tieyu

    2016-01-01

    A novel and facile method was developed to prepare a visible-light driven TiO2 /Ag-AgCl@polypyrrole (PPy) photocatalyst with Ag-AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag-AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag-AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2 /Ag-AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible-light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag-AgCl nanoparticles and the PPy shell. Furthermore, the TiO2 /Ag-AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Effects of Ag Nanoparticles on Growth and Fat Body Proteins in Silkworms (Bombyx mori).

    Science.gov (United States)

    Meng, Xu; Abdlli, Nouara; Wang, Niannian; Lü, Peng; Nie, Zhichao; Dong, Xin; Lu, Shuang; Chen, Keping

    2017-12-01

    Ag nanoparticles (AgNPs), a widely used non-antibiotic, antibacterial material, have shown toxic and other potentially harmful effects in mammals. However, the deleterious effects of AgNPs on insects are still unknown. Here, we studied the effects of AgNPs on the model invertebrate organism Bombyx mori. After feeding silkworm larvae different concentrations of AgNPs, we evaluated the changes of B. mori body weights, survival rates, and proteomic differences. The results showed that low concentrations (mori. Although high concentrations (≥800 mg/L) of AgNPs also improved B. mori growth, they resulted in silkworm death. An analysis of fat body proteomic differences revealed 13 significant differences in fat body protein spots, nine of which exhibited significantly downregulated expression, while four showed significantly upregulated expression. Reverse transcription-polymerase chain reaction results showed that at an AgNP concentration of 1600 mg/L, the expression levels of seven proteins were similar to the transcription levels of their corresponding genes. Our results suggest that AgNPs lowered the resistance to oxidative stress, affected cell apoptosis, and induced cell necrosis by regulating related protein metabolism and metabolic pathways in B. mori.

  16. Monomer functionalized silica coated with Ag nanoparticles for enhanced SERS hotspots

    Science.gov (United States)

    Newmai, M. Boazbou; Verma, Manoj; Kumar, P. Senthil

    2018-05-01

    Mesoporous silica (SiO2) spheres are well-known for their excellent chromatographic properties such as the relatively high specific surface, large pore volume, uniform particle size, narrow pore size distribution with favorable pore connectivity; whereas the noble metal Ag nanoparticles have unique size/shape dependant surface plasmon resonance with wide ranging applications. Thus, the desire to synchronize both their properties for specific applications has naturally prompted research in the design and synthesis of core-shell type novel nanoAg@mesoSiO2 nanocomposites, which display potential utility in applications such as photothermal therapy, photocatalysis, molecular sensing, and photovoltaics. In the present work, SiO2 spheres were carefully functionalized with the monomer, N-vinyl pyrrolidone (NVP), which cohesively controls the uniform mass transfer of Ag+ metal ions, thereby enabling its sequential reduction to zerovalent Ag (in the presence of slightly excess NaOH) by electron transfer from nucleophilic attack of the NVP vinyl group by the water molecules even under ambient conditions. Complete metal nanoshell coverage of the silica surface was obtained after multiple Ag deposition cycles, as systematically confirmed from the BET, TEM, optical and FTIR characterization. Our present Ag-coated silica spheres were directly utilized as viable SERS substrates with high sensitivity in contrast with other long chain polymer/surfactant coated silica spheres, owing to the presence of significant number of nanogaps enhanced SERS 'hotspots', which were methodically analyzed utilizing two example analytes, such as crystal violet (CV) and calendula officinalis (CaF).

  17. A micro-Raman study of live, single red blood cells (RBCs treated with AgNO3 nanoparticles.

    Directory of Open Access Journals (Sweden)

    Aseefhali Bankapur

    Full Text Available Silver nanoparticles (Ag NPs are known to exhibit broad antimicrobial activity. However, such activity continues to raise concerns in the context of the interaction of such NPs with biomolecules. In a physiological environment NPs interact with individual biological cells either by penetrating through the cell membrane or by adhering to the membrane. We have explored the interaction of Ag NPs with single optically-trapped, live erythrocytes (red blood cells, RBCs using Raman Tweezers spectroscopy. Our experiments reveal that Ag NPs induce modifications within an RBC that appear to be irreversible. In particular we are able to identify that the heme conformation in an RBC transforms from the usual R-state (oxy-state to the T-state (deoxy-state. We rationalize our observations by proposing a model for the nanoparticle cytotoxicity pathway when the NP size is larger than the membrane pore size. We propose that the interaction of Ag NPs with the cell surface induces damage brought about by alteration of intracellular pH caused by the blockage of the cell membrane transport.

  18. Vertically oriented TiO(x)N(y) nanopillar arrays with embedded Ag nanoparticles for visible-light photocatalysis.

    Science.gov (United States)

    Jiang, Weitao; Ullah, Najeeb; Divitini, Giorgio; Ducati, Caterina; Kumar, R Vasant; Ding, Yucheng; Barber, Zoe H

    2012-03-27

    We present a straightforward method to produce highly crystalline, vertically oriented TiO(x)N(y) nanopillars (up to 1 μm in length) with a band gap in the visible-light region. This process starts with reactive dc sputtering to produce a TiN porous film, followed by a simple oxidation process at elevated temperatures in oxygen or air. By controlling the oxidation conditions, the band gap of the prepared TiO(x)N(y) can be tuned to different wavelength within the range of visible light. Furthermore, in order to inhibit carrier recombination to enhance the photocatalytic activity, Ag nanoparticles have been embedded into the nanogaps between the TiO(x)N(y) pillars by photoinduced reduction of Ag(+) (aq) irradiated with visible light. Transmission electron microscopy reveals that the Ag nanoparticles with a diameter of about 10 nm are uniformly dispersed along the pillars. The prepared TiO(x)N(y) nanopillar matrix and Ag:TiO(x)N(y) network show strong photocatalytic activity under visible-light irradiation, evaluated via degradation of Rhodamine B. © 2012 American Chemical Society

  19. Novel manufacturing process of nanoparticle/Al composite filler metals of tungsten inert gas welding by accumulative roll bonding

    Energy Technology Data Exchange (ETDEWEB)

    Fattahi, M., E-mail: fattahi.put@gmail.com [Technical Inspection Engineering Department, Petroleum University of Technology, Abadan (Iran, Islamic Republic of); Noei Aghaei, V. [Aerospace Engineering Department, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Dabiri, A.R. [Technical Inspection Engineering Department, Petroleum University of Technology, Abadan (Iran, Islamic Republic of); Amirkhanlou, S. [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Akhavan, S.; Fattahi, Y. [Materials Engineering Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    2015-11-11

    In the present work, accumulative roll bonding (ARB) was used as an effective method for manufacturing nanoparticle/Al composite filler metals of tungsten inert gas (TIG) welding. After welding, the distribution of ceramic nanoparticles and mechanical properties of welds were investigated. By applying ARB, ceramic nanoparticles were uniformly dispersed in the composite filler metals. Consequently, the welds produced by these filler metals had a uniform dispersion of ceramic nanoparticles in their compositions. The test results showed that the yield strength of welds was greatly increased when using the nanoparticle/Al composite filler metals. The improvement in the yield strength was attributed to the coefficient of thermal expansion mismatch and Orowan strengthening mechanisms. Therefore, according to the results presented in this paper, it can be concluded that the nanoparticle/Al composite filler metals can serve as a novel filler metal for TIG welding of aluminum and its alloys.

  20. Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO{sub 3} film by decorating with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qing; Shen, Mingrong; Fang, Liang, E-mail: lfang@suda.edu.cn [College of Physics, Optoelectronics and Energy and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006 (China); Zhou, Yang; You, Lu; Wang, Junling [School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore)

    2016-01-11

    Polycrystalline BiFeO{sub 3} (BFO) films are fabricated on Pt/Ti/SiO{sub 2}/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.

  1. Rapid chromatographic separation of dissoluble Ag(I) and silver-containing nanoparticles of 1-100 nanometer in antibacterial products and environmental waters.

    Science.gov (United States)

    Zhou, Xiao-Xia; Liu, Rui; Liu, Jing-Fu

    2014-12-16

    Sensitive and rapid methods for speciation analysis of nanoparticulate Ag (NAg) and Ag(I) in complex matrices are urgently needed for understanding the environmental effects and biological toxicity of silver nanoparticles (AgNPs). Herein we report the development of a universal liquid chromatography (LC) method for rapid and high resolution separation of dissoluble Ag(I) from nanoparticles covering the entire range of 1-100 nm in 5 min. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag(I) was eluted as a baseline separated peak. The dissoluble Ag(I) was quantified by the online coupled ICP-MS with a detection limit of 0.019 μg/L. The NAg was quantified by subtracting the dissoluble Ag(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. While the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute NAg and Ag(I) from the column, the use of 500 Å poresize column is the key to baseline separation of Ag(I) from ∼ 1 nm AgNPs. The feasibility of the proposed method was demonstrated in speciation analysis of dissoluble Ag(I) and NAg in antibacterial products and environmental waters, with very good chromatographic repeatability (relative standard deviations) in both peak area (<2%) and retention time (<0.6%), excellent spiked recoveries in the range of 84.7-102.7% for Ag(I) and 81.3-106.3% for NAg. Our work offers a novel approach to rapid and baseline separation of dissoluble metal ions from their nanoparticulate counterparts covering the whole range of 1-100 nm.

  2. Effects of laser fluence and liquid media on preparation of small Ag nanoparticles by laser ablation in liquid

    Science.gov (United States)

    Moura, Caroline Gomes; Pereira, Rafael Santiago Floriani; Andritschky, Martin; Lopes, Augusto Luís Barros; Grilo, João Paulo de Freitas; Nascimento, Rubens Maribondo do; Silva, Filipe Samuel

    2017-12-01

    This study aims to assess a method for preparation of small and highly stable Ag nanoparticles by nanosecond laser ablation in liquid. Effect of liquid medium and laser fluence on the size, morphology and structure of produced nanoparticles has been studied experimentally. Pulses of a Nd:YAG laser of 1064 nm wavelength at 35 ns pulse width at different fluences were employed to irradiate the silver target in different environments (water, ethanol and acetone). The UV-Visible absorption spectra of nanoparticles exhibit surface plasmon resonance absorption peak in the UV region. STEM and TEM micrographs were used to evaluate the size and shape of nanoparticles. The stability of silver colloids in terms of oxidation at different liquid media was analyzed by SAED patterns. The results showed that characteristics of Ag nanoparticles and their production rate were strongly influenced by varying laser fluence and liquid medium. Particles from 2 to 80 nm of diameter were produced using different conditions and no oxidation was found in ethanol and acetone media. This work puts in evidence a promising approach to produce small nanoparticles by using high laser fluence energy.

  3. Enhanced antibacterial activity of silver nanoparticles/halloysite nanotubes/graphene nanocomposites with sandwich-like structure.

    Science.gov (United States)

    Yu, Liang; Zhang, Yatao; Zhang, Bing; Liu, Jindun

    2014-04-11

    A sandwich-like antibacterial reagent (Ag/HNTs/rGO) was constructed through the direct growth of silver nanoparticles on the surface graphene-based HNTs nanosheets. Herein, various nanomaterials were combined by adhesion effect of DOPA after self-polymerization. Ag/HNTs/rGO possess enhanced antibacterial ability against E. coli and S. aureus compared with individual silver nanoparticles, rGO nanosheets or their nanocomposites.

  4. Fabrication of silver nanoparticles embedded into polyvinyl alcohol (Ag/PVA) composite nanofibrous films through electrospinning for antibacterial and surface-enhanced Raman scattering (SERS) activities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhijie; Wu, Yunping [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng 475004 (China); Wang, Zhihua, E-mail: zhwang@henu.edu.cn [College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Zou, Xueyan; Zhao, Yanbao [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng 475004 (China); Sun, Lei, E-mail: sunlei@hneu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng 475004 (China)

    2016-12-01

    Silver nanoparticle-embedded polyvinyl alcohol (PVA) nanofibers were prepared through electrospinning technique, using as antimicrobial agents and surface-enhanced Raman scattering (SERS) substrates. Ag nanoparticles (NPs) were synthesized in liquid phase, followed by evenly dispersing in PVA solution. After electrospinning of the mixed solution at room temperature, the PVA embedded with Ag NPs (Ag/PVA) composite nanofibers were obtained. The morphologies and structures of the as-synthesized Ag nanoparticles and Ag/PVA fibers were characterized by the techniques of transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Ag NPs have an average diameter of 13.8 nm, were found to be uniformly dispersed in PVA nanofibers. The Ag/PVA nanofibers provided robust antibacterial activities against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) microorganisms. It's also found that Ag/PVA nanofibers make a significant contribution to the high sensitivity of SERS to 4-mercaptophenol (4-MPh) molecules. - Highlights: • Ag NPs embedded in the PVA electropun nanofibrous films were synthesized successfully. • The as-synthesized nanofibrous film mats exhibit excellent antibacterial properties and SERS activates. • The mechanism of antibacterial and SERS effects were proposed.

  5. Fabrication of silver nanoparticles embedded into polyvinyl alcohol (Ag/PVA) composite nanofibrous films through electrospinning for antibacterial and surface-enhanced Raman scattering (SERS) activities

    International Nuclear Information System (INIS)

    Zhang, Zhijie; Wu, Yunping; Wang, Zhihua; Zou, Xueyan; Zhao, Yanbao; Sun, Lei

    2016-01-01

    Silver nanoparticle-embedded polyvinyl alcohol (PVA) nanofibers were prepared through electrospinning technique, using as antimicrobial agents and surface-enhanced Raman scattering (SERS) substrates. Ag nanoparticles (NPs) were synthesized in liquid phase, followed by evenly dispersing in PVA solution. After electrospinning of the mixed solution at room temperature, the PVA embedded with Ag NPs (Ag/PVA) composite nanofibers were obtained. The morphologies and structures of the as-synthesized Ag nanoparticles and Ag/PVA fibers were characterized by the techniques of transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Ag NPs have an average diameter of 13.8 nm, were found to be uniformly dispersed in PVA nanofibers. The Ag/PVA nanofibers provided robust antibacterial activities against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) microorganisms. It's also found that Ag/PVA nanofibers make a significant contribution to the high sensitivity of SERS to 4-mercaptophenol (4-MPh) molecules. - Highlights: • Ag NPs embedded in the PVA electropun nanofibrous films were synthesized successfully. • The as-synthesized nanofibrous film mats exhibit excellent antibacterial properties and SERS activates. • The mechanism of antibacterial and SERS effects were proposed.

  6. Visualization of interaction between inorganic nanoparticles and bacteria or fungi

    DEFF Research Database (Denmark)

    Chwalibog, André; Sawosz, Ewa; Hotowy, Anna Malgorzata

    2010-01-01

    Purpose: The objective of the present investigation was to evaluate the morphologic characteristics of self-assemblies of diamond (nano-D), silver (nano-Ag), gold (nano-Au), and platinum (nano-Pt) nanoparticles with Staphylococus aureus (bacteria) and Candida albicans (fungi), to determine...... interaction between the nanoparticles and microorganisms showed that nano-D, which are dielectrics and exhibit a positive zeta potential, were very different from the membrane potentials of microorganisms, and uniformly surrounded the microorganisms, without causing visible damage and destruction of cells...... and cell wall. Conclusion: Nano-Ag, nano-Au, and nano-Pt (all metal nanoparticles) are harmful to bacteria and fungi. In contrast, nano-D bind closely to the surface of microorganisms without causing visible damage to cells, and demonstrating good self-assembling ability. The results indicate that both...

  7. Green synthesis of halloysite nanotubes supported Ag nanoparticles for photocatalytic decomposition of methylene blue

    International Nuclear Information System (INIS)

    Zou Meiling; Zhu Han; Xu Congsheng; Du Mingliang; Fu Yaqin

    2012-01-01

    Using tea polyphenols (TPs) as a reductant, Ag nanoparticles (AgNPs) supported on halloysite nanotubes (HNTs) were simply and greenly synthesized for the photocatalytic decomposition of methylene blue (MB). HNTs were initially functionalized by N-β-aminoethyl-γ-aminopropyl trimethoxysilane (AEAPTMS) to introduce amino groups to form N-HNTs to fasten the AgNPs; then AgNPs were synthesized and ‘anchored’ on the surface of the HNTs. Fourier transform infrared spectroscopy was employed to testify the amino groups on the surface of the HNTs. Transmission electron microscopy, field-emission scanning electron microscopy and x-ray diffraction were utilized to characterize the structure and morphology of the synthesized HNTs supported by the AgNPs (AgNPs-N-HNTs). The results showed that the AgNPs had been synthesized and ‘anchored’ onto the surface of the HNTs with a diameter of about 20-30 nm. X-ray photoelectron spectroscopy analysis revealed the chelating interaction between the AgNPs and N atoms together with the TP molecular. The photocatalytic activity of the as-prepared AgNPs-N-HNTs catalyst was evaluated by decomposition of MB; the results showed that the prepared catalyst exhibited excellent catalytic activity and high adsorption capability to MB. (paper)

  8. Curve thermoluminescent analysis of ZrO2 doped with nanoparticles and Ag nano fibers

    International Nuclear Information System (INIS)

    Mendoza A, D.; Villa S, G.; Gutierrez W, C.; Perez H, R.; Gonzalez M, P.

    2008-01-01

    This paper presents the results obtained from the analysis of the high temperature thermoluminescence response induced by UV radiation in pure zirconium (ZrO 2 ) and doped with Ag nanoparticles and Ag nano fibers. The zirconium samples were obtained by the sol-gel method and irradiated with a UV lamp for different times. The results showed that the presence of the dopants change the characteristics of the traps associated with the high temperature peak which is located at 230 C for pure zirconium, and that the greater influence is due the presence of Ag nano fibers, inducing a shift to lower temperatures. It also presents the thermoluminescence response as a function of irradiation time. (Author)

  9. Evolution of Ternary AuAgPd Nanoparticles by the Control of Temperature, Thickness, and Tri-Layer

    Directory of Open Access Journals (Sweden)

    Sundar Kunwar

    2017-11-01

    Full Text Available Metallic alloy nanoparticles (NPs possess great potential to enhance the optical, electronic, chemical, and magnetic properties for various applications by the control of morphology and elemental composition. This work presents the fabrication of ternary AuAgPd alloy nanostructures on sapphire (0001 via the solid-state dewetting of sputter-deposited tri-metallic layers. Based on the systematic control of temperature, thickness, and deposition order of tri-layers, the composite AuAgPd alloy nanoparticles (NPs with various shape, size, and density are demonstrated. The metallic tri-layers exhibit various stages of dewetting based on the increasing growth temperatures between 400 and 900 °C at 15 nm tri-layer film thickness. Specifically, the nucleation of tiny voids and hillocks, void coalescence, the growth and isolated nanoparticle formation, and the shape transformation with Ag sublimation are observed. With the reduced film thickness (6 nm, tiny alloy NPs with improved structural uniformity and spatial arrangement are obtained due to enhanced dewetting. The growth trend of alloy NPs is drastically altered by changing the deposition order of metallic tri-layers. The overall evolution is governed by the surface diffusion and inter-mixing of metallic atoms, Rayleigh-like instability, surface and interface energy minimization, and equilibrium state of the system. The UV-VIS-NIR reflectance spectra reveal the formation of an absorption band and reflectance maxima at specific wavelengths based on the morphology and composition of AuAgPd alloy NPs. In addition, Raman spectra analysis shows the modulation of intensity and peak position of natural vibration modes of sapphire (0001.

  10. Evaluation of genotoxic effect of silver nanoparticles (Ag-Nps) in vitro and in vivo

    International Nuclear Information System (INIS)

    Tavares, Priscila; Balbinot, Fernanda; Martins de Oliveira, Hugo; Elibio Fagundes, Gabriela; Venâncio, Mireli; Vieira Ronconi, João Vitor; Merlini, Aline; Streck, Emílio L.; Marques da Silva, Paula; Moraes de Andrade, Vanessa

    2012-01-01

    Silver nanoparticles (Ag-NPs) are the most prominent nanoproducts. Due to their antimicrobial activity, they have been incorporated in different materials, such as catheters, clothes, electric home appliance, and many others. The genotoxicity of Ag-NPs (5–45 nm), in different concentrations and times of exposure, was evaluated by the comet assay in in vitro and in vivo conditions, respectively, using human peripheral blood and Swiss mice. The results showed the genotoxic effect of Ag-NPs in vitro, in all the doses tested in the initial hour of exposure, possibly through the reactive oxygen species generation. Nevertheless, the values for this damage decrease with time, indicating that the DNA may have been restored by the repair system. In the in vivo conditions, we found no genotoxicity of Ag-NPs in any hour of exposure and any dose investigated, which can be attributed to the activation of a cellular antioxidant network and the hydrophobic nature of Ag-NPs. Now, it is absolutely necessary to investigate the role of Ag-NPs in different cell lines in vivo.

  11. Evaluation of genotoxic effect of silver nanoparticles (Ag-Nps) in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Priscila; Balbinot, Fernanda; Martins de Oliveira, Hugo; Elibio Fagundes, Gabriela [PPGCS, Universidade do Extremo Sul Catarinense, Laboratorio de Biologia Celular e Molecular (Brazil); Venancio, Mireli; Vieira Ronconi, Joao Vitor; Merlini, Aline [Universidade do Extremo Sul Catarinense, Laboratorio de Sintese de Complexos Multifuncionais (Brazil); Streck, Emilio L. [Programa de Pos-Graduacao em Ciencias da Saude, Unidade Academica de Ciencias da Saude, Universidade do Extremo Sul Catarinense, Laboratorio de Fisiopatologia Experimental (Brazil); Marques da Silva, Paula [Universidade do Extremo Sul Catarinense, Laboratorio de Sintese de Complexos Multifuncionais (Brazil); Moraes de Andrade, Vanessa, E-mail: vmoraesdeandrade@yahoo.com.br [PPGCS, Universidade do Extremo Sul Catarinense, Laboratorio de Biologia Celular e Molecular (Brazil)

    2012-03-15

    Silver nanoparticles (Ag-NPs) are the most prominent nanoproducts. Due to their antimicrobial activity, they have been incorporated in different materials, such as catheters, clothes, electric home appliance, and many others. The genotoxicity of Ag-NPs (5-45 nm), in different concentrations and times of exposure, was evaluated by the comet assay in in vitro and in vivo conditions, respectively, using human peripheral blood and Swiss mice. The results showed the genotoxic effect of Ag-NPs in vitro, in all the doses tested in the initial hour of exposure, possibly through the reactive oxygen species generation. Nevertheless, the values for this damage decrease with time, indicating that the DNA may have been restored by the repair system. In the in vivo conditions, we found no genotoxicity of Ag-NPs in any hour of exposure and any dose investigated, which can be attributed to the activation of a cellular antioxidant network and the hydrophobic nature of Ag-NPs. Now, it is absolutely necessary to investigate the role of Ag-NPs in different cell lines in vivo.

  12. Ag-Cu Bimetallic Nanoparticles Prepared by Microemulsion Method as Catalyst for Epoxidation of Styrene

    Directory of Open Access Journals (Sweden)

    Hong-Kui Wang

    2012-01-01

    Full Text Available Ag/Cu bimetallic nanocatalysts supported on reticulate-like γ-alumina were prepared by a microemulsion method using N2H4·H2O as the reducing agent. The catalysts were activated by calcination followed with hydrogen reduction at 873K, and the properties were confirmed using various characterization techniques. Compared with metal oxides particles, Ag-Cu particles exhibited smaller sizes (<5 nm after calcination in H2 at 873K. XPS results indicated that the binding energies changed with the Ag/Cu ratios, suggesting that increasing the copper content gave both metals a greater tendency to lose electrons. Furthermore, Ag-Cu bimetallic nanoparticles supported on γ-alumina showed better catalytic activity on the epoxidation of styrene as compared with the corresponding monometallic silver or copper. The styrene oxide selectivity could reach 76.6% at Ag/Cu molar ratio of 3/1, while the maximum conversion (up to 94.6% appeared at Ag/Cu molar ratio of 1/1 because of the maximum interaction between silver and copper.

  13. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO{sub 2} nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    Energy Technology Data Exchange (ETDEWEB)

    Nischk, Michał [Department of Chemical Technology, Faculty of Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza 11/12 St., 80-233 Gdansk (Poland); Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Mazierski, Paweł [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland); Wei, Zhishun [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Siuzdak, Katarzyna [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk (Poland); Kouame, Natalie Amoin [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Kowalska, Ewa [Institute for Catalysis, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Remita, Hynd [Laboratoire de Chimie Physique, CNRS—UMR 8000,Université Paris-Sud, Université Paris-Saclay, Bâtiment 349, 91405 Orsay (France); Zaleska-Medynska, Adriana, E-mail: adriana.zaleska@ug.edu.pl [Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 63 Wita Stwosza St., 80-308 Gdansk (Poland)

    2016-11-30

    Highlights: • TiO{sub 2} nanotubes were modified with Cu, AgCu, Bi nanoparticles via gamma radiolysis. • Excessive amount of deposited metal decreased photocatalytic activity. • AgCu-modified samples were more active than Cu-modified (with the same Cu content). • AgCu nanoparticles exist in a core{sub (Ag)}-shell{sub (Cu)} form. • Examined photocatalysts were resistant towards photocorrosion processes. - Abstract: TiO{sub 2} nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Ag{sub core}-Cu{sub shell} form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  14. Silver nanoparticles from silver halide photography to plasmonics

    CERN Document Server

    Tani, Tadaaki

    2015-01-01

    This book provides systematic knowledge and ideas on nanoparticles of Ag and related materials. While Ag and metal nanoparticles are essential for plasmonics, silver halide (AgX) photography relies to a great extent on nanoparticles of Ag and AgX which have the same crystal structure and have been studied extensively for many years. This book has been written to combine the knowledge of nanoparticles of Ag and related materials in plasmonics and AgX photography in order to provide new ideas for metal nanoparticles in plasmonics. Chapters 1–3 of this book describe the structure and formation of nanoparticles of Ag and related materials. Systematic descriptions of the structure and preparation of Ag, Au, and noble-metal nanoparticles for plasmonics are followed by and related to those of nanoparticles of Ag and AgX in AgX photography. Knowledge of the structure and preparation of Ag and AgX nanoparticles in photography covers nanoparticles with widely varying sizes, shapes, and structures, and formation proce...

  15. Direct in situ activation of Ag{sup 0} nanoparticles in synthesis of Ag/TiO{sub 2} and its photoactivity

    Energy Technology Data Exchange (ETDEWEB)

    Jaafar, N.F. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Jalil, A.A., E-mail: aishah@cheme.utm.my [Institute of Hydrogen Economy, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Efendi, J. [Department of Chemistry, Universitas Negeri Padang, Jl. Prof. Hamka, Air Tawar, Padang, West Sumatera (Indonesia); Mukti, R.R. [Division of Inorganic and Physical Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl Ganesha No. 10, Bandung 40132 (Indonesia); Jusoh, R.; Jusoh, N.W.C. [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Karim, A.H. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Salleh, N.F.M. [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Suendo, V. [Division of Inorganic and Physical Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl Ganesha No. 10, Bandung 40132 (Indonesia)

    2015-05-30

    Graphical abstract: - Highlights: • Ag{sup 0} loaded on TiO{sub 2} was prepared by a direct in situ electrochemical method. • 5 wt% Ag–TiO{sub 2} demonstrated the best photocatalytic degradation of 2-CP. • Isomorphous substitution of Ag with Ti occurred to form Ti−O−Ag bonds. • Ag{sup 0} and oxygen vacancies trapped electrons to enhance e–H{sup +} separation. • Substitution of Ag in the TiO{sub 2} structure decreased the number of oxygen vacancies. - Abstract: Metallic Ag nanoparticles (Ag{sup 0}) were successfully activated using a direct in situ electrochemical method before being supported on TiO{sub 2}. Catalytic testing showed that 5 wt% Ag–TiO{sub 2} gave the highest photodegradation (94%) of 50 mg L{sup −1} 2-chlorophenol (2-CP) at pH 5 using 0.375 g L{sup −1} catalyst within 6 h, while under similar conditions, 1 wt% and 10 wt% Ag–TiO{sub 2} only gave 75% and 78% degradation, respectively. Characterization results illustrated that the photoactivity was affected by the amount of Ag{sup 0} and oxygen vacancies which act as an electrons trap to enhance the electron–hole separation. While, the Ag−O−Ti bonds formation reduced the photoactivity. The degradation followed a pseudo-first order Langmuir–Hinshelwood model where adsorption was the controlling step. Study on the effect of scavengers showed that the hole (H{sup +}) and hydroxyl radical (OH·) play important roles in the photodegradation. The regenerated photocatalyst was still stable after five cycling runs.

  16. A facile method for electrospinning of Ag nanoparticles/poly (vinyl alcohol)/carboxymethyl-chitosan nanofibers

    International Nuclear Information System (INIS)

    Zhao, Yinghui; Zhou, Ying; Wu, Xiaomian; Wang, Lu; Xu, Ling; Wei, Shicheng

    2012-01-01

    Highlights: ► AgNPs/PVA/CM-chitosan nanofibers were prepared via electrospinning method. ► AgNPs were in situ synthesized in electrospinning solution via a facile method. ► AgNPs distributed homogeneously on the surface of nanofibers. ► The prepared nanofibers possessed certain antibacterial ability against Escherichia coli. ► The AgNPs containing nanofibers had potential as antibacterial biomaterial. - Abstract: A facile method to prepare silver nanoparticles (AgNPs) containing nanofibers via electrospinning has been demonstrated. AgNPs were in situ synthesized in poly (vinyl alcohol) (PVA)/carboxymethyl-chitosan (CM-chitosan) blend aqueous solution before electrospinning. UV–vis spectra, viscosity and conductivity of the electrospinning solution were measured to investigate their effects on the electrospinning procedure. The morphology of AgNPs/PVA/CM-chitosan nanofibers was observed by Field Emission Scanning Electron Microscopy. The formation and morphology of AgNPs were investigated by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. The resulted nanofibers have smooth surface and uniform diameters ranging from 295 to 343 nm. The diameters of AgNPs mainly distributed in the range of 4–14 nm, and the electrostatic interaction between AgNPs and fibers was observed. Finally, in vitro Ag release from the nanofibers was measured and the antibacterial behavior of the nanofibers against Escherichia coli was studied by bacterial growth inhibition halos and bactericidal kinetic testing. The AgNPs/PVA/CM-chitosan nanofibers possessed certain antibacterial ability, which makes them capable for antibacterial biomaterials.

  17. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    Science.gov (United States)

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  18. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions.

    Directory of Open Access Journals (Sweden)

    Yi-Huang Hsueh

    Full Text Available The superior antimicrobial properties of silver nanoparticles (Ag NPs are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10-50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES and extended X-ray absorption fine structure (EXAFS analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation.

  19. Vancomycin-functionalised Ag-TiO{sub 2} phototoxicity for bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Wan Yi [Chinese Academy of Sciences, Key Lab of Corrosion Science, Shandong Province, Institute of Oceanology, 7 Nanhai Road, Qingdao 266071 (China); Zhang Dun, E-mail: zhangdun@ms.qdio.ac.cn [Chinese Academy of Sciences, Key Lab of Corrosion Science, Shandong Province, Institute of Oceanology, 7 Nanhai Road, Qingdao 266071 (China); Wang Yi; Qi Peng; Wu Jiajia; Hou Baorong [Chinese Academy of Sciences, Key Lab of Corrosion Science, Shandong Province, Institute of Oceanology, 7 Nanhai Road, Qingdao 266071 (China)

    2011-02-15

    Research highlights: {yields} A multivalent interaction between Van-Ag-TiO{sub 2} and SRB. {yields} Van-Ag-TiO{sub 2} allow for selective photokilling of pathogen. {yields} Van-Ag-TiO{sub 2} show certain bactericidal property in dark. - Abstract: This study reports on the synthesis of vancomycin (Van)-functionalised Ag-TiO{sub 2} nanoparticles and their enhanced bactericidal activities. Van-Ag-TiO{sub 2} nanoparticles were prepared by nanoparticle deposition and chemical cross-linking reactions. The catalysts showed high efficiency for the degradation of methylene blue under ultraviolet (UV) illumination. The photocatalytic inactivation of the sulphate-reducing bacteria, Desulfotomaculum, was also studied under UV light irradiation and in the dark using aqueous mixtures of Ag, Ag-SiO{sub 2}, Ag-TiO{sub 2}, and Van-Ag-TiO{sub 2}. The Van-Ag-TiO{sub 2} nanoparticles showed a capacity to target Van-sensitive bacteria. They also effectively prevented bacterial cell growth through the functionalised nanoparticles under UV irradiation for 1 h. To investigate the specificity of the catalyst phototoxicity, a Van-resistant bacteria, Vibrio anguillarum, was used as the negative control. The results indicated that Van-Ag-TiO{sub 2} nanoparticles had a higher selective phototoxicity for Van-sensitive bacteria. Therefore, the antibiotic molecule-functionalised core-shell nanoparticles allow for selective photokilling of pathogenic bacteria.

  20. Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles.

    Science.gov (United States)

    Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

    2018-01-01

    In this study, we analyzed the antimicrobial activities of poly- N -isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH 2 -based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO 3 using NaBH 4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria depending on the nanoparticle size and amount of AgNO 3 used during fabrication.

  1. Stability of molybdenum nanoparticles in Sn-3.8Ag-0.7Cu solder during multiple reflow and their influence on interfacial intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Arafat, M.M., E-mail: arafat_mahmood@yahoo.com; Johan, Mohd Rafie, E-mail: mrafiej@um.edu.my

    2012-02-15

    This work investigates the effects of molybdenum nanoparticles on the growth of interfacial intermetallic compound between Sn-3.8Ag-0.7Cu solder and copper substrate during multiple reflow. Molybdenum nanoparticles were mixed with Sn-3.8Ag-0.7Cu solder paste by manual mixing. Solder samples were reflowed on a copper substrate in a 250 Degree-Sign C reflow oven up to six times. The molybdenum content of the bulk solder was determined by inductive coupled plasma-optical emission spectrometry. It is found that upon the addition of molybdenum nanoparticles to Sn-3.8Ag-0.7Cu solder, the interfacial intermetallic compound thickness and scallop diameter decreases under all reflow conditions. Molybdenum nanoparticles do not appear to dissolve or react with the solder. They tend to adsorb preferentially at the interface between solder and the intermetallic compound scallops. It is suggested that molybdenum nanoparticles impart their influence on the interfacial intermetallic compound as discrete particles. The intact, discrete nanoparticles, by absorbing preferentially at the interface, hinder the diffusion flux of the substrate and thereby suppress the intermetallic compound growth. - Highlights: Black-Right-Pointing-Pointer Mo nanoparticles do not dissolve or react with the SAC solder during reflow. Black-Right-Pointing-Pointer Addition of Mo nanoparticles results smaller IMC thickness and scallop diameter. Black-Right-Pointing-Pointer Mo nanoparticles influence the interfacial IMC through discrete particle effect.

  2. Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

    Science.gov (United States)

    Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

    2015-07-01

    Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet-visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films.

  3. Single gold nanoparticle plasmonic spectroscopy for study of chemical-dependent efflux function of single ABC transporters of single live Bacillus subtilis cells.

    Science.gov (United States)

    Browning, Lauren M; Lee, Kerry J; Cherukuri, Pavan K; Huang, Tao; Songkiatisak, Preeyaporn; Warren, Seth; Xu, Xiao-Hong Nancy

    2018-03-26

    ATP-binding cassette (ABC) membrane transporters serve as self-defense transport apparatus in many living organisms and they can selectively extrude a wide variety of substrates, leading to multidrug resistance (MDR). The detailed molecular mechanisms remain elusive. Single nanoparticle plasmonic spectroscopy highly depends upon their sizes, shapes, chemical and surface properties. In our previous studies, we have used the size-dependent plasmonic spectra of single silver nanoparticles (Ag NPs) to study the real-time efflux kinetics of the ABC (BmrA) transporter and MexAB-OprM transporter in single live cells (Gram-positive and Gram-negative bacterium), respectively. In this study, we prepared and used purified, biocompatible and stable (non-aggregated) gold nanoparticles (Au NPs) (12.4 ± 0.9 nm) to study the efflux kinetics of single BmrA membrane transporters of single live Bacillus subtillis cells, aiming to probe chemical dependent efflux functions of BmrA transporters and their potential chemical sensing capability. Similar to those observed using Ag NPs, accumulation of the intracellular Au NPs in single live cells (WT and ΔBmrA) highly depends upon the cellular expression of BmrA and the NP concentration (0.7 and 1.4 nM). The lower accumulation of intracellular Au NPs in WT (normal expression of BmrA) than ΔBmrA (deletion of bmrA) indicates that BmrA extrudes the Au NPs out of the WT cells. The accumulation of Au NPs in the cells increases with NP concentration, suggesting that the Au NPs most likely passively diffuse into the cells, similar to antibiotics. The result demonstrates that such small Au NPs can serve as imaging probes to study the efflux function of the BmrA membrane transporter in single live cells. Furthermore, the dependence of the accumulation rate of intracellular Au NPs in single live cells upon the expression of BmrA and the concentration of the NPs is about twice higher than that of the same sized Ag NPs. This interesting finding

  4. Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

    Science.gov (United States)

    Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

    2016-01-26

    One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life.

  5. Elucidating the real-time Ag nanoparticle growth on α-Ag2WO4 during electron beam irradiation: experimental evidence and theoretical insights.

    Science.gov (United States)

    Pereira, Wyllamanney da Silva; Andrés, Juan; Gracia, Lourdes; San-Miguel, Miguel A; da Silva, Edison Z; Longo, Elson; Longo, Valeria M

    2015-02-21

    Why and how Ag is formed when electron beam irradiation takes place on α-Ag2WO4 in a vacuum transmission electron microscopy chamber? To find an answer, the atomic-scale mechanisms underlying the formation and growth of Ag on α-Ag2WO4 have been investigated by detailed in situ transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) studies, density functional theory based calculations and ab initio molecular dynamics simulations. The growth process at different times, chemical composition, size distribution and element distribution were analyzed in depth at the nanoscale level using FE-SEM, operated at different voltages (5, 10, 15, and 20 kV), and TEM with energy dispersive spectroscopy (EDS) characterization. The size of Ag nanoparticles covers a wide range of values. Most of the Ag particles are in the 20-40 nm range. The nucleation and formation of Ag on α-Ag2WO4 is a result of structural and electronic changes in the AgOx (x = 2,4, 6, and 7) clusters used as constituent building blocks of this material, consistent with metallic Ag formation. First principle calculations point out that Ag-3 and Ag-4-fold coordinated centers, located in the sub-surface of the (100) surface, are the most energetically favorable to undergo the diffusion process to form metallic Ag. Ab initio molecular dynamics simulations and the nudged elastic band (NEB) method were used to investigate the minimum energy pathways of these Ag atoms from positions in the first slab layer to outward sites on the (100) surface of α-Ag2WO4. The results point out that the injection of electrons decreases the activation barrier for this diffusion step and this unusual behavior results from the presence of a lower energy barrier process.

  6. Simple and Sensitive Colorimetric Assay for Pb2+ Based on Glutathione Protected Ag Nanoparticles by Salt Amplification.

    Science.gov (United States)

    Chen, Zhang; Li, Huidong; Chu, Lin; Liu, Chenbin; Luo, Shenglian

    2015-02-01

    A simple and sensitive colorimetric assay for Pb2+ detection has been reported using glutathione protected silver nanoparticles (AgNPs) by salt amplification. The naked AgNPs aggregate under the influence of salt. Glutathione (GSH) can bind to AgNPs via Ag-S bond, helping AgNPs to against salt-induced aggregation. However, GSH binding to AgNPs can be compromised by the interaction between Pb2+ and GSH. As a result, Pb2+-mediated aggregation of AgNPs under the influence of salt is reflected by the UV-Visible spectrum, and the qualitative and quantitative detection for Pb2+ is accomplished, with the detection range 0.5-4 µM and a detection limit of 0.5 µM. At the same time, Pb2+ in real water sample is detected. Furthermore, the high selectivity and low cost of the assay means it is promising for enviromental applications.

  7. Low temperature sintering of Ag nanoparticles/graphene composites for paper based writing electronics

    International Nuclear Information System (INIS)

    Wang, Fuliang; He, Hu; Zhu, Haixin

    2016-01-01

    With the great demand in the applications of flexible electronics, the methods leading to improvements in the electrical and mechanical performance have been widely investigated. In this work, we firstly prepared a hybrid composite ink using Ag nanoparticles and graphene. Then, a hot-press sintering process was deployed to obtain the desired electrical tracks which could be applied in flexible electronics. We have systematically investigated the effects of sintering time, pressure and temperature, as well as the different percentage of weight (wt%) of graphene for the electrical and mechanical performance of sintered electrical tracks. We achieved reasonably low electrical resistivity at low sintering temperature (120 °C). Specifically, the resistivity reaches 6.19  ×  10 −8 Ω · m which is just 3.87 times higher than the value of bulk silver. Additionally, the prepared hybrid composite ink obtained better electrical reliability against bending test comparing with Ag nanoparticle ink. Finally, the optimal wt% of graphene and potential effect to the electrical and mechanical performance were also investigated. (paper)

  8. Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

    Science.gov (United States)

    Nguyen, Thi Kim Lan; Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Hien Nguyen, Quoc

    2013-12-01

    Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag+ dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag+ is occurred by hydrated electron (e-aq) and hydrogen atom (H•) generated during radiolysis of ethanol/water. The conversion doses (Ag+ → Ag0) were determined by UV-Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5-40 nm for Ag+ concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg-1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc.

  9. Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles.

    Science.gov (United States)

    Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

    2016-04-06

    A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO₃ solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

  10. Bimetallic Ag-Pd nanoparticles-decorated graphene oxide: a fascinating three-dimensional nanohybrid as an efficient electrochemical sensing platform for vanillin determination

    International Nuclear Information System (INIS)

    Li, Junhua; Feng, Haibo; Li, Jun; Jiang, Jianbo; Feng, Yonglan; He, Lingzhi; Qian, Dong

    2015-01-01

    Highlights: • A 3D Ag-Pd/GO nanohybrid was fabricated via a green and in situ chemical route. • Ag-Pd/GO shows excellent electro-catalytic properties for the oxidation of vanillin. • The 3D hybrid-based sensor shows excellent performances for the vanillin detection. • This proposed method was successfully used to detect vanillin in children’s snacks. - Abstract: In this work, a fascinating hybrid based on Ag-Pd bimetallic nanoparticles-decorated graphene oxide (Ag-Pd/GO) has been successfully synthesized by a green and in situ chemical reduction strategy. The resultant hybrid was particularly characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet-visible spectroscopy and electrochemical techniques. The morphological results illustrate that Ag-Pd nanoparticles in microspheric appearances are highly dispersed and embedded on the GO layers, resulting in a rough surface and three-dimensional (3D) microstructure with a high Ag-Pd content in the matrix. The as-synthesized 3D Ag-Pd/GO hybrid displays distinctly enhanced electrocatalytic activity for the vanillin oxidation in comparison with that of the monometal-decorated GO, revealing a synergistic effect of the matrix GO and the doped bimetallic Ag-Pd. Therefore, the Ag-Pd/GO composite can be used as an enhanced electrochemical sensing platform for the sensitive determination of vanillin, and the fabricated sensor displays a wide detection range of 0.02–45 μmol dm −3 , low detection limit of 5 nmol dm −3 and satisfactory recoveries between 98.8 % and 103.5 %. All the results demonstrate that the 3D hybrids integrated graphene with bimetallic nanoparticles are promising candidates for the development of high-performance electrochemical sensors

  11. A facile method for electrospinning of Ag nanoparticles/poly (vinyl alcohol)/carboxymethyl-chitosan nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yinghui; Zhou, Ying [Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wu, Xiaomian [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Orthodontics College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Wang, Lu [Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871 (China); Xu, Ling, E-mail: lingxu@pku.edu.cn [Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); PKU-HKUST ShenZhen-HongKong Institution, Shenzhen 518057 (China); Wei, Shicheng, E-mail: sc-wei@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Peking University, Beijing 100081 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer AgNPs/PVA/CM-chitosan nanofibers were prepared via electrospinning method. Black-Right-Pointing-Pointer AgNPs were in situ synthesized in electrospinning solution via a facile method. Black-Right-Pointing-Pointer AgNPs distributed homogeneously on the surface of nanofibers. Black-Right-Pointing-Pointer The prepared nanofibers possessed certain antibacterial ability against Escherichia coli. Black-Right-Pointing-Pointer The AgNPs containing nanofibers had potential as antibacterial biomaterial. - Abstract: A facile method to prepare silver nanoparticles (AgNPs) containing nanofibers via electrospinning has been demonstrated. AgNPs were in situ synthesized in poly (vinyl alcohol) (PVA)/carboxymethyl-chitosan (CM-chitosan) blend aqueous solution before electrospinning. UV-vis spectra, viscosity and conductivity of the electrospinning solution were measured to investigate their effects on the electrospinning procedure. The morphology of AgNPs/PVA/CM-chitosan nanofibers was observed by Field Emission Scanning Electron Microscopy. The formation and morphology of AgNPs were investigated by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. The resulted nanofibers have smooth surface and uniform diameters ranging from 295 to 343 nm. The diameters of AgNPs mainly distributed in the range of 4-14 nm, and the electrostatic interaction between AgNPs and fibers was observed. Finally, in vitro Ag release from the nanofibers was measured and the antibacterial behavior of the nanofibers against Escherichia coli was studied by bacterial growth inhibition halos and bactericidal kinetic testing. The AgNPs/PVA/CM-chitosan nanofibers possessed certain antibacterial ability, which makes them capable for antibacterial biomaterials.

  12. Room temperature synthesis and photocatalytic property of AgO/Ag2Mo2O7 heterojunction nanowires

    International Nuclear Information System (INIS)

    Hashim, Muhammad; Hu, Chenguo; Wang, Xue; Wan, Buyong; Xu, Jing

    2012-01-01

    Graphical abstract: The AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The AgO nanoparticles start embedding into the nanowires with increasing reaction temperature or time. Highlights: ► AgO/Ag 2 Mo 2 O 7 heterojunction NWs were synthesized at room temperature for the first time. ► AgO particles embed into the Ag 2 Mo 2 O 7 NWs with increase in reaction time and temperature. ► The heterojunction NWs display much better photocatalytic activity than the none-heterojunction NWs. ► The catalytic mechanism was proposed. -- Abstract: AgO/Ag 2 Mo 2 O 7 heterojunction nanowires were synthesized at temperatures of 25 °C, 50 °C, 80 °C, and 110 °C, under magnetic stirring in solution reaction. The catalytic activity of AgO/Ag 2 Mo 2 O 7 nanowires was evaluated by the degradation of Rhodmine B dye under the irradiation of the simulated sunlight. The synthesized samples were characterized by X-ray diffractometer, energy dispersive spectrometry, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. The results show that the AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The length of the nanowires is up to 10 μm and the size of the AgO nanoparticles is 10–20 nm. The length of nanowires increases with increasing reaction time and temperature while the AgO particles are gradually embedded into the nanowires. The photocatalytic activity is greatly improved for the AgO/Ag 2 Mo 2 O 7 heterojunction nanowires compared with that of the pure Ag 2 Mo 2 O 7 nanowires, indicating a remarkable role of AgO particles on the Ag 2 Mo 2 O 7 nanowires in the photodegradation.

  13. Immunotoxicity of Silver Nanoparticles (AgNPs) on the Leukocytes of Common Bottlenose Dolphins (Tursiops truncatus).

    Science.gov (United States)

    Li, Wen-Ta; Chang, Hui-Wen; Yang, Wei-Cheng; Lo, Chieh; Wang, Lei-Ya; Pang, Victor Fei; Chen, Meng-Hsien; Jeng, Chian-Ren

    2018-04-04

    Silver nanoparticles (AgNPs) have been extensively used and are considered as an emerging contaminant in the ocean. The environmental contamination of AgNPs is expected to increase greatly over time, and cetaceans, as the top ocean predators, will suffer the negative impacts of AgNPs. In the present study, we investigate the immunotoxicity of AgNPs on the leukocytes of cetaceans using several methods, including cytomorphology, cytotoxicity, and functional activity assays. The results reveal that 20 nm Citrate-AgNPs (C-AgNP 20 ) induce different cytomorphological alterations and intracellular distributions in cetacean polymorphonuclear cells (cPMNs) and peripheral blood mononuclear cells (cPBMCs). At high concentrations of C-AgNP 20 (10 and 50 μg/ml), the time- and dose-dependent cytotoxicity in cPMNs and cPBMCs involving apoptosis is demonstrated. C-AgNP 20 at sub-lethal doses (0.1 and 1 μg/ml) negatively affect the functional activities of cPMNs (phagocytosis and respiratory burst) and cPBMCs (proliferative activity). The current study presents the first evidence of the cytotoxicity and immunotoxicity of AgNPs on the leukocytes of cetaceans and improves our understanding of environmental safety concerning AgNPs. The dose-response data of AgNPs on the leukocytes of cetaceans are invaluable for evaluating the adverse health effects in cetaceans and for proposing a conservation plan for marine mammals.

  14. Ag-Modified In2O3 Nanoparticles for Highly Sensitive and Selective Ethanol Alarming

    Directory of Open Access Journals (Sweden)

    Jinxiao Wang

    2017-09-01

    Full Text Available Pure In2O3 nanoparticles are prepared by a facile precipitation method and are further modified by Ag. The synthesized samples are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and UV-Vis spectra. The results show the successful heterojunction formation between Ag and In2O3. Gas sensing property measurements show that the 5 mol % Ag-modified In2O3 sensor has the response of 67 to 50 ppm ethanol, and fast response and recovery time of 22.3 and 11.7 s. The response is over one magnitude higher than that of pure In2O3, which can be attributed to the enhanced catalytic activity of Ag-modified In2O3 as compared with the pure one. The mechanism of the gas sensor can be explained by the spillover effect of Ag, which enhances the oxygen adsorption onto the surface of In2O3 and thus give rise to the higher activity and larger surface barrier height.

  15. Synthesis and characterization of Ag nanoparticles decorated mesoporous sintered activated carbon with antibacterial and adsorptive properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenxia; Xiao, Kaijun, E-mail: fekjxiao@scut.edu.cn; He, Tinglin; Zhu, Liang, E-mail: zhuliang@scut.edu.cn

    2015-10-25

    In this study, the sliver nanoparticles (AgNPs) immobilized on the sintered activated carbon (Ag/SAC) were synthesized by the ultrasonic-assisted impregnation method and were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption. SEM showed that the AgNPs were well embedded in the SAC and immersion time had an important influence on final morphologies of AgNPs. Longer immersing duration caused significant aggregation of the AgNPs. The XRD data revealed that the successful synthesis of AgNPs on the SAC and immobilizing AgNPs on sintered active carbon did not change the crystalline degree of SAC. Texture characteristics were determined by analysis of the N{sub 2}/77 K isotherms. The minimum inhibitory concentration (MIC) of Ag/SAC against Escherichia coli (DH5α) and Staphyloccocus aureus (ATCC 29213) was evaluated by a broth dilution method. MICs such as 5 mg/L (against E. coli) and 10 mg/L (against S. aureus) suggest that Ag/SAC have predominant antibacterial activity compared to active carbon. - Highlights: • Sintered active carbon (SAC) was coated with Ag via a facile approach. • The Ag/SAC exhibit good adsorption properties and excellent antibacterial effects. • The Ag/SAC was durable and stable in the application of water purification.

  16. Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

    International Nuclear Information System (INIS)

    Nguyen, Thi Kim Lan; Dang, Van Phu; Nguyen, Ngoc Duy; Le, Anh Quoc; Nguyen, Quoc Hien; Nguyen, Thuy Ai Trinh

    2013-01-01

    Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag + dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag + is occurred by hydrated electron (e − aq ) and hydrogen atom (H • ) generated during radiolysis of ethanol/water. The conversion doses (Ag + → Ag 0 ) were determined by UV–Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5–40 nm for Ag + concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg −1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc. (paper)

  17. The effect of silver nanoparticles (AgNPs) on proliferation and apoptosis of in ovo cultured glioblastoma multiforme (GBM) cells.

    Science.gov (United States)

    Urbańska, Kaja; Pająk, Beata; Orzechowski, Arkadiusz; Sokołowska, Justyna; Grodzik, Marta; Sawosz, Ewa; Szmidt, Maciej; Sysa, Paweł

    2015-01-01

    Recently, it has been shown that silver nanoparticles (AgNPs) provide a unique approach to the treatment of tumors, especially those of neuroepithelial origin. Thus, the aim of this study was to evaluate the impact of AgNPs on proliferation and activation of the intrinsic apoptotic pathway of glioblastoma multiforme (GBM) cells cultured in an in ovo model. Human GBM cells, line U-87, were placed on chicken embryo chorioallantoic membrane. After 8 days, the tumors were divided into three groups: control (non-treated), treated with colloidal AgNPs (40 μg/ml), and placebo (tumors supplemented with vehicle only). At the end of the experiment, all tumors were isolated. Assessment of cell proliferation and cell apoptosis was estimated by histological, immunohistochemical, and Western blot analyses. The results show that AgNPs can influence GBM growth. AgNPs inhibit proliferation of GBM cells and seem to have proapoptotic properties. Although there were statistically significant differences between control and AgNP groups in the AI and the levels of active caspase 9 and active caspase 3, the level of these proteins in GBM cells treated with AgNPs seems to be on the border between the spontaneous apoptosis and the induced. Our results indicate that the antiproliferative properties of silver nanoparticles overwhelm proapoptotic ones. Further research focused on the cytotoxic effect of AgNPs on tumor and normal cells should be conducted.

  18. A novel green synthesis of Fe{sub 3}O{sub 4}-Ag core shell recyclable nanoparticles using Vitis vinifera stem extract and its enhanced antibacterial performance

    Energy Technology Data Exchange (ETDEWEB)

    Venkateswarlu, Sada; Natesh Kumar, B.; Prathima, B. [Analytical and inorganic Division of Chemistry, S.V. University, Tirupati-517502, Andhra Pradesh (India); Anitha, K. [Department of Chemistry, S.K. University, Anantapur-515003, Andhra Pradesh (India); Jyothi, N.V.V., E-mail: nvvjyothi01@gmail.com [Analytical and inorganic Division of Chemistry, S.V. University, Tirupati-517502, Andhra Pradesh (India)

    2015-01-15

    We described a novel and eco-friendly method for preparing Fe{sub 3}O{sub 4}-Ag core shell nanoparticles (CSNPs) with high magnetism and potent antibacterial activity. The Fe{sub 3}O{sub 4}-Ag CSNPs were obtained using waste material of Vitis vinifera (grape) stem extract as the green solvent, reducing and capping agent. The result recorded from X-ray powder diffraction (XRD), UV–vis spectrum, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) supports the biosynthesis and characterization of Fe{sub 3}O{sub 4}-Ag CSNPs. From transmission electron microscopy (TEM) the size of the Fe{sub 3}O{sub 4}-Ag nanoparticles was measured below 50 nm; high-resolution TEM (HRTEM) indicates the core shell structure; and selected area electron diffraction (SAED) has revealed polycrystalline nature. Vibrating sample magnetometer (VSM) shows the ferromagnetic nature of Fe{sub 3}O{sub 4}-Ag CSNPs at room temperature with saturation magnetization of 15.74 emu/g. Further, these biogenic nanoparticles were highly hazardous to microorganisms. The antibacterial activity of biogenic Fe{sub 3}O{sub 4}-Ag CSNPs showed potent inhibitory activity against both Gram-positive and Gram-negative pathogens. These nanoparticles may also be reusable because of its excellent ferromagnetic property.

  19. Fabrication of uniformly dispersed Ag nanoparticles loaded TiO{sub 2} nanotube arrays for enhancing photoelectrochemical and photocatalytic performances under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Junhui; Zhang, Shengsen; Wang, Hongjuan; Yu, Hao; Peng, Feng, E-mail: cefpeng@scut.edu.cn

    2014-12-15

    Graphical abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method, which exhibited the enhanced photoelectrochemical and photocatalytic performances under visible-light irradiation due to the more effective separation of photo-generated electron–hole pairs and faster interfacial charge transfer. - Highlights: • Highly dispersed Ag nanoparticles (NPs) are successfully prepared by polyol method. • Ag NPs are uniformly loaded on the surface of the TiO{sub 2} nanotube arrays (NTs). • Ag/TiO{sub 2}-NTs exhibit the enhanced photocatalytic activity under visible-light. • The enhanced photocurrent is explained by electrochemical impedance spectroscopy. - Abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method. The as-prepared Ag/TiO{sub 2}-NTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–vis diffusion reflectance spectroscopy. Photoelectrochemical behaviors were investigated via photocurrent response and electrochemical impedance spectroscopy (EIS). Photocatalytic activity of Ag/TiO{sub 2}-NTs was evaluated by degradation of acid orange II under visible light irradiation. The results showed that photocatalytic efficiency of Ag/TiO{sub 2}-NTs is more than 5 times higher than that of pure TiO{sub 2} NTs. Comparing with the electrochemical deposition method, the photocatalytic activity of Ag/TiO{sub 2}-NTs prepared by polyol method has been obviously increased.

  20. Homogeneous synthesis of Ag nanoparticles-doped water-soluble cellulose acetate for versatile applications.

    Science.gov (United States)

    Cao, Jie; Sun, Xunwen; Zhang, Xinxing; Lu, Canhui

    2016-11-01

    We report a facile and efficient approach for synthesis of well-dispersed and stable silver nanoparticles (Ag NPs) using water-soluble cellulose acetate (CA) as both reductant and stabilizer. Partially substituted CA with highly active hydroxyl groups and excellent water-solubility is able to reduce silver ions in homogeneous aqueous medium effectively. The synthesized Ag NPs were characterized by UV-vis spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscope analysis. The as-prepared Ag NPs were well-dispersed, showing a surface plasmon resonance peak at 426nm. The resulted Ag NPs@CA nanohybrids exhibit high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . Meanwhile, the nanohybrids are also effective in inhibiting the growth of bacterial. This environmentally friendly method promotes the use of renewable natural resources to prepare a variety of inorganic-organic materials for catalysis, antibacterial, sensors and other applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Antimicrobial and cell viability measurement of bovine serum albumin capped silver nanoparticles (Ag/BSA) loaded collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film.

    Science.gov (United States)

    Bakare, Rotimi; Hawthrone, Samantha; Vails, Carmen; Gugssa, Ayele; Karim, Alamgir; Stubbs, John; Raghavan, Dharmaraj

    2016-03-01

    Bacterial infection of orthopedic devices has been a major concern in joint replacement procedures. Therefore, this study is aimed at formulating collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film loaded with bovine serum albumin capped silver nanoparticles (Ag/BSA NPs) to inhibit bacterial growth while retaining/promoting osteoblast cells viability. The nanoparticles loaded collagen immobilized PHBV film was characterized for its composition by X-ray Photoelectron Spectroscopy and Anodic Stripping Voltammetry. The extent of loading of Ag/BSA NPs on collagen immobilized PHBV film was found to depend on the chemistry of the functionalized PHBV film and the concentration of Ag/BSA NPs solution used for loading nanoparticles. Our results showed that more Ag/BSA NPs were loaded on higher molecular weight collagen immobilized PHEMA-g-PHBV film. Maximum loading of Ag/BSA NPs on collagen immobilized PHBV film was observed when 16ppm solution was used for adsorption studies. Colony forming unit and optical density measurements showed broad antimicrobial activity towards Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa at significantly lower concentration i.e., 0.19 and 0.31μg/disc, compared to gentamicin and sulfamethoxazole trimethoprim while MTT assay showed that released nanoparticles from Ag/BSA NPs loaded collagen immobilized PHBV film has no impact on MCTC3-E1 cells viability. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Lignin-derived electrospun carbon nanofiber mats with supercritically deposited Ag nanoparticles for oxygen reduction reaction in alkaline fuel cells

    International Nuclear Information System (INIS)

    Lai, Chuilin; Kolla, Praveen; Zhao, Yong; Fong, Hao; Smirnova, Alevtina L.

    2014-01-01

    Highlights: • Electrospun carbon nanofiber mats were prepared from a natural product of lignin. • The freestanding mats were flexible with BET specific surface area of ∼583 m 2 /g. • The mats were surface-deposited with Ag nanoparticles via the scCO 2 method. • Novel electrocatalytic systems of Ag/ECNFs exhibited high activities towards ORR. - Abstract: Ag nanoparticles (AgNPs) (11, 15, and 25 wt.%) were deposited on the surface of the freestanding and mechanically flexible mats consisting of lignin-derived electrospun carbon nanofibers (ECNFs) by the supercritical CO 2 method followed by the thermal treated at 180 °C. The electrochemical activity of Ag/ECNFs electrocatalyst systems towards oxygen reduction reaction (ORR) was studied in 0.1 M KOH aqueous solution using the rotating disk/rotating ring disk electrode (RDE/RRDE) technique. The SEM, TEM, and XRD results indicated that, the spherical AgNPs were uniformly distributed on the ECNF surface with sizes in the range of 2-10 nm. The electrocatalytic results revealed that, all of the Ag/ECNFs systems exhibited high activity in ORR and demonstrated close-to-theoretical four-electron pathway. In particular, the mass activity of 15 wt.% Ag/ECNFs system was the highest (119 mA mg −1 ), exceeding that of HiSPEC 4100™ commercial Pt/C catalyst (98 mA mg −1 ). This study suggested that the lignin-derived ECNF mats surface-deposited with AgNPs would be promising as cost-effective and highly efficient electrocatalyst for ORR in alkaline fuel cells

  3. Study of fungicidal properties of colloidal silver nanoparticles (AgNPs on trout egg pathogen, Saprolegnia sp.

    Directory of Open Access Journals (Sweden)

    Seyed Ali Johari

    2015-05-01

    Full Text Available Silver nanoparticles (AgNPs are known to have bactericidal and fungicidal effects. Since, there is few information available on the interaction of colloidal nanosilver with fish pathogens. Hence, the current study investigated the effects of colloidal AgNPs on the in vitro growth of the fish pathogen Saprolegnia sp.. Before the experiments, various important properties of AgNPs were well-characterized. The antifungal activity of AgNPs was then evaluated by determining the minimum inhibitory concentrations (MICs using two-fold serial dilutions of colloidal nanosilver in a glucose yeast extract agar at 22ºC. The growth of Saprolegnia sp. on the AgNPs agar treatments was compared to that of nanosilver-free agar as controls. The results showed that AgNPs have an inhibitory effect on the in vitro growth of the tested fungi. The MIC of AgNPs for Saprolegnia sp. was calculated at 1800 mg/L, which is equal to 0.18 percent. It seems that AgNPs could be a proper replacement for teratogenic and toxic agents, such as malachite green. In addition, the indirect use of AgNPs could be a useful method for providing new antifungal activity in aquaculture systems.

  4. Dielectric spectroscopy of Ag-starch nanocomposite films

    Science.gov (United States)

    Meena; Sharma, Annu

    2018-04-01

    In the present work Ag-starch nanocomposite films were fabricated via chemical reduction route. The formation of Ag nanoparticles was confirmed using transmission electron microscopy (TEM). Further the effect of varying concentration of Ag nanoparticles on the dielectric properties of starch has been studied. The frequency response of dielectric constant (ε‧), dielectric loss (ε″) and dissipation factor tan(δ) has been studied in the frequency range of 100 Hz to 1 MHz. Dielectric data was further analysed using Cole-Cole plots. The dielectric constant of starch was found to be 4.4 which decreased to 2.35 in Ag-starch nanocomposite film containing 0.50 wt% of Ag nanoparticles. Such nanocomposites with low dielectric constant have potential applications in microelectronic technologies.

  5. Promising biocidal activity of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) as anti-infective agents against perilous pathogens.

    Science.gov (United States)

    Manukumar, H M; Umesha, S; Kumar, H N Naveen

    2017-09-01

    The advent of biodegradable polymer-encapsulated drug nanoparticles has made an exciting area of drug delivery research. The present study investigated novel and simple route for synthesis of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) using chitosan and thymol as reducing, capping agent respectively to understand the therapeutic efficacy. The UV-vis spectroscopy, DLS, FT-IR, SEM, EDS, XRD used for characterization and radical scavenging activity, anti-microbial and biocompatibility was taken to ascertain an efficacy of novel T-C@AgNPs. The T-C@AgNPs intense peak at 490nm indicates the formation of nanoparticles and had average particle size of 28.94nm with spherical shape, monodisperse state in water, also exhibited excellent biocompatibility of cubic shaped pure silver element containing T-C@AgNPs. The antibacterial activity was studied for gram positive and gram negative food-borne pathogens and effective inhibition at 100μgmL -1 to S. aureus, S. epidermidis, S. haemolyticus (10.08, 10.00, 11.23mm) and S. typhimurium, P. aeruginosa and S. flexneri (9.28, 9.33, 12.03mm) compared to antibiotic Streptomycin. This study revealed the efficacy against multiple food-borne pathogens and therapeutic efficacy of T-C@AgNPs offers a valuable contribution in the area of nanotechnology. This proved to be a first-class novel antimicrobial material for the first time in this study. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Formation and properties of hyaluronan/nano Ag and hyaluronan-lecithin/nano Ag films.

    Science.gov (United States)

    Khachatryan, Gohar; Khachatryan, Karen; Grzyb, Jacek; Fiedorowicz, Maciej

    2016-10-20

    A facile and environmentally friendly method of the preparation of silver nanoparticles embedded in hyaluronan (Hyal/Ag) and hyaluronan-lecithin (Hyal-L/Ag) matrix was developed. Thin, elastic foils were prepared from gels by an in situ synthesis of Ag in an aqueous solution of sodium hyaluronate (Hyal), using aq. d-(+)-xylose solution as a reducing agent. The gels were applied to a clean, smooth, defatted Teflon surface and left for drying in the air. The dry foils were stored in a closed container. UV-vis spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectra confirmed formation of about 10nm ball-shaped Ag nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC) and thermogravimetric (TGA) analyses, whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). An increase in the molecular weight of the hyaluronate after generation of Ag nanoparticles was observed. The foils showed specific properties. The study confirmed that silver nanoparticles can be successfully prepared with environmentally friendly method, using hyaluronan as a stabilizing template. Hyaluronan and hyaluronan-lecithin matrices provide nanocrystals uniform in size and shape. The composites demonstrated a bacteriostatic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jia [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Xu, Shicai [Shandong Provincial Key Laboratory of Biophysics, College of Physics and Electronic Information, Dezhou University, Dezhou 253023 (China); Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Jiang, Shouzhen, E-mail: jiang_sz@126.com [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Shandong Provincial Key Laboratory of Optics and Photonic Device, Jinan 250014 (China); Ning, Tingyin [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Shandong Provincial Key Laboratory of Optics and Photonic Device, Jinan 250014 (China)

    2017-02-28

    Highlights: • We directly grown AgNPs on substrate by annealing method in the quartz tube. Compare with spin-coating Ag nanoparticles solution method, we got more uniform distribution of AgNPs and the AgNPs better adsorption on the substrate. • We use a simple and lost-cost method to obtain the pyramidal silicon (PSi). The PSi possessing well-separated pyramid arrays can make contribution to the homogeneity and sensitivity of the substrate. • In our work, graphene oxide (GO) film is uniformly deposited on AgNPs and PSi by using a spin-coating method. The GO films endow the hybrid system a good stability and enhance the homogeneity and sensitivity of the substrate. - Abstract: In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10{sup −12} M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R{sup 2} of 612 and 773 cm{sup −1} can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow

  8. Amnesic shellfish poisoning biotoxin detection in seawater using pure or amino-functionalized Ag nanoparticles and SERS.

    Science.gov (United States)

    Müller, Csilla; Glamuzina, Branko; Pozniak, Iva; Weber, Karina; Cialla, Dana; Popp, Jürgen; Cîntă Pînzaru, Simona

    2014-12-01

    Domoic acid (DA) biotoxin responsible for the amnesic shellfish poisoning (ASP) has been unambiguously detected in seawater in a broad range of concentration, with both pure and amino-functionalized Ag nanoparticles employed for surface enhanced Raman scattering (SERS). To achieve this, a comprehensive SERS study on DA dissolved in distilled water has been conducted. SERS of DA dissolved in seawater in concentrations ranging from 3.3 × 10(-4) to 3.3 × 10(-8) mol l(-1) exhibited specific signal, completely different to those of the corresponding DA aqueous solutions, due to the seawater interference in the overall SERS effect. In order to assess the capability of the technique as a cheaper alternative for rapid and unambiguous detection of the DA biotoxin in seawater, three detection schemes have been proposed. DA was detectable at 0.33 nmoll(-1) concentration (0.33) dissolved in distilled water and 0.033 nmol l(-1) (0.033 ppb) in seawater respectively, much lower than the admitted level by the current regulation. A solvent specific interaction of DA with the NPs was concluded, since DA aqueous solution added to Ag nanoparticles provided different SERS signal compared to that of DA directly dissolved in seawater. Employing amino-functionalized Ag nanoparticles with 4-aminothiophenol as SERS tag, SERS signal of DA on amino-AgNPs revealed significant specificity associated with the aromatic primary amine interaction of the SERS tag with DA, thus allowing DA detection in seawater at 4.16 × 10(-4) mol l(-1) concentration, much higher than in the case of pure NPs. To highlight the findings, a brief literature review to date on the DA biotoxin detection was also provided. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Electro spinning of Poly(ethylene-co-vinyl alcohol) Nano fibres Encapsulated with Ag Nanoparticles for Skin Wound Healing

    International Nuclear Information System (INIS)

    Xu, Ch.; Wang, B.; Lu, T.; Xu, F.; Xu, F.; Wang, B.; Xu, F.

    2011-01-01

    Skin wound healing is an urgent problem in clinics and military activities. Although significant advances have been made in its treatment, there are several challenges associated with traditional methods, for example, limited donor skin tissue for transplantation and inflammation during long-term healing time. To address these challenges, in this study we present a method to fabricate Poly(ethylene-co-vinyl alcohol) (EVOH) nano fibres encapsulated with Ag nanoparticle using electro spinning technique. The fibres were fabricated with controlled diameters (59 nm 3μm) by regulating three main parameters, that is, EVOH solution concentration, the electric voltage, and the distance between the injection needle tip (high-voltage point) and the fibre collector. Ag was added to the nano fibres to offer long-term anti-inflammation effect by slow release of Ag nanoparticles through gradual degradation of EVOH nano fibre. The method developed here could lead to new dressing materials for treatment of skin wounds.

  10. A Novel Strategy for Synthesis of Gold Nanoparticle Self Assemblies

    NARCIS (Netherlands)

    Verma, Jyoti; Lal, Sumit; van Veen, Henk A.; van Noorden, Cornelis J. F.

    2014-01-01

    Gold nanoparticle self assemblies are one-dimensional structures of gold nanoparticles. Gold nanoparticle self assemblies exhibit unique physical properties and find applications in the development of biosensors. Methodologies currently available for lab-scale and commercial synthesis of gold

  11. Preparation of AgBr@SiO{sub 2} core@shell hybrid nanoparticles and their bactericidal activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuanyuan [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Yang, Lisu [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Henna Sports School, Zhengzhou 450045 (China); Zhao, Yanbao, E-mail: yanbaozhao@126.com [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Li, Binjie; Sun, Lei; Luo, Huajuan [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China)

    2013-04-01

    AgBr@SiO{sub 2} core@shell hybrid nanoparticles (NPs) were successfully prepared by sol-gel method. Their morphology and structure were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The hybrid NPs are predominantly spherical in shape, with an average diameter of 180–200 nm, and each NP contains one inorganic core. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the hybrid NPs were examined against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), respectively. Results indicated that the AgBr@SiO{sub 2} NPs had excellent antibacterial activity. - Highlights: ► Presents a novel antibacterial agent “AgBr@ SiO{sub 2} NPs”. ► AgBr@SiO{sub 2} hybrid NPs could provide long-term antimicrobial effect. ► AgBr@SiO{sub 2} hybrid NPs have excellent antibacterial activity.

  12. A low-cost, environment-friendly and solvent-free route for synthesis of AgBr nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Shahsavani, E.; Khalaji, A.D.; Feizi, N.; Das, D.; Matalobos, J.S.; Kučeráková, Monika; Dušek, Michal

    2015-01-01

    Roč. 82, Jun (2015), s. 18-25 ISSN 0749-6036 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : AgBr * nanoparticles * thiosemicarbazone * XRD * SEM * TEM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.117, year: 2015

  13. Frequency upconversion in Er3+ doped tungsten tellurite glass containing Ag nanoparticles

    Science.gov (United States)

    Mahajan, S. K.; Parashar, J.

    2018-05-01

    The frequency upconversion emission in Er3+ doped TeO2-WO3-Li2O containing Ag nanoparticle (TWLEOAG) glasses at 980nm excitation is reported. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around 525nm and 650 nm. The spherical AgNPs with average size ˜38 nm in the glassy matrix is evidenced from the TEM measurement. Under 980nm laser excitation upconversion emission spectra show two major emission at 550nm and 638nm originating from 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively was observed. Upconversion emission enhancement factor 7 fold has been measured for sample heat treated during 40h. However for 18h heat treated TWLEOAG sample under 980 nm flash lamp excitation produced Intense green compare to red emission. Since the 980nm frequency is far from the AgNPs surface plasmon resonance frequency, visible emission ehancement is attributed to local field increase in proximity of the Ag NPs and not energy tranfer from NPs to emitters. Possible energy transfer upconversion mechanism has been also discussed.

  14. Hierarchical Ag mesostructures for single particle SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Minwei, E-mail: xuminwei@xjtu.edu.cn; Zhang, Yin

    2017-01-30

    Highlights: • Hierarchical Ag mesostructures with the size of 250, 360 and 500 nm are synthesized via a seed-mediated approach. • The Ag mesostructures present the tailorable size and highly roughened surfaces. • The average enhancement factors for individual Ag mesostructures were estimated to be as high as 10{sup 6}. - Abstract: Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250–500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 10{sup 6}.

  15. Organometallic approach to polymer-protected antibacterial silver nanoparticles: optimal nanoparticle size-selection for bacteria interaction

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, Julian; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M.; Monge, Miguel, E-mail: miguel.monge@unirioja.es; Olmos, M. Elena [Universidad de La Rioja, Centro de Investigacion en Sintesis Quimica (CISQ), Departamento de Quimica (Spain); Saenz, Yolanda; Torres, Carmen [Centro de Investigacion Biomedica de La Rioja, Area de Microbiologia Molecular (Spain)

    2012-12-15

    The optimal size-specific affinity of silver nanoparticles (Ag NPs) towards E. coli bacteria has been studied. For this purpose, Ag NPs coated with polyvinylpyrrolidone (PVP) and cellulose acetate (CA) have been prepared using an organometallic approach. The complex NBu{sub 4}[Ag(C{sub 6}F{sub 5}){sub 2}] has been treated with AgClO{sub 4} in a 1:1 molar ratio giving rise to the nanoparticle precursor [Ag(C{sub 6}F{sub 5})] in solution. Addition of an excess of PVP (1) or CA (2) and 5 h of reflux in tetrahydrofuran (THF) at 66 Degree-Sign C leads to Ag NPs of small size (4.8 {+-} 3.0 nm for PVP-Ag NPs and 3.0 {+-} 1.2 nm for CA-Ag NPs) that coexist in both cases with larger nanoparticles between 7 and 25 nm. Both nanomaterials display a high antibacterial effectiveness against E. coli. The TEM analysis of the nanoparticle-bacterial cell membrane interaction shows an optimal size-specific affinity for PVP-Ag NPs of 5.4 {+-} 0.7 nm in the presence of larger size silver nanoparticles.Graphical AbstractAn organometallic approach permits the synthesis of small size silver nanoparticles (ca 5 nm) as a main population in the presence of larger size nanoparticles. Optimal silver nanoparticle size-selection (5.4 nm) for the interaction with the bacterial membrane is achieved.

  16. Nano Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua, E-mail: liangyh@heuu.edu.cn; Cui, Wenquan, E-mail: wkcui@163.com

    2015-01-01

    Graphical abstract: - Highlights: • The plasmatic Ag@AgBr surface-sensitized Bi{sub 2}WO{sub 6} composite photocatalysts. • Ag@AgBr greatly increased visible-light absorption for Bi{sub 2}WO{sub 6}. • The plasmonic photocatalysts exhibited enhanced activity for the degradation of MB, phenol and salicylic acid. - Abstract: Nano Ag@AgBr decorated on the surface of flower-like Bi{sub 2}WO{sub 6} (hereafter designated Ag@AgBr/Bi{sub 2}WO{sub 6}) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi{sub 2}WO{sub 6}, and was approximately 20 nm in size. Ag@AgBr/Bi{sub 2}WO{sub 6} composites exhibited excellent UV–vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi{sub 2}WO{sub 6}. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi{sub 2}WO{sub 6} and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi{sub 2}WO{sub 6} samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi{sub 2}WO{sub 6}, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi{sub 2}WO{sub 6} sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi{sub 2}WO{sub 6} photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi{sub 2

  17. Ligand mediated synthesis of AgInSe2 nanoparticles with tetragonal/orthorhombic crystal phases

    International Nuclear Information System (INIS)

    Abazović, Nadica D.; Čomor, Mirjana I.; Mitrić, Miodrag N.; Piscopiello, Emanuela; Radetić, Tamara; Janković, Ivana A.; Nedeljković, Jovan M.

    2012-01-01

    Nanosized AgInSe 2 particles (d ∼ 7–25 nm) were synthesized using colloidal chemistry method at 270 °C. As solvents/surface ligands 1-octadecene, trioctylphosphine, and oleylamine were used. It was shown that choice of ligand has crucial impact not only on final crystal phase of nanoparticles, but also at mechanism of crystal growth. X-ray diffraction and TEM/HRTEM techniques were used to identify obtained crystal phases and to measure average size and shape of nanoparticles. UV/Vis data were used to estimate band-gap energies of obtained samples. It was shown that presented routes can provide synthesis of nanoparticles with desired crystal phase (tetragonal and/or orthorhombic), with band-gap energies in the range from 1.25 to 1.53 eV.

  18. Microscopy based studies on the interaction of bio-based silver nanoparticles with Bombyx mori Nuclear Polyhedrosis virus.

    Science.gov (United States)

    Tamilselvan, Selvaraj; Ashokkumar, Thirunavukkarasu; Govindaraju, Kasivelu

    2017-04-01

    In the present investigation, silver nanoparticles (AgNPs) interactions with Bombyx mori Nuclear Polyhedrosis virus (BmNPV) were characterized using High-Resolution Scanning Electron Microscopy (HR-SEM), Energy Dispersive X-ray Analysis (EDAX), Transmission Electron Microscopy (TEM), Atomic Force Microcopy (AFM) and Confocal Microscope (CM). HR-SEM study reveals that the biosynthesized AgNPs have interacted with BmNPV and were found on the surface. TEM micrographs of normal and viral polyhedra treated with AgNPs showed that the nanoparticles were accumulated in the membrane and it was noted that some of the AgNPs successfully penetrated the membrane by reaching the capsid of BmNPV. AFM and confocal microscopy studies reveal that the disruption in the shell membrane tends to lose its stability due to exposure of AgNPs to BmNPV. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

    Science.gov (United States)

    Pisarek, Marcin; Nowakowski, Robert; Kudelski, Andrzej; Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria; Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D.

    2015-12-01

    Self-organized Al2O3 nanoporous/nanotubular (Al2O3-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al2O3-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al2O3-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm2 - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on the top of the largest pores is responsible for the highest SERS activity of the resulting Ag-NPs/Al2O3-NP/Al composite layer, since it produces a variety of cavities and slits which function as resonators for the adsorbed molecules. The Ag-NPs/MeOx-NP/Me composite layers obtained ensure a good reproducibility of the SERS measurements.

  20. Cube-like Fe3O4@SiO2@Au@Ag magnetic nanoparticles: a highly efficient SERS substrate for pesticide detection

    Science.gov (United States)

    Sun, Mei; Zhao, Aiwu; Wang, Dapeng; Wang, Jin; Chen, Ping; Sun, Henghui

    2018-04-01

    As a novel surface-enhanced Raman spectroscopic (SERS) nanocomposite, cube-like Fe3O4@SiO2@Au@Ag magnetic nanoparticles (NPs) were synthesized for the first time. Cube-like α-Fe2O3 NPs with uniform size were achieved by optimizing reaction temperature and time. Firstly, the cube-like Fe3O4@SiO2 with good dispersity was achieved by calcining α-Fe2O3@SiO2 NPs in hydrogen atmosphere at 360 °C for 2.5 h, followed by self-assembling a PEI shell via sonication. Furthermore, the Au@Ag particles were densely assembled on the Fe3O4@SiO2 NPs to form the Fe3O4@SiO2@Au@Ag composite structure via strong Ag-N interaction. The obtained nanocomposites exhibited an excellent SERS behavior, reflected by the low detection of limit (p-ATP) at the 5 × 10-14 M level. Moreover, these nanocubes were used for the detection of thiram, and the detection limit can reach 5 × 10-11 M. Meanwhile, the U.S. Environmental Protection Agency specifies that the residue in fruit must be lower than 7 ppm. Hence, the resulting substrate with high SERS activity has great practical potential applications in the rapid detection of chemical, biological, and environment pollutants with a simple portable Raman instrument at trace level.

  1. Size-dependent melting modes and behaviors of Ag nanoparticles: a molecular dynamics study

    Science.gov (United States)

    Liang, Tianshou; Zhou, Dejian; Wu, Zhaohua; Shi, Pengpeng

    2017-12-01

    The size-dependent melting behaviors and mechanisms of Ag nanoparticles (NPs) with diameters of 3.5-16 nm were investigated by molecular dynamics (MD). Two distinct melting modes, non-premelting and premelting with transition ranges of about 7-8 nm, for Ag NPs were demonstrated via the evolution of distribution and transition of atomic physical states during annealing. The small Ag NPs (3.5-7 nm) melt abruptly without a stable liquid shell before the melting point, which is characterized as non-premelting. A solid-solid crystal transformation is conducted through the migration of adatoms on the surface of Ag NPs with diameters of 3.5-6 nm before the initial melting, which is mainly responsible for slightly increasing the melting point of Ag NPs. On the other hand, surface premelting of Ag NPs with diameters of 8-16 nm propagates from the outer shell to the inner core with initial anisotropy and late isotropy as the temperature increases, and the close-packed facets {111} melt by a side-consumed way which is responsible for facets {111} melting in advance relative to the crystallographic plane {111}. Once a stable liquid shell is formed, its size-independent minimum thickness is obtained, and a three-layer structure of atomic physical states is set up. Lastly, the theory of point defect-pair (vacancy-interstitial) severing as the mechanism of formation and movement of the solid-liquid interface was also confirmed. Our study provides a basic understanding and theoretical guidance for the research, production and application of Ag NPs.

  2. Cyclodextrin-Triazole Derivative Functionalized on Ag-SiO{sub 2} Core-Shell Nanoparticles via Click Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gun Bae; Singu, Bal Sydulu; Hong, Sang Eun; Yoon, Kuk Ro [Hannam Univ., Daejeon (Korea, Republic of)

    2016-09-15

    Click chemistry has provided a versatile strategy for functionalization in solution chemistry under mild reaction conditions with a high degree of functional group compatibility. Initially, silver (Ag) nanoparticles were prepared by the chemical reduction method, followed by the synthesis of silver–silica (Ag–SiO{sub 2}) core–shell nanoparticles by the Stöber method. The Ag–SiO2 core shell nanoparticles were functionalized with the alkyne derivative. The cycloaddition reaction between the azide-functionalized cyclodextrin and the alkyne-functionalized Ag–SiO{sub 2} core–shell nanoparticles was carried out via the copper-catalyzed click reaction, leading to the formation of the cyclodextrin-triazole derivative on the Ag–SiO{sub 2} core–shell nanoparticles. The presence of the resulting cyclodextrin-triazole derivative on the silver–silica core–shell nanoparticles was confirmed by Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA).

  3. Intercorrelated Ag{sub 3}PO{sub 4} nanoparticles decorated with graphic carbon nitride: Enhanced stability and photocatalytic activities for water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jia; Chai, Yuanyuan; Liu, Qianqian; Zhang, Lu; Dai, Wei-Lin, E-mail: wldai@fudan.edu.cn

    2017-05-01

    Highlights: • Ag{sub 3}PO{sub 4} nanoparticles decorated with graphite-like carbon nitride material (g-C{sub 3}N{sub 4}). • Synthesized by a template-free in situ precipitation method. • Excellent (7 times higher) photooxidation ability. • Much more stable than pure Ag{sub 3}PO{sub 4} in the photodegradation process. • Formation of heterojunction between Ag{sub 3}PO{sub 4} and g-C{sub 3}N{sub 4} contributed to the separation efficiency. - Abstract: The method of decorating Ag{sub 3}PO{sub 4} nanoparticles with carbon nitride material (g-C{sub 3}N{sub 4}) is demonstrated as an efficient pathway to remarkably improve the stability and photocatalytic performance of Ag{sub 3}PO{sub 4} nanoparticles which have been widely used in photocatalysis, but limited by the instability. The improved material herein results in the largely enhanced photocatalytic performance for water purification under visible light irradiation, which was nearly 7 times as high as that of pure Ag{sub 3}PO{sub 4}. Meanwhile, the as-obtained materials show the unique stable property, mainly contributed by the protection effect of decorated g-C{sub 3}N{sub 4} sheet. Additionally, the radical trapping experiments revealed that the introduction of g-C{sub 3}N{sub 4} transformed the photocatalytic mechanism to some degree, where ·O{sub 2}{sup −} played a more important role. The tremendous enhancement in catalytic performance may be attributed to the larger surface area, controllable particle size and the synergistic effect between Ag{sub 3}PO{sub 4} and g-C{sub 3}N{sub 4}, promoting the separation efficiency of the photogenerated electron-hole pairs. The decorating system can in principle be broadly put into use for unstable photocatalysts.

  4. Immobilized Pd-Ag bimetallic nanoparticles on polymeric nanofibers as an effective catalyst: effective loading of Ag with bimetallic functionality through Pd nucleated nanofibers

    Science.gov (United States)

    Shanmugam Ranjith, Kugalur; Celebioglu, Asli; Uyar, Tamer

    2018-06-01

    Here, we present a precise process for synthesizing Pd-Ag bimetallic nanoparticles (NPs) onto polymeric nanofibers by decorating Pd-NPs through atomic layer deposition followed by a chemical reduction process for tagging Ag nanostructures with bimetallic functionality. The results show that Pd-NPs act as a nucleation platform for tagging Ag and form Pd-Ag bimetallic NPs with a monodisperse nature with significant catalytic enhancement to the reaction rate over the bimetallic nature of the Pd-Ag ratio. A Pd-NP decorated polymeric nanofibrous web acts as an excellent platform for the encapsulation or interaction of Ag, which prevents agglomeration and promotes the interaction of Ag ions only on the surface of the Pd-NPs. We observed an effective reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4) to access the catalytic activity of Pd-Ag bimetallic NPs on a free-standing flexible polymeric nanofibrous web as a support. The captive formation of the polymeric nanofibrous web with Pd-Ag bimetallic functionality exhibited superior and stable catalytic performance with reduction rates of 0.0719, 0.1520, and 0.0871 min‑1 for different loadings of Ag on Pd decorated nanofibrous webs such as Pd/Ag(0.01), Pd/Ag(0.03), and Pd/Ag(0.05), respectively. The highly faceted Pd-Ag NPs with an immobilized nature improves the catalytic functionality by enhancing the binding energy of the 4-NP adsorbate to the surface of the NPs. With the aid of bimetallic functionality, the nanofibrous web was demonstrated as a hybrid heterogeneous photocatalyst with a 3.16-fold enhancement in the reaction rate as compared with the monometallic decorative nature of NaBH4 as a reducing agent. The effective role of the monodisperse nature of Pd ions with an ultralow content as low as 3 wt% and the tunable ratio of Ag on the nanofibrous web induced effective catalytic activity over multiple cycles.

  5. Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, N.K., E-mail: nora.sousa@dem.uc.pt [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Calderon, S. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Carvalho, I. [GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); CEB—Centre of Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, 4710-057 Braga (Portugal); Henriques, M. [CEB—Centre of Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, 4710-057 Braga (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Carvalho, S. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); GRF-CFUM, Physics Department, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal)

    2016-07-30

    Highlights: • Amorphous carbon (a-C), Ag/a-C and Ag coatings were deposited by magnetron sputtering. • a-C/Ag coating shows antibacterial activity against S. epidermidis. • The formation of nano-galvanic couples in a-C/Ag enhances the Ag{sup +} ionization rate. • The Ag{sup +} ionization occurs along with Ag nanoparticles agglomeration in 0.9% NaCl. - Abstract: Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag{sup +} due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

  6. Characterization and electrocatalytic activity of Pt–M (M=Cu, Ag, and Pd) bimetallic nanoparticles synthesized by pulsed plasma discharge in water

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Min; Cho, Ah-Rong; Lee, Sang-Yul, E-mail: sylee@kau.ac.kr [Korea Aerospace University, Department of Materials Engineering, Center for Surface Technology and Applications (Korea, Republic of)

    2015-07-15

    The synthetic approach for electrocatalysts is one of the most important methods of determining electrocatalytic performance. In this work, we synthesized Pt and Pt–M (M=Cu, Ag, and Pd) bimetallic nanoparticles using a pulsed plasma discharge in water. A morphological investigation revealed that the as-synthesized Pt and Pt–M bimetallic nanoparticles constituted a nanochain network structure interconnected with primary nanoparticles of 4–6 nm in size, and the nanochains grew from the primary nanoparticles via the oriented attachment. The Z-contrast, EDX line scanning, and XRD analysis confirmed that the Pt was alloyed with M without elemental segregation or phase segregation. Furthermore, it was found that the composition difference was dependent on the electrode temperature determined by the power density and thermal parameters. The electrochemical results revealed that the electrocatalytic activity, stability, and durability of the Pt–Ag bimetallic nanoparticles were superior with respect to the methanol oxidation reaction, which could be attributed to the downshift of the d-band center via electronic modification.

  7. Ag29(BDT)12(TPP)4: A Tetravalent Nanocluster

    KAUST Repository

    AbdulHalim, Lina G.

    2015-06-24

    The bottom-up assembly of nanoparticles into diverse ordered solids is a challenge because it requires nanoparticles, which are often quasi-spherical, to have interaction anisotropy akin to atoms and molecules. Typically, anisotropy has been introduced by changing the shape of the inorganic nanoparticle core. Here, we present the design, self-assembly, optical properties and total structural determination of Ag29(BDT)12(TPP)4, an atomically precise tetravalent nanocluster (NC) (BDT: 1,3-benzenedithiols; TPP: triphenylphosphine). It features four unique tetrahedrally symmetrical binding surface sites facilitated by the supramolecular assembly of 12 BDT—wide footprint bidentate thiols—in the ligand shell. When each of these sites was selectively functionalized by a single phosphine ligand, particle stability, synthetic yield and the propensity to self-assemble into macroscopic crystals increased. The solid crystallized NCs have a substantially narrowed optical bandgap compared to that of the solution state, suggesting strong inter-particle electronic coupling occurs in the solid state.

  8. Ag29(BDT)12(TPP)4: A Tetravalent Nanocluster

    KAUST Repository

    AbdulHalim, Lina G.; Bootharaju, Megalamane Siddaramappa; Tang, Qing; Del Gobbo, Silvano; AbdulHalim, Rasha; Eddaoudi, Mohamed; Jiang, De-en; Bakr, Osman

    2015-01-01

    The bottom-up assembly of nanoparticles into diverse ordered solids is a challenge because it requires nanoparticles, which are often quasi-spherical, to have interaction anisotropy akin to atoms and molecules. Typically, anisotropy has been introduced by changing the shape of the inorganic nanoparticle core. Here, we present the design, self-assembly, optical properties and total structural determination of Ag29(BDT)12(TPP)4, an atomically precise tetravalent nanocluster (NC) (BDT: 1,3-benzenedithiols; TPP: triphenylphosphine). It features four unique tetrahedrally symmetrical binding surface sites facilitated by the supramolecular assembly of 12 BDT—wide footprint bidentate thiols—in the ligand shell. When each of these sites was selectively functionalized by a single phosphine ligand, particle stability, synthetic yield and the propensity to self-assemble into macroscopic crystals increased. The solid crystallized NCs have a substantially narrowed optical bandgap compared to that of the solution state, suggesting strong inter-particle electronic coupling occurs in the solid state.

  9. Visible-light photoactivity of plasmonic silver supported on mesoporous TiO2 nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

    Science.gov (United States)

    Jaafar, N. F.; Jalil, A. A.; Triwahyono, S.

    2017-01-01

    Various weight loadings of Ag (1-10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti3+ site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag0 and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag0, TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

  10. Architecture of poly(o-phenylenediamine)–Ag nanoparticle composites for a hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Wang Li; Zhu Haozhi; Song Yonghai; Liu Li; He Zhifang; Wan Lingli; Chen Shouhui; Xiang Ying; Chen Shusheng; Chen Jie

    2012-01-01

    Graphical abstract: Schematic representation of the formation process of AgNPs/PoPD/GCE via a two-step procedure consisting of electropolymerization of o-PD and electrodeposition of AgNPs and their application in H 2 O 2 detection. Highlights: ► o-Phenylenediamine (o-PD) was electropolymerized on a glassy carbon electrode (GCE). ► The conductive PoPD film was three-dimensional (3D) porous structure. ► Ag NPs formed by electrodepositing and uniformly dispersed on the 3D PoPD film. ► AgNPs/PoPD/GCE displayed good electrocatalytic activity to the reduction of H 2 O 2 . - Abstract: A novel strategy to fabricate a hydrogen peroxide (H 2 O 2 ) sensor was developed by electrodepositing Ag nanoparticles (AgNPs) on a poly(o-phenylenediamine) (PoPD) film modified glassy carbon electrode (GCE). Firstly, the o-phenylenediamine was polymerized on a GCE by potential cycling to produce PoPD film. Then the AgNPs were electrodeposited on the PoPD film to form AgNPs/PoPD/GCE. The morphology of the electropolymerized PoPD film and the electrodeposited AgNPs were characterized by atomic force microscopy. The results showed the PoPD film was porous and the AgNPs dispersed uniformly on the PoPD film. Cylic voltammetry and amperometry were used to evaluate electrocatalytic properties of the AgNPs/PoPD/GCE. The electrode displayed good electrocatalytic activity in the reduction of H 2 O 2 and could be used as a sensor for H 2 O 2 detection. The sensor exhibited fast amperometric response to H 2 O 2 with high selectivity, good reproducibility and stability. The linear range was 6.0 μM to 67.3 mM with a detection limit of 1.5 μM. Thus, it is considered to be an ideal candidate for practical application.

  11. 1-Hexadecylamine as both reducing agent and stabilizer to synthesize Au and Ag nanoparticles and their SERS application

    International Nuclear Information System (INIS)

    Hou Xiaomiao; Zhan, Xiaoling; Fang Yan; Chen Shutang; Li Na; Zhou Qi

    2011-01-01

    1-Hexadecylamine (HDA)-capped Au and Ag nanoparticles (NPs) have been successfully prepared by a one-pot solution growth method. The HDA is used as both reducing agent and stabilizer in the synthetic process is favorable for investigating the capping mechanism of Au and Ag NPs’ surface. The growth process and characterization of Au and Ag NPs are determined by Ultraviolet–visible (UV–vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). Experimental results demonstrate that the HDA-capped Au and Ag NPs are highly crystalline and have good optical properties. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 2-thionaphthol are obtained on the Au and Ag NPs modified glass surface, respectively, indicating that the as-synthesized noble metal NPs have potentially high sensitive optical detection application.

  12. 1-Hexadecylamine as both reducing agent and stabilizer to synthesize Au and Ag nanoparticles and their SERS application

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xiaomiao; Zhan, Xiaoling, E-mail: zhangxl@bit.edu.cn [Beijing Institute of Technology, Department of Chemistry, School of Science (China); Fang Yan, E-mail: fangyan@mail.cnu.edu.cn [Capital Normal University, Beijing Key Lab for Nano-Photonics and Nano-Structure (NPNS), Department of Physics (China); Chen Shutang; Li Na; Zhou Qi [Beijing Institute of Technology, Department of Chemistry, School of Science (China)

    2011-05-15

    1-Hexadecylamine (HDA)-capped Au and Ag nanoparticles (NPs) have been successfully prepared by a one-pot solution growth method. The HDA is used as both reducing agent and stabilizer in the synthetic process is favorable for investigating the capping mechanism of Au and Ag NPs' surface. The growth process and characterization of Au and Ag NPs are determined by Ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). Experimental results demonstrate that the HDA-capped Au and Ag NPs are highly crystalline and have good optical properties. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 2-thionaphthol are obtained on the Au and Ag NPs modified glass surface, respectively, indicating that the as-synthesized noble metal NPs have potentially high sensitive optical detection application.

  13. Ultra-fine structures of Pd-Ag-HAp nanoparticle deposition on protruded TiO2 barrier layer for dental implant

    Science.gov (United States)

    Jang, Jae-Myung; Kim, Seung-Dai; Park, Tae-Eon; Choe, Han-Cheol

    2018-02-01

    The biocompatibility structure of an implant surface is of great importance to the formation of new bone tissue around the dental implant and also has a significant chemical reaction in the osseointegration process. Thus, ultra-fine Pd-Ag-HAp nanoparticles have been electrodeposited on protruded TiO2 barrier layer in mixed electrolyte solutions. Unusual protrusions patterns, which are assigned to Pd-Ag-HAp nanoparticles, can be clearly differentiated from a TiO2 nanotube oxide layer formed by an anodizing process. In the chemical bonding state, the surface characteristics of Pd/Ag/HAp compounds have been investigated by FE-SEM, EDS mapping analysis, and XPS analysis. The mapping dots of the elements including Ti, Ca, Pd, Ag, and P showed a homogeneous distribution throughout the entire surface when deposited onto the protruded TiO2 barrier layer. The XPS spectra of Ti-2p, O-1S, Pd-3d, and Ag-3d have been investigated, with the major XPS peak indicating Pd-3d. The Ag-3d level was clearly observed with further scanning of the Ca-2p region. Based on the results of the chemical states, the structural properties of the protrusion patterns were also examined after being deposited onto the barrier oxide film, resulting in the representative protrusion patterns being mainly composed of Pd-Ag-HAp compounds. The results of the soaking evaluation showed that the protrusion patterns and the protruded TiO2 barrier layer were all effective in regards to biocompatibility.

  14. Intercorrelated Ag3PO4 nanoparticles decorated with graphic carbon nitride: Enhanced stability and photocatalytic activities for water treatment

    Science.gov (United States)

    Ren, Jia; Chai, Yuanyuan; Liu, Qianqian; Zhang, Lu; Dai, Wei-Lin

    2017-05-01

    The method of decorating Ag3PO4 nanoparticles with carbon nitride material (g-C3N4) is demonstrated as an efficient pathway to remarkably improve the stability and photocatalytic performance of Ag3PO4 nanoparticles which have been widely used in photocatalysis, but limited by the instability. The improved material herein results in the largely enhanced photocatalytic performance for water purification under visible light irradiation, which was nearly 7 times as high as that of pure Ag3PO4. Meanwhile, the as-obtained materials show the unique stable property, mainly contributed by the protection effect of decorated g-C3N4 sheet. Additionally, the radical trapping experiments revealed that the introduction of g-C3N4 transformed the photocatalytic mechanism to some degree, where rad O2- played a more important role. The tremendous enhancement in catalytic performance may be attributed to the larger surface area, controllable particle size and the synergistic effect between Ag3PO4 and g-C3N4, promoting the separation efficiency of the photogenerated electron-hole pairs. The decorating system can in principle be broadly put into use for unstable photocatalysts.

  15. Hierarchical Ag/AgCl-TiO{sub 2} hollow spheres with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu Long; Yin, Hao Yong [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Nie, Qiu Lin, E-mail: nieqiulin@hdu.edu.cn [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Wei Wei [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Yang; LiYuan, Qiu [College of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-01-01

    The hierarchical Ag/AgCl-TiO{sub 2} hollow spheres were synthesized by depositing Ag/AgCl nanoparticles on TiO{sub 2} hollow spheres via a precipitation photoreduction method, and they were further characterized using TGA, SEM, TEM, XRD, XPS, UV–vis DRS and photoelectric chemical analysis. The analysis showed that the hierarchical Ag/AgCl-TiO{sub 2} hollow spheres exhibited the highest photocatalytic activity, which was approximately 13 times higher than that of TiO{sub 2} hollow spheres. The high photocatalytic activity of the composites is due to efficient electron-hole pairs separation at the photocatalyst interfaces, and localized surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction. - Highlights: • TiO{sub 2} hollow spheres were prepared by a sacrificial template method. • The hollow spheres were modified with Ag/AgCl to form the heterojunctions. • The modification may produce synergistic effect of LSPR and hollow structure. • Visible light photocatalytic activity was enhanced on this hollow catalyst. • The mechanism of the improved photocatalytic performance was discussed.

  16. Ameliorative role of nano-ceria against amine coated Ag-NP induced toxicity in Labeo rohita

    Science.gov (United States)

    Khan, Muhammad Saleem; Qureshi, Naureen Aziz; Jabeen, Farhat

    2018-03-01

    Silver nanoparticles (Ag-NPs) and its byproducts can spread pollution in aquatic habitat. Liver and gills are key target for toxicity. Oxidative stress, tissue alterations, and hemotoxicity are assumed to be associated with Ag-NPs in target animals. Cerium oxide nanoparticles (nano-ceria) show antioxidant potential in scavenging the free radicals generated in Ag-NP-induced oxidative stress. We determined ameliorated role of nano-ceria against Ag-NP-induced toxicity in fresh water Labeo rohita (L. rohita). Four groups were used in study including control, nano-ceria, Ag-NPs, and Ag-NPs + nano-ceria. Ag-NPs (30 mg l-1) and nano-ceria (50 µg kg-1) were given through water and prepared feed, respectively. The samples were taken after 28 days. Results demonstrated that pre-treatment of nano-ceria recovered L. rohita from Ag-NP-induced toxicity and oxidative stress. Nano-ceria pre-treatment actively mimics the activity of GST, GSH, CAT, and SOD. Furthermore, Ag-NPs' treatment caused severe inflammation and necrosis in hepatic parenchyma which leaded to congestion of blood in hepatic tissues. Accumulation of a yellow pigment in hepatic tissue was also seen due to necrosis of affected cells. In nano-ceria pre-treatment, there was no congestion in hepatic tissue. Vacuolization of cells and necrosis in some area was recorded in nano-ceria pre-treated group, but the gill and hepatic tissue showed improvement against Ag-NP-induced damage. Nano-ceria pre-treatment also improved hematological parameters in Ag-NP-treated fish. This study concluded that Ag-NP-induced toxicity in treated fish and pre-treatment of nano-ceria show ameliorative role.

  17. Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

    Science.gov (United States)

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    animals group. Histopathological investigation reveals decreased fat accumulation, appearance of binucleated cells in nanoparticle treated animals and showed mere normal cells induced by DEN. Argyrophilic nucleolar organiser region (AgNORs) had a significant decrease in number of acidic proteins and mast cells assay showed decrease of metachromatic cells in nanoparticles treated animal groups over control. Present results strongly suggest that biomolecule coated silver nanoparticles exposure showed potential hepatoprotective effect against DEN induced liver cancer and could be used as an effective anticancer nanodrug. Copyright © 2017. Published by Elsevier B.V.

  18. Raman bands in Ag nanoparticles obtained in extract of Opuntia ficus-indica plant

    Science.gov (United States)

    Bocarando-Chacon, J.-G.; Cortez-Valadez, M.; Vargas-Vazquez, D.; Rodríguez Melgarejo, F.; Flores-Acosta, M.; Mani-Gonzalez, P. G.; Leon-Sarabia, E.; Navarro-Badilla, A.; Ramírez-Bon, R.

    2014-05-01

    Silver nanoparticles have been obtained in an extract of Opuntia ficus-indica plant. The size and distribution of nanoparticles were quantified by atomic force microscopy (AFM). The diameter was estimated to be about 15 nm. In addition, energy dispersive X-ray spectroscopy (EDX) peaks of silver were observed in these samples. Three Raman bands have been experimentally detected at 83, 110 and 160 cm-1. The bands at 83 and 110 cm-1 are assigned to the silver-silver Raman modes (skeletal modes) and the Raman mode located at 160 cm-1 has been assigned to breathing modes. Vibrational assignments of Raman modes have been carried out based on the Density Functional Theory (DFT) quantum mechanical calculation. Structural and vibrational properties for small Agn clusters with 2≤n≤9 were determined. Calculated Raman modes for small metal clusters have an approximation trend of Raman bands. These Raman bands were obtained experimentally for silver nanoparticles (AgNP).

  19. The impact of anticancer activity upon Beta vulgaris extract mediated biosynthesized silver nanoparticles (ag-NPs) against human breast (MCF-7), lung (A549) and pharynx (Hep-2) cancer cell lines.

    Science.gov (United States)

    Venugopal, K; Ahmad, H; Manikandan, E; Thanigai Arul, K; Kavitha, K; Moodley, M K; Rajagopal, K; Balabhaskar, R; Bhaskar, M

    2017-08-01

    The present study tried for a phyto-synthetic method of producing silver nanoparticles (Ag-NPs) with size controlled as and eco-friendly route that can lead to their advanced production with decorative tranquil morphology. By inducing temperature fluctuation of the reaction mixture from 25 to 80°C the plasmon resonance band raised slowly which had an ultimate effect on size and shape of Ag-NPs as shown by UV-visible spectroscopy and TEM results. The biosynthesized nanoparticles showed good cytotoxic impact against MCF-7, A549 and Hep2 cells compared to normal cell lines. Compared to control plates, the percentage of cell growth inhibition was found to be high with as concentrations of Ag-NPs becomes more as determined by MTT assay. The AO/EtBr staining observations demonstrated that the mechanism of cell death induced by Ag-NPs was due to apoptosis in cancer cells. These present results propose that the silver nanoparticles (Ag-NPs) may be utilized as anticancer agents for the treatment of various cancer types. However, there is a need for study of in vivo examination of these nanoparticles to find their role and mechanism inside human body. Further, studies we plan to do biomarker fabrication from the green synthesized plant extract nanoparticles like silver, gold and copper nanoparticles with optimized shape and sizes and their enhancement of these noble nanoparticles. Copyright © 2017. Published by Elsevier B.V.

  20. Glancing-incidence X-ray diffraction of Ag nanoparticles in gold lustre decoration of Italian Renaissance pottery

    Energy Technology Data Exchange (ETDEWEB)

    Bontempi, E.; Colombi, P.; Depero, L.E. [Universita di Brescia, Laboratorio di Chimica per le Tecnologie and INSTM, Brescia (Italy); Cartechini, L. [Universita di Perugia, Istituto di Scienze e Tecnologie Molecolari-CNR, Sezione di Perugia, Perugia (Italy); Presciutti, F.; Brunetti, B.G. [Universita di Perugia, INSTM and Centro di Eccellenza SMAArt, Dipartimento di Chimica, Perugia (Italy); Sgamellotti, A. [Universita di Perugia, Istituto di Scienze e Tecnologie Molecolari-CNR, Sezione di Perugia, Perugia (Italy); Universita di Perugia, INSTM and Centro di Eccellenza SMAArt, Dipartimento di Chimica, Perugia (Italy)

    2006-06-15

    Lustre is known as one of the most significant decorative techniques of Medieval and Renaissance pottery in the Mediterranean basin, characterized by brilliant gold and red metallic reflections and iridescence effects. Previous studies by various techniques (SEM-EDS and TEM, UV-VIS, XRF, RBS and EXAFS) demonstrated that lustre consists of a heterogeneous metal-glass composite film, formed by Cu and Ag nanoparticles dispersed within the outer layer of a tin-opacified lead glaze. In the present work the investigation of an original gold lustre sample from Deruta has been carried out by means of glancing-incidence X-ray diffraction techniques (GIXRD). The study was aimed at providing information on structure and depth distribution of Ag nanoparticles. Exploiting the capability of controlling X-ray penetration in the glaze by changing the incidence angle, we used GIXRD measurements to estimate non-destructively thickness and depth of silver particles present in the first layers of the glaze. (orig.)

  1. Glancing-incidence X-ray diffraction of Ag nanoparticles in gold lustre decoration of Italian Renaissance pottery

    International Nuclear Information System (INIS)

    Bontempi, E.; Colombi, P.; Depero, L.E.; Cartechini, L.; Presciutti, F.; Brunetti, B.G.; Sgamellotti, A.

    2006-01-01

    Lustre is known as one of the most significant decorative techniques of Medieval and Renaissance pottery in the Mediterranean basin, characterized by brilliant gold and red metallic reflections and iridescence effects. Previous studies by various techniques (SEM-EDS and TEM, UV-VIS, XRF, RBS and EXAFS) demonstrated that lustre consists of a heterogeneous metal-glass composite film, formed by Cu and Ag nanoparticles dispersed within the outer layer of a tin-opacified lead glaze. In the present work the investigation of an original gold lustre sample from Deruta has been carried out by means of glancing-incidence X-ray diffraction techniques (GIXRD). The study was aimed at providing information on structure and depth distribution of Ag nanoparticles. Exploiting the capability of controlling X-ray penetration in the glaze by changing the incidence angle, we used GIXRD measurements to estimate non-destructively thickness and depth of silver particles present in the first layers of the glaze. (orig.)

  2. Glancing-incidence X-ray diffraction of Ag nanoparticles in gold lustre decoration of Italian Renaissance pottery

    Science.gov (United States)

    Bontempi, E.; Colombi, P.; Depero, L. E.; Cartechini, L.; Presciutti, F.; Brunetti, B. G.; Sgamellotti, A.

    2006-06-01

    Lustre is known as one of the most significant decorative techniques of Medieval and Renaissance pottery in the Mediterranean basin, characterized by brilliant gold and red metallic reflections and iridescence effects. Previous studies by various techniques (SEM-EDS and TEM, UV-VIS, XRF, RBS and EXAFS) demonstrated that lustre consists of a heterogeneous metal-glass composite film, formed by Cu and Ag nanoparticles dispersed within the outer layer of a tin-opacified lead glaze. In the present work the investigation of an original gold lustre sample from Deruta has been carried out by means of glancing-incidence X-ray diffraction techniques (GIXRD). The study was aimed at providing information on structure and depth distribution of Ag nanoparticles. Exploiting the capability of controlling X-ray penetration in the glaze by changing the incidence angle, we used GIXRD measurements to estimate non-destructively thickness and depth of silver particles present in the first layers of the glaze.

  3. Silver bioaccumulation dynamics in a freshwater invertebrate after aqueous and dietary exposures to nanosized and ionic Ag

    Science.gov (United States)

    le Croteau, Marie-Noe; Misra, Superb K.; Luoma, Samuel N.; Valsami-Jones, Eugenia

    2011-01-01

    We compared silver (Ag) bioavailability and toxicity to a freshwater gastropod after exposure to ionic silver (Ag+) and to Ag nanoparticles (Ag NPs) capped with citrate or with humic acid. Silver form, exposure route, and capping agent influence Ag bioaccumulation dynamics in Lymnaea stagnalis. Snails efficiently accumulated Ag from all forms after either aqueous or dietary exposure. For both exposure routes, uptake rates were faster for Ag+ than for Ag NPs. Snails efficiently assimilated Ag from Ag NPs mixed with diatoms (assimilation efficiency (AE) ranged from 49 to 58%) and from diatoms pre-exposed to Ag+ (AE of 73%). In the diet, Ag NPs damaged digestion. Snails ate less and inefficiently processed the ingested food, which adversely impacted their growth. Loss rates of Ag were faster after waterborne exposure to Ag NPs than after exposure to dissolved Ag+. Once Ag was taken up from diet, whether from Ag+ or Ag NPs, Ag was lost extremely slowly. Large Ag body concentrations are thus expected in L. stagnalis after dietborne exposures, especially to citrate-capped Ag NPs. Ingestion of Ag associated with particulate materials appears as the most important vector of uptake. Nanosilver exposure from food might trigger important environmental risks.

  4. Generation of Hybrid Peptide-Silver Nanoparticles for Antibacterial and Antifouling Applications

    KAUST Repository

    Seferji, Kholoud

    2018-05-01

    An alarming increase of antibiotic-resistant bacterial strains has made the demand for novel antibacterial agents, for example, more effective antibiotics, highly crucial. One of the oldest antimicrobial agents is elementary silver which has been used for thousands of years. Even in our days, elementary silver is used for medical purposes, such as for burns, wounds, and microbial infections. We have taken the effectiveness of elementary silver into consideration to generate novel antibacterial and antifouling agents. Our innovative antibacterial agents are hybrid peptide silver nanoparticles (CH-01-AgNPs) that are created de novo and in situ from a silver nitrate solution (AgNO3) in the presence of ultrashort self-assembling peptides compounds. The nucleation of CH-01-AgNPs is initiated by irradiating the peptide solution mixed with the AgNO3 solution using ultraviolet (UV) light at a wavelength of 254 nm, in the absence of any reducing or capping agents. Obviously, the peptide itself serves as the reducing agent. The ultrashort peptides are four amino acids in length with an innate ability to self-assemble into nanofibrous scaffolds. Using these ultrashort peptides CH-01 we were able to create hybrid peptide silver nanoparticles CH-01-AgNPs with a diameter of 4-6 nm. The synthesized CH-01-AgNPs were further characterized using ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering, and X-ray photoelectron spectroscopy. The antibacterial and antifouling activity of CH-01-AgNPs were then investigated using either gram-negative bacteria, such as antibiotic-resistant Top10 Escherichia coli and Pseudomonas aeruginosa PDO300, or gram-positive bacteria, such as Staphylococcus aureus CECT 976. The hybrid nanoparticles demonstrated very promising antibacterial and antifouling activity with higher antibacterial and antifouling activity as commercial silver nanoparticles. Quantitative Polymerase Chain Reaction (qPCR) results showed

  5. A systematic review on silver nanoparticles-induced cytotoxicity: Physicochemical properties and perspectives

    Directory of Open Access Journals (Sweden)

    Mahmuda Akter

    2018-01-01

    Full Text Available With the development of nanotechnology, silver nanoparticles (Ag-NPs have become one of the most in-demand nanoparticles owing to their exponential number of uses in various sectors. The increased use of Ag-NPs-enhanced products may result in an increased level of toxicity affecting both the environment and living organisms. Several studies have used different model cell lines to exhibit the cytotoxicity of Ag-NPs, and their underlying molecular mechanisms. This review aimed to elucidate different properties of Ag-NPs that are responsible for the induction of cellular toxicity along with the critical mechanism of action and subsequent defense mechanisms observed in vitro. Our results show that the properties of Ag-NPs largely vary based on the diversified synthesis processes. The physiochemical properties of Ag-NPs (e.g., size, shape, concentration, agglomeration, or aggregation interaction with a biological system can cause impairment of mitochondrial function prior to their penetration and accumulation in the mitochondrial membrane. Thus, Ag-NPs exhibit properties that play a central role in their use as biocides along with their applicability in environmental cleaning. We herein report a current review of the synthesis, applicability, and toxicity of Ag-NPs in relation to their detailed characteristics.

  6. Pulsed laser deposition of Ag nanoparticles on titanium hydroxide/oxide nanobelt arrays for highly sensitive surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Jing, Yuting; Wang, Huanwen; Zhao, Jie; Yi, Huan; Wang, Xuefeng

    2015-01-01

    Highlights: • Silver nanoparticles (NPs) were deposited on Ti(OH) 4 nanobelt by pulsed laser deposition (PLD). • The highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18. • Ag 2 O play important role for the high sensitivity Raman phenomenon. • Charge transfer from Ag NPs is also responsible for the enhancement ability. - Abstract: Surface-enhanced Raman scattering (SERS) substrate of Ti(OH) 4 nanobelt arrays (NBAs) was synthesized by a hydrothermal reaction, on which silver nanoparticles (NPs) were deposited by pulsed laser deposition (PLD). Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed the effective high specific surface area with silver NPs decorated on three-dimensional NBAs. Using rhodamine 6G (R6G) as an analyte molecule, the highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18 were obtained. It has been found that the specific morphology of these composite nanobelt arrays and the formation of Ag 2 O play important role for the high sensitivity Raman phenomenon. In addition, the surface plasmon resonance wavelength of Ag decorated Ti(OH) 4 NBAs and the charge transfer from Ag NPs are also responsible for the enhancement ability. For comparison SERS was investigated with silver particles decorated on TiO 2 NBAs, which is much less active

  7. Green synthesis of graphene/Ag nanocomposites

    International Nuclear Information System (INIS)

    Yuan Wenhui; Gu Yejian; Li Li

    2012-01-01

    Graphical abstract: A facile and green approach to synthesis of GNS/AgNPs is reported by employing sodium citrate as reductant, and this study represents the use of biocompounds for nontoxic and scalable production of GNS/AgNPs under a suitable concentration of silver ions and the prepared GNS/AgNPs can be used in the field of disinfection. Highlights: ► Graphene/Ag nanocomposites were prepared by a green and facile strategy based on sodium citrate. ► The influence of AgNO 3 amount on particle size and size range of AgNPs was studied. ► The surface plasmon resonance properties of AgNPs on graphene was investigated. ► The antibacterial activity of silver nanoparticles was retained in the nanocomposites. - Abstract: Graphene/Ag nanocomposites (GNS/AgNPs) were fabricated via a green and facile method, employing graphite oxide (GO) as a precursor of graphene, AgNO 3 as a precursor of Ag nanoparticles, and sodium citrate as an environmentally friendly reducing and stabilizing agent. The synthesized GNS/AgNPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectra (RS), respectively. The results indicated that graphite oxide was completely reduced to graphene, and the silver ion was reduced by sodium citrate simultaneously. Under a suitable dosage of silver ions, well-dispersed AgNPs on the graphene sheets mostly centralized at 20–25 nm. The surface plasmon resonance property of AgNPs on graphene showed that there was a interaction between AgNPs and graphene supports. In addition, antibacterial activity of silver nanoparticles was retained in the nanocomposites, suggesting that they can be potentially used as a graphene-based biomaterial.

  8. Understanding the fate and biological effects of Ag- and TiO2-nanoparticles in the environment: The quest for advanced analytics and interdisciplinary concepts

    International Nuclear Information System (INIS)

    Schaumann, Gabriele E.; Philippe, Allan; Bundschuh, Mirco; Metreveli, George; Klitzke, Sondra; Rakcheev, Denis; Grün, Alexandra

    2015-01-01

    Engineered inorganic nanoparticles (EINP) from consumers' products and industrial applications, especially silver and titanium dioxide nanoparticles (NP), are emitted into the aquatic and terrestrial environments in increasing amounts. However, the current knowledge on their environmental fate and biological effects is diverse and renders reliable predictions complicated. This review critically evaluates existing knowledge on colloidal aging mechanisms, biological functioning and transport of Ag NP and TiO 2 NP in water and soil and it discusses challenges for concepts, experimental approaches and analytical methods in order to obtain a comprehensive understanding of the processes linking NP fate and effects. Ag NP undergo dissolution and oxidation with Ag 2 S as a thermodynamically determined endpoint. Nonetheless, Ag NP also undergo colloidal transformations in the nanoparticulate state and may act as carriers for other substances. Ag NP and TiO 2 NP can have adverse biological effects on organisms. Whereas Ag NP reveal higher colloidal stability and mobility, the efficiency of NOM as a stabilizing agent is greater towards TiO 2 NP than towards Ag NP, and multivalent cations can dominate the colloidal behavior over NOM. Many of the past analytical obstacles have been overcome just recently. Single particle ICP-MS based methods in combination with field flow fractionation techniques and hydrodynamic chromatography have the potential to fill the gaps currently hampering a comprehensive understanding of fate and effects also at a low field relevant concentrations. These analytical developments will allow for mechanistically orientated research and transfer to a larger set of EINP. This includes separating processes driven by NP specific properties and bulk chemical properties, categorization of effect-triggering pathways directing the EINP effects towards specific recipients, and identification of dominant environmental parameters triggering fate and effect of

  9. Toxicological Effects of Caco-2 Cells Following Short-Term and Long-Term Exposure to Ag Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ni Chen

    2016-06-01

    Full Text Available Extensive utilization increases the exposure of humans to Ag nanoparticles (NPs via the oral pathway. To comprehensively address the action of Ag NPs to the gastrointestinal systems in real situations, i.e., the long-term low-dose exposure, we evaluated and compared the toxicity of three Ag NPs (20–30 nm with different surface coatings to the human intestine cell Caco-2 after 1-day and 21-day exposures, using various biological assays. In both the short- and long-term exposures, the variety of surface coating predominated the toxicity of Ag NPs in a descending order of citrate-coated Ag NP (Ag-CIT, bare Ag NP (Ag-B, and poly (N-vinyl-2-pyrrolidone-coated Ag NP (Ag-PVP. The short-term exposure induced cell growth inhibition and death. The cell viability loss appeared after cells were exposed to 0.7 μg/mL Ag-CIT, 0.9 μg/mL Ag-B or >1.0 μg/mL Ag-PVP for 24 h. The short-term and higher-dose exposure also induced reactive oxygen species (ROS generation, mitochondrial damage, cell membrane leakage, apoptosis, and inflammation (IL-8 level. The long-term exposure only inhibited the cell proliferation. After 21-day exposure to 0.4 μg/mL Ag-CIT, the cell viability dropped to less than 50%, while cells exposed to 0.5 μg/mL Ag-PVP remained normal as the control. Generally, 0.3 μg/mL is the non-toxic dose for the long-term exposure of Caco-2 cells to Ag NPs in this study. However, cells presented inflammation after exposure to Ag NPs with the non-toxic dose in the long-term exposure.

  10. Investigation of the cytotoxic and antileishmanal effects of fagonia indica l. extract and extract mediated silver nanoparticles (AgNPs)

    International Nuclear Information System (INIS)

    Ullah, I.; Shinwari, Z. K.; Khalil, A. T.

    2017-01-01

    Leishmaniasis is one of the globally neglected tropical disease cause by protozoan parasite of the genus Leishmania. In Pakistan, cutaneous leishmaniasis is more sporadic in the Afghan refugee camps, which is concern for the local villager and Pakistani population. In the current study an approache was made to synthesise biogenic silver nanoparticles using Fagonia indica leaf extract. Furthermore, the antileishmanial activity of the nanoparticles was evaluated compared to the crude extracts against Leishmania tropica which is the causative agent of cutenious leishmaniasis. MTT cell viability assay was used to determine the non toxicological concentration of the extract and nanoparticle in macrophage cell lines (J774), and the antileishmanial activity. We found that silver nanoparticles are not toxic to macropage cell above 30 μg/ml. where as the IC/sub 50/ against leishmania parsites was calculated as 8.16+-0.63 μg/ml and 4.8+-0.819 μg/ml for extract and AgNPs respectively. We also determine the infection index of the parasite in the macrophage cell. The infectivity of parasites also decreases as compared to control group after activation of macrophages. We further, evaluate the mechanism of growth inhibition using Griess reagent for the estimation of nitrogen oxide. We found that both the extract and AgNPs produce an elevated level of nitrogen oxide free radical. These radical produce oxidative stress in the cell that lead to the reduced metabolic activities of the parasites and ultimate death. Overall, the results indicate that Fagonia indica leves extract and AgNPs are potent antileishmanial agents. (author)

  11. The effect of nanoparticles size on photocatalytic and antimicrobial properties of Ag-Pt/TiO{sub 2} photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zielińska-Jurek, Anna, E-mail: annjurek@pg.gda.pl [Department of Chemical Technology, Faculty of Chemistry, Gdansk University of Technology, 80-233 Gdansk (Poland); Wei, Zhishun [Catalysis Research Center, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan); Wysocka, Izabela [Department of Chemical Technology, Faculty of Chemistry, Gdansk University of Technology, 80-233 Gdansk (Poland); Szweda, Piotr [Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdansk University of Technology, 80-233 Gdansk (Poland); Kowalska, Ewa [Catalysis Research Center, Hokkaido University, N21, W10, 001-0021, Sapporo (Japan)

    2015-10-30

    Graphical abstract: - Highlights: • Enhanced photocatalytic activity under visible light for bimetallic Ag-Pt/TiO{sub 2} was observed. • Phenol was removed efficiently after 60 min irradiation under Vis. • Most active sample contains fine Pt (1–3 nm) on TiO{sub 2}. • Ag/TiO{sub 2}, Ag-Pt/TiO{sub 2} revealed antimicrobial activity. - Abstract: Ag-Pt-modified TiO{sub 2} nanocomposites were synthesized using the sol–gel method. Bimetallic modified TiO{sub 2} nanoparticles exhibited improved photocatalytic activity under visible-light irradiation, better than monometallic Ag/TiO{sub 2} and Pt/TiO{sub 2} nanoparticles (NPs). All modified powders showed localized surface plasmon resonance (LSPR) in visible region. The photocatalysts’ characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption (BET method for specific surface area) showed that sample with the highest photocatalytic activity had anatase structure, about 93 m{sup 2}/g specific surface area, maximum plasmon absorption at ca. 420 nm and contained small NPs of silver of 6 nm and very fine platinum NPs of 3 nm. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/vis light irradiation. It was found that size of platinum was decisive for the photocatalytic activity under visible light irradiation, i.e., the smaller Pt NPs were, the higher was photocatalytic activity. While, antimicrobial activities, estimated for bacteria Escherichia coli and Staphylococcus aureus, and pathogenic fungi belonging to Candida family, were only observed for photocatalysts containing silver, i.e., Ag/TiO{sub 2} and Ag-Pt/TiO{sub 2} nanocomposites.

  12. Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Boomi, Pandi [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Prabu, Halliah Gurumallesh, E-mail: hgprabu2010@gmail.com [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Manisankar, Paramasivam [Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi 630 003, Tamil Nadu (India); Ravikumar, Sundaram [Department of Oceanography and Coastal Area Studies, School of Marine Sciences, Alagappa University, Thondi Campus 623 409, Tamil Nadu (India)

    2014-05-01

    Graphical abstract: - Highlights: • New method of synthesizing PANI-Ag-Au nanocomposite. • Surface Plasmon resonance and formation of composite at nano level were analyzed. • HR-TEM study revealed uniform distribution of nanoparticles. • PANI-Ag-Au nanocomposite exhibited good antibacterial activity. - Abstract: Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

  13. Understanding the growth mechanism of stabilizer-free Ag nanoparticles on reduced graphene oxide: the role of CO

    International Nuclear Information System (INIS)

    Gao Weiyin; Ran Chenxin; Wang Minqiang; Yao Xi; He Delong; Bai Jinbo

    2013-01-01

    In this study, one-step approach to prepare stabilizer-free Ag–graphene nanocomposites using DMAc-assisted thermal reduction method with uniform distribution of “near spherical” Ag nanoparticles (Ag NPs) in the range of 16–20 nm is reported. Interestingly, from the change of absorption spectrum as a function of reaction time, we observed that the characteristic absorption peak of Ag NPs shows no peak position shift in a quite long time without extra stabilizer while red-shift and broaden after continuous reaction. To explain this phenomenon, we further proposed a growth mechanism that CO, which is generated from reduction of functional groups on GO, adsorbed on the surface of Ag NPs and leaded to growth cease of Ag NPs into a narrow size distribution during the reduction of GO. Meanwhile, Ag NPs can catalyze the oxidation of adsorbed-CO to CO 2 in the presence of O 2 which can easily desorb from Ag surfaces. Hence, after fully removal of functional groups on GO, continuous supply of CO was cutoff while the desorption of adsorbed-CO was still happening continually, so Ag NPs start to gradually grow and resulting in aggregation. Moreover, the dosage of less DMAc or more AgNO 3 would cause the anisotropic growth and form multiply twinned structure of Ag NPs. Our study presents a useful understanding on the growth of Ag NPs on graphene.

  14. Study of the Performance of the Organic Extracts of Chenopodium ambrosioides for Ag Nanoparticle Synthesis

    Directory of Open Access Journals (Sweden)

    Luis M. Carrillo-López

    2016-01-01

    Full Text Available There are many ways to obtain metal nanoparticles: biological, physical, and chemical ways and combinations of these approaches. Synthesis assisted with plant extracts has been widely documented. However, one issue that is under discussion refers to the metabolites responsible for reduction and stabilization that confine nanoparticle growth and prevent coalescence between nanoparticles in order to avoid agglomeration/precipitation. In this study, Ag nanoparticles were synthesized using organic extracts of Chenopodium ambrosioides with different polarities (hexane, dichloromethane, and methanol. Each extract was phytochemically characterized to identify the nature of the metabolites responsible for nanoparticle formation. With methanol extract, the compounds responsible for reducing and stabilizing silver nanoparticle were associated with the presence of phenolic compounds (flavonoids and tannins, while, with dichloromethane and hexane extracts, the responsible compounds were mainly terpenoids. Large part of the reducing activity of secondary metabolites in C. ambrosioides is closely related to compounds with antioxidant capacity, such as phenolic compounds (flavone glycoside and isorhamnetin, which are the main constituents of the methanol extracts. Otherwise, terpenoids (trans-diol, α-terpineol, monoterpene hydroperoxides, and apiole are the central metabolites present in dichloromethane and hexane extracts.

  15. Micro-PIXE study of Ag in digestive glands of a nano-Ag fed arthropod (Porcellio scaber, Isopoda, Crustacea)

    International Nuclear Information System (INIS)

    Tkalec, Ziva Pipan; Drobne, Damjana; Vogel-Mikus, Katarina; Pongrac, Paula; Regvar, Marjana; Strus, Jasna; Pelicon, Primoz; Vavpetic, Primoz; Grlj, Natasa; Remskar, Maja

    2011-01-01

    Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

  16. Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

    International Nuclear Information System (INIS)

    Xie Kunpeng; Sun Lan; Wang Chenglin; Lai Yuekun; Wang Mengye; Chen Hongbo; Lin Changjian

    2010-01-01

    A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO 2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO 2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO 2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO 2 nanotube arrays was 51%, much higher than that of pure TiO 2 nanotube arrays. Ag/TiO 2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO 2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO 2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO 2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.

  17. Green synthesis of gold and silver nanoparticles using Hibiscus rosa sinensis

    Science.gov (United States)

    Philip, Daizy

    2010-03-01

    Biological synthesis of gold and silver nanoparticles of various shapes using the leaf extract of Hibiscus rosa sinensis is reported. This is a simple, cost-effective, stable for long time and reproducible aqueous room temperature synthesis method to obtain a self-assembly of Au and Ag nanoparticles. The size and shape of Au nanoparticles are modulated by varying the ratio of metal salt and extract in the reaction medium. Variation of pH of the reaction medium gives silver nanoparticles of different shapes. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR spectroscopy. Crystalline nature of the nanoparticles in the fcc structure are confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. From FTIR spectra it is found that the Au nanoparticles are bound to amine groups and the Ag nanoparticles to carboxylate ion groups.

  18. Synthesis and characterization of self-bridged silver vanadium oxide/CNTs composite and its enhanced lithium storage performance.

    Science.gov (United States)

    Liang, Liying; Liu, Haimei; Yang, Wensheng

    2013-02-07

    The improvement of the electrochemical properties of electrode materials with large capacity and good capacity retention is becoming an important task in the field of lithium ion batteries (LIBs). We designed a function-oriented hybrid material consisting of silver vanadium oxide (β-AgVO(3)) nanowires modified with uniform Ag nanoparticles and multi-walled carbon nanotubes (CNTs) as a high-performance cathode material for LIBs. The Ag nanoparticles which precipitated automatically in the synthetic process act as a bridge between the β-AgVO(3) nanowires and CNTs, creating a self-bridged network structure. The Ag particles at the junction of the nanowires and CNTs facilitate electron transport from the CNTs to the nanowires, and thereby improve the electrical conductivity of the β-AgVO(3) nanowires and the composite. Moreover, the self-bridged network is hierarchically porous with a high surface area. When used as a cathode material, this composite electrode reveals high discharge capacities, excellent rate capability, and good cycling stability. The improved performance of the composite arises from its unique nanosized β-AgVO(3) nanowires with short diffusion pathway for lithium ions, efficient electron collection and transfer in the presence of Ag nanoparticles, together with excellent electrical conductivity of CNTs.

  19. Effect of Heat Treatments on Microstructures and Tensile Properties of Cu-3 wt%Ag-0.5 wt%Zr Alloy

    Science.gov (United States)

    Chen, Gang; Wang, ChuanJie; Zhang, Ying; Yi, Cen; Zhang, Peng

    2018-03-01

    The microstructures and tensile properties of Cu-3 wt%Ag-0.5 wt%Zr alloy sheets under different aging treatments are investigated in this research. As one kind of precipitate, Ag nanoparticles with coherent orientation relationship with matrix precipitate. However, after the peak-age point, most of Ag nanoparticles grow into short rod shape with the interface translating to semi-coherent, which leads to the lower strength of over-aging sample. The yield strength is estimated by considering solid solute, grain boundary and precipitation strengthening mechanisms. The result shows that the Ag precipitates provide the main strengthening role. Then a constitutive equation representing the evolution of dislocation density with plastic strain is built by considering work-hardening behavior coming from shearable and non-shearable precipitates which is mainly the particles containing Zr. The flow stress contributed by shearable particle hardening is higher than that of non-shearable one. Due to the coarsening of grain boundary precipitates and low rate of damage accumulation of these non-shearable particles, the micro-cracks nucleate easily at grain boundary which leads to intergranular fracture.

  20. Synthesis by picosecond laser ablation of ligand-free Ag and Au nanoparticles for SERS applications

    Science.gov (United States)

    Fazio, Enza; Spadaro, Salvatore; Santoro, Marco; Trusso, Sebastiano; Lucotti, Andrea.; Tommasini, Matteo.; Neri, Fortunato; Maria Ossi, Paolo

    2018-01-01

    The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS) measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

  1. Ag1 Pd1 Nanoparticles-Reduced Graphene Oxide as a Highly Efficient and Recyclable Catalyst for Direct Aryl C-H Olefination.

    Science.gov (United States)

    Hu, Qiyan; Liu, Xiaowang; Wang, Guoliang; Wang, Feifan; Li, Qian; Zhang, Wu

    2017-12-14

    The efficient and selective palladium-catalyzed activation of C-H bonds is of great importance for the construction of diverse bioactive molecules. Despite significant progress, the inability to recycle palladium catalysts and the need for additives impedes the practical applications of these reactions. Ag 1 Pd 1 nanoparticles-reduced graphene oxide (Ag 1 Pd 1 -rGO) was used as highly efficient and recyclable catalyst for the chelation-assisted ortho C-H bond olefination of amides with acrylates in good yields with a broad substrate scope. The catalyst can be recovered and reused at least 5 times without losing activity. A synergistic effect between the Ag and Pd atoms on the catalytic activity was found, and a plausible mechanism for the AgPd-rGO catalyzed C-H olefination is proposed. These findings suggest that the search for such Pd-based bimetallic alloy nanoparticles is a new method towards the development of superior recyclable catalysts for direct aryl C-H functionalization under mild conditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties

    OpenAIRE

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-01-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160?nm and an average length of 2??m. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255?nm...

  3. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    International Nuclear Information System (INIS)

    Im, A-Rang; Kim, Jee Young; Kim, Yeong Shik; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie

    2013-01-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds. (paper)

  4. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    Science.gov (United States)

    Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

  5. Ag nanoparticle–ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach

    International Nuclear Information System (INIS)

    Li, Zhou; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Fan, Yubo; Tang, Haoying; Liu, Tengjiao; Jiang, Peng; Wang, Zhong Lin

    2014-01-01

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a ‘dip-in and light-irradiation’ green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems. (paper)

  6. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens

    International Nuclear Information System (INIS)

    Boxi, Siddhartha Sankar; Mukherjee, Khushi; Paria, Santanu

    2016-01-01

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO 2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag–S and disulfide bonds (R–S–S–R) in cellular protein, which leads to cell damage. During photocatalysis generated • OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling. (paper)

  7. Both released silver ions and particulate Ag contribute to the toxicity of AgNPs to earthworm Eisenia fetida

    NARCIS (Netherlands)

    Li, L.; , van, Gestel C.A.M.

    2015-01-01

    To disentangle the contribution of ionic and nanoparticulate Ag to the overall toxicity to the earthworm Eisenia fetida, a semi-permeable membrane strategy was used to separate Ag+ released from silver nanoparticles (AgNPs) in an aqueous exposure. Internal Ag fractionation, activities of antioxidant

  8. Synthesis of silver nanoparticles by radiolysis, photolysis and chemical reduction of AgNO3 in Hibiscus sabdariffa infusion (karkade)

    International Nuclear Information System (INIS)

    Cataldo, Franco; Ursini, Ornella; Angelini, Giancarlo

    2016-01-01

    Silver nanoparticles of different average diameters were synthesized by γ-radiolysis, UV-photolysis and chemical reduction of AgNO 3 solutions in Hibiscus sabdariffa infusion commonly known as 'karkade'. The UV-photolysis was performed either by using a conventional Hg low pressure lamp emitting at 254 nm and also by using a new compact UV-LED source emitting at 360 nm. The kinetics rate constant of silver nanoparticles synthesis produced by γ-radiolysis and UV photolysis were determined and the average diameter of the resulting nanoparticles was estimated. (author)

  9. One pot synthesis of Ag nanoparticle modified ZnO microspheres in ethylene glycol medium and their enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Tian Chungui; Li Wei; Pan Kai; Zhang Qi; Tian Guohui; Zhou Wei; Fu Honggang

    2010-01-01

    Ag nanoparticles (NPs) modified ZnO microspheres (Ag/ZnO microspheres) were prepared by a facile one pot strategy in ethylene glycol (EG) medium. The EG played two important roles in the synthesis: it could act as a reaction media for the formation of ZnO and reduce Ag + to Ag 0 . A series of the characterizations indicated the successful combination of Ag NPs with ZnO microspheres. It was shown that Ag modification could greatly enhance the photocatalytic efficiency of ZnO microspheres by taking the photodegradation of Rhodamine B as a model reaction. With appropriate ratio of Ag and ZnO, Ag/ZnO microspheres showed the better photocatalytic performance than commercial Degussa P-25 TiO 2 . Photoluminescence and surface photovoltage spectra demonstrated that Ag modification could effectively inhibit the recombination of the photoinduced electron and holes of ZnO. This is responsible for the higher photocatalytic activity of Ag/ZnO composites. -- Graphical abstract: A 'one-pot' strategy was developed for preparing the Ag/ZnO microspheres in ethylene glycol. The composites exhibited superior photocatalytic performance for photodegradation of Rhodamine B dye in water. Display Omitted

  10. Transfer Study of Silver Nanoparticles in Poultry Production.

    Science.gov (United States)

    Gallocchio, Federica; Biancotto, Giancarlo; Cibin, Veronica; Losasso, Carmen; Belluco, Simone; Peters, Ruud; van Bemmel, Greet; Cascio, Claudia; Weigel, Stefan; Tromp, Peter; Gobbo, Federica; Catania, Salvatore; Ricci, Antonia

    2017-05-10

    Silver nanoparticles (AgNPs) are of interest due to their antimicrobial activity and are seen as potential candidates to replace antibiotics in animal husbandry. A few studies have focused on this new application, but they lack any considerations about residual accumulation of AgNPs in edible animal tissues and animal products. In this research, a 22 day in vivo study was carried out by oral administration of 20 nm spherical PVP coated AgNPs to hens. Six doses of approximately 1 mg kg -1 of AgNPs-PVP each were administered to animals throughout the experimentation. Atomic absorption spectroscopy (AAS) was used for quantitative determination of residual total Ag in different organs and matrices. The analyses showed that Ag accumulates in livers (concentration ranging from 141 μg kg -1 to 269 μg kg -1 ) and yolks (concentration ranging from 20 μg kg -1 to 49 μg kg -1 ) but not in muscles, kidneys, and albumen belonging to hens of the treated group (tG2). Ag was not detected in animals of the control group (uG1) (i.e., total Ag animals. spICP-MS highlighted that part of residual Ag found in livers (about 5-20%) is in NP form with an average dimension of approximately 20 nm. SEM-EDX technique confirmed the presence of AgNPs only in livers of treated animals. The results show that feeding AgNPs to hens may become a source of consumer exposure to AgNPs. As far as we know this is the first study showing transfer of AgNPs or reaction products thereof from animal feed to animal products.

  11. Digestive ripening facilitated atomic diffusion at nanosize regime: Case of AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Neha [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Klabunde, Kenneth J. [Department of Chemistry, Kansas State University, Manhattan, KS 66506 (United States)

    2014-10-15

    Highlights: • A digestive ripening facilitated interatomic diffusion process is presented. • Nearly monodisperse AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles were synthesized. • Optimization of reaction temperature facilitates interatomic transfer. • Presence of excess ligand plays a crucial role in the digestive ripening process. - Abstract: Monodisperse colloidal gold–indium (AuIn{sub 2}) intermetallic nanoparticles have been synthesized from Au and In colloids using the digestive ripening process. Formation of the intermetallic proceeds via digestive ripening facilitated atomic diffusion of Au and In atoms from the Au and In nanoparticles followed simultaneously by their growth in the solution. Optimization of the reaction temperature was found to be crucial for the formation of AuIn{sub 2} intermetallic from gold and indium nanoparticles. Transmission electron microscopy revealed the presence of nearly monodisperse nanoparticles of Au and AuIn{sub 2} with particle size distribution of 3.7 ± 1.0 nm and 5.0 ± 1.6 nm, respectively. UV–visible spectral studies brought out the absence of SPR band in pure AuIn{sub 2} intermetallic nanoparticles. Optical study and electron microscopy, in combination with powder X-ray diffraction established phase pure AuIn{sub 2} intermetallic nanoparticles unambiguously. The potential of such an unprecedented approach has been further exploited in the synthesis of Ag{sub 3}In intermetallic nanoparticles with the dimension of less than 10 nm.

  12. Fabrication of antimicrobial bacterial cellulose–Ag/AgCl nanocomposite using bacteria as versatile biofactory

    International Nuclear Information System (INIS)

    Liu Chuang; Yang Dong; Wang Yuangui; Shi Jiafu; Jiang Zhongyi

    2012-01-01

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total “biologic” route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC–Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  13. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chuang [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China); Yang Dong; Wang Yuangui [Tianjin University, Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology (China); Shi Jiafu; Jiang Zhongyi, E-mail: zhyjiang@tju.edu.cn [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China)

    2012-08-15

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total 'biologic' route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  14. Reduction of silver nanoparticles onto graphene oxide nanosheets with N,N-dimethylformamide and SERS activities of GO/Ag composites

    International Nuclear Information System (INIS)

    Yang Yingkui; He Chengen; He Wenjie; Yu Linjuan; Peng Rengui; Xie Xiaolin; Wang Xianbao; Mai Yiuwing

    2011-01-01

    Silver nanoparticles (Ag NPs) have been homogeneously deposited onto graphene oxide (GO) nanosheets by an optimal method, in which N,N-dimethylformamide (DMF) as a co-dispersant of GO and reductant of sliver ions is added to an aqueous suspension of GO and AgNO 3 . GO nanosheets are uniformly covered by Ag NPs with a narrow size distribution and inter-particle gap. Raman signals of GO are greatly enhanced after deposition owing to the charge transfer interaction of GO with Ag NPs. The GO/Ag composite can be further utilized as an effective surface-enhanced Raman scattering (SERS) active substrate. Several new Raman bands and frequency shifts are clearly observed in using 4-aminothiophenol (4-ATP) as a Raman probe on GO/Ag compared to the normal Raman spectrum of solid 4-ATP. The Raman enhancement arises from a major electromagnetic effect and a minor chemical effect.

  15. Visible-light photoactivity of plasmonic silver supported on mesoporous TiO2 nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

    International Nuclear Information System (INIS)

    Jaafar, N.F.; Jalil, A.A.; Triwahyono, S.

    2017-01-01

    Highlights: • Ag 0 loaded on MTN was prepared by a direct in-situ electrochemical method. • The introduction of Ag 0 lowers the band gap and increases the number of OV and TSD. • Ag 0 acted as an electrons trapper and also a plasmonic sensitizer. • The formation of Ti-O-Ag in 10 wt% Ag-MTN decreased the amount of Ag 0 , TSD and OV. • 5 wt% Ag-MTN gave the highest percentage of photodegradation of 2-CP. - Abstract: Various weight loadings of Ag (1–10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti 3+ site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag 0 and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag 0 , TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

  16. Rapid visual detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) based on hydrophobic effect.

    Science.gov (United States)

    Zheng, Li-Qing; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2014-01-01

    In this work, a rapid, sensitive and low-cost colorimetric method for detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) was developed. The quaternary ammonium surfactants induce the aggregation of Ag NPs through the hydrophobic effect, which is a novel aggregation mechanism of Ag NPs. The addition of cationic surfactant results in color change of Ag NPs solution from yellow to red and finally to colorless, which is due to the broadening of the surface plasmon band. The color change was monitored using a UV-vis spectrophotometer. The LOD of different cationic surfactants was in the range of 0.5-5 µM. More importantly, this detection method was successfully utilized to the disinfectant residual sample. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

  17. Understanding the fate and biological effects of Ag- and TiO{sub 2}-nanoparticles in the environment: The quest for advanced analytics and interdisciplinary concepts

    Energy Technology Data Exchange (ETDEWEB)

    Schaumann, Gabriele E., E-mail: schaumann@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Philippe, Allan, E-mail: philippe@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Bundschuh, Mirco, E-mail: mirco.bundschuh@slu.se [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Ecotoxicology and Environment, Fortstr. 7, D-76829 Landau (Germany); Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment, Lennart Hjelms väg 9, SE-75007 Uppsala (Sweden); Metreveli, George, E-mail: metreveli@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Klitzke, Sondra, E-mail: sondra.klitzke@tu-berlin.de [Albert-Ludwigs-Universität Freiburg, Institute of Forest Sciences, Chair of Soil Ecology, 79085 Freiburg i.Br. (Germany); Berlin University of Technology, Institute of Ecology, Department of Soil Science, Ernst-Reuter-Platz 1, D-10587 Berlin (Germany); Rakcheev, Denis, E-mail: rakcheev@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Grün, Alexandra, E-mail: alexg@uni-koblenz.de [Universität Koblenz-Landau, Institute for Integrated Natural Sciences, Dept. of Biology, Universitätsstr. 1, D-56070 Koblenz (Germany); and others

    2015-12-01

    Engineered inorganic nanoparticles (EINP) from consumers' products and industrial applications, especially silver and titanium dioxide nanoparticles (NP), are emitted into the aquatic and terrestrial environments in increasing amounts. However, the current knowledge on their environmental fate and biological effects is diverse and renders reliable predictions complicated. This review critically evaluates existing knowledge on colloidal aging mechanisms, biological functioning and transport of Ag NP and TiO{sub 2} NP in water and soil and it discusses challenges for concepts, experimental approaches and analytical methods in order to obtain a comprehensive understanding of the processes linking NP fate and effects. Ag NP undergo dissolution and oxidation with Ag{sub 2}S as a thermodynamically determined endpoint. Nonetheless, Ag NP also undergo colloidal transformations in the nanoparticulate state and may act as carriers for other substances. Ag NP and TiO{sub 2} NP can have adverse biological effects on organisms. Whereas Ag NP reveal higher colloidal stability and mobility, the efficiency of NOM as a stabilizing agent is greater towards TiO{sub 2} NP than towards Ag NP, and multivalent cations can dominate the colloidal behavior over NOM. Many of the past analytical obstacles have been overcome just recently. Single particle ICP-MS based methods in combination with field flow fractionation techniques and hydrodynamic chromatography have the potential to fill the gaps currently hampering a comprehensive understanding of fate and effects also at a low field relevant concentrations. These analytical developments will allow for mechanistically orientated research and transfer to a larger set of EINP. This includes separating processes driven by NP specific properties and bulk chemical properties, categorization of effect-triggering pathways directing the EINP effects towards specific recipients, and identification of dominant environmental parameters triggering

  18. Synthesis of Ag and Au nanoparticles embedded in carbon film: Optical, crystalline and topography analysis

    Science.gov (United States)

    Gholamali, Hediyeh; Shafiekhani, Azizollah; Darabi, Elham; Elahi, Seyed Mohammad

    2018-03-01

    Atomic force microscopy (AFM) images give valuable information about surface roughness of thin films based on the results of power spectral density (PSD) through the fast Fourier transform (FFT) algorithms. In the present work, AFM data are studied for silver and gold nanoparticles (Ag NPs a-C: H and Au NPs a-C: H) embedded in amorphous hydrogenated carbon films and co-deposited on glass substrate via of RF-Sputtering and RF-Plasma Enhanced Chemical Vapor Deposition methods. Here, the working gas is acetylene and the targets are Ag and Au. While time and power are constant, the only variable parameter in this study is initial pressure. In addition, the crystalline structure of Ag NPs a-C: H and Au NPs a-C: H are studied using X-ray diffraction (XRD). UV-visible spectrophotometry will also investigate optical properties and localized surface plasmon resonance (LSPR) of samples.

  19. Titanium Surface Priming with Phase-Transited Lysozyme to Establish a Silver Nanoparticle-Loaded Chitosan/Hyaluronic Acid Antibacterial Multilayer via Layer-by-Layer Self-Assembly.

    Science.gov (United States)

    Zhong, Xue; Song, Yunjia; Yang, Peng; Wang, Yao; Jiang, Shaoyun; Zhang, Xu; Li, Changyi

    2016-01-01

    The formation of biofilm around implants, which is induced by immediate bacterial colonization after installation, is the primary cause of post-operation infection. Initial surface modification is usually required to incorporate antibacterial agents on titanium (Ti) surfaces to inhibit biofilm formation. However, simple and effective priming methods are still lacking for the development of an initial functional layer as a base for subsequent coatings on titanium surfaces. The purpose of our work was to establish a novel initial layer on Ti surfaces using phase-transited lysozyme (PTL), on which multilayer coatings can incorporate silver nanoparticles (AgNP) using chitosan (CS) and hyaluronic acid (HA) via a layer-by-layer (LbL) self-assembly technique. In this study, the surfaces of Ti substrates were primed by dipping into a mixture of lysozyme and tris(2-carboxyethyl)phosphine (TCEP) to obtain PTL-functionalized Ti substrates. The subsequent alternating coatings of HA and chitosan loaded with AgNP onto the precursor layer of PTL were carried out via LbL self-assembly to construct multilayer coatings on Ti substrates. The results of SEM and XPS indicated that the necklace-like PTL and self-assembled multilayer were successfully immobilized on the Ti substrates. The multilayer coatings loaded with AgNP can kill planktonic and adherent bacteria to 100% during the first 4 days. The antibacterial efficacy of the samples against planktonic and adherent bacteria achieved 65%-90% after 14 days. The sustained release of Ag over 14 days can prevent bacterial invasion until mucosa healing. Although the AgNP-containing structure showed some cytotoxicity, the toxicity can be reduced by controlling the Ag release rate and concentration. The PTL priming method provides a promising strategy for fabricating long-term antibacterial multilayer coatings on titanium surfaces via the LbL self-assembly technique, which is effective in preventing implant-associated infections in the

  20. Novel biosynthesis of Ag-hydroxyapatite: Structural and spectroscopic characterization

    Directory of Open Access Journals (Sweden)

    Álvaro de Jesús Ruíz-Baltazar

    2018-06-01

    Full Text Available Silver-doped hydroxyapatite (Ag-HAP was obtained by green synthesis route. The dopant silver nanoparticles (AgNPs were obtained by biosynthesis based on Melissa officinalis extract. This research is focused on the characterization and the use of the nontoxic and environment-friendly Ag-HAP nanocomposite. The structural and morphological characterization of Ag-HAP nanocomposite was carried out by scanning electron microscopy (SEM, X-ray diffraction, Fourier-transform infrared (FT-IR and Raman spectroscopy. The obtained nanoparticles exhibited a great interaction with the HAP matrix, performing an Ag-HAP nanocomposite. Changes in the structure of the Ag-HAP nanocomposite were corroborated by the different characterization techniques. Additionally, a homogeneous distribution of the AgNPs on the HAP structure was observed. The heterogeneous nucleation process employed to doping the HAP, offer a functional route to obtain a green composite with potentials applications in multiple fields, such as tissue engineering, bone repair as well as protein. These properties can be evaluated in subsequent studies. Keywords: Green synthesis, Ag nanoparticles, Hydroxyapatite, Structural characterization, Spectroscopy

  1. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO3) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils

    International Nuclear Information System (INIS)

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A.M.; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J.

    2015-01-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. - Highlights: • Toxicity of silver nanoparticles in soils increased with time. • Standard tests do not adequately assess toxicity of silver NPs to earthworms. • Internal Ag in earthworms did not always explain toxicity after shorter aging times. • With aging time, Ag ion and Ag NP effect in soils will merge to a common value. - Toxicity of silver nanoparticles in soils increased with time with the result that commonly applied tests of 28 days exposure with freshly spiked soils do not adequately assess the environmental hazard of silver nanoparticles

  2. High magnetic coercivity of FePt-Ag/MgO granular nanolayers

    Science.gov (United States)

    Roghani, R.; Sebt, S. A.; Khajehnezhad, A.

    2018-06-01

    L10-FePt ferromagnetic nanoparticles have a hight coercivity of Tesla order. Thus, these nanoparticles, with size of 10 to 15 nm and uniform surface distribution, are suitable in magnetic data storage technology with density of more than 1GB. In order to improve structural and magnetic properties of FePt nanoparticles, some elements and combinations have been added to compound. In this research, we show that due to the presence of the Ag, the phase transition temperature of FePt from fcc to L10-fct phase decreases. The presence of Ag as an additive in FePt-Ag nanocomposite, increases the magnetic coercivity. This nanocomposite, with 10% Ag, was deposited by magnetron sputtering on the MgO heat layer. VSM results of 10 nm nanoparticles show that coercivity has increased up to 1.4 T. XRD and FESEM results confirm that the size of the L10-FePt nanoparticles are 10 nm and their surface distribution are uniform. Ag gradually form nano scale clusters with separate lattice and FePt-Ag nanocomposite appears. The result of this process is emptiness of Ag position in FePt-fcc lattice. So, the mobility of Fe and Pt atoms in this lattice increases and it can be possible for them to move in lower temperature. This mechanism explain the effect of Ag on decreasing the transition temperature to fct-L10 phase, and hight coercivity of FePt nanoparticles.

  3. Synthesis and characterization of novel plasmonic Ag/AgX-CNTs (X = Cl, Br, I) nanocomposite photocatalysts and synergetic degradation of organic pollutant under visible light.

    Science.gov (United States)

    Shi, Huixian; Chen, Jiangyao; Li, Guiying; Nie, Xin; Zhao, Huijun; Wong, Po-Keung; An, Taicheng

    2013-08-14

    A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition-precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, scanning electron microscopy, and ultraviolet-visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.

  4. Synthesis, characterization of Ag-Au core-shell bimetal nanoparticles and its application for electrocatalytic oxidation/sensing of L-methionine

    Energy Technology Data Exchange (ETDEWEB)

    Murugavelu, M.; Karthikeyan, B., E-mail: bkarthi_au@yahoo.com

    2017-01-01

    The Ag-Au core-shell bimetal nanoparticles (BNPs) was prepared using chemical reduction method. The prepared Ag-Au core-shell BNPs were characterized by UV–Visible (UV–Vis) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) pattern. These results showed the Ag-Au BNPs exhibited core-shell shape. The Ag-Au core-shell BNPs was examined towards electrocatalytic oxidation of L-methionine (L-Met) by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. According to the results, L-Met is determined with detection limit of 30 μM. Interference studies in biological buffer was also studied. - Highlights: • The Ag-Au core-shell BNPs are synthesized and characterized • Ag-Au core-shell BNPs modified (Ag-Au/GCE) has been examined for L-methionine oxidation/sensing by using electrochemical method. • The Ag-Au/GCE exhibited good performance for the detection of L-methionine.

  5. Bipyridine based metallogels: an unprecedented difference in photochemical and chemical reduction in the in situ nanoparticle formation.

    Science.gov (United States)

    Tatikonda, Rajendhraprasad; Bertula, Kia; Nonappa; Hietala, Sami; Rissanen, Kari; Haukka, Matti

    2017-02-28

    Metal co-ordination induced supramolecular gelation of low molecular weight organic ligands is a rapidly expanding area of research due to the potential in creating hierarchically self-assembled multi-stimuli responsive materials. In this context, structurally simple O-methylpyridine derivatives of 4,4'-dihydroxy-2,2'-bipyridine ligands are reported. Upon complexation with Ag(i) ions in aqueous dimethyl sulfoxide (DMSO) solutions the ligands spontaneously form metallosupramolecular gels at concentrations as low as 0.6 w/v%. The metal ions induce the self-assembly of three dimensional (3D) fibrillar networks followed by the spontaneous in situ reduction of the Ag-centers to silver nanoparticles (AgNPs) when exposed to daylight. Significant size and morphological differences of the AgNP's was observed between the standard chemical and photochemical reduction of the metallogels. The gelation ability, the nanoparticle formation and rheological properties were found to be depend on the ligand structure, while the strength of the gels is affected by the water content of the gels.

  6. In-situ electrochemical coating of Ag nanoparticles onto graphite electrode with enhanced performance for Li-ion batteries

    International Nuclear Information System (INIS)

    Yun, Jiaojiao; Wang, Yan; Gao, Tian; Zheng, Huiyuan; Shen, Ming; Qu, Qunting; Zheng, Honghe

    2015-01-01

    The effects of silver hexafluorophosphate (AgPF 6 ) as an electrolyte additive on the electrochemical behaviors of graphite anode are systematically studied by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The surface structure and composition of graphite electrode after electrochemical cycles are investigated through scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. It is found that Ag nanoparticles derived from electrochemical reduction of Ag + are homogenously distributed on the graphite surface. Significant improvements on the discharge capacity, rate behavior, and low-temperature performance of graphite electrode are obtained. The reasons are associated with the decreased resistances of solid-electrolyte interface and charge-transfer process, which improve the electrode kinetics for Li + intercalation/deintercalation

  7. Photocatalytic activity of silver oxide capped Ag nanoparticles constructed by air plasma irradiation

    Science.gov (United States)

    Fang, Yingcui; Wu, Qingmeng; Li, Huanhuan; Zhang, Bing; Yan, Rong; Chen, Junling; Sun, Mengtao

    2018-04-01

    We construct a kind of structure of silver oxide capped silver nanoparticles (AgNPs) by cost-efficient air plasma irradiation, and study its visible-light driven photocatalytic activity (PA). By controlling the oxidization time, the relationship between the intensity of the localized surface plasmon resonance (LSPR) and the PA is well established. The PA reaches the maximum when the LSPR of AgNPs is nearly completely damped (according to absorption spectra); however, under this condition, the LSPR still works, confirmed with the high efficient selective transformation of p-Aminothiophenol (PATP) to p, p'-dimercaptoazobenzene (DMAB) under visible light. The mechanism of the LSPR damping induced PA improvement is discussed. We not only provide a cost-efficient approach to construct a LSPR strong damping structure but also promote the understanding of LSPR strong damping and its relationship with photocatalysis.

  8. Preparation of Agcore/Aushell bimetallic nanoparticles from physical mixtures of Au clusters and Ag ions under dark conditions and their catalytic activity for aerobic glucose oxidation

    International Nuclear Information System (INIS)

    Zhang, Haijun; Toshima, Naoki; Takasaki, Kanako; Okumura, Mitsutaka

    2014-01-01

    Graphical abstract: The synthesis, characterization and catalytic activities for glucose oxidation of AgAu bimetallic nanoparticles (BNPs) with size of less than 2 nm are reported. The catalytic activity of Ag 10 Au 90 BNPs was about two times higher than that of Au NPs, even the BNPs have a larger particle size than that of Au NPs. -- Highlights: • Ag core /Au shell BNPs with size of less than 2.0 nm were prepared. • No any reducing reagents and lights were used for the preparation of the BNPs. • The catalytic activity of the BNPs is about two times higher than that of Au NPs. -- Abstract: AgAu bimetallic nanoparticles (BNPs), one of the most extensively studied bimetallic systems in the literatures, could have various structures and compositions depending on their preparation conditions. In the present work, catalytically highly active PVP-protected Ag core /Au shell BNPs of about 2.5 nm in diameter were fabricated from physical mixtures of aqueous dispersions of Au nanoparticles and Ag + ions under dark conditions without using any reducing agents. The prepared Ag core /Au shell BNP colloidal catalysts, which possessed a high activity for aerobic glucose oxidation, were characterized by Ultraviolet–visible spectrophotometry (UV–Vis), Inductive coupled plasma emission spectrometer (ICP), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Energy disperse spectroscopy (EDS) in High-resolution scanning transmission electron microscopy (HR-STEM). The highest activity (11,360 mol-glucose h −1 mol-metal −1 ) was observed for the BNPs with the Ag/Au atomic ratio of 1/9, the TOF value of which is about two times higher than that of Au nanoparticles with the particle size of 1.3 nm. The enhanced catalytic activity of the prepared Ag core /Au shell BNPs compared to Au NPs can be ascribed to the presence of negatively charged Au atoms resulted from electron donations from neighboring Ag atoms and PVP due to electronic charge

  9. Nanoparticle Surface Specific Adsorption of Zein and Its Self-assembled Behavior of Nanocubes Formation in Relation to On-Off SERS: Understanding Morphology Control of Protein Aggregates.

    Science.gov (United States)

    Navdeep; Banipal, Tarlok Singh; Kaur, Gurinder; Bakshi, Mandeep Singh

    2016-01-27

    Zein, an industrially important protein, is characterized in terms of its food and pharmaceutical coating applications by using surface enhanced Raman spectroscopy (SERS) on Au, Ag, and PbS nanoparticles (NPs). Its specific surface adsorption behavior on Ag NPs produced self-assembled zein nanocubes which demonstrated on and off SERS activity. Both SERS characterization as well as nanocube formation of zein helped us to understand the complex protein aggregation behavior in shape controlled morphologies, a process with significant ramifications in protein crystallization to achieve ordered morphologies. Interestingly, nanocube formation was promoted in the presence of Ag rather than Au or PbS NPs under in situ synthesis and discussed in terms of specific adsorption. Zein fingerprinting was much more clear and enhanced on Au surface in comparison to Ag while PbS did not demonstrate SERS due to its semiconducting nature.

  10. AgCl-doped CdSe quantum dots with near-IR photoluminescence.

    Science.gov (United States)

    Kotin, Pavel Aleksandrovich; Bubenov, Sergey Sergeevich; Mordvinova, Natalia Evgenievna; Dorofeev, Sergey Gennadievich

    2017-01-01

    We report the synthesis of colloidal CdSe quantum dots doped with a novel Ag precursor: AgCl. The addition of AgCl causes dramatic changes in the morphology of synthesized nanocrystals from spherical nanoparticles to tetrapods and finally to large ellipsoidal nanoparticles. Ellipsoidal nanoparticles possess an intensive near-IR photoluminescence ranging up to 0.9 eV (ca. 1400 nm). In this article, we explain the reasons for the formation of the ellipsoidal nanoparticles as well as the peculiarities of the process. The structure, Ag content, and optical properties of quantum dots are also investigated. The optimal conditions for maximizing both the reaction yield and IR photoluminescence quantum yield are found.

  11. Polypyrrole-poly(3,4-ethylenedioxythiophene)-Ag (PPy-PEDOT-Ag) nanocomposite films for label-free electrochemical DNA sensing.

    Science.gov (United States)

    Radhakrishnan, S; Sumathi, C; Umar, Ahmad; Jae Kim, Sang; Wilson, J; Dharuman, V

    2013-09-15

    The electrochemical DNA hybridization sensing of bipolymer polypyrrole and poly(3,4-ethylenedioxythiophene) (PPy-PEDOT) nanotubes functionalized with Ag nanoparticles has been investigated. The bipolymer nanotubes are prepared by simple chemical route and silver nanoparticles (Ag) further deposited over the PPy-PEDOT nanotubes to form PPy-PEDOT-Ag nanocomposite films. DNA labeled at 5'end using 6-mercapto-1-hexhane (HS-ssDNA) is immobilized on the PPy-PEDOT-Ag surface to form PPy-PEDOT-Ag-S-ssDNA and hybridization sensing is done in phosphate buffer. The presence of Ag nanoparticles (~28±5nm) well dispersed in the polymer composite with high surface area, high electrical conductivity and catalytic activity provides desirable microenvironment for the immobilization of probe DNA with controlled orientation leading to increased hybridization efficiency with target DNA. The morphological and structural characterizations by a scanning electron microscope (SEM) and X-ray diffraction (XRD) confirm the nanotube structure of composite polymer while Raman measurements indicate the efficient interactions between the PPy, PEDOT, Ag and HS-ssDNA. The sensor effectively discriminates different target DNA sequences with PPy-PEDOT-Ag-S-ssDNA substrate. The observed dynamic detection range is found between 1×10(-11)M and 1×10(-14)M with the lowest detection limit (3 σ/b) of 5.4×10(-15)M. This observed value is of higher sensitivity than that for MWCNT-Ag, PANi-Au, MWCNT-PPy-Au and PPy-PANi-Au composites reported previously. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The optical and mechanical properties of PVA-Ag nanocomposite films

    Energy Technology Data Exchange (ETDEWEB)

    El-Shamy, A.G.; Attia, W.; Abd El-Kader, K.M., E-mail: kamalmarei@yahoo.com

    2014-03-25

    Highlights: • We prepared PVA -Ag composite films which used in different filed of applications. • The XRD results showed Ag nanoparticles entering the polymer PVA matrix. • Optical band gap as a result of doping has been found to be reduced significantly. • Young's modulus increases while the strain decreases due to increasing Ag content. -- Abstract: Poly (vinyl alcohol) (PVA) loaded silver (Ag) nanoparticles were successfully prepared by chemical reduction methods. The synthesized nanoparticles are characterized using UV–visible spectrophotometer, X-ray diffractometer (XRD) and Transmission electron microscope (TEM). The contents of the inorganic phase in the nanocomposites were determined by using atomic absorption spectroscopy (AA) for silver, and were found to be 0.2, 0.4, 0.8 and 1.5 wt.%. Optical absorption studies in the wavelength range 190–900 nm showed additional peak at 420 nm for differently doped films, in addition to the peak at 200 nm for undoped PVA film. There is observable change in the absorbed intensity at 420 nm with filling levels. This is due to the link between the Ag metal ion and the polymer OH- groups. The indirect energy gaps were calculated. It was found that Young’s modulus and the strength at the break increase, while the energy gaps and the strain decrease as the concentration of Ag content is increased. The XRD results showed that the Ag nanoparticles entering the polymer PVA matrix and the crystallinity was strongly influenced by the amount of Ag nanoparticles. The electron diffraction image for the highest concentration sample shows the crystalline nature of the silver metal nanoparticles. TEM of the nanocomposite films revealed the presence of Ag particles with average diameter of 12 nm.

  13. Visible-light induced photocatalysis of AgCl@Ag/titanate nanotubes/nitrogen-doped reduced graphite oxide composites

    Science.gov (United States)

    Pan, Hongfei; Zhao, Xiaona; Fu, Zhanming; Tu, Wenmao; Fang, Pengfei; Zhang, Haining

    2018-06-01

    High recombination rate of photogenerated electron-hole pairs and relatively narrow photoresponsive range of TiO2-based photocatalysts are the remaining challenges for their practical applications. To address such challenges, photocatalysts consisting of AgCl covered Ag nanoparticles (AgCl@Ag), titanate nanotubes (TiNT), and nitrogen-doped reduced graphite oxide (rGON) are fabricated through alkaline hydrothermal process, followed by deposition and in situ surface-oxidation of silver nanoparticles. In the synthesized photocatalysts, the titanate nanotubes have average length of about 100 nm with inner diameters of about 5 nm and the size of the formed silver nanoparticles is in the range of 50-100 nm. The synthesized photocatalyst degrades almost all the model organic pollutant Rhodamine B in 35 min and remains 90% of photocatalytic efficiency after 5 degradation cycles under visible light irradiation. Since the oxidant FeCl3 applied for oxidation of surface Ag to AgCl is difficult to be completely removed due to the high adsorption capacity of TiNT and rGON, the effect of reside Fe atoms on photocatalytic activity is evaluated and the results reveal that the residue Fe atom only affect the initial photodegradation performance. Nevertheless, the results demonstrate that the formed composite catalyst is a promising candidate for antibiosis and remediation in aquatic environmental contamination.

  14. Photocatalytic deposition of Ag nanoparticles on TiO2: Metal precursor effect on the structural and photoactivity properties

    Directory of Open Access Journals (Sweden)

    E. Albiter

    2015-09-01

    Full Text Available A series of 1 wt.% Ag–TiO2 photocatalysts were obtained by photodeposition using different organic (acetylacetonate, Ag-A and inorganic (nitrate, Ag-N, and perchlorate, Ag-C silver precursors in order to determinate the influence of the silver precursor on final properties of the photocatalysts. The resulting photocatalytic materials were characterized by different techniques (UV–Vis DRS, TEM/HRTEM and XPS and their photocatalytic activity was evaluated in the degradation of rhodamine B (used as model pollutant in aqueous solution under simulated solar light. The photocatalytic reduction of Ag species to Ag0 on TiO2 was higher with silver nitrate as precursor compared to acetylacetonate or perchlorate. All the Ag-modified TiO2 photocatalysts exhibited a surface plasmon resonance effect in the visible region (400–530 nm indicating different metal particle sizes depending on the Ag precursor used in their synthesis. A higher photocatalytic activity was obtained with all the Ag/TiO2 samples compared with non-modified TiO2. The descending order of photocatalytic activity was as follows: Ag-A/TiO2 ≈ Ag-N/TiO2 > Ag-C/TiO2 > TiO2-P25. The enhanced photoactivity was attributed to the presence of different amounts Ag0 nanoparticles homogeneously distributed on Ag2O and TiO2, trapping the photogenerated electrons and avoiding charge recombination.

  15. Eco-friendly biosynthesis, anticancer drug loading and cytotoxic effect of capped Ag-nanoparticles against breast cancer

    Science.gov (United States)

    Naz, M.; Nasiri, N.; Ikram, M.; Nafees, M.; Qureshi, M. Z.; Ali, S.; Tricoli, A.

    2017-11-01

    The work aimed to prepare silver nanoparticles (Ag-NPs) from silver nitrate and various concentrations of the seed extract ( Setaria verticillata) by a green synthetic route. The chemical and physical properties of the resulting Ag-NPs were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry and ultraviolet-visible (UV-Vis) spectrophotometry. Anticancer activity of Ag-NPs (5-20 nm) had dose-dependent cytotoxic effect against breast cancer (MCF7-FLV) cells. The in vitro toxicity was studied on adult earthworms (Lumbricina) resulting in statistically significant ( P < 0.05) inhibition. The prepared NPs were loaded with hydrophilic anticancer drugs (ACD), doxorubicin (DOX) and daunorubicin (DNR), for developing a novel drug delivery carrier having significant adsorption capacity and efficiency to remove the side effects of the medicines effective for leukemia chemotherapy.

  16. Self-Assembled Polyelectrolyte Nanoparticles as Fluorophore-Free Contrast Agents for Multicolor Optical Imaging

    Directory of Open Access Journals (Sweden)

    Da Hye Shin

    2015-03-01

    Full Text Available In this work, we describe the fabrication of self-assembled polyelectrolyte nanoparticles that provide a multicolor optical imaging modality. Poly(γ-glutamic acid(γ-PGA formed self-assembled nanoparticles through electrostatic interactions with two different cationic polymers: poly(L-lysine(PLL and chitosan. The self-assembled γ-PGA/PLL and γ-PGA/chitosan nanoparticles were crosslinked by glutaraldehyde. Crosslinking of the ionic self-assembled nanoparticles with glutaraldehyde not only stabilized the nanoparticles but also generated a strong autofluorescence signal. Fluorescent Schiff base bonds (C=N and double bonds (C=C were generated simultaneously by crosslinking of the amine moiety of the cationic polyelectrolytes with monomeric glutaraldehyde or with polymeric glutaraldehyde. The unique optical properties of the nanoparticles that resulted from the crosslinking by glutaraldehyde were analyzed using UV/Vis and fluorescence spectroscopy. We observed that the fluorescence intensity of the nanoparticles could be regulated by adjusting the crosslinker concentration and the reaction time. The nanoparticles also exhibited high performance in the labeling and monitoring of therapeutic immune cells (macrophages and dendritic cells. These self-assembled nanoparticles are expected to be a promising multicolor optical imaging contrast agent for the labeling, detection, and monitoring of cells.

  17. Toxicity assessment of silver nanoparticles in Persian sturgeon (Acipenser persicus) and starry sturgeon (Acipenser stellatus) during early life stages.

    Science.gov (United States)

    Banan, Ashkan; Kalbassi Masjed Shahi, Mohammad Reza; Bahmani, Mahmoud; Yazdani Sadati, Mohammad Ali

    2016-05-01

    Silver nanoparticles (AgNPs) are widely used in consumer products mainly due to their antimicrobial action. The rapidly increasing use of nanoparticles (NPs) has driven more attention to their possible ecotoxicological effects. In this study, the acute toxicity of colloidal AgNPs was evaluated during the embryonic stage of Persian sturgeon (Acipenser persicus) and starry sturgeon (Acipenser stellatus) at concentrations of 0, 0.25, 0.5, 1, 2, 4, and 8 mg/L. Fertilized eggs (75 eggs per replicate) were exposed to aforementioned concentrations for 96 h in triplicate. 96-h LC50 values in Persian sturgeon and starry sturgeon were calculated as 0.163 and 0.158 mg/L, respectively. Furthermore, in starry sturgeon, the short-term effects of AgNPs on the hatching rate, survival rate, and Ag accumulation during early life stages (before active feeding commences) were also analyzed at concentrations of 0, 0.025, 0.05, and 0.1 mg/L of colloidal AgNPs. The highest silver accumulation occurred in larvae exposed to 0.1 mg/L AgNPs; however, the body burden of silver did not alter survival rate, and there were no significant differences among treatments. Based on the obtained results from the acute toxicity exposures, AgNPs induced a concentration-dependent toxicity in both species during early life stages, while complementary studies are suggested for investigating their short-term effects in detail.

  18. Visible-light photoactivity of plasmonic silver supported on mesoporous TiO{sub 2} nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

    Energy Technology Data Exchange (ETDEWEB)

    Jaafar, N.F. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Jalil, A.A., E-mail: aishahaj@utm.my [Centre of Hydrogen Energy, Institute of Future Energy, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia)

    2017-01-15

    Highlights: • Ag{sup 0} loaded on MTN was prepared by a direct in-situ electrochemical method. • The introduction of Ag{sup 0} lowers the band gap and increases the number of OV and TSD. • Ag{sup 0} acted as an electrons trapper and also a plasmonic sensitizer. • The formation of Ti-O-Ag in 10 wt% Ag-MTN decreased the amount of Ag{sup 0}, TSD and OV. • 5 wt% Ag-MTN gave the highest percentage of photodegradation of 2-CP. - Abstract: Various weight loadings of Ag (1–10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti{sup 3+} site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag{sup 0} and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag{sup 0}, TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

  19. Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

    International Nuclear Information System (INIS)

    Qu Jiao; Yuan Xing; Wang Xinhong; Shao Peng

    2011-01-01

    A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg -1 in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg -1 ) and accumulated biomass (with a mean dry weight of 25.7 g plant -1 ) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources. - Highlights: → P. alkekengi plants were used to remediate the Zn-contaminated soils. → Zn in P. alkekengi plants were used as a material to synthesize ZnO nanoparticles. → P. alkekengi plants absorbed large amounts of Zn from soils into its aerial parts. → The synthesized ZnO nanoparticles were not uniform. → The mean size of synthesized ZnO nanoparticles was 72.5 nm. - ZnO nanoparticles were synthesized using P. alkekengi plants, which absorbed large amounts of Zn from contaminated soils.

  20. Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

    Energy Technology Data Exchange (ETDEWEB)

    Qu Jiao, E-mail: qujiao@bhu.edu.cn [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China); Yuan Xing, E-mail: yuanx@nenu.edu.cn [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China); Wang Xinhong; Shao Peng [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China)

    2011-07-15

    A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg{sup -1} in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg{sup -1}) and accumulated biomass (with a mean dry weight of 25.7 g plant{sup -1}) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources. - Highlights: > P. alkekengi plants were used to remediate the Zn-contaminated soils. > Zn in P. alkekengi plants were used as a material to synthesize ZnO nanoparticles. > P. alkekengi plants absorbed large amounts of Zn from soils into its aerial parts. > The synthesized ZnO nanoparticles were not uniform. > The mean size of synthesized ZnO nanoparticles was 72.5 nm. - ZnO nanoparticles were synthesized using P. alkekengi plants, which absorbed large amounts of Zn from contaminated soils.