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Sample records for capped cds nanoparticles

  1. Sulfonsuccinate (AOT Capped Pure and Mn-Doped CdS Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. Venkatesan

    2012-01-01

    Full Text Available CdS nanoparticles and thin films are well known for their excellent semiconducting properties. When transition metal ions are doped into the CdS, it exhibits magnetic properties in addition to semiconducting properties and they are termed as dilute magnetic semiconductors (DMSs. In this paper, we discuss the preparation of sodium bis(2-ethylhexyl sulfonsuccinate (AOT capped CdS nanoparticles and thin films doped with magnetic impurity Mn. Sodium bis(2-ethulexyl sulfonsuccinate (AOT, capping agent promotes the uniform formation of nanoparticles. Optical characterizations are made using the UV-Vis spectrometer, PL, and FTIR. XRD shows the hexagonal structure of the CdS. SEM images and EDS measurements were made for the thin films. EPR shows the clear hyperfine lines corresponding to Mn2+ ion in the CdS nanoparticles.

  2. Formation of CdS nanoparticles using starch as capping agent

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, P. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion 11500, Mexico D.F. (Mexico); Munoz-Aguirre, N. [Seccion de Estudios de Posgrado e Investigacion, ESIME-IPN Azcapotzalco, Av. Las Granjas 682, Col. Santa Catarina, 02550 Mexico D.F. (Mexico); Martinez, E. San-Martin [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion 11500, Mexico D.F. (Mexico); Seccion de Estudios de Posgrado e Investigacion, ESIME-IPN Azcapotzalco, Av. Las Granjas 682, Col. Santa Catarina, 02550 Mexico D.F. (Mexico); Departamento de Fisica, CINVESTAV-IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico); Gonzalez, G. [Departamento de Fisica, CINVESTAV-IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)], E-mail: bato@fis.cinvestav.mx; Zelaya, O.; Mendoza, J. [Departamento de Fisica, CINVESTAV-IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)

    2008-11-30

    CdS nanoparticles have been synthesized using starch as capping agent in aqueous solution. The morphology and crystalline structure of such samples were measured by high-resolution transmission electron microscopy and X-ray diffraction, respectively. The average grain size of the nanoparticles determined by these techniques was of the order of 5 nm. Photoluminescence of CdS nanoparticles shows a strong emission peak below to the band gap bulk semiconductor attributed to center trap states, also the broadening peak was interpreted in terms of electron-phonon interaction.

  3. Effect of precursor concentration, temperature and capping group on the morphology of CdS nanoparticles

    CSIR Research Space (South Africa)

    Moloto, N

    2008-01-01

    Full Text Available A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The CdS...

  4. Effect of temperature, precursor concentration and capping group on the shape of Cds nanoparticles

    CSIR Research Space (South Africa)

    Moloto, N

    2009-01-01

    Full Text Available A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The CdS...

  5. Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

    International Nuclear Information System (INIS)

    Darwish, Maher; Mohammadi, Ali; Assi, Navid

    2016-01-01

    Highlights: • PVP-stabilized CdS nanoparticles have been fabricated by a polyol-microwave method. • CdS nanoparticles were characterized and the size was approximately 48 ± 10 nm. • Catalytic activity of our nanoparticles was examined for tartrazine degradation. • Remarkable results were obtained under both UV and visible light irradiations. - Abstract: Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.

  6. Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, Maher, E-mail: m-darwish@razi.tums.ac.ir [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mohammadi, Ali, E-mail: alimohammadi@tums.ac.ir [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Assi, Navid, E-mail: navid_a30@yahoo.com [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2016-02-15

    Highlights: • PVP-stabilized CdS nanoparticles have been fabricated by a polyol-microwave method. • CdS nanoparticles were characterized and the size was approximately 48 ± 10 nm. • Catalytic activity of our nanoparticles was examined for tartrazine degradation. • Remarkable results were obtained under both UV and visible light irradiations. - Abstract: Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.

  7. Dichloro (bis[diphenylthiourea] cadmium complex as a precursor for HDA-capped CdS nanoparticles and their solubility in water

    Directory of Open Access Journals (Sweden)

    Tshinyadzo R. Tshikhudo

    2010-07-01

    Full Text Available A single-source precursor route has been explored by using the diphenylthiourea cadmium complex as the source of cadmium sulphide (CdS nanoparticles. The reaction was carried out using hexadecylamine (HDA as the solvent and stabilising agent for the particles. The phenylthiourea complex was synthesised and characterised by means of a combination of spectroscopic techniques, microanalysis and X-ray crystal structural analysis. The diphenylthiourea complex was thermolysed in HDA at 120 °C for 1 h to produce CdS nanoparticles. The CdS nanoparticles prepared were made water-soluble via a ligand exchange reaction involving the use of pyridine to displace HDA. The pyridine was, in turn, replaced by glucose and glucuronic acid. The absorption and emission spectra showed the typical features of quantum confinement for the nanoparticles for both HDA-capped and glucose- or glucuronic acid-capped CdS nanoparticles. The change in the capping groups, from HDA to glucose and glucuronic acid, resulted in absorption and emission features that were almost similar, with only slight red-shifting and tailing.

  8. Synthesis and Characterization of Hexadecylamine Capped ZnS, CdS, and HgS Nanoparticles Using Heteroleptic Single Molecular Precursors

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2014-01-01

    Full Text Available Zn(II, Cd(II, and Hg(II complexes of tetramethyl thiuram disulfides and 1-ethoxylcarbonyl-1-ethylenecarbonyl-2-dithiolate were synthesized and characterized by elemental analysis, FTIR, and 1H- and 13C-NMR spectroscopy. The complexes were thermolysed in hexadecylamine as single molecule precursors to prepare HDA capped ZnS, CdS, and HgS nanoparticles. The optical and structural properties of the nanoparticles are reported. ZnS nanoparticles existed in the hexagonal phase with particle sizes of 8–15 nm; the CdS nanoparticles in the cubic phase have particle sizes in the range 4–7 nm and the HgS nanoparticles indexed to face-centered cubic phase have an average particle size of 7–12 nm.

  9. Dichloro (bis[diphenylthiourea]) cadmium complex as a precursor for HDA-capped CdS nanoparticles and their solubility in water

    OpenAIRE

    Tshinyadzo R. Tshikhudo; Manuel Fernandes; Makwena J. Moloto; Poslet M. Shumbula

    2010-01-01

    A single-source precursor route has been explored by using the diphenylthiourea cadmium complex as the source of cadmium sulphide (CdS) nanoparticles. The reaction was carried out using hexadecylamine (HDA) as the solvent and stabilising agent for the particles. The phenylthiourea complex was synthesised and characterised by means of a combination of spectroscopic techniques, microanalysis and X-ray crystal structural analysis. The diphenylthiourea complex was thermolysed in HDA at 120 ºC for...

  10. Biosynthesis of CdS nanoparticles in banana peel extract.

    Science.gov (United States)

    Zhou, Guang Ju; Li, Shuo Hao; Zhang, Yu Cang; Fu, Yun Zhi

    2014-06-01

    Cadmium sulfide (CdS) nanoparticles (NPs) were synthesized by using banana peel extract as a convenient, non-toxic, eco-friendly 'green' capping agent. Cadmium nitrate and sodium sulfide are main reagents. A variety of CdS NPs are prepared through changing reaction conditions (banana extracts, the amount of banana peel extract, solution pH, concentration and reactive temperature). The prepared CdS colloid displays strong fluorescence spectrum. X-ray diffraction analysis demonstrates the successful formation of CdS NPs. Fourier transform infra-red (FTIR) spectrogram indicates the involvement of carboxyl, amine and hydroxyl groups in the formation of CdS NPs. Transmission electron microscope (TEM) result reveals that the average size of the NPs is around 1.48 nm.

  11. Synthesis of CdS nanoparticles quantum dots capped by 2,2′-dithiodibenzoic acid and study of its interaction with some transition metal ions

    International Nuclear Information System (INIS)

    Hosseini, Mohammad Saeid; Jahanbani, Hamideh

    2013-01-01

    In this work, CdS quantum dots (QDs) capped by 2,2′-dithiodibenzoic acid (DDBA) were prepared at one step. The size, shape, components and spectral properties of DDBA-capped-CdS QDs were characterized by transmission electron microscopy, infrared spectrometry and spectroflourometry. The results showed that the prepared QDs with an average diameter of 15 nm have a favorable fluorescence, which is highly affected by pH of the environment. Interaction of some heavy metal ions including Ag(I), Hg(II), Cu(II), Fe(II), Ni(II), pb(II), Mn(II), Zn(II) and Co(II) with DDBA-capped-CdS QDs was investigated at different buffering pH media. Based on the fluorescence quenching of the QDs in the presence of metal ion of interest, feasibility of their determinations were examined according to the Stern–Volmer equation. The investigations showed that Ag(I) ions can be determined in the presence of many co-existence metal ions at the buffering pH of 7. This method was then applied for Ag(I) measurement in some environmental samples, satisfactorily. -- Highlights: ► A new CdS quantum dot capped with 2,2′-dithiodibenzoic acid (DDBA) was prepared. ► The prepared QDs benefit from a favorable fluorescence. ► Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. ► The determination of Ag(I) is feasible in the presence of many co-existence metal ions. ► The method benefits from high-speed and considerable simplicity for Ag(I) determination

  12. Synthesis and Characterization of CdS Nanoparticles with Strong Electrolyte Behavior

    International Nuclear Information System (INIS)

    Zhang Yu; Fu, Degang; Liu Juzheng

    2000-01-01

    The CdS nanoparticles whose structure is similar to a strong electrolyte were synthesized by the colloidal chemical method. The CdS nanoparticles with Cd 2+ -rich surface are capped by the electrically neutral ligand of 2,2'-bipyridine (bpy), and the counterion, BPh 4 - , is adsorbed around the particle as balance charge. The ω donation from 2,2'-bipyridine at 2-position to the Cd 2+ -rich surface of the CdS nanoparticles was characterized by X-ray photoelectron spectroscopy (XPS). These CdS nanoparticles can redisperse in pyridine (py) or DMF, and have high stability. The determination of electroconductivity and the electrophoresis deposition in dilute solution containing the CdS nanoparticles further prove the rationality of the above electrolyte structure of the CdS nanoparticles

  13. Preconcentration determination of arsenic species by sorption of As(V) on Amberlite IRA-410 coupled with fluorescence quenching of L-cysteine capped CdS nanoparticles.

    Science.gov (United States)

    Hosseini, Mohammad Saeid; Nazemi, Sahar

    2013-10-07

    A simple and accurate method for arsenic speciation analysis in natural and drinking water samples is described in which preconcentration of arsenic as As(V) was coupled with spectrofluorometric determination. The extracted As(V) species with a column containing Amberlite IRA-410 were subjected to L-cysteine capped CdS quantum dots (QDs) and the fluorescence quenching of the QDs due to reduction of As(V) by L-cysteine was considered as a signal relevant to As(V) concentration. The As(III) species were also determined after oxidation of As(III) ions to As(V) with H2O2 and measurement of the total arsenic content. In treatment with 400 mL portions of water samples containing 30 μg L(-1) As(V), the relative standard deviation was 2.8%. The detection limit of arsenic was also found to be 0.75 μg L(-1) (1 × 10(-8) M). The reliability of proposed method was confirmed using certified reference materials. The trace amounts of arsenic species were then determined in different water samples, satisfactorily.

  14. Growth kinetics and long-term stability of CdS nanoparticles in aqueous solution under ambient conditions

    International Nuclear Information System (INIS)

    Mullaugh, Katherine M.; Luther, George W.

    2011-01-01

    The ubiquity of naturally occurring nanoparticles in the aquatic environment is now widely accepted, but a better understanding of the conditions that promote their formation and persistence is needed. Using cadmium sulfide (CdS) as a model metal sulfide species, thiolate-capped CdS nanoparticles were prepared in the laboratory to evaluate how aquatic conditions influence metal sulfide nanoparticle growth and stability. This work examines CdS nanoparticle growth directly in aqueous solution at room temperature by utilizing the size-dependent spectroscopic properties of semiconductors detectable by UV/vis. CdS nanoparticle growth was governed by oriented attachment, a non-classical mechanism of crystallization in which small precursor nanoparticles coalesce to form larger nanoparticle products. Nanoparticle growth was slowed with increasing capping agent and decreasing ionic strength. In addition to examining the short-term (hours) growth of the nanoparticles, a long-term study was conducted in which cysteine-capped CdS nanoparticles were monitored over 3 weeks in solutions of various ionic strengths. The long-term study revealed an apparent shift from small nanoparticles to nanoparticles twice their original size, suggesting nanoparticle growth may continue through oriented attachment over longer time scales. High-ionic strength solutions resulted in salt-induced aggregation and eventual settling of nanoparticles within days, whereas low-ionic strength solutions were stable against settling over the course of the experiment. Sulfide recovery from cysteine-capped CdS nanoparticles as acid volatile sulfide was nearly quantitative after 2 weeks in fully oxygenated water, demonstrating significantly slowed oxidation of sulfide when complexed to Cd(II) within CdS nanoparticles. The nanoparticles were also shown to be resistant to oxidation by Fe(III) (hydr)oxide. This study illustrates that aggregation, rather than chemical oxidation, is likely more important to the

  15. Rapid biosynthesis of cadmium sulfide (CdS) nanoparticles using ...

    African Journals Online (AJOL)

    Rapid biosynthesis of cadmium sulfide (CdS) nanoparticles using culture supernatants of Escherichia coli ATCC 8739, Bacillus subtilis ATCC 6633 and Lactobacillus ... The process of extracellular and fast biosynthesis may help in the development of an easy and eco-friendly route for the synthesis of CdS nanoparticles.

  16. Synthesis of water soluble CdS nanoparticles and study of their DNA damage activity

    Directory of Open Access Journals (Sweden)

    Kumar Suranjit Prasad

    2017-05-01

    Full Text Available This study reports a novel method for preparation of water soluble CdS nanoparticles using leaf extract of a plant, Asparagus racemosus. The extract of the leaf tissue which worked as a stabilizing and capping agent, assisted the formation of nanoparticles. Nanoparticles were characterized using a UV–vis spectrophotometer, Photoluminescence, TEM, EDAX, XRD and FT-IR. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, crystalline, CdS of diameter ranging from 2 to 8 nm. X-ray diffraction studies showed the formation of 111, 220 and 311 planes of face-centered cubic (fcc CdS. EDAX analysis confirmed the presence of Cd and S in nanosphere. The cytotoxicity test using MTT assay as well as DNA damage analysis using comet assay revealed that synthesized nano CdS quantum dots (QDs caused less DNA damage and cell death of lymphocytes than pure CdS nanoparticles.

  17. Simple and green synthesis of protein-conjugated CdS nanoparticles and spectroscopic study on the interaction between CdS and zein

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Dezhi, E-mail: dezhiqin@163.com; Zhang, Li; Du, Xian; Wang, Yabo; Zhang, Qiuxia [Pingdingshan University, College of Chemistry and Environmental Engineering (China)

    2016-09-15

    The present study demonstrates the role of zein molecules in synthesizing CdS nanoassemblies through protein-directed, green synthetic approach. Zein molecules can as capping ligand and stabilizing agent to regulate the nucleation and growth of CdS nanocrystals, and the obtained products are organic–inorganic nanocomposites. The analysis of surface charge and conductivity indicates that strong electrostatic force restricts mobility of ions, which creates a local supersaturation surrounding the binding sites of zein and reduces the activated energy of nucleation. The interaction between Cd{sup 2+}/CdS and zein molecules was systematically investigated through spectroscopy techniques. Fourier transform infrared (FT-IR) spectra were used to envisage the binding of the functional groups of zein with the surface of CdS nanoparticles. Ultraviolet visible (UV–Vis) and photoluminescence (PL) spectra results show that Cd{sup 2+}/CdS might interact with the aromatic amino acids of protein molecules and change its chemical microenvironment. The quantum-confined effect of nanocrystals is confirmed by optical absorption spectrum due to the small size (3–5 nm) of CdS particles. The data of circular dichroism (CD) spectra indicate that the formation of CdS nanocrystals could lead to the conformational change of zein molecules. Moreover, the possible mechanism of CdS nanocrystals growth in zein solution was also discussed. The weak interactions such as Van der Waals, hydrophobic forces and hydrogen bonds in zein molecules should play a crucial factor in the self-assembly of small nanoparticles.

  18. Enhancement of visible light photocatalytic activity of ZnS and CdS nanoparticles based on organic and inorganic coating

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, Nayereh, E-mail: nayereh.soltani@gmail.com [Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Saion, Elias; Yunus, W. Mahmood Mat; Erfani, Maryam; Navasery, Manizheh; Bahmanrokh, Ghazaleh [Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Rezaee, Kadijeh [Department of Nuclear Engineering, Faculty of Advance Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2014-01-30

    Coating of ZnS and CdS nanoparticles with organic and inorganic materials can extend their light absorption in the visible region and their stability against photo-corrosion. Such materials could emerge as excellent photocatalysts for the elimination of pollutants from aqueous media using solar energy. In this study, PVP (polyvinyl pyrrolidone)-capped ZnS and CdS nanoparticles, ZnS/CdS and CdS/ZnS core shell nanoparticles were synthesized by microwave irradiation method and characterized using different techniques. The XRD patterns exhibited cubic and hexagonal structures for coated ZnS and CdS nanoparticles, respectively. Morphological evaluation of TEM images showed that the nanoparticles are generally spherical in shape. The UV–visible spectra confirmed a shift in the band gap of coated nanoparticles to longer or shorter wavelengths due to size and potential-well effects. The photocatalytic activity of nanoparticles toward dye degradation under visible light was found to be improved after coating. PVP-capped ZnS and CdS exhibited an enhancement in the initial methylene blue degradation efficiency by a factor of about 1.3. ZnS nanoparticles coated by CdS displayed the initial efficiency 3.2 times higher than bare ZnS. The maximum dye removal was obtained in presence of CdS/ZnS core shells which is 1.4 times more efficient than bare CdS.

  19. Characterization of chemically synthesized CdS nanoparticles

    Indian Academy of Sciences (India)

    Similar to the effects of charge carriers on optical properties, confinement of optical and acoustic phonons leads to interesting changes in the phonon spectra. In the present work, we have synthesized nanoparticles of CdS using chemical precipitation technique. The crystal structure and grain size of the particles are studied ...

  20. The toxic effects of l-Cysteine-capped cadmium sulfide nanoparticles on the aquatic plant Spirodela polyrrhiza

    International Nuclear Information System (INIS)

    Khataee, Alireza; Movafeghi, Ali; Nazari, Fatemeh; Vafaei, Fatemeh; Dadpour, Mohammad Reza; Hanifehpour, Younes; Joo, Sang Woo

    2014-01-01

    Plants play an important role in the fate of nanoparticles in the environment through their uptake, bioaccumulation, and transfer to trophic chains. However, the impacts of nanoparticles on plants as essential components of all ecosystems are not well documented. In the present study, the toxic effects of l-Cysteine-capped CdS nanoparticles on Spirodela polyrrhiza as an aquatic higher plant species were studied. l-Cysteine-capped CdS nanoparticles were synthesized using hydrothermal method and their characteristics were determined by XRD, SEM, HR-TEM, and FT-IR techniques. The diameter of majority of synthesized nanoparticles was about 15–20 nm. Subsequently, the uptake of l-Cysteine-capped CdS nanoparticles by the plant species was confirmed using epifluorescence microscopy. The activity of peroxidase and superoxide dismutase as antioxidant enzymes was assayed and the relative frond number was calculated in the presence of different concentrations of l-Cysteine-capped CdS nanoparticles. The obtained results revealed the toxic effects of the synthesized nanoparticles on S. polyrrhiza, leading to growth reduction and significant changes in antioxidant enzymes’ activity.Graphical Abstract

  1. The toxic effects of l-Cysteine-capped cadmium sulfide nanoparticles on the aquatic plant Spirodela polyrrhiza

    Energy Technology Data Exchange (ETDEWEB)

    Khataee, Alireza, E-mail: ar_khataee@yahoo.com [University of Tabriz, Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry (Iran, Islamic Republic of); Movafeghi, Ali [University of Tabriz, Department of Plant Biology, Faculty of Natural Sciences (Iran, Islamic Republic of); Nazari, Fatemeh [University of Tabriz, Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry (Iran, Islamic Republic of); Vafaei, Fatemeh [University of Tabriz, Department of Plant Biology, Faculty of Natural Sciences (Iran, Islamic Republic of); Dadpour, Mohammad Reza [University of Tabriz, Department of Horticultural Science, Faculty of Agriculture (Iran, Islamic Republic of); Hanifehpour, Younes; Joo, Sang Woo, E-mail: swjoo@yu.ac.kr [Yeungnam University, School of Mechanical Engineering (Korea, Republic of)

    2014-12-15

    Plants play an important role in the fate of nanoparticles in the environment through their uptake, bioaccumulation, and transfer to trophic chains. However, the impacts of nanoparticles on plants as essential components of all ecosystems are not well documented. In the present study, the toxic effects of l-Cysteine-capped CdS nanoparticles on Spirodela polyrrhiza as an aquatic higher plant species were studied. l-Cysteine-capped CdS nanoparticles were synthesized using hydrothermal method and their characteristics were determined by XRD, SEM, HR-TEM, and FT-IR techniques. The diameter of majority of synthesized nanoparticles was about 15–20 nm. Subsequently, the uptake of l-Cysteine-capped CdS nanoparticles by the plant species was confirmed using epifluorescence microscopy. The activity of peroxidase and superoxide dismutase as antioxidant enzymes was assayed and the relative frond number was calculated in the presence of different concentrations of l-Cysteine-capped CdS nanoparticles. The obtained results revealed the toxic effects of the synthesized nanoparticles on S. polyrrhiza, leading to growth reduction and significant changes in antioxidant enzymes’ activity.Graphical Abstract.

  2. A simple route to shape controlled CdS nanoparticles

    Science.gov (United States)

    Nejo, Ayorinde O.; Nejo, Adeola A.; Pullabhotla, Rajasekhar V. S. R.; Revaprasadu, Neerish

    2013-02-01

    We report the synthesis of CdS nanoparticles in the form of spheres, triangles and wire-like structures. The method involves the reaction of reduced sulfur with a cadmium salt followed by thermolysis in hexadecylamine (HDA). The different shapes were obtained by variation of reaction conditions such as reaction time, temperature and cadmium source. The optical studies show the particles to be quantum confined and luminescent at room temperature.

  3. Synthesis and spectral studies on Cd(II) dithiocarbamate complexes and their use as precursors for CdS nanoparticles

    Science.gov (United States)

    Sathiyaraj, Ethiraj; Padmavathy, Krishnaraj; Kumar, Chandran Udhaya; Krishnan, Kannan Gokula; Ramalingan, Chennan

    2017-11-01

    Bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (1) and (2,2‧-bipyridine) bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (2) have been synthesized and characterized by FT-IR, 1HNMR and 13C NMR analyses. For the complex 2, single crystal X-ray diffraction analysis and computational studies (optimized geometry, HOMO-LUMO and MEP) have been executed employing DFT/B3LYP method with LANL 2DZ basic set. The optimized bond lengths and bond angles agree well with the experimental results. The complexes 1 and 2 have been used as single source precursors for the synthesis of ethyleneglycol capped CdS1 and CdS2 nanoparticles, respectively. CdS1 and CdS2 nanoparticles have been synthesized by solvothermal method. PXRD, SEM, Elemental colour mapping, EDAX, TEM and UV-Vis spectroscopy have been used to characterize the as-prepared CdS nanoparticles. The X-ray diffraction pattern confirms both their hexagonal structures.

  4. Study of optical phonon modes of CdS nanoparticles using Raman

    Indian Academy of Sciences (India)

    In this paper we report the study of optical phonon modes of nanoparticles of CdS using Raman spectroscopy. Nanoparticle sample for the present study was synthesized through chemical precipitation technique. The CdS nanoparticles were then subjected to heat treatment at low temperature (150°C) for extended time ...

  5. Biosynthesis and characterization of cadmium sulfide nanoparticles – An emphasis of zeta potential behavior due to capping

    International Nuclear Information System (INIS)

    Sankhla, Aryan; Sharma, Rajeshwar; Yadav, Raghvendra Singh; Kashyap, Diwakar; Kothari, S.L.; Kachhwaha, S.

    2016-01-01

    Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m 2 /g and 117 ± 2.41 m 2 /g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area and

  6. Biosynthesis and characterization of cadmium sulfide nanoparticles – An emphasis of zeta potential behavior due to capping

    Energy Technology Data Exchange (ETDEWEB)

    Sankhla, Aryan, E-mail: aaryansankhla@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Sharma, Rajeshwar; Yadav, Raghvendra Singh [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Kashyap, Diwakar [Department of Biological Chemistry, Ariel University, Ariel, 40700 (Israel); Kothari, S.L. [Institute of Biotechnology, Amity University, Jaipur, 303002 (India); Kachhwaha, S. [Department of Botany, University of Rajasthan, Jaipur, 302004 (India)

    2016-02-15

    Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m{sup 2}/g and 117 ± 2.41 m{sup 2}/g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area

  7. Synthesis and structural characterization of CdS nanoparticles using nitrogen adducts of mixed diisopropylthiourea and dithiolate derivatives of Cd(II) complexes

    Science.gov (United States)

    Osuntokun, Jejenija; Ajibade, Peter A.

    2015-07-01

    [Cd(diptu)2(ced)], [Cd(diptu)2(ced)(bpy)], [Cd(diptu)2(ced)(phen)], (where diptu = diisopropyl thiourea; ced = 1-cyano-1-carboethoxylethylene-2,2‧-dithiolate; bpy = 2,2‧-bipyridine and phen = 1,10-phenanthroline) have been prepared and used as single source precursors for the preparation of hexadecylamine capped CdS nanoparticles. The precursor complexes were characterized by elemental analysis, FTIR and TGA. The structural properties of the nanoparticles were investigated using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy techniques (SEM). The optical properties of the nanoparticles were studied using UV-Visible and photoluminescence spectroscopy. The XRD analysis showed that the nanoparticles were indexed to the hexagonal phase of CdS and the TEM results showed CdS nanoparticles with average crystallite sizes of 4.00-8.80 nm.

  8. Microwave assisted synthesis of CdS nanoparticles and their size evolution

    International Nuclear Information System (INIS)

    Lopez, I. A.; Vazquez, A.; Gomez, I.

    2013-01-01

    The study of the size evolution of CdS nanoparticles in aqueous dispersion is presented in this paper. The sodium citrate was employed as stabilizer of CdS nanoparticles synthesized by microwave assisted synthesis. Analysis of this study was carried out by UV-Vis spectrophotometry, by comparison of the band gap energy using theoretical and empirical models. Results obtained show that the synthesis conditions produce CdS nanoparticles with diameters below of 6 nm, which remains stabilized by at least 14 days. These characteristics were confirmed by transmission electron microscopy. The X-ray diffraction pattern confirms cubic phase of the CdS nanoparticles. (Author)

  9. Microwave assisted synthesis of CdS nanoparticles and their size evolution

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, I. A.; Vazquez, A.; Gomez, I., E-mail: idaliagomezmx@yahoo.com.mx [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Laboratorio de Materiales I, Av. Universidad, Cd. Universitaria, 66451 San Nicolas de los Garza, Nuevo Leon (Mexico)

    2013-05-01

    The study of the size evolution of CdS nanoparticles in aqueous dispersion is presented in this paper. The sodium citrate was employed as stabilizer of CdS nanoparticles synthesized by microwave assisted synthesis. Analysis of this study was carried out by UV-Vis spectrophotometry, by comparison of the band gap energy using theoretical and empirical models. Results obtained show that the synthesis conditions produce CdS nanoparticles with diameters below of 6 nm, which remains stabilized by at least 14 days. These characteristics were confirmed by transmission electron microscopy. The X-ray diffraction pattern confirms cubic phase of the CdS nanoparticles. (Author)

  10. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Abstract. A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  11. Mechanistic aspects of biogenic synthesis of CdS nanoparticles using Bacillus licheniformis

    International Nuclear Information System (INIS)

    Tripathi, R M; Shrivastav, Archana; Bhadwal, Akhshay Singh; Singh, Priti; Singh, M P; Shrivastav, B R

    2014-01-01

    A novel eco-friendly effort has been made for the synthesis of cadmium sulfide (CdS) nanoparticles using bacterial biomass. Although some articles have been reported on CdS nanoparticles synthesis by bacteria, here we have synthesized CdS nanoparticles using non-pathogenic bacteria Bacillus licheniformis MTCC 9555. UV-Vis spectroscopy was carried out to confirm the formation of CdS nanoparticles; the peak occurring at 368 nm gives the indication of synthesis of CdS nanoparticles. The size and morphology of the synthesized CdS nanoparticles were analyzed by transmission electron microscopy (TEM) and the nanoparticles are found to have a narrow size of 5.1 ± 0.5 nm with spherical morphology. Further, the nanoparticles were examined by energy dispersive x-ray (EDX) spectroscopy to identify the presence of elements and confirmed the existence of Cd and S in single nanoparticles. X-ray diffraction (XRD) analysis exhibited 2θ values corresponding to CdS nanocrystals. Fourier transform infrared spectroscopy (FTIR) provides the evidence for the presence of proteins as possible biomolecules responsible for the stabilization of the synthesized CdS nanoparticles. (papers)

  12. Mechanistic aspects of biogenic synthesis of CdS nanoparticles using Bacillus licheniformis

    Science.gov (United States)

    Tripathi, R. M.; Singh Bhadwal, Akhshay; Singh, Priti; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.

    2014-06-01

    A novel eco-friendly effort has been made for the synthesis of cadmium sulfide (CdS) nanoparticles using bacterial biomass. Although some articles have been reported on CdS nanoparticles synthesis by bacteria, here we have synthesized CdS nanoparticles using non-pathogenic bacteria Bacillus licheniformis MTCC 9555. UV-Vis spectroscopy was carried out to confirm the formation of CdS nanoparticles; the peak occurring at 368 nm gives the indication of synthesis of CdS nanoparticles. The size and morphology of the synthesized CdS nanoparticles were analyzed by transmission electron microscopy (TEM) and the nanoparticles are found to have a narrow size of 5.1 ± 0.5 nm with spherical morphology. Further, the nanoparticles were examined by energy dispersive x-ray (EDX) spectroscopy to identify the presence of elements and confirmed the existence of Cd and S in single nanoparticles. X-ray diffraction (XRD) analysis exhibited 2θ values corresponding to CdS nanocrystals. Fourier transform infrared spectroscopy (FTIR) provides the evidence for the presence of proteins as possible biomolecules responsible for the stabilization of the synthesized CdS nanoparticles.

  13. Mn2+ anchored CdS polymer nanocomposites: An efficient alternative for Mn2+ doped CdS nanoparticles

    International Nuclear Information System (INIS)

    Saikia, Bhaskar Jyoti; Nath, Bikash Chandra; Borah, Chandramika; Dolui, Swapan Kumar

    2015-01-01

    A chelating bi-functional polymer brushes was prepared via atom transfer radical polymerization using grafting-from methodology. Mn 2+ -anchored CdS-polymer nanocomposites were synthesized using this graft copolymer by simple chelation method resulting in emission at about 620 nm which originates from the fluorescence of manganese ions embedded on the surface of CdS nanoparticles. This method provides an efficient straightforward substitute of Mn 2+ dopped CdS nanoparticles. Optical properties of the composites were investigated which indicates that simple Mn 2+ chelation and subsequent binding of CdS in a polymer matrix can have similar effect in the luminescence property as those synthesized via complex doping methods. Moreover this methodology can be applied for synthesis of any metal anchored nanocomposites proficiently and cost effectively in large-scale production. - Highlights: • A chelating bifunctional copolymer brush was synthesized via ATRP. • CdS nanoparticles and Mn 2+ were coupled with the bifunctional polymer. • Composites showed emission properties similar to Mn 2+ doped CdS nanoparticles. • Side chain length of the polymers also affect the emission properties of the composites.

  14. Re-dispersible Li+ and Eu3+ co-doped CdS nanoparticles ...

    Indian Academy of Sciences (India)

    Also, it can be used as sensor for drug delivery in our body [12,13]. In the present work, we prepare re-dispersible CdS, Li+- and Eu3+-doped CdS nanoparticles in organic solvent by urea hydrolysis at 170◦C and their lumines- cence properties are studied. We propose the mechanism of re-dispersion of CdS nanoparticles ...

  15. Synthesis of CdS nanoparticles based on DNA network templates

    International Nuclear Information System (INIS)

    Yao Yong; Song Yonghai; Wang Li

    2008-01-01

    CdS nanoparticles have been successfully synthesized by using DNA networks as templates. The synthesis was carried out by first dropping a mixture of cadmium acetate and DNA on a mica surface for the formation of the DNA network template and then transferring the sample into a heated thiourea solution. The Cd 2+ reacted with thiourea at high temperature and formed CdS nanoparticles on the DNA network template. UV-vis spectroscopy, photoluminescence, x-ray diffraction and atomic force microscopy (AFM) were used to characterize the CdS nanoparticles in detail. AFM results showed that the resulted CdS nanoparticles were directly aligned on the DNA network templates and that the synthesis and assembly of CdS nanoparticles was realized in one step. CdS nanoparticles fabricated with this method were smaller than those directly synthesized in a thiourea solution and were uniformly aligned on the DNA networks. By adjusting the density of the DNA networks and the concentration of Cd 2+ , the size and density of the CdS nanoparticles could be effectively controlled and CdS nanoparticles could grow along the DNA chains into nanowires. The possible growth mechanism has also been discussed in detail

  16. Photoactivable caps for reactive metal nanoparticles

    Science.gov (United States)

    Patel, Ashish

    The synthesis and stabilization of reactive metal nanoparticles is often challenging under normal atmospheric conditions. This problem can be alleviated by capping and passivation. Our lab has focused on forming polymer coatings on the surface of reactive metal nanoparticles. We discovered a convenient and effective route for stabilization of aluminum nanoparticles (Al NPs), which uses the nascent metal core as a polymerization initiator for various organic monomers. In our previous work, we used this method to passivate the Al NPs using variety of epoxides and copolymers of epoxides and alkenes. These products have demonstrated air stability for weeks to months with little to no degradation in the active Al content. Since our previously synthesized Al NP's were not beneficial for rapid and efficient thermodynamic access to the active Al core, our goal was find polymers that could easily be photochemically activated to enhance such access. Since poly(methyl methacrylate) (PMMA) has photodegrading properties, we used PMMA as a capping agent to passivate Al NPs. In this work, we present capping and stabilization of Al NPs with PMMA, and also with 1,2-epoxyhexane/ PMMA. In our previous work, we increased the stability of Al NP capped with 1,2-epoxy-9-decene by adding 1,13-tetradecadiene as a cross-linker. Here, we used the methyl methacrylate (MMA) monomer as cross-linker for Al NP capped with 1,2-epoxy-9-decene. We have also used the MMA as capping agent. We use powder x-ray diffractametry (PXRD), differential scanning calorimetry (DSC), and thermogravity analysis (TGA) to confirm the presence of elemental Al and ATR-FTIR to confirm the presence of polymers.

  17. pH dependent interaction of biofunctionalized CdS nanoparticles with nucleobases and nucleotides: A fluorimetric study

    International Nuclear Information System (INIS)

    Chatterjee, Anindita; Priyam, Amiya; Bhattacharya, Subhash C.; Saha, Abhijit

    2007-01-01

    The interaction of DNA bases and corresponding nucleotides with CdS nanoparticles (NPs), biofunctionalized by cysteine, has been investigated by absorption and fluorescence spectroscopy. Unique enhancement effect of adenine, in contrast to other nucleobases, on the luminescence of cysteine capped CdS (cys-CdS) NPs at both pH 7.5 and 10.5 was found, the extent of enhancement being much higher at pH 10.5. At the latter pH, the difference optical absorption spectra show development of new peak at 278 nm with corresponding decrease in the absorption of adenine at 260 nm, which is attributed to binding of adenine anion to the CdS surface through N7 of the purine ring. Appearance of a new band at 478 cm -1 and concomitant shift in the C 8 -N 7 vibrations to 1610 cm -1 in the FTIR spectra of cys-CdS NPs with adenine also suggest Cd-N7 binding on the particle surface. Amongst various nucleotides, ATP exhibited maximum luminescence enhancement on CdS NPs for a given change in concentration in the micro-molar range at physiological pH. A quantitative correlation between ATP concentration and PL enhancement of CdS NPs has been established, a step which in future might assist in developing new protocols for fluorescence sensing of adenine nucleotides under certain pathological conditions

  18. Influence of Irradiation Time on properties of CdS Nanoparticles Synthesized using Microwave Irradiation

    International Nuclear Information System (INIS)

    Nayereh Soltani; Elias SSaion; Maryam Erfani; Mohd Zobir Hussein; Robiah Yunus

    2011-01-01

    Different sizes of cadmium sulfide nanoparticles which exhibit obvious quantum confinement effect have been synthesized of cadmium chloride and thioacetamide through the simple and rapid microwave method. The properties of these CdS nanoparticles were examined with varying irradiation time from 10 to 40 min using a pulse regime. The obtained CdS particles were characterized by X-ray diffraction (XRD), transition electron microscopy (TEM) and UV-visible (UV-Vis) spectroscopy. The effects of irradiation time on the size, degree of crystallinity, yield of reaction and optical band gap of CdS nanoparticles are investigated. (author)

  19. Preparation of CdS Nanoparticles by First-Year Undergraduates

    Science.gov (United States)

    Winkelmann, Kurt; Noviello, Thomas; Brooks, Stephen

    2007-01-01

    The first year undergraduates use a simple method to synthesize 5-nm CdS nanoparticles in a water-in-oil microemulsion. The quantum size effect, the relationship between colors, optical absorbance, band-gap energy and the CdS particles affected by the formation of micelles are observed.

  20. The fluorescence quenching mechanism of coumarin 120 with CdS nanoparticles in aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Murat; Bozkurt, Ebru; Meral, Kadem; Arık, Mustafa; Onganer, Yavuz, E-mail: yonganer@atauni.edu.tr

    2015-01-15

    The interaction of coumarin 120 (C120) with CdS nanoparticles (CdS NPs) in aqueous suspension was examined by using UV–vis absorption, steady-state, time-resolved fluorescence, and electron paramagnetic resonance (EPR) spectroscopy techniques. The fluorescence intensity of C120 was quenched with increasing the amount of CdS NPs in the aqueous suspension. The spectroscopic data revealed that the C120 molecules adsorbed on CdS NPs via electrostatic interactions. The apparent association constant (K{sub app}) and the degree of association (α) for C120/CdS NPs were determined as 130.3 M{sup −1} and 0.51 for 4 nm CdS NPs and 624.3 M{sup −1} and 0.71 for 8 nm CdS NPs, respectively. The photoinduced EPR studies exhibited that no electron transfers between CdS and C120 taking place. The results revealed that the fluorescence quenching of C120 with different CdS NPs is due to the formation of a non-fluorescent complex. - Highlights: • Interaction of C120 with CdS NPs in aqueous solution was spectroscopically examined. • Nonfluorescent C120–CdS NPs complexes in aqueous solution were formed. • In the system, CdS NPs in aqueous solution acted as a fluorescence quencher.

  1. The fluorescence quenching mechanism of coumarin 120 with CdS nanoparticles in aqueous suspension

    International Nuclear Information System (INIS)

    Acar, Murat; Bozkurt, Ebru; Meral, Kadem; Arık, Mustafa; Onganer, Yavuz

    2015-01-01

    The interaction of coumarin 120 (C120) with CdS nanoparticles (CdS NPs) in aqueous suspension was examined by using UV–vis absorption, steady-state, time-resolved fluorescence, and electron paramagnetic resonance (EPR) spectroscopy techniques. The fluorescence intensity of C120 was quenched with increasing the amount of CdS NPs in the aqueous suspension. The spectroscopic data revealed that the C120 molecules adsorbed on CdS NPs via electrostatic interactions. The apparent association constant (K app ) and the degree of association (α) for C120/CdS NPs were determined as 130.3 M −1 and 0.51 for 4 nm CdS NPs and 624.3 M −1 and 0.71 for 8 nm CdS NPs, respectively. The photoinduced EPR studies exhibited that no electron transfers between CdS and C120 taking place. The results revealed that the fluorescence quenching of C120 with different CdS NPs is due to the formation of a non-fluorescent complex. - Highlights: • Interaction of C120 with CdS NPs in aqueous solution was spectroscopically examined. • Nonfluorescent C120–CdS NPs complexes in aqueous solution were formed. • In the system, CdS NPs in aqueous solution acted as a fluorescence quencher

  2. Enhanced photoelectrochemical properties of TiO2 nanorod arrays decorated with CdS nanoparticles

    International Nuclear Information System (INIS)

    Xie, Zheng; Wang, Weipeng; Liu, Can; Li, Zhengcao; Liu, Xiangxuan; Zhang, Zhengjun

    2014-01-01

    TiO 2 nanorod arrays (TiO 2 NRAs) sensitized with CdS nanoparticles were fabricated via successive ion layer adsorption and reaction (SILAR), and TiO 2 NRAs were obtained by oxidizing Ti NRAs obtained through oblique angle deposition. The TiO 2 NRAs decorated with CdS nanoparticles exhibited excellent photoelectrochemical and photocatalytic properties under visible light, and the one decorated with 20 SILAR cycles CdS nanoparticles shows the best performance. This can be attributed to the enhanced separation of electrons and holes by forming heterojunctions of CdS nanoparticles and TiO 2 NRAs. This provides a promising way to fabricate the material for solar energy conversion and wastewater degradation. (paper)

  3. Programmable Self-assembly of Hydrocarbon-capped Nanoparticles: Role of Chain Conformations

    Science.gov (United States)

    Waltmann, Curt; Horst, Nathan; Travesset, Alex

    Nanoparticle superlattices (NPS), i.e. crystalline arrangements of nanoparticles, are materials with fascinating structures, which in many cases are not possible to attain from simple atoms or molecules. They also span a wide range of possible applications such as metamaterials, new energy sources, catalysis, and many others. In this talk, we present a theoretical and computational description of the self-assembly of nanoparticles with hydrocarbons as capping ligands. Usually, these systems have been described with hard sphere packing models. In this talk, we show that the conformations of the hydrocarbon chains play a fundamental role in determining the equilibrium phases, including and especially in binary systems. The work of CW was supported by a DOE-SULI internship from May-December 2016, and by NSF, DMR-CMMT 1606336 CDS&E: Design Principles for Ordering Nanoparticles into Super-crystals after January 1st.

  4. Effect of silver doping on the elastic properties of CdS nanoparticles

    Science.gov (United States)

    Dey, P. C.; Das, R.

    2018-05-01

    CdS and Ag doped CdS (CdS/Ag) nanoparticles have been prepared via chemical method from a Cadmium acetate precursor and Thiourea. The synthesized CdS and CdS/Ag nanoparticles have been characterized by the X-ray Diffraction and High Resolution Transmission Electron Microscope. Here, these nanoparticles have been synthesized at room temperature and all the characterization have also been done at room temperature only. The XRD results reveal that the products are crystalline with cubic zinc blende structure. HRTEM images show that the prepared nanoparticles are nearly spherical in shape. Williamson-Hall method and Size-Strain Plot (SSP) have been used to study the individual contribution of crystalline sizes and lattice strain on the peak broadening of the CdS and CdS/Ag nanoparticles. The different modified model of Williamson-Hall method such as, uniform deformation model, uniform stress deformation model and uniform energy density deformation model and SSP method have been used to calculate the different physical parameter such as lattice strain, stress and energy density for all diffraction peaks of the XRD, corresponding to the CdS and silver doped CdS (CdS/Ag). The obtained results reveal that the average particle size of the prepared CdS and CdS/Ag nanoparticles estimated from the HRTEM images, Williamson-Hall analysis and SSP method are highly correlated with each other. Further, all these result confirms that doping of Ag significantly affects the elastic properties of CdS.

  5. Synthesis and study of optical and thermal properties of Mn doped CdS nanoparticles using polyvinylpyrrolidone

    International Nuclear Information System (INIS)

    Rajesh Kumar, M.; Murugadoss, G.

    2014-01-01

    High quality and monodispersed CdS:Mn (1–5%) nanoparticles were synthesized by chemical precipitation method using PVP as surfactant. The structure and morphology of the CdS:Mn were investigated by means of XRD, FT-IR, TEM, UV–visible, PL, EPR and TG-DTA. XRD study was confirmed the formation cubic structured CdS:Mn nanoparticles. The optical absorption of Mn doped CdS nanoparticles was found to be 420–432 nm, which is significantly decreased from the bulk CdS material. Photoluminescence spectroscopy of the CdS:Mn nanocrystals showed a strong emission peak at 535 nm near the band edge along with a week green emission around 575 nm. The PL property of annealed (255 °C–850 °C) samples was also investigated under different excitations. The presence of PVP on the CdS:Mn surface and incorporated the Mn ion into CdS lattice were identified by FT-IR and EPR spectroscopy, respectively. TEM result showed spherical with monodispersed particles with typical size of 3.8–4.3 nm, which is a favorable characteristic for many applications. The major weight loss and gain were found in the thermogravimetric analysis (TGA) which corresponds to the decomposition and oxidation of the samples. -- Highlights: • An optimum concentration of Mn was selected through optical study. • PL emission was improved by addition of capping agent. • The PL enhancement indicates good crystal quality and monodisperse of the synthesized CdS:Mn nanoparticles by chemical method

  6. In situ coating multiwalled carbon nanotubes with CdS nanoparticles

    International Nuclear Information System (INIS)

    Liu Yangqiao; Gao Lian

    2005-01-01

    CdS nanoparticles were homogeneously coated on multiwalled carbon nanotubes by an in situ method through introducing thiol groups onto the tube wall using a novel method. A cationic polyelectrolyte containing reactive imine groups, polyethyleneimine (PEI), was firstly adsorbed on the surface of nanotubes. 3-Mercaptopropionic acid (MPA) was then anchored by an amidation reaction between its carboxyl group and the imine group of the polyelectrolyte under the activation of carbodiimide reagents. These -SH terminated MWCNTs were coated with CdS nanoparticles by an in situ method. The phase composition, microstructure, and the UV-vis properties of the CdS coated MWCNTs were characterized. The addition of the carbodiimide reagents played an important role in linking the MPA with PEI covalently and subsequently coating the MWCNTs with CdS homogeneously. A blue shift in the absorption edge was observed for the MWCNTs-CdS hybrid material due to the quantum size effect

  7. Synthesis of N-acetyl-L-cysteine capped Mn:doped CdS quantum dots for quantitative detection of copper ions

    Science.gov (United States)

    Yang, Xiupei; Jia, Zhihui; Cheng, Xiumei; Luo, Na; Choi, Martin M. F.

    2018-06-01

    In this work, a new assembled copper ions sensor based on the Mn metal-enhanced fluorescence of N-acetyl-L-cysteine protected CdS quantum dots (NAC-Mn:CdS QDs) was developed. The NAC and Mn:CdS QDs nanoparticles were assembled into NAC-Mn:CdS QDs complexes through the formation of Cdsbnd S and Mnsbnd S bonds. As compared to NAC capped CdS QDs, higher fluorescence quantum yields of NAC-Mn:CdS QDs was observed, which is attributed to the surface plasmon resonance of Mn metal. In addition, the fluorescence intensity of as-formed complexes weakened in the presence of copper ions. The decrease in fluorescence intensity presented a linear relationship with copper ions concentration in the range from 0.16-3.36 μM with a detection limit of 0.041 μM . The characterization of as-formed QDs was analyzed by photoluminescence (PL), ultra violet-visible (UV-vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) respectively. Furthermore, the recoveries and relative standard deviations of Cu2+ spiked in real water samples for the intra-day and inter-day analyses were 88.20-117.90, 95.20-109.90, 0.80-5.80 and 1.20-3.20%, respectively. Such a metal-enhanced QDs fluorescence system may have promising application in chemical and biological sensors.

  8. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Science.gov (United States)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na2S and Cd(CH3COO)2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  9. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Kalayc Latin-Small-Letter-Dotless-I , Oezlem A. [Bulent Ecevit University, Department of Physics (Turkey); Duygulu, Oezguer [TUBITAK Marmara Research Center, Materials Institute (Turkey); Hazer, Baki, E-mail: bkhazer@karaelmas.edu.tr [Bulent Ecevit University, Department of Chemistry (Turkey)

    2013-01-15

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na{sub 2}S and Cd(CH{sub 3}COO){sub 2} simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  10. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    International Nuclear Information System (INIS)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na 2 S and Cd(CH 3 COO) 2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether–THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV–vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV–vis absorbance spectra and fluorescence emission spectra.

  11. Optical Properties of ZnO Nanoparticles Capped with Polymers

    Directory of Open Access Journals (Sweden)

    Atsushi Noguchi

    2011-06-01

    Full Text Available Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG and polyvinyl pyrrolidone (PVP were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging

  12. Toxicity of cadmium sulfide (CdS) nanoparticles against Escherichia coli and HeLa cells

    International Nuclear Information System (INIS)

    Hossain, Sk Tofajjen; Mukherjee, Samir Kumar

    2013-01-01

    Highlights: • Toxic effect of CdS NPs on the growth and cell division in E. coli was studied. • CdS NPs affected cell surface topology and cell division. • Downregulation of both FtsZ and FtsQ was observed due to NPs exposure. • CdS NPs affected HeLa cell morphology with fragmented nuclei. • All such effects might be due to elevated oxidative stress. -- Abstract: The present study endeavours to assess the toxic effect of synthesized CdS nanoparticles (NPs) on Escherichia coli and HeLa cells. The CdS NPs were characterized by DLS, XRD, TEM and AFM studies and the average size of NPs was revealed as ∼3 nm. On CdS NPs exposure bacterial cells changed morphological features to filamentous form and damage of the cell surface was found by AFM study. The expression of two conserved cell division components namely ftsZ and ftsQ in E. coli was decreased both at transcriptional and translational levels upon CdS NPs exposure. CdS NPs inhibited proper cell septum formation without affecting the nucleoid segregation. Viability of HeLa cells declined with increasing concentration of CdS NPs and the IC 50 value was found to be 4 μg/mL. NPs treated HeLa cells showed changed morphology with condensed and fragmented nuclei. Increased level of reactive oxygen species (ROS) was found both in E. coli and HeLa cells on CdS NPs exposure. The inverse correlation between declined cell viabilities and elevated ROS level suggested that oxidative stress seems to be the key event by which NPs induce toxicity both in E. coli and HeLa cells

  13. CdS nanoparticle sensitized titanium dioxide decorated graphene for enhancing visible light induced photoanode

    International Nuclear Information System (INIS)

    Yousefzadeh, S.; Faraji, M.; Nien, Y.T.; Moshfegh, A.Z.

    2014-01-01

    Highlights: • CdS nanoparticles were deposited on TiO 2 /graphene film by different SILAR cycles. • The visible light absorption increased due to graphene and CdS nanoparticles. • The highest photocurrent density was achieved for nanocomposite with 30 CdS cycles. • A mechanism has been suggested for nanocomposite photoanodes, significantly. - Abstract: CdS/TiO 2 /graphene (CTG) nanocomposite thin films were synthesized by a facile production route. The TiO 2 /graphene (TG) nanocomposite was initially fabricated by sol-gel method in such a way that TiO 2 nanoparticles loaded on graphene oxide (GO) sheet via photocatalytic process. Then, CdS nanoparticles were deposited on the TG thin film by successive ion layer adsorption and reaction process (SILAR) approach. Based on atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the TG thin film possessed a larger surface area as compared with the pure TiO 2 thin film due to presence of graphene sheet. UV/visible spectroscopy exhibited that visible absorption of the CTG samples increased with increasing CdS SILAR deposition cycle (n). Enhanced photocurrent response of the CTG(n) photoanodes measured as compared with the TG and T photoanodes due to good electrical conductivity and large surface area of graphene as well as the visible light-harvesting ability of CdS nanoparticles. Maximum photocurrent density of about 4.5 A/m 2 and electron life time of about 5 s was measured for the CTG(30) photoanodes

  14. CdS nanoparticle sensitized titanium dioxide decorated graphene for enhancing visible light induced photoanode

    Energy Technology Data Exchange (ETDEWEB)

    Yousefzadeh, S.; Faraji, M. [Physics Department, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Nien, Y.T. [Department of Materials Science and Engineering, National Formosa University, Taiwan (China); Moshfegh, A.Z., E-mail: moshfegh@sharif.edu [Physics Department, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2014-11-30

    Highlights: • CdS nanoparticles were deposited on TiO{sub 2}/graphene film by different SILAR cycles. • The visible light absorption increased due to graphene and CdS nanoparticles. • The highest photocurrent density was achieved for nanocomposite with 30 CdS cycles. • A mechanism has been suggested for nanocomposite photoanodes, significantly. - Abstract: CdS/TiO{sub 2}/graphene (CTG) nanocomposite thin films were synthesized by a facile production route. The TiO{sub 2}/graphene (TG) nanocomposite was initially fabricated by sol-gel method in such a way that TiO{sub 2} nanoparticles loaded on graphene oxide (GO) sheet via photocatalytic process. Then, CdS nanoparticles were deposited on the TG thin film by successive ion layer adsorption and reaction process (SILAR) approach. Based on atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the TG thin film possessed a larger surface area as compared with the pure TiO{sub 2} thin film due to presence of graphene sheet. UV/visible spectroscopy exhibited that visible absorption of the CTG samples increased with increasing CdS SILAR deposition cycle (n). Enhanced photocurrent response of the CTG(n) photoanodes measured as compared with the TG and T photoanodes due to good electrical conductivity and large surface area of graphene as well as the visible light-harvesting ability of CdS nanoparticles. Maximum photocurrent density of about 4.5 A/m{sup 2} and electron life time of about 5 s was measured for the CTG(30) photoanodes.

  15. Microstructural and optical properties of CdS nanoparticles synthesized by sol gel method

    Science.gov (United States)

    Mahdi, Hadeel Salih; Parveen, Azra; Agrawal, Shraddha; Azam, Ameer

    2018-05-01

    Semiconductor nanoparticles of CdS are of great interest for both fundamental research and industrial development due to their unique size-dependent optical and electronic properties and their exciting utilization in the fields of light-emitting diode, electro-chemical cells, laser, hydrogen producing catalyst, biological label. We present a scheme to measure the optical properties of CdS nanoparticles The peaks were indexed by powder-x software. The XRD pattern analysis showed that CdS composition was found to have hexagonal structure with well crystalline nature. the surface morphology and the composition of the samples were investigated by SEM (JEOL, japan). The image shows the presence of large spherical aggregates of smaller individual nanoparticles of various sizes for pure cds. to check the chemical composition of the material, energy dispersive X-ray (EDX) spectroscopic analysis was also performed which further confirmed the presence of cd and s ions in the matrix. The optical absorption spectra of CdS sample was recorded by uv-vis spectrophotometer in the range of 200 to 800 nm.

  16. Dielectric properties of CdS nanoparticles synthesized by soft ...

    Indian Academy of Sciences (India)

    If the field applied to the condenser is time-dependent (as in an alternating current), so ... tematically the dielectric properties of CdS synthesized by a soft chemical method .... The real parts of conductivity spectra can be explained by the power ...

  17. Diffusion mediated agglomeration of CdS nanoparticles via Langmuir–Blodgett technique

    International Nuclear Information System (INIS)

    Das, Nayan Mani; Roy, Dhrubojyoti; Gupta, P.S.

    2013-01-01

    Graphical abstract: - Highlights: • Diffusion mediated agglomeration of CdS nanoparticles are discussed. • Formation of CdS nanoparticles are confirmed by the change of chain length in XRD. • AFM shows the agglomeration of particles with a film swelling of about 5 Å. • UV–vis absorbance suggests that the grown particles show quantum confinement. • Hexagonal form of particle was confirmed by UV–vis reflectivity. - Abstract: We have reported a diffusion mediated agglomeration of cadmium sulphide (CdS) nanoparticles within cadmium arachidate (CdA 2 ) film matrix. The structural morphology and formation of CdS nanoparticles are characterized by X-ray diffraction (XRD), X-ray reflectivity (XRR), atomic force microscopy (AFM) and ultraviolet-visible spectroscopy techniques. X-ray diffraction (XRD) results show a change in bilayer difference from 53.04 Å to 43 Å after the sulphidation. An epitaxial growth of the films by ∼5 Å after sulphidation is confirmed from atomic force microscopy studies. The particle size calculated form UV–vis absorption edges are found to be varying from 2.6 nm to 3.3 nm for the different layers. A lateral dimension of 72–80 nm from AFM measurements and a size of 2.6–3.3 nm have confirmed one side flat pseudo two-dimensional disk-like nanoparticles. UV–vis reflectivity peak at E 1 (A) confirms the formation of hexagonal CdS nanoparticles along the c-axis

  18. Anodic stripping voltammetry of synthesized CdS nanoparticles at boron-doped diamond electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Mohammad; Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Saepudin, Endang [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Einaga, Yasuaki [Department of Chemistry, Keio University (Japan)

    2016-04-19

    Cadmium sulphide (CdS) nanoparticles were chemically synthesized using reverse micelles microreactor methods. By using different washing treatments, UV-Vis spectroscopy showed that the absorption peaks appeared at 465 nm, 462 nm, 460 nm, and 459 nm respectively for CdS nanoparticles without and with 1, 2, and 3 times washing treatments using pure water. In comparison with the absorbance peak of bulk CdS at 512 nm, the shifted absorption peaks, indicates that the different sizes of CdS can be prepared. Anodic stripping voltammetry of the CdS nanoparticles was then studied at a boron-doped diamond electrode using 0.1 M KClO{sub 4} and 0.1 M HClO{sub 4} as the electrolytes. A scan rate of 100 mV/s with a deposition potential of -1000 mV (vs. Ag/AgCl) for 60 s at a potential scan from -1600 mV to +800 mV (vs. Ag/AgCl) was applied as the optimum condition of the measurements. Highly-accurate linear calibration curves (R{sup 2} = 0.99) in 0.1 M HClO{sub 4} with the sensitivity of 0.075 mA/mM and the limit of detection of 81 µM in 0.1 M HClO{sub 4} can be achieved, which is promising for an application of CdS nanoparticles as a label for biosensors.

  19. Biosynthesis of CdS nanoparticles: A fluorescent sensor for sulfate-reducing bacteria detection.

    Science.gov (United States)

    Qi, Peng; Zhang, Dun; Zeng, Yan; Wan, Yi

    2016-01-15

    CdS nanoparticles were synthesized with an environmentally friendly method by taking advantage of the characteristic metabolic process of sulfate-reducing bacteria (SRB), and used as fluorescence labels for SRB detection. The presence of CdS nanoparticles was observed within and immediately surrounded bacterial cells, indicating CdS nanoparticles were synthesized both intracellularly and extracellularly. Moreover, fluorescent properties of microbial synthesized CdS nanoparticles were evaluated for SRB detection, and a linear relationship between fluorescence intensity and the logarithm of bacterial concentration was obtained in the range of from 1.0×10(2) to 1.0×10(7)cfu mL(-1). The proposed SRB detection method avoided the use of biological bio-recognition elements which are easy to lose their specific recognizing abilities, and the bacterial detection time was greatly shortened compared with the widely used MPN method which would take up to 15 days to accomplish the detection process. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Study of optical phonon modes of CdS nanoparticles using Raman ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. The reduction in the grain size to nanometer range can bring about radical changes in almost all of the properties of semiconductors. CdS nanoparticles have attracted considerable scientific interest because they exhibit strongly size-dependent optical and electrical properties. In the case of nanostructured ...

  1. Mechanism of charge transport in ligand-capped crystalline CdTe nanoparticles according to surface photovoltaic and photoacoustic results

    Energy Technology Data Exchange (ETDEWEB)

    Li Kuiying, E-mail: kuiyingli@ysu.edu.cn [National Laboratory of Metastable Materials Manufacture Technology and Science, Yanshan University, Hebei Str. 438, Qinhuangdao, Hebei Province 066004 (China); Zhang Hao [Key Laboratory for Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 (China); Yang Weiyong; Wei Sailing [National Laboratory of Metastable Materials Manufacture Technology and Science, Yanshan University, Hebei Str. 438, Qinhuangdao, Hebei Province 066004 (China); Wang Dayang, E-mail: dayang@mpikg-golm.mpg.de [Max Planck Institute of Colloids and Interfaces, Potsdam 14424 (Germany)

    2010-09-01

    By combining surface photovoltaic and photoacoustic techniques, we probed the photogenerated charge transport channels of 3-mercaptopropionic acid (MPA)- and 2-mercaptoethylamine (MA)-capped crystalline CdTe nanoparticles on illumination with UV-near IR light. The results experimentally confirmed the presence of a CdS shell outside the CdTe core that formed through the self-assembly and decomposition of mercapto ligands during CdTe preparation. The data revealed that the CdS layer was partly responsible for the deexcitation behavior of the photogenerated carriers, which is related to the quantum tunnel effect. Experiments demonstrated that two quantum wells were located at wavelengths of 440 and 500 nm in buried interfacial space-charge regions, whereas the formation of a ligand layer obstructed charge transfer transitions of the core CdTe nanoparticles to a certain extent.

  2. The effect of different pH modifier on formation of CdS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoxiao, Ren [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhao Gaoling [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)], E-mail: glzhao@zju.edu.cn; Hong, Li; Wei, Wu; Gaorong, Han [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2008-10-06

    CdS nanoparticles were prepared by hydrothermal method. The effects of pH modifier on the properties of CdS particles were studied. NaOH and NH{sub 4}OH were chosen as the pH modifier. The morphology and optical properties of CdS particles were characterized by transmitted electron microscope (TEM) and optical absorption spectra analysis, respectively. The particle size of the samples whose pH modifier is NaOH was smaller than that of the CdS samples with NH{sub 4}OH at the same pH value. Optical absorption edge of CdS shifted to longer wavelength with increasing pH value. Optical absorption edge of the samples with NH{sub 4}OH as pH modifier shifted to the longer wavelength more significantly than that of those samples with NaOH as pH modifier. When CdS particles were adsorbed to the TiO{sub 2} electrodes, the photoelectrochemical property of CdS-sensitized TiO{sub 2} electrode showed that the samples with NH{sub 4}OH as pH modifier had higher photocurrent than those samples with NaOH.

  3. The effect of different pH modifier on formation of CdS nanoparticles

    International Nuclear Information System (INIS)

    Ren Xiaoxiao; Zhao Gaoling; Li Hong; Wu Wei; Han Gaorong

    2008-01-01

    CdS nanoparticles were prepared by hydrothermal method. The effects of pH modifier on the properties of CdS particles were studied. NaOH and NH 4 OH were chosen as the pH modifier. The morphology and optical properties of CdS particles were characterized by transmitted electron microscope (TEM) and optical absorption spectra analysis, respectively. The particle size of the samples whose pH modifier is NaOH was smaller than that of the CdS samples with NH 4 OH at the same pH value. Optical absorption edge of CdS shifted to longer wavelength with increasing pH value. Optical absorption edge of the samples with NH 4 OH as pH modifier shifted to the longer wavelength more significantly than that of those samples with NaOH as pH modifier. When CdS particles were adsorbed to the TiO 2 electrodes, the photoelectrochemical property of CdS-sensitized TiO 2 electrode showed that the samples with NH 4 OH as pH modifier had higher photocurrent than those samples with NaOH

  4. In situ capping for size control of monochalcogenide (ZnS, CdS and SnS) nanocrystals produced by anaerobic metal-reducing bacteria

    International Nuclear Information System (INIS)

    Jang, Gyoung Gug; Datskos, Panos G; Jacobs, Christopher B; Ivanov, Ilia N; Joshi, Pooran C; Meyer, Harry M III; Armstrong, Beth L; Kidder, Michelle; Graham, David E; Moon, Ji-Won

    2015-01-01

    Metal monochalcogenide quantum dot nanocrystals of ZnS, CdS and SnS were prepared by anaerobic, metal-reducing bacteria using in situ capping by oleic acid or oleylamine. The capping agent preferentially adsorbs on the surface of the nanocrystal, suppressing the growth process in the early stages, thus leading to production of nanocrystals with a diameter of less than 5 nm. (paper)

  5. Au Nanoparticles as Interfacial Layer for CdS Quantum Dot-sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhu Guang

    2010-01-01

    Full Text Available Abstract Quantum dot-sensitized solar cells based on fluorine-doped tin oxide (FTO/Au/TiO2/CdS photoanode and polysulfide electrolyte are fabricated. Au nanoparticles (NPs as interfacial layer between FTO and TiO2 layer are dip-coated on FTO surface. The structure, morphology and impedance of the photoanodes and the photovoltaic performance of the cells are investigated. A power conversion efficiency of 1.62% has been obtained for FTO/Au/TiO2/CdS cell, which is about 88% higher than that for FTO/TiO2/CdS cell (0.86%. The easier transport of excited electron and the suppression of charge recombination in the photoanode due to the introduction of Au NP layer should be responsible for the performance enhancement of the cell.

  6. Synthesis of anisotropic CdS nanostructures via a single-source route

    CSIR Research Space (South Africa)

    Rajasekhar Pullabhotla, VSR

    2011-02-01

    Full Text Available A cadmium tetrahydroisoquinoline dithiocarbamate (DTC) complex has been used as single-source precursor for the synthesis of highly faceted hexadecylamine (HDA) capped CdS nanoparticles. Hexagonal and close to cubic shaped particles with distinct...

  7. Thermal and Optical Properties of CdS Nanoparticles in Thermotropic Liquid Crystal Monomers

    Directory of Open Access Journals (Sweden)

    Marc Alnot

    2010-03-01

    Full Text Available Two new mesogenic monomers, namely 3,3’-dimethoxy-4,4’-di(hydroxyhexoxy-N-benzylidene-o-Tolidine (Ia and 4,4’-di(6-hydroxyhexoxy-N-benzylidene-o-Tolidine (IIa, were reacted with cadmium sulfide (CdS via an in situ chemical precipitation method in ethanol to produce CdS nanocomposites. A series of different mass compositions of CdS with Ia and IIa ranging from 0.1:1.0 to 1.0:1.0 (w/w were prepared and characterized using X-ray Diffraction (XRD, Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR, Transmission Electron Microscopy (TEM, Polarizing Optical Microscopy (POM and Differential Scanning Calorimetry (DSC, X-ray Photoelectron Spectroscopy (XPS and Photoluminescence Spectroscopy (PL. XRD showed that the broad peaks are ascribed to the formation of cubic CdS nanoparticles in both Ia and IIa. The average particle size for both nanocomposites was less than 5 nm with a narrower size distribution when compared with pure CdS nanoparticles. The analyses from POM and DSC demonstrated that mass composition from 0.1:1.0 up to 0.5:1.0 of CdS:Ia nanocomposites showed their enantiotropic nematic phase. On the other hand, polarizing optical microscopy (POM for IIa nanocomposites showed that the liquid crystal property vanished completely when the mass composition was at 0.2:1.0. PL emissions for CdS: Ia or IIa nanocomposites indicated deep trap defects occurred in these both samples. The PL results revealed that addition of CdS to Ia monomers suppressed the photoluminescence intensity of Ia. However, the introduction of CdS to IIa monomers increased the photoluminescence and was at a maximum when the mass composition was 0.3:1.0, then decreased in intensity as more CdS was added. The XPS results also showed that the stoichiometric ratios of S/Cd were close to 1.0:1.0 for both types of nanocomposites for a mass composition of 1.0:1.0 (CdS:matrix.

  8. Synthesis and spectroscopic study of CdS nanoparticles using hydrothermal method

    Science.gov (United States)

    AL-Mamoori, Mohammed H. K.; Mahdi, Dunia K.; Al-Shrefi, Saif M.

    2018-05-01

    In this work, cadmium sulfide nanoparticles (powder) with diameter 50.8 nm was prepared using hydrothermal method. The structural and optical properties of CdS nanoparticles was studied by X-ray diffraction, FESEM, EDS, FTIR, UV-Diffuse Reflectance spectroscopy and Photoluminance spectrum. X-ray diffraction reveal the formation the purity of prepared phase of CdS particles with hexagonal wurtzite structure with particle size 31.8nm by using sheerer equation. The energy dispersion scattering (EDS) examination explains that the sample is composed of a large amount of Cd and S which are exactly CdS nanoparticles and there is a very small trace of (Zn) and (O) element observed because of there is a small pollutions in the measurement place of samples. FESEM shows the spherical shape of nanoparticles with around 50.8 nm diameter. The optical absorption spectral study identified the red shift of the sample in comparison to bulk ZnO in three dimensions. Photoluminance spectrum (PL) at room temperature showed that there are two luminescence peaks at 433.14 nm and 518.21nm. Samples demonstrate a sharp emission band at around 433.18 nm, which is attributed to the typical exciton luminescence. The broad band at 518.21nm which were attributed to the trapped luminescence. The green emission band at 518.21 nm was associated with the emission due to electronic transition from the conduction band to an accepter level due to interstitial sulphur ion.

  9. Phase- and shape-controlled hydrothermal synthesis of CdS nanoparticles, and oriented attachment growth of its hierarchical architectures

    Science.gov (United States)

    Cao, Yali; Hu, Pengfei; Jia, Dianzeng

    2013-01-01

    Hydrothermal strategies were successfully used to control the phases and morphologies of CdS nanocrystals. In the absence of an external direction-controlling process, the hexagonal and cubic phase well-defined leaf- and flower-like CdS nanocrystals were controlled obtained via adjusting the reaction duration or the concentration of surfactant. Oriented attachment growth modes were suggested for the formation of CdS superstructures, which was clarified through the tracing of temporal evolution of CdS nanoparticles. The CdS superstructures were structured by primary building nanoparticles, and held excellent visible emission with a peak in the green regions. This strategy is very helpful for studying the phase and morphology controlled fabrication of sulfides nanocrystals.

  10. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Wintec

    *For correspondence. Also at the Chemical Biology Unit,. Jawaharlal Nehru Centre for Advanced Scientific Research,. Bangalore 560 064. Facially amphiphilic thiol capped gold and silver nanoparticles. †. SHREEDHAR BHAT a and UDAY MAITRA*. Department of Organic Chemistry, Indian Institute of Science, Bangalore ...

  11. Structural and Thermal Studies of ZnS and CdS Nanoparticles in Polymer Matrices

    OpenAIRE

    Osuntokun, Jejenija; Ajibade, Peter A.

    2016-01-01

    We report the synthesis and structural studies of ZnS and CdS nanoparticles in polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), and poly(methyl methacrylate) (PMMA) matrices. The metal sulfides/polymer nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, electronic spectroscopy (UV-Vis), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The particle sizes as calculated from the absorption spectra were in agree...

  12. Growth of CdS nanoparticles by chemical method and its ...

    Indian Academy of Sciences (India)

    carbon film supported on the copper grid and was kept for some time for drying. Transmission electron ... Wang et al obtained CdS nanoparticles having a band gap of. 2.79 eV [21]. .... [16] S Yu, Y Wu, J Yang, Z Han, Y Quan, X Liu and Y Xie, Chem. Matter 10 ... [22] U K Gautam, R Seshadri and C N R Rao, Chem. Phys. Lett.

  13. Synthesis of Stabilized Myrrh-Capped Hydrocolloidal Magnetite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ayman M. Atta

    2014-07-01

    Full Text Available Herein we report a new method for synthesizing stabilized magnetic nanoparticle (MNP colloids. A new class of monodisperse water-soluble magnetite nano-particles was prepared by a simple and inexpensive co-precipitation method. Iron ions and iodine were prepared by the reaction between ferric chloride and potassium iodide. The ferrous and ferric ions were hydrolyzed at low temperature at pH 9 in the presence of iodine to produce iron oxide nanoparticles. The natural product myrrh gum was used as capping agent to produce highly dispersed coated magnetite nanoparticles. The structure and morphology of the magnetic nanogel was characterized by Fourier transform infrared spectroscopy (FTIR and transmission electron microscopy (TEM, and X-ray diffraction (XRD was used to examine the crystal structure of the produced magnetite nanoparticles.

  14. Influence of CdS nanoparticles grain morphology on laser-induced absorption

    Science.gov (United States)

    Ebothé, Jean; Michel, Jean; Kityk, I. V.; Lakshminarayana, G.; Yanchuk, O. M.; Marchuk, O. V.

    2018-06-01

    Using external illumination of a 7 nanosecond (ns) doubled frequency Nd: YAG laser emitting at λ = 532 nm with frequency repetition 10 Hz it was established a possibility of significant changes of the absorption at the probing wavelength 1150 nm of continuous wave (cw) He-Ne laser for the CdS nanoparticles embedded into the PVA polymer matrix. The effect is observed only during the two beam laser coherent treatment and this effect is a consequence of interference of two coherent beams. It is shown a principal role of the grain morphology in the efficiency of the process, which is more important than the nanoparticle sizes. The photoinduced absorption is manifested in the space distribution of the probing laser beam. The principal role of the grain interfaces between the nanoparticle interfaces and the surrounding polymer matrix is shown. The effect is almost independent of the nanoparticle sizes. It may be used for laser operation by nanocomposites.

  15. Structural and optical properties of hydrazine hydrate capped cadmium sulphide nanoparticles

    Science.gov (United States)

    Solanki, Rekha Garg; Rajaram, P.

    2018-05-01

    Semiconductor nanoparticles have received considerable interest due to their size-dependent optical properties. CdS is an important semiconductor material widely used in low cost photovoltaic devices, light-emitting diodes and biological imaging. The nanoparticles of CdS were prepared by a simple chemical precipitation method in aqueous medium. The reaction was carried out at room temperature. The cadmium sulphide nanoparticles were characterized using X-ray powder diffraction (XRD) and UV-visible spectroscopy. The lattice strain, crystallite size and dislocation density were calculated using the Williamson-Hall (W-H) method. The band gap was obtained from the UV-Visible spectra of CdS nanoparticles. The band gap of CdS nanoparticles is around 2.68 eV and the crystallite size is around 5.8 nm.

  16. Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiazhi; Yu, Junwei [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Fan, Jun [School of Environment, Nanjing University, Nanjing 210093 (China); Sun, Dongping [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Tang, Weihua [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Xuejie [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China)

    2011-05-15

    In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl{sub 2} and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

  17. Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application

    International Nuclear Information System (INIS)

    Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie

    2011-01-01

    In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl 2 and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

  18. Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application.

    Science.gov (United States)

    Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie

    2011-05-15

    In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl(2) and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Protein capped nanosilver free radical oxidation: role of biomolecule capping on nanoparticle colloidal stability and protein oxidation.

    Science.gov (United States)

    Ahumada, Manuel; Bohne, Cornelia; Oake, Jessy; Alarcon, Emilio I

    2018-05-03

    We studied the effect of human serum albumin protein capped spherical nanosilver on the nanoparticle stability upon peroxyl radical oxidation. The nanoparticle-protein composite is less prone to oxidation compared to the individual components. However, higher concentrations of hydrogen peroxide were formed in the nanoparticle-protein system.

  20. Starch mediated CdS nanoparticles and their photocatalytic performance under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Firdaus, Farha, E-mail: Farha-firdaus@yahoo.co.in [Chemistry Section, Women’s College, Aligarh Muslim University, Aligarh 202002 UP (India); Faraz, Mohd [Department of Chemistry, Faculty of Science, Aligarh Muslim University, Aligarh 202002 (India)

    2016-05-06

    Green synthesis of Cadmium Sulphide (CdS-S) nanoparticles is of considerable interest due to its biocompatible and nontoxicity. Here, we present a biomolecule stimulated chemical method was adopted for the successful synthesis of CdS-S nanoparticles using starch as a capping agent. The CdS-S nanoparticles were characterized by various analytical techniques. The CdS-S nanoparicles exhibit photocatalytic activity against methyl orange (MO) at pH 9 in Visible light and the reaction follows pseudo first-order kinetics. The comparative photocatalytic activity revealed that CdS-S nanoparticles remarkably enhanced activities as compared to the commercial TiO{sub 2} nanoparticles. The outcome of these studies offers valuable for planning CdS-S nanoparticles having photocatalytic activities helpful for the formulation of waste water remediation.

  1. Starch mediated CdS nanoparticles and their photocatalytic performance under visible light irradiation

    International Nuclear Information System (INIS)

    Firdaus, Farha; Faraz, Mohd

    2016-01-01

    Green synthesis of Cadmium Sulphide (CdS-S) nanoparticles is of considerable interest due to its biocompatible and nontoxicity. Here, we present a biomolecule stimulated chemical method was adopted for the successful synthesis of CdS-S nanoparticles using starch as a capping agent. The CdS-S nanoparticles were characterized by various analytical techniques. The CdS-S nanoparicles exhibit photocatalytic activity against methyl orange (MO) at pH 9 in Visible light and the reaction follows pseudo first-order kinetics. The comparative photocatalytic activity revealed that CdS-S nanoparticles remarkably enhanced activities as compared to the commercial TiO 2 nanoparticles. The outcome of these studies offers valuable for planning CdS-S nanoparticles having photocatalytic activities helpful for the formulation of waste water remediation.

  2. Structural and Thermal Studies of ZnS and CdS Nanoparticles in Polymer Matrices

    Directory of Open Access Journals (Sweden)

    Jejenija Osuntokun

    2016-01-01

    Full Text Available We report the synthesis and structural studies of ZnS and CdS nanoparticles in polyvinylpyrrolidone (PVP, poly(vinyl alcohol (PVA, and poly(methyl methacrylate (PMMA matrices. The metal sulfides/polymer nanocomposites were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy, electronic spectroscopy (UV-Vis, transmission electron microscopy (TEM, and thermogravimetric analysis (TGA. The particle sizes as calculated from the absorption spectra were in agreement with the results obtained from TEM and XRD data. They showed metal sulfides nanoparticles in the polymers matrices with average crystallite sizes of 1.5–6.9 nm. The TGA results indicate that incorporation of the nanoparticles significantly altered the thermal properties of the respective polymers with ZnS/PVA and CdS/PVA nanocomposites displaying higher thermal stability than the other polymer nanocomposites.

  3. A novel "dual-potential" electrochemiluminescence aptasensor array using CdS quantum dots and luminol-gold nanoparticles as labels for simultaneous detection of malachite green and chloramphenicol.

    Science.gov (United States)

    Feng, Xiaobin; Gan, Ning; Zhang, Huairong; Yan, Qing; Li, Tianhua; Cao, Yuting; Hu, Futao; Yu, Hongwei; Jiang, Qianli

    2015-12-15

    A novel type of "dual-potential" electrochemiluminescence (ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for simultaneous detection of malachite green (MG) and chloramphenicol (CAP) in one single assay. The SPCE substrate consisted of a common Ag/AgCl reference electrode, carbon counter electrode and two carbon working electrodes (WE1 and WE2). In the system, CdS quantum dots (QDs) were modified on WE1 as cathode ECL emitters and luminol-gold nanoparticles (L-Au NPs) were modified on WE2 as anode ECL emitters. Then the MG aptamer complementary strand (MG cDNA) and CAP aptamer complementary strand (CAP cDNA) were attached on CdS QDs and L-Au NPs, respectively. The cDNA would hybridize with corresponding aptamer that was respectively tagged with cyanine dye (Cy5) (as quenchers of CdS QDs) and chlorogenic acid (CA) (as quenchers of l-Au NPs) using poly(ethylenimine) (PEI) as a bridging agent. PEI could lead to a large number of quenchers on the aptamer, which increased the quenching efficiency. Upon MG and CAP adding, the targets could induce strand release due to the highly affinity of analytes toward aptamers. Meanwhile, it could release the Cy5 and CA, which recovered cathode ECL of CdS QDs and anode ECL of L-Au NPs simultaneously. This "dual-potential" ECL strategy could be used to detect MG and CAP with the linear ranges of 0.1-100 nM and 0.2-150 nM, with detection limits of 0.03 nM and 0.07 nM (at 3sB), respectively. More importantly, this designed method was successfully applied to determine MG and CAP in real fish samples and held great potential in the food analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. A DFT study of the effects of Sc doping on electronic and optical properties of CdS nanoparticles

    Directory of Open Access Journals (Sweden)

    Ur Rehman Shafiq

    2015-12-01

    Full Text Available In the present work a systematic study was carried out to understand the influence of Sc doping on electronic and optical properties of CdS nanoparticles. The geometry optimization and symmetry computation for CdS and Sc doped CdS nanoparticles using Density Functional Theory (DFT on B3LYP level with the QZ4P for Cd and DZ2P for sulphur and Sc were performed by Amsterdam Density Functional (ADF. The results show that HOMO-LUMO gap as well as electronic and optical properties of CdS clusters vary with Sc doping. The HOMO-LUMO gap is affected by the dopant and its value decreases to 0.6 eV. Through considering the numerical integration scheme in the ADF package, we investigated different vibrational modes and our calculated Raman and IR spectra are consistent with the reported result. The calculated IR and Raman peaks of CdS and Sc doped CdS clusters were in the range of 100 to 289 cm−1, 60 cm−1 to 350 cm−1 and 99 cm−1 to 282 cm−1, 60 cm−1 to 350 cm−1, respectively, which was also confirmed by experiment as well as a blue shift occurrence. Subsequently, for deeper research of pure and doped CdS clusters, their absorption spectra were calculated using time-dependent DFT method.

  5. Ultrasensitive electrochemiluminescent immunoassay for morphine using a gold electrode modified with CdS quantum dots, polyamidoamine, and gold nanoparticles

    International Nuclear Information System (INIS)

    Fei, Wenjuan; Chen, Feifei; Sun, Li; Li, Qianhua; Wu, Ying; Yang, Jianping

    2014-01-01

    We report on a novel electrochemiluminescent (ECL) immunoassay for the ultrasensitive determination of morphine by making use of a gold electrode which was modified with a nanocomposite film containing self-assembled polyamidoamine (PAMAM) CdS quantum dots and electrodeposited gold nanoparticles (Au-NPs). The highly uniform and well-dispersed quantum dots were capped with PAMAM dendrimers. Due to the synergistic effect of the modified quantum dots and the electrodeposited Au-NPs, the ECL response is dramatically enhanced. Under optimal experimental conditions, the immunoreaction between morphine and anti-morphine antibody resulted in a decrease of the ECL signal because of steric hindrance. The calibration plot is linear in the morphine concentration range from 0.2 to 180 ng•mL −1 , with a detection limit as low as 67 pg•mL −1 . The sensor was successfully applied to the determination of morphine in blood plasma. This kind of assay is expected to pave new avenues in label-free drug assays. (author)

  6. Optical and AFM study of electrostatically assembled films of CdS and ZnS colloid nanoparticles

    International Nuclear Information System (INIS)

    Suryajaya; Nabok, A.; Davis, F.; Hassan, A.; Higson, S.P.J.; Evans-Freeman, J.

    2008-01-01

    CdS and ZnS semiconducting colloid nanoparticles coated with the organic shell, containing either SO 3 - or NH 2 + groups, were prepared using the aqueous phase synthesis. The multilayer films of CdS (or ZnS) were deposited onto glass, quartz and silicon substrates using the technique of electrostatic self-assembly. The films produced were characterized with UV-vis spectroscopy, spectroscopic ellipsometry and atomic force microscopy. A substantial blue shift of the main absorption band with respect to the bulk materials was found for both CdS and ZnS films. The Efros equation in the effective mass approximation (EMA) theoretical model allowed the evaluation of the nanoparticle radius of 1.8 nm, which corresponds well to the ellipsometry results. AFM shows the formation of larger aggregates of nanoparticles on solid surfaces

  7. Growth, characterization and estimation of lattice strain and size in CdS nanoparticles: X-ray peak profile analysis

    Science.gov (United States)

    Solanki, Rekha Garg; Rajaram, Poolla; Bajpai, P. K.

    2018-05-01

    This work is based on the growth, characterization and estimation of lattice strain and crystallite size in CdS nanoparticles by X-ray peak profile analysis. The CdS nanoparticles were synthesized by a non-aqueous solvothermal method and were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-visible spectroscopy. XRD confirms that the CdS nanoparticles have the hexagonal structure. The Williamson-Hall (W-H) method was used to study the X-ray peak profile analysis. The strain-size plot (SSP) was used to study the individual contributions of crystallite size and lattice strain from the X-rays peaks. The physical parameters such as strain, stress and energy density values were calculated using various models namely, isotropic strain model, anisotropic strain model and uniform deformation energy density model. The particle size was estimated from the TEM images to be in the range of 20-40 nm. The Raman spectrum shows the characteristic optical 1LO and 2LO vibrational modes of CdS. UV-visible absorption studies show that the band gap of the CdS nanoparticles is 2.48 eV. The results show that the crystallite size estimated from Scherrer's formula, W-H plots, SSP and the particle size calculated by TEM images are approximately similar.

  8. Size control synthesis of starch capped-gold nanoparticles

    International Nuclear Information System (INIS)

    Tajammul Hussain, S.; Iqbal, M.; Mazhar, M.

    2009-01-01

    Metallic gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl 4 ] - solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure. The characterization of synthesized gold nanoparticles by UV-vis spectroscopy, high resolution transmission electron microscopy (HRTEM), electron diffraction analysis, X-ray diffraction (XRD), and X-rays photoelectron spectroscopy (XPS) indicate that average size of pure gold nanoparticles is 3.5 nm, they are spherical in shape and are pure metallic gold. The concentration effects of [AuCl 4 ] - anions, starch, ethylene glycol, and hydrazine, on particle size, were investigated, and the stabilization mechanism of Au nanoparticles by starch polymer molecules was also studied by FT-IR and thermogravimetric analysis (TGA). FT-IR and TGA analysis shows that hydroxyl groups of starch are responsible of capping and stabilizing gold nanoparticles. The UV-vis spectrum of these samples shows that there is blue shift in surface plasmon resonance peak with decrease in particle size due to the quantum confinement effect, a supporting evidence of formation of gold nanoparticles and this shift remains stable even after 3 months.

  9. Cellulose acetate fibers covered by CdS nanoparticles for hybrid solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, Hugo; Martinez-Alonso, Claudia [Centro de Investigacion en Energia, UNAM, Priv. Xochicalco S/N, Temixco, Morelos 62580 (Mexico); Castillo-Ortega, Monica [Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); Hu, Hailin, E-mail: hzh@cie.unam.mx [Centro de Investigacion en Energia, UNAM, Priv. Xochicalco S/N, Temixco, Morelos 62580 (Mexico)

    2012-09-20

    In this work cellulose acetate (CA) fibers with a diameter of approximately 1 {mu}m were immersed in a cadmium sulfide (CdS) precursor solution. After 3 h the original white color CA fibers became yellow and maintained the same form, suggesting the deposition of CdS on fiber surface. SEM images showed that CA fibers were covered by uniformly sized CdS nanoparticles of approximately 100 nm. XRD and optical absorption spectra indicated that they contained mostly cubic crystalline phase with the optical band gap of 2.43 eV. CdS coated CA fibers, called CdS(CA) fibers, were dispersed in a polar dispersant (dimethyl sulfoxide, DMSO) and then mixed with a poly(3-hexylthiophene) (P3HT) solution in a non-polar solvent (dichlorobenzene, DCB). The mixture was cast onto a transparent conductive glass substrate (Indium-Tin-Oxide, ITO), and after solvent evaporation a thin layer of CdS(CA)-P3HT composite was formed. It is observed that the volume relation between the polar dispersant and non-polar solvent influences the solubility of the P3HT product in the composite coating and the photovoltaic performance of the corresponding cell as well. The mass ratio between CdS(CA) fibers and P3HT in the composite layer affects the optical absorption of the composite. The best photovoltaic performance was obtained in CdS(CA)-P3HT based cells with a volume relation between DCB and DMSO of 3.5-1, a mass ratio between CdS(CA) and P3HT of 1:1, and a rapid drying process for composite coatings.

  10. Photovoltaic performance enhancement of CdS quantum dot-sensitized TiO2 photoanodes with plasmonic gold nanoparticles

    International Nuclear Information System (INIS)

    Liu, Aiping; Ren, Qinghua; Zhao, Ming; Xu, Tao; Yuan, Ming; Zhao, Tingyu; Tang, Weihua

    2014-01-01

    Highlights: • CdS QD-sensitized TiO 2 porous photoanode with plasmonic gold. • A prominent light absorption enhancement of hybrid was attained by gold plasmon. • The photovoltaic response of hybrid was tunable by CdS amount. • The Au/TiO 2 /CdS hybrid had a potential application in energy conversion devices. -- Abstract: The CdS quantum dot-sensitized TiO 2 films with plasmonic gold nanoparticles were designed as photoanodes by the electrodeposition of gold combined with the “successive ionic layer adsorption and reaction” (SILAR) method for CdS deposition on porous TiO 2 films. A prominent enhancement in light absorption of Au/TiO 2 /CdS hybrid was attained by efficient light scattering of gold plasmons as sub-wavelength antennas and concentrators. The photogenerated electron formed in the near-surface region of TiO 2 and CdS were facilitated to transfer to the plasmonic gold, resulting in the enhancement of photocurrent and incident photon-to-current conversion efficiency of hybrid photoanode upon photoirradiation. Furthermore, the photovoltaic response of hybrid was highly tunable with respect to the number of SILAR cycles applied to deposit CdS. The thicker absorber layer with less porous structure and larger CdS crystals might limit the electrolyte diffusion into the hybrid electrode and impose a barrier for electron tunneling and transferring. The highly versatile and tunable properties of Au/TiO 2 /CdS photoanodes demonstrated their potential application in energy conversion devices

  11. Study of electrostatically self-assembled thin films of CdS and ZnS nanoparticle semiconductors

    Science.gov (United States)

    Suryajaya

    In this work, CdS and ZnS semiconducting colloid nanoparticles coated with organic shell, containing either SO[3-] or NH[2+] groups, were deposited as thin films using the technique of electrostatic self-assembly. The films produced were characterized with UV-vis spectroscopy and spectroscopic ellipsometry - for optical properties; atomic force microscopy (AFM) - for morphology study; mercury probe - for electrical characterisation; and photon counter - for electroluminescence study. UV-vis spectra show a substantial blue shift of the main absorption band of both CdS and ZnS, either in the form of solutions or films, with respect to the bulk materials. The calculation of nanoparticles' radii yields the value of about 1.8 nm for both CdS and ZnS.The fitting of standard ellipsometry data gave the thicknesses (d) of nanoparticle layers of around 5 nm for both CdS and ZnS which corresponds well to the size of particles evaluated from UV-vis spectral data if an additional thickness of the organic shell is taken into account. The values of refractive index (n) and extinction coefficient (k) obtained were about 2.28 and 0.7 at 633 nm wavelength, for both CdS and ZnS.Using total internal reflection (TIRE), the process of alternative deposition of poly-allylamine hydrochloride (PAH) and CdS (or ZnS) layers could be monitored in-situ. The dynamic scan shows that the adsorption kinetic of the first layer of PAH or nanoparticles was slower than that of the next layer. The fitting of TIRE spectra gavethicknesses of about 7 nm and 12 nm for CdS and ZnS, respectively. It supports the suggestion of the formation of three-dimensional aggregates of semiconductor nanoparticles intercalated with polyelectrolyte.AFM images show the formation of large aggregates of nanoparticles, about 40-50 nm, for the films deposited from original colloid solutions, while smaller aggregates, about 12-20 nm, were obtained if the colloid solutions were diluted.Current-voltage (I-V) and capacitance

  12. Evolution of different morphologies of CdS nanoparticles by thermal decomposition of bis(thiourea)cadmium chloride in various solvents

    International Nuclear Information System (INIS)

    Gaur, Rama; Jeevanandam, P.

    2015-01-01

    CdS nanoparticles with different morphologies have been synthesized by thermal decomposition of bis(thiourea)cadmium chloride in different solvents without the use of any ligand/surfactant. CdS nanoparticles with pyramid, sponge-like and hexagonal disc-like morphologies were obtained in diphenyl ether (DPE), 1-octadecene (ODE) and ethylene glycol (EG), respectively. In addition, CdS nanoparticles with unique morphologies were obtained when the decomposition of the complex was carried out in mixed solvents (DPE–EG and ODE–EG). Extensive characterization of the CdS nanoparticles was carried out using powder X-ray diffraction, FT-IR spectroscopy, thermal analysis, field-emission scanning electron microscopy, diffuse reflectance spectroscopy and photoluminescence spectroscopy, and detailed mechanism of the formation of CdS nanoparticles with different morphologies in various solvents has been proposed

  13. Synthesis and Use of [Cd(Detu2(OOCCH32]·H2O as Single Molecule Precursor for Cds Nanoparticles

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2013-01-01

    Full Text Available Substituted thiourea ligands are of interest because they possess various donor sites for metal ions and their application in separation of metal ions and as antimicrobial agents. The coordination of the sulfur donor atom led to interest in them as precursor for semiconductor nanoparticles. In this study, cadmium(II complex of diethylthiourea was synthesized and characterized by elemental analysis, FTIR, and X-ray crystallography. Single crystal X-ray structure of the complex showed that the octahedral geometry around the Cd ion consists of two molecules of diethylthiourea acting as monodentate ligands and two chelating acetate ions. The thermal decomposition of the compound showed that it decomposed to give CdS. The compound was thermolysed in hexadecylamine (HDA to prepare HDA-capped CdS nanoparticles. The absorption spectrum showed blue shifts in its absorption band edges which clearly indicated quantum confinement effect, and the emission spectrum showed characteristic band edge luminescence. The broad diffraction peaks of the XRD pattern showed the materials to be of the nanometric size.

  14. Synthesis of poly (3-hexyl thiophene-2,5-diyl) in presence of CdS nanoparticles: microscopic and spectroscopic studies

    Energy Technology Data Exchange (ETDEWEB)

    Nicho, M. E.; Jaimes, W. [Universidad Autonoma del Estado de Morelos, Centro de Investigacion en Ingenierias y Ciencias Aplicadas, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos (Mexico); Rivas A, M. E.; Quevedo L, M. A. [University of Texas at Dallas, Department of Materials Science and Engineering, 800 West Campbell Road, Richardson, Texas 75252 (United States); Hu, H., E-mail: menicho@uaem.mx [UNAM, Instituto de Energias Renovables, 62580 Temixco, Morelos (Mexico)

    2017-11-01

    In this paper, the synthesis of nano composites of poly(3-hexyl thiophene-2,5-diyl) (P3HT) and cadmium sulfide (CdS) nanoparticles are reported. CdS nanoparticles were first synthesized using chemical precipitation. Then P3HT was synthesized by direct oxidation of 3-hexyl thiophene with FeCl{sub 3} as oxidant in presence of CdS nanoparticles. The goal of this work was to investigate the effect of the CdS nanoparticles during the synthesis of P3HT. The resulting films of P3HT/CdS nano composites were investigated by Fourier Transform Infrared Spectroscopy (Ft-IR), Ultraviolet-Visible Spectroscopy (UV-Vis), X-ray diffraction, Transmission electron microscopy (Tem), Atomic force microscopy (AFM) and Scanning electron microscopy (Sem). Homogeneous distribution of CdS nanoparticles in P3HT was demonstrated by Sem, AFM and Tem. Ft-IR analysis showed interaction between CdS and the S atoms of the thiophene rings. This result, together with UV-Vis spectra and XRD pattern suggest a better arrangement of the polymer chains. It is possible that the CdS nanoparticles are coupled with the unpaired electrons of S atoms in the thiophene rings through the positive delocalized charge, resulting in a more ordered P3HT polymer matrix with embedded CdS nanoparticles. (Author)

  15. Formation mechanism of CdS nanoparticles with tunable luminescence via a non-ionic microemulsion route

    International Nuclear Information System (INIS)

    Angelescu, Daniel G.; Munteanu, Gabriel; Anghel, Dan F.; Peretz, Sandu; Maraloiu, Adrian V.; Teodorescu, Valentin S.

    2013-01-01

    We investigated the synthesis of CdS nanoparticles via an optimized water-in-oil microemulsion route that used the non-ionic surfactant-based system H 2 O–n-octane–Brij30/1-octanol. For that purpose, a microemulsion that contained Cd(II) ions (μe1) and another microemulsion that contained S 2− ions (μe2) were combined. To investigate the ways in which the non-ionic microemulsion characteristics controlled the size and emission properties of colloidal CdS quantum dots, μe1 and μe2 with tunable and robust similar structure were prepared. This requirement was fulfilled by matching the water emulsification failure boundary (wefb) of the two microemulsions and carrying out synthesis along this boundary. Dynamic light scattering and fluorescence probe techniques were used to investigate the size and interfacial organization of the microemulsion water droplets, and the CdS nanoparticles were characterized by UV–Vis and static fluorescence spectrometry, TEM and HRTEM. Nanoparticles of diameter 4.5–5.5 nm exhibiting enhanced band edge emission were produced by increasing the water content of the precursor microemulsions. The experimental results were combined with a Monte Carlo simulation approach to demonstrate that growth via coagulation of seed nuclei represented the driving mechanism for the CdS nanoparticle formation in the water-in-oil microemulsion.

  16. Formation mechanism of CdS nanoparticles with tunable luminescence via a non-ionic microemulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Angelescu, Daniel G., E-mail: dangelescu@hotmail.com; Munteanu, Gabriel [Quantum Chemistry and Molecular Structure Laboratory, Romanian Academy, ' Ilie Murgulescu' Institute of Physical Chemistry (Romania); Anghel, Dan F.; Peretz, Sandu [Romanian Academy, ' Ilie Murgulescu' Institute of Physical Chemistry, Colloidal Laboratory (Romania); Maraloiu, Adrian V.; Teodorescu, Valentin S. [National Institute of Materials Physics, Institute of Atomic Physics (Romania)

    2013-01-15

    We investigated the synthesis of CdS nanoparticles via an optimized water-in-oil microemulsion route that used the non-ionic surfactant-based system H{sub 2}O-n-octane-Brij30/1-octanol. For that purpose, a microemulsion that contained Cd(II) ions ({mu}e1) and another microemulsion that contained S{sup 2-} ions ({mu}e2) were combined. To investigate the ways in which the non-ionic microemulsion characteristics controlled the size and emission properties of colloidal CdS quantum dots, {mu}e1 and {mu}e2 with tunable and robust similar structure were prepared. This requirement was fulfilled by matching the water emulsification failure boundary (wefb) of the two microemulsions and carrying out synthesis along this boundary. Dynamic light scattering and fluorescence probe techniques were used to investigate the size and interfacial organization of the microemulsion water droplets, and the CdS nanoparticles were characterized by UV-Vis and static fluorescence spectrometry, TEM and HRTEM. Nanoparticles of diameter 4.5-5.5 nm exhibiting enhanced band edge emission were produced by increasing the water content of the precursor microemulsions. The experimental results were combined with a Monte Carlo simulation approach to demonstrate that growth via coagulation of seed nuclei represented the driving mechanism for the CdS nanoparticle formation in the water-in-oil microemulsion.

  17. Interactions between citrate-capped gold nanoparticles and polymersomes

    Science.gov (United States)

    Zhang, Xiaohan; Lopez, Anand; Liu, Yibo; Wang, Feng; Liu, Juewen

    2018-06-01

    Polymersomes are vesicles formed by self-assembled amphiphilic block copolymers. Polymersomes generally have better stability than liposomes and they have been widely used in making drug delivery vehicles. In this work, the interaction between two types of polymersomes and citrate-capped gold nanoparticles (AuNPs) was studied. The following two polymers: poly(2-methyloxazoline-b-dimethylsiloxane-b-2-methyloxazoline) (called P1) and poly(butadiene-b-ethylene oxide) (called P2) were respectively used to form polymersomes. While P1 only formed spherical vesicle structures, worm-like structures were also observed with P2 as indicated by cryo-TEM. Both polymersomes adsorbed AuNPs leading to their subsequent aggregation. A lower polymersome concentration produced more obvious aggregation of AuNPs as judged from the color change. Capping AuNPs with glutathione inhibited adsorption of AuNPs. Considering the surface property of the polymers, the interaction with AuNPs was likely due to van der Waals forces. P1 polymersomes encapsulated calcein stably and AuNPs did not induce leakage. The P1/AuNP complex was more efficiently internalized by HeLa cells compared to free P1 polymersomes, further indicating a stable adsorption under cell culture conditions. In summary, this work indicates citrate-capped AuNPs form stable adsorption complexes with these polymersomes and their interactions have been explored.

  18. Photoelectrochemical detection of enzymatically generated CdS nanoparticles: Application to development of immunoassay.

    Science.gov (United States)

    Barroso, Javier; Saa, Laura; Grinyte, Ruta; Pavlov, Valeri

    2016-03-15

    We report an innovative photoelectrochemical process (PEC) based on graphite electrode modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP). The system relies on the in situ enzymatic generation of CdS quantum dots (QDs). Alkaline phosphatase (ALP) catalyzes the hydrolisis of sodium thiophosphate (TP) to hydrogen sulfide (H2S) which in the presence Cd(2+) ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365 nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os-PVP complex on the surface of graphite electrode at applied potential of 0.31 V vs. Ag/AgCl. A novel immunoassay based on specific enzyme linked immunosorbent assay (ELISA) combined with the PEC methodology was developed. Having selected the affinity interaction between bovine serum albumine (BSA) with anti-BSA antibody (AB) as a model system, we built the PEC immunoassay for AB. The new assay displays a linear range up to 20 ngmL(-1) and a detection limit (DL) of 2 ngmL(-1) (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP). Copyright © 2015 Elsevier B.V. All rights reserved.

  19. EPR and photoluminescence properties of Mn2+ doped CdS nanoparticles synthesized via co-precipitation method.

    Science.gov (United States)

    Gupta, Atul K; Kripal, Ram

    2012-10-01

    The structural properties of Mn doped CdS (Mn:CdS) nanoparticles (NPs) are studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-vis), Photoluminescence (PL), Raman and Electron paramagnetic resonance (EPR) spectroscopy. XRD analysis shows the nanostructure with 2-4 nm of average crystallite size. The planes (110), (103) and (112) in XRD pattern distinguish the wurtzite structure of the Mn:CdS NPs. The intensity of the plane (102) increases as the doping concentration of Mn(2+) increases. UV-vis absorption spectra show blue shift as compared to bulk CdS. The optical band gap energy of Mn(2+) (0, 0.35, 0.70 and 1.35 at.%) doped CdS NPs corresponding to absorption edge are found to be 5.29, 5.28, 5.25 and 5.21 eV, respectively. The intensity of luminescence is changing with the concentration of Mn(2+) doped in CdS NPs. Raman spectra show blue shift in fundamental optical phonon mode (1LO) as well as second optical phonon mode (2LO) as compared to bulk CdS. The intensity ratio of the 2LO to 1LO modes slightly decreases as Mn(2+) concentration increases. EPR shows the existence of Mn(2+) with different local structures in CdS nanoparticles. The values of spectroscopic splitting factor (g) and hyperfine interaction constant (A) decrease as Mn(2+) concentration increases in CdS NPs. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Effect of Gd{sup 3+} doping and reaction temperature on structural and optical properties of CdS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Gajanan, E-mail: pandeygajanan@rediffmail.com [Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, 226025, (U.P.) (India); Dixit, Supriya; Shrivastava, A.K. [School of Studies in Physics, Jiwaji University, Gwalior, 474011, (M.P.) (India)

    2015-10-15

    Graphical abstract: - Highlights: • Cd{sub 1−x}Gd{sub x}S nanoparticles have been prepared in aqueous medium in presence of CTAB. • From XRD, EDX and ICP-OES study, successful doping of Gd{sup 3+} in CdS has been proved. • Gd{sup 3+} doping reduced size of NCs, while temperature increased size and altered shape. • Gd{sup 3+} doping and reaction temperature influenced the optical properties of NCs. - Abstract: CdS and Gd{sup 3+} ions doped CdS nanoparticles have been prepared at two reaction temperatures 90 and 120 °C in aqueous medium in presence of cationic surfactant cetyltrimethylammonium bromide. X-ray diffraction study revealed predominant formation of zinc blend CdS and Gd:CdS at 90 °C, while at 120 °C, phase pure wurtzite CdS and Gd:CdS were formed. From EDX spectra and ICP-OES analysis, successful doping of Gd{sup 3+} ions in CdS host has been proved. Fourier transform infrared spectroscopy results show the interaction of CTAB through headgroup at the nanoparticles surface. In the transmission electron microscopy images, it has been observed that the reaction temperature and Gd{sup 3+} doping played critical role on size and shape of nanocrystals. In UV–visible absorption as well as photoluminescence emission spectra, size and shape-dependent quantum confinement effect has been observed. On Gd{sup 3+} doping, surface states related emission peak shifted to higher wavelength, while intensity of peaks increased on increasing temperature.

  1. Simulation studies on structural and thermal properties of alkane thiol capped gold nanoparticles.

    Science.gov (United States)

    Devi, J Meena

    2017-06-01

    The structural and thermal properties of the passivated gold nanoparticles were explored employing molecular dynamics simulation for the different surface coverage densities of the self-assembled monolayer (SAM) of alkane thiol. The structural properties of the monolayer protected gold nanoparticles such us overall shape, organization and conformation of the capping alkane thiol chains were found to be influenced by the capping density. The structural order of the thiol capped gold nanoparticles enhances with the increase in the surface coverage density. The specific heat capacity of the alkane thiol capped gold nanoparticles was found to increase linearly with the thiol coverage density. This may be attributed to the enhancement in the lattice vibrational energy. The present simulation results suggest, that the structural and thermal properties of the alkane thiol capped gold nanoparticles may be modified by the suitable selection of the SAM coverage density. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Synthesis and application of luminescent single CdS quantum dot encapsulated silica nanoparticles directed for precision optical bioimaging

    Directory of Open Access Journals (Sweden)

    Veeranarayanan S

    2012-07-01

    Full Text Available Srivani Veeranarayanan, Aby Cheruvathoor Poulose, M Sheikh Mohamed, Yutaka Nagaoka, Seiki Iwai, Yuya Nakagame, Shosaku Kashiwada, Yasuhiko Yoshida, Toru Maekawa, D Sakthi KumarBio Nano Electronics Research Centre, Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe, JapanAbstract: This paper presents the synthesis of aqueous cadmium sulfide (CdS quantum dots (QDs and silica-encapsulated CdS QDs by reverse microemulsion method and utilized as targeted bio-optical probes. We report the role of CdS as an efficient cell tag with fluorescence on par with previously documented cadmium telluride and cadmium selenide QDs, which have been considered to impart high levels of toxicity. In this study, the toxicity of bare QDs was efficiently quenched by encapsulating them in a biocompatible coat of silica. The toxicity profile and uptake of bare CdS QDs and silica-coated QDs, along with the CD31-labeled, silica-coated CdS QDs on human umbilical vein endothelial cells and glioma cells, were investigated. The effect of size, along with the time-dependent cellular uptake of the nanomaterials, has also been emphasized. Enhanced, high-specificity imaging toward endothelial cell lines in comparison with glioma cells was achieved with CD31 antibody-conjugated nanoparticles. The silica-coated nanomaterials exhibited excellent biocompatibility and greater photostability inside live cells, in addition to possessing an extended shelf life. In vivo biocompatibility and localization study of silica-coated CdS QDs in medaka fish embryos, following direct nanoparticle exposure for 24 hours, authenticated the nanomaterials' high potential for in vivo imaging, augmented with superior biocompatibility. As expected, CdS QD-treated embryos showed 100% mortality, whereas the silica-coated QD-treated embryos stayed viable and healthy throughout and after the experiments, devoid of any deformities. We provide highly cogent and convincing evidence for such

  3. Surface-modified CdS nanoparticles as a fluorescent probe for the selective detection of cysteine

    International Nuclear Information System (INIS)

    Negi, Devendra P S; Chanu, T Inakhunbi

    2008-01-01

    We present a novel method for the selective detection of cysteine, a sulfur-containing amino acid, which plays a crucial role in many important biological functions such as protein folding. Surface-modified colloidal CdS nanoparticles have been used as a fluorescent probe to selectively detect cysteine in the presence of other amino acids in the micromolar concentration range. Cysteine quenches the emission of CdS in the 0.5-10 μM concentration range, whereas the other amino acids do not affect its emission. Among the other amino acids, histidine is most efficient in quenching the emission of the CdS nanoparticles. The sulfur atom of cysteine plays a crucial role in the quenching process in the 0.5-10 μM concentration range. Cysteine is believed to quench the emission of the CdS nanoparticles by binding to their surface via its negatively charged sulfur atom. This method can potentially be applied for its detection in biological samples.

  4. Photoelectrochemical and Raman characterization of In2O3 mesoporous films sensitized by CdS nanoparticles

    Directory of Open Access Journals (Sweden)

    Mikalai V. Malashchonak

    2013-04-01

    Full Text Available The method of successive ion layer adsorption and reaction was applied for the deposition of CdS nanoparticles onto a mesoporous In2O3 substrate. The filling of the nanopores in In2O3 films with CdS particles mainly occurs during the first 30 cycles of the SILAR deposition. The surface modification of In2O3 with CdS nanoparticles leads to the spectral sensitization of photoelectrochemical processes that manifests itself in a red shift of the long-wavelength edge in the photocurrent spectrum by 100–150 nm. Quantum-confinement effects lead to an increase of the bandgap from 2.49 to 2.68 eV when decreasing the number of SILAR cycles from 30 to 10. The spectral shift and the widening of the Raman line belonging to CdS evidences the lattice stress on the CdS/In2O3 interfaces and confirms the formation of a close contact between the nanoparticles.

  5. Facile synthesis of organically capped PbS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nejo, Ayorinde O.; Nejo, Adeola A.; Pullabhotla, Rajasekhar V.S.R. [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa (South Africa); Revaprasadu, Neerish, E-mail: nrevapra@pan.uzulu.ac.za [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa (South Africa)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer Hexadecylamine and tri-n-octylphosphine oxide capped PbS nanoparticles have been synthesized. Black-Right-Pointing-Pointer By varying the reaction conditions various morphologies were formed. Black-Right-Pointing-Pointer The formation of the anisotropic particles is due to different growth mechanisms. - Abstract: PbS nanocubes and nanorods were successfully synthesized through a facile route using hexadecylamine (HDA) and tri-n-octylphosphine oxide (TOPO) as surfactants. The structure and morphology of the as-prepared PbS nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM. The morphology of the PbS was influenced by the variation in lead source and organic surfactant. Particles in the shape of spheres, perfect cubes and rods were obtained by variation in reaction conditions. A possible growth mechanism to explain the formation of these PbS nanocubes and nanorods is also discussed.

  6. Synthesis of aluminum nanoparticles capped with copolymerizable epoxides

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Brandon J. [Saint Louis University, Department of Chemistry (United States); Bunker, Christopher E. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Propulsion Directorate (United States); Guliants, Elena A. [University of Dayton Research Institute, Department of Electrical and Computer Engineering (United States); Hayes, Sophia E. [Washington University, Department of Chemistry (United States); Kheyfets, Arthur [Saint Louis University, Department of Chemistry (United States); Wentz, Katherine M. [Washington University, Department of Chemistry (United States); Buckner, Steven W., E-mail: buckners@slu.edu; Jelliss, Paul A., E-mail: jellissp@slu.edu [Saint Louis University, Department of Chemistry (United States)

    2013-06-15

    We report on the synthesis of air-stable aluminum nanoparticles (Al NPs) capped with 1,2-epoxy-9-decene. Long-chain epoxides have proven to be effective capping agents for Al NPs as the epoxide ring is highly susceptible to ring-opening polymerization, leading to the formation of putative polyether loops on the nascent Al NP surface. However, these materials are observed to degrade within several hours to days following exposure to ambient air. By inducing polymerization of the additional terminal alkene functionality on the epoxide, we have produced Al NPs that exhibit both a shelf life of {approx}6 weeks and a high active Al content. Transmission electron microscopy confirms that these spherical nanostructures, {approx}25 nm in diameter, are embedded in a covalently bound polymer matrix that serves as a prophylactic barrier against water/air (H{sub 2}O/O{sub 2}) degradation, and {sup 27}Al solid-state NMR is used to nondestructively confirm the presence of both metallic Al{sup 0} and oxidized Al{sup 3+}. In addition, we have induced polymerization of the epoxide terminal alkene functionality with a long-chain diene monomer, 1,13-tetradecadiene, leading to the formation of Al NPs protected by an extremely hydrophobic polymer matrix. These core-shell nanomaterials also have high active Al contents along with extremely long shelf lives (up to 6 months upon air exposure).

  7. Photovoltage method for the research of CdS and ZnO nanoparticles and hybrid MEH-PPV/nanoparticle structures

    Czech Academy of Sciences Publication Activity Database

    Toušková, J.; Toušek, J.; Rohovec, Jan; Růžička, A.; Polonskyi, O.; Urbánek, P.; Kuřitka, I.

    2014-01-01

    Roč. 16, č. 3 (2014), Art. 2314 ISSN 1388-0764 Institutional support: RVO:67985831 Keywords : CdS * energy conversion * MEH-PPV * nanoparticles * photovoltage spectra * transmission electron microscopy * ZnO Subject RIV: DD - Geochemistry Impact factor: 2.184, year: 2014

  8. 'Green' synthesis of starch capped CdSe nanoparticles at room temperature

    International Nuclear Information System (INIS)

    Li Jinhua; Ren Cuiling; Liu Xiaoyan; Hu Zhide; Xue Desheng

    2007-01-01

    The nearly monodisperse starch capped CdSe nanoparticles were successfully synthesized by a simple and 'green' route at room temperature. The as-prepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis absorption and photoluminescence (PL) spectra. The XRD analysis showed that the starch capped CdSe nanoparticles were of the cubic structure, the average particle size was calculated to be about 3 nm according to the Debye-Scherrer equation. TEM micrographs exhibited that the starch capped CdSe nanoparticles were well dispersed than the uncapped CdSe nanoparticles, the mean particles size of the capped CdSe was about 3 nm in the TEM image, which was in good agreement with the XRD

  9. Enhancing Photocatalytic Degradation of Methyl Blue Using PVP-Capped and Uncapped CdSe Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kgobudi Frans Chepape

    2017-01-01

    Full Text Available Quantum confinement of semiconductor nanoparticles is a potential feature which can be interesting for photocatalysis, and cadmium selenide is one simple type of quantum dot to use in the following photocatalytic degradation of organic dyes. CdSe nanoparticles capped with polyvinylpyrrolidone (PVP in various concentration ratios were synthesized by the chemical reduction method and characterized. The transmission electron microscopy (TEM analysis of the samples showed that 50% PVP-capped CdSe nanoparticles were uniformly distributed in size with an average of 2.7 nm and shape which was spherical-like. The photocatalytic degradation of methyl blue (MB in water showed efficiencies of 31% and 48% when using uncapped and 50% PVP-capped CdSe nanoparticles as photocatalysts, respectively. The efficiency of PVP-capped CdSe nanoparticles indicated that a complete green process can be utilized for photocatalytic treatment of water and waste water.

  10. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection

    International Nuclear Information System (INIS)

    Sharma, Anshu; Rawat, Kamla; Solanki, Pratima R; Bohidar, H B; Baral, Dinesh

    2015-01-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe 3 O 4 )) nanoparticles (NPs) have been synthesized by the co-precipitation method and capped by citric acid (CA). These NPs were electrophoretically deposited onto indium-tin-oxide (ITO)-coated glass substrate and used for immobilization of monoclonal antibodies against Vibrio cholerae (Ab) and bovine serum albumin (BSA) for Vibrio cholerae detection using an electrochemical technique. The structural and morphological studies of Fe 3 O 4 and CA-Fe 3 O 4 /ITO were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) techniques. The average crystalline size of Fe 3 O 4 , CA-Fe 3 O 4 nanoparticles obtained were about 29 ± 1 nm and 37 ± 1 nm, respectively. The hydrodynamic radius of the nanoparticles was found to be 77.35 nm (Fe 3 O 4 ) and 189.51 nm (CA-Fe 3 O 4 ) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe 2 O 3 /ITO immunosensor exhibits a good detection range of 12.5–500 ng mL −1 with a low detection limit of 0.32 ng mL −1 , sensitivity 0.03 Ω/ng ml −1 cm −2 , and reproducibility more than 11 times. (paper)

  11. Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

    International Nuclear Information System (INIS)

    Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J.

    2012-01-01

    A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH 4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

  12. 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.

  13. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Science.gov (United States)

    Wen, Li; Lin, Zhonghua; Gu, Pingying; Zhou, Jianzhang; Yao, Bingxing; Chen, Guoliang; Fu, Jinkun

    2009-02-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  14. CdS nanoparticles/CeO_2 nanorods composite with high-efficiency visible-light-driven photocatalytic activity

    International Nuclear Information System (INIS)

    You, Daotong; Pan, Bao; Jiang, Fan; Zhou, Yangen; Su, Wenyue

    2016-01-01

    Graphical abstract: Coupling CdS with CeO_2 can effectively improve the light-harvesting ability of wide-band gap CeO_2 NRs as the photoinduced electrons on the conduction band of CdS are transfered to the conduction band of CeO_2. - Highlights: • Coupling CdS can effectively improve the light-harvesting ability of wide-band gap CeO_2. • CdS/CeO_2 composites show high photocatalytic activity under visible light irradiation. • The mechanism of photocatalytic H_2 evolution over CdS/CeO_2 was proposed. - Abstract: Different mole ratios of CdS nanoparticles (NPs)/CeO_2 nanorods (NRs) composites with effective contacts were synthesized through a two-step hydrothermal method. The crystal phase, microstructure, optical absorption properties, electrochemical properties and photocatalytic H_2 production activity of these composites were investigated. It was concluded that the photogenerated charge carriers in the CdS NPs/CeO_2 NRs composite with a proper mole ratio (1:1) exhibited the longest lifetime and highest separation efficiency, which was responsible for the highest H_2-production rate of 8.4 mmol h"−"1 g"−"1 under visible-light irradiation (λ > 420 nm). The superior photocatalytic H_2 evolution properties are attributed to the transfer of visible-excited electrons of CdS NPs to CeO_2 NRs, which can effectively extend the light absorption range of wide-band gap CeO_2 NRs. This work provides feasible routes to develop visible-light responsive CeO_2-based nanomaterial for efficient solar utilization.

  15. Oleic acid capped PbS nanoparticles: Synthesis, characterization and tribological properties

    International Nuclear Information System (INIS)

    Chen Shuang; Liu Weimin

    2006-01-01

    Oleic acid (OA) capped PbS nanoparticles were chemically synthesized and characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray electron diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The triboligical properties of the capped PbS nanoparticles as additive in liquid paraffin was investigated using a four-ball machine. The lubricating mechanisms were discussed along with the analyses results of XPS and scanning electron microscope (SEM). Results show that OA-capped PbS nanoparticles, with an average diameter of about 8 nm, are able to prevent water adsorption, oxidation and are capable of being dispersed stably in organic solvents or mineral oil. OA-capped PbS nanoparticles as an additive in liquid paraffin perform good antiwear and friction-reduction properties owing to the formation of a boundary film

  16. Turning “on” and “off” nucleation and growth: Microwave assisted synthesis of CdS clusters and nanoparticles

    International Nuclear Information System (INIS)

    Ferrer, Edmy; Nater, Sariann; Rivera, Daniel; Colon, Jean Marie; Zayas, Francisco; Gonzalez, Miguel; Castro, Miguel E.

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► Cadmium acetate and DMSO were employed as ion precursors. ► New approach to controlled CdS nanoparticle synthesis. ► CdS clusters and nanoparticles synthesis achieved using microwave irradiation. ► Microwave irradiation turns on and off nanoparticle growth. ► The formation of clusters, embryos and nanoparticles studied with optical spectroscopy. -- Abstract: We report here on the formation of CdS NP from the microwave assisted reaction of Cd(CH 3 CO 2 ) 2 with dimethylsulfoxide (DMSO). DMSO serves as the solvent and a controlled source of sulfide ions to form (CdS) 1≤n≤5 clusters at the early stages of the process. The clusters grow into CdS nanoparticles, with diameters that range from 1.6 nm up to over 250 nm, with microwave heating. The time dependence of the onset of light absorption and absorbance are consistent with a concurrent nucleation and growth processes. The formation of clusters and nuclei and their subsequent reactions is controlled by turning on and off the energy supply consistent with an energy barrier to the formation of CdS nanostructures.

  17. Enhancing Photocatalytic Degradation of Methyl Blue Using PVP-Capped and Uncapped CdSe Nanoparticles

    OpenAIRE

    Chepape, Kgobudi Frans; Mofokeng, Thapelo Prince; Nyamukamba, Pardon; Mubiayi, Kalenga Pierre; Moloto, Makwena Justice

    2017-01-01

    Quantum confinement of semiconductor nanoparticles is a potential feature which can be interesting for photocatalysis, and cadmium selenide is one simple type of quantum dot to use in the following photocatalytic degradation of organic dyes. CdSe nanoparticles capped with polyvinylpyrrolidone (PVP) in various concentration ratios were synthesized by the chemical reduction method and characterized. The transmission electron microscopy (TEM) analysis of the samples showed that 50% PVP-capped Cd...

  18. Pseudorotaxane capped mesoporous silica nanoparticles for 3,4-methylenedioxymethamphetamine (MDMA) detection in water

    DEFF Research Database (Denmark)

    Lozano-Torres, Beatriz; Pascual, Lluís; Bernardos, Andrea

    2017-01-01

    Mesoporous silica nanoparticles loaded with fluorescein and capped by a pseudorotaxane, formed between a naphthalene derivative and cyclobis(paraquat-p-phenylene) (CBPQT4+), were used for the selective and sensitive fluorogenic detection of 3,4-methylenedioxymethamphetamine (MDMA).......Mesoporous silica nanoparticles loaded with fluorescein and capped by a pseudorotaxane, formed between a naphthalene derivative and cyclobis(paraquat-p-phenylene) (CBPQT4+), were used for the selective and sensitive fluorogenic detection of 3,4-methylenedioxymethamphetamine (MDMA)....

  19. Structural, spectroscopic and biological investigation of copper oxides nanoparticles with various capping agents

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, A., E-mail: ana.maria.nowak@gmail.com [A. Chelkowski Institute of Physics, University of Silesia, Katowice (Poland); Szade, J.; Talik, E.; Ratuszna, A. [A. Chelkowski Institute of Physics, University of Silesia, Katowice (Poland); Ostafin, M. [Agricultural University of Cracow, Department of Microbiology, Krakow (Poland); Peszke, J. [A. Chelkowski Institute of Physics, University of Silesia, Katowice (Poland)

    2014-06-01

    Powder composed of copper oxides nanoparticles with various capping agents has been synthesized and characterized with the use of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Polyvinyl alcohol (PVA), glycol propylene, glycerin and glycerin plus ammonia were used as capping agents. The scanning electron microscopy (SEM) studies showed that nanoparticles form agglomerates with the size from 80 to 120 nm while particles size determined from the XRD experiment was in the range from 7 to 21 nm. XPS and XRD experiments revealed that depending on capping and reducing agents used in the synthesis nanoparticles are composed of Cu{sub 2}O, CuO or a mixture of them. The biological activity test performed for a selected sample where the capping agent was glycerin plus ammonia has shown promising killing/inhibiting behavior, very effective especially for Gram negatives bacteria. - Highlights: • We obtained copper oxide nanoparticles in a powder form. • Several capping agents were tested. • Structural and chemical tests showed that the main component were Cu{sub 2}O and CuO. • The size of nanoparticles was in the range 7–21 nm. • Nanoparticles with glycerin and ammonia capping agent showed good antibacterial properties.

  20. Effect of capping agents: Structural, optical and biological properties of ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Javed, Rabia [Department of Biotechnology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Usman, Muhammad, E-mail: uk_phy@yahoo.com [Department of Physics, Faculty of Natural Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Department of Physics, School of Science and Engineering, Lahore University of Management Sciences, Lahore 54729 (Pakistan); Tabassum, Saira; Zia, Muhammad [Department of Biotechnology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2016-11-15

    Highlights: • ZnO nanoparticles have been effectively capped with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) shown by the data of XRD, FTIR and UV–visible spectroscopy. • Reduction in size occurred from 34 nm to 26 nm due to capping agent and band gap energy increases with the decrease in the particle size. • Antibacterial activity against Gram-positive bacteria is greater than the Gram-negative bacteria. • All biological assays reveal highest activities in capped ZnO nanoparticles as compared to the uncapped ZnO nanoparticles. • Highest antibacterial activity has been exhibited by ZnO-PVP while highest antioxidant and antidiabetic activities have been conferred by ZnO- PEG. - Abstract: Different biological activities of capped and uncapped ZnO nanoparticles were investigated, and the effects of potential capping agents on these biological activities were studied. ZnO nanoparticles were synthesized and capped by polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) using a simple chemical method of co-precipitation. Characterization by X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and UV–vis spectroscopy confirmed the crystallinity, size, functional group, and band gap of synthesized nanoparticles. Reduction in size occurred from 34 nm to 26 nm due to surfactant. Results of all biological activities indicated significantly higher values in capped as compared to uncapped nanoparticles. Antibacterial activity against Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC15224), and Acetobacter was obtained. This activity was more prominent against Gram-positive bacteria, and ZnO-PVP nanoparticles elucidated highest antibacterial activity (zone of inhibition 17 mm) against Gram-positive, Bacillus subtilis species. Antioxidant activities including total flavonoid content, total phenolic content, total antioxidant capacity, total reducing power and %age inhibition of DPPH, and

  1. Effect of capping agents: Structural, optical and biological properties of ZnO nanoparticles

    International Nuclear Information System (INIS)

    Javed, Rabia; Usman, Muhammad; Tabassum, Saira; Zia, Muhammad

    2016-01-01

    Highlights: • ZnO nanoparticles have been effectively capped with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) shown by the data of XRD, FTIR and UV–visible spectroscopy. • Reduction in size occurred from 34 nm to 26 nm due to capping agent and band gap energy increases with the decrease in the particle size. • Antibacterial activity against Gram-positive bacteria is greater than the Gram-negative bacteria. • All biological assays reveal highest activities in capped ZnO nanoparticles as compared to the uncapped ZnO nanoparticles. • Highest antibacterial activity has been exhibited by ZnO-PVP while highest antioxidant and antidiabetic activities have been conferred by ZnO- PEG. - Abstract: Different biological activities of capped and uncapped ZnO nanoparticles were investigated, and the effects of potential capping agents on these biological activities were studied. ZnO nanoparticles were synthesized and capped by polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) using a simple chemical method of co-precipitation. Characterization by X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and UV–vis spectroscopy confirmed the crystallinity, size, functional group, and band gap of synthesized nanoparticles. Reduction in size occurred from 34 nm to 26 nm due to surfactant. Results of all biological activities indicated significantly higher values in capped as compared to uncapped nanoparticles. Antibacterial activity against Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC15224), and Acetobacter was obtained. This activity was more prominent against Gram-positive bacteria, and ZnO-PVP nanoparticles elucidated highest antibacterial activity (zone of inhibition 17 mm) against Gram-positive, Bacillus subtilis species. Antioxidant activities including total flavonoid content, total phenolic content, total antioxidant capacity, total reducing power and %age inhibition of DPPH, and

  2. Synthesis of water soluble glycine capped silver nanoparticles and their surface selective interaction

    International Nuclear Information System (INIS)

    Agasti, Nityananda; Singh, Vinay K.; Kaushik, N.K.

    2015-01-01

    Highlights: • Synthesis of water soluble silver nanoparticles at ambient reaction conditions. • Glycine as stabilizing agent for silver nanoparticles. • Surface selective interaction of glycine with silver nanoparticles. • Glycine concentration influences crystalinity and optical property of silver nanoparticles. - Abstract: Synthesis of biocompatible metal nanoparticles has been an area of significant interest because of their wide range of applications. In the present study, we have successfully synthesized water soluble silver nanoparticles assisted by small amino acid glycine. The method is primarily based on reduction of AgNO 3 with NaBH 4 in aqueous solution under atmospheric air in the presence of glycine. UV–vis spectroscopy, transmission electron microscopy (TEM), X–ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG) and differential thermal analysis (DTA) techniques used for characterization of resulting silver nanoparticles demonstrated that, glycine is an effective capping agent to stabilize silver nanoparticles. Surface selective interaction of glycine on (1 1 1) face of silver nanoparticles has been investigated. The optical property and crystalline behavior of silver nanoparticles were found to be sensitive to concentration of glycine. X–ray diffraction studies ascertained the phase specific interaction of glycine on silver nanoparticles. Silver nanoparticles synthesized were of diameter 60 nm. We thus demonstrated an efficient synthetic method for synthesis of water soluble silver nanoparticles capped by amino acid under mild reaction conditions with excellent reproducibility

  3. Attenuated effects of chitosan-capped gold nanoparticles on LPS-induced toxicity in laboratory rats

    International Nuclear Information System (INIS)

    Stefan, Marius; Melnig, Viorel; Pricop, Daniela; Neagu, Anca; Mihasan, Marius; Tartau, Liliana; Hritcu, Lucian

    2013-01-01

    The impact of nanoparticles in medicine and biology has increased rapidly in recent years. Gold nanoparticles (AuNP) have advantageous properties such as chemical stability, high electron density and affinity to biomolecules. However, the effects of AuNP on human body after repeated administration are still unclear. Therefore, the purpose of the present study was to evaluate the effects of gold-11.68 nm (AuNP1, 9.8 μg) and gold-22.22 nm (AuNP2, 19.7 μg) nanoparticles capped with chitosan on brain and liver tissue reactivity in male Wistar rats exposed to lipopolysaccharide (LPS from Escherichia coli serotype 0111:B4, 250 μg) upon 8 daily sessions of intraperitoneal administration. Our results suggest that the smaller size of chitosan-capped AuNP shows the protective effects against LPS-induced toxicity, suggesting a very high potential for biomedical applications. - Highlights: ► Smaller size of chitosan-capped gold nanoparticles acts against LPS-induced toxicity. ► Larger size of chitosan-capped gold nanoparticles agglomerated inside neurons and induced toxicity in combination with LPS. ► Chitosan has excellent biocompatible proprieties. ► Smaller size of chitosan-capped gold nanoparticles demonstrates great potential in biomedical applications.

  4. Synthesis, effect of capping agents, structural, optical and photoluminescence properties of ZnO nanoparticles

    International Nuclear Information System (INIS)

    Singh, A.K.; Viswanath, V.; Janu, V.C.

    2009-01-01

    Zinc oxide nanoparticles were synthesized using chemical method in alcohol base. During synthesis three capping agents, i.e. triethanolamine (TEA), oleic acid and thioglycerol, were used and the effect of concentrations was analyzed for their effectiveness in limiting the particle growth. Thermal stability of ZnO nanoparticles prepared using TEA, oleic acid and thioglycerol capping agents, was studied using thermogravimetric analyzer (TGA). ZnO nanoparticles capped with TEA showed maximum weight loss. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological characterization of ZnO nanoparticles. Particle size was evaluated using effective mass approximation method from UV-vis spectroscopy and Scherrer's formula from XRD patterns. XRD analysis revealed single crystal ZnO nanoparticles of size 12-20 nm in case of TEA capping. TEA, oleic acid and thioglycerol capped synthesized ZnO nanoparticles were investigated at room temperature photoluminescence for three excitation wavelengths i.e. 304, 322 and 325 nm, showing strong peaks at about 471 nm when excited at 322 and 325 nm whereas strong peak was observed at 411 for 304 nm excitation.

  5. Turning “on” and “off” nucleation and growth: Microwave assisted synthesis of CdS clusters and nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, Edmy; Nater, Sariann; Rivera, Daniel; Colon, Jean Marie; Zayas, Francisco; Gonzalez, Miguel [Chemical Imaging Center, Department of Chemistry, The University of Puerto Rico at Mayaguez, Mayaguez, PR 00680 (United States); Castro, Miguel E., E-mail: miguel.castro2@upr.edu [Chemical Imaging Center, Department of Chemistry, The University of Puerto Rico at Mayaguez, Mayaguez, PR 00680 (United States)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► Cadmium acetate and DMSO were employed as ion precursors. ► New approach to controlled CdS nanoparticle synthesis. ► CdS clusters and nanoparticles synthesis achieved using microwave irradiation. ► Microwave irradiation turns on and off nanoparticle growth. ► The formation of clusters, embryos and nanoparticles studied with optical spectroscopy. -- Abstract: We report here on the formation of CdS NP from the microwave assisted reaction of Cd(CH{sub 3}CO{sub 2}){sub 2} with dimethylsulfoxide (DMSO). DMSO serves as the solvent and a controlled source of sulfide ions to form (CdS){sub 1≤n≤5} clusters at the early stages of the process. The clusters grow into CdS nanoparticles, with diameters that range from 1.6 nm up to over 250 nm, with microwave heating. The time dependence of the onset of light absorption and absorbance are consistent with a concurrent nucleation and growth processes. The formation of clusters and nuclei and their subsequent reactions is controlled by turning on and off the energy supply consistent with an energy barrier to the formation of CdS nanostructures.

  6. PEG capped CaS nanoparticles synthesized by wet chemical co-precipitation method

    Science.gov (United States)

    Rekha, S.; Anila, E. I.

    2018-04-01

    Calcium sulfide (CaS) nanoparticles capped with polyethyleneglycol (PEG) were synthesized using wet chemical co-precipitation method. The structural and optical properties of the prepared sample were studied by X-ray diffractogram (XRD), transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS) and photoluminescence (PL) spectrum. The structure of CaS nanoparticles is cubic as demonstrated by the X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) analysis. TEMimage revealed the spherical morphology of the particles with diameter in the range 15-20 nm. The optical band gap of the prepared sample was determined from the DRS and its value was found to be 4.1 eV. The PL studies showed that the relative intensity of the PEG capped CaS nanoparticles was higher than that of uncapped CaS nanoparticles. The presence of various functional groups in the capped samples were examined by Fourier Transform Infrared (FTIR) spectroscopy.

  7. Hydrothermal synthesis of CdS nanoparticle/functionalized graphene sheet nanocomposites for visible-light photocatalytic degradation of methyl orange

    International Nuclear Information System (INIS)

    Yan, Shancheng; Wang, Bojun; Shi, Yi; Yang, Fan; Hu, Dong; Xu, Xin; Wu, Jiansheng

    2013-01-01

    CdS nanoparticle/functionalized graphene sheet (CdS NP/FGS) nanocomposites were successfully prepared in a one-step hydrothermal synthesis route. The samples were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy. In addition, the photocatalytic performance of CdS NP/FGS composites and pure CdS in the degradation of methyl orange (MO) was examined using visible light. Results show that the addition of FGS can enhance the photocatalytic performance of CdS NP/FGS composites with a maximum degradation efficiency of 98.1% under visible light irradiation as compared with pure CdS (60.1%). This finding can be attributed to three reasons. First is the strong redox ability of CdS in the nanocomposite with smaller crystal size. Second is the increase in specific surface area for more adsorbed MO. Third is the reduction in electron–hole pair recombination with the introduction of FGS. Based on their high photocatalytic activity, the CdS NP/FGS composites can be expected to be a practical visible light photocatalyst.

  8. Hydrothermal synthesis of CdS nanoparticle/functionalized graphene sheet nanocomposites for visible-light photocatalytic degradation of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shancheng, E-mail: yansc@njupt.edu.cn [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wang, Bojun [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Shi, Yi [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yang, Fan; Hu, Dong; Xu, Xin; Wu, Jiansheng [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China)

    2013-11-15

    CdS nanoparticle/functionalized graphene sheet (CdS NP/FGS) nanocomposites were successfully prepared in a one-step hydrothermal synthesis route. The samples were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy. In addition, the photocatalytic performance of CdS NP/FGS composites and pure CdS in the degradation of methyl orange (MO) was examined using visible light. Results show that the addition of FGS can enhance the photocatalytic performance of CdS NP/FGS composites with a maximum degradation efficiency of 98.1% under visible light irradiation as compared with pure CdS (60.1%). This finding can be attributed to three reasons. First is the strong redox ability of CdS in the nanocomposite with smaller crystal size. Second is the increase in specific surface area for more adsorbed MO. Third is the reduction in electron–hole pair recombination with the introduction of FGS. Based on their high photocatalytic activity, the CdS NP/FGS composites can be expected to be a practical visible light photocatalyst.

  9. Single-Source Molecular Precursor for Synthesis of CdS Nanoparticles and Nanoflowers

    Science.gov (United States)

    Salavati-Niasari, Masoud; Sobhani, Azam

    2012-04-01

    CdS Semiconductor nanostructures were synthesized by using two different methods. Using triphenylphosphine (C18H15P) and oleylamine (C18H37N) as surfactant, CdS semiconductor nanocrystals with a size ranging from 30 to 90 nm can be synthesized by thermal decomposition of precursor [bis(thiosemicarbazide)cadmium(II)]. CdS nanoflowers were synthesized via hydrothermal decomposition of [bis(thiosemicarbazide) cadmium(II)] without any surfactant. X-ray diffraction (XRD) patterns confirm that the resulting samples were a pure hexagonal phase of CdS. The optical property test indicates that the absorption peak of the samples shifts towards short wavelength, and the blue shift phenomenon might be ascribed to the quantum effect.

  10. Photosensitization of TiO2 P25 with CdS Nanoparticles for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Trenczek-Zając A.

    2017-06-01

    Full Text Available A TiO2/CdS coupled system was prepared by mixing the TiO2 P25 with CdS synthesized by means of the precipitation method. It was found that the specific surface area (SSA of both components is extremely different and equals 49.5 for TiO2 and 145.4 m2·g−1 for CdS. The comparison of particle size distribution and images obtained by means of transmission electron microscopy (TEM showed agglomeration of nanocomposites. X-ray diffraction (XRD patterns suggest that CdS crystallizes in a mixture of cubic and hexagonal phases. Optical reflectance spectra revealed a gradual shift of the fundamental absorption edge towards longer wavelengths with increasing CdS molar fraction, which indicates an extension of the absorption spectrum of TiO2. The photocatalytic activity in UV and UV-vis was tested with the use of methyl orange (MO. The Langmuir–Hinshelwood model described well the photodegradation process of MO. The results showed that the photocatalytic behaviour of the TiO2/CdS mixture is significantly better than that of pure nanopowders.

  11. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Energy Technology Data Exchange (ETDEWEB)

    Wen Li [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Lin Zhonghua [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Gu Pingying [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Zhou Jianzhang [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Yao Bingxing [Xiamen University, School of Life Sciences (China); Chen Guoliang; Fu Jinkun, E-mail: wenli_1976@163.co [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China)

    2009-02-15

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 {sup o}C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 {+-} 0.8 nm size were formed by using Bacillus megatherium D01.

  12. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    International Nuclear Information System (INIS)

    Wen Li; Lin Zhonghua; Gu Pingying; Zhou Jianzhang; Yao Bingxing; Chen Guoliang; Fu Jinkun

    2009-01-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 o C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  13. Controlled synthesis of PbS-Au nanostar-nanoparticle heterodimers and cap-like Au nanoparticles

    Science.gov (United States)

    Zhao, Nana; Li, Lianshan; Huang, Teng; Qi, Limin

    2010-11-01

    Uniform PbS-Au nanostar-nanoparticle heterodimers consisting of one Au nanoparticle grown on one horn of a well-defined six-horn PbS nanostar were prepared using the PbS nanostars as growth substrates for the selective deposition of Au nanoparticles. The size of the Au nanoparticles on the horns of the PbS nanostars could be readily adjusted by changing the PbS concentration for the deposition of Au nanoparticles. An optimum cetyltrimethylammonium bromide concentration and temperature were essential for the selective deposition of uniform Au nanoparticles on single horns of the PbS nanostars. Unusual PbS-Au nanoframe-nanoparticle heterodimers were obtained by etching the PbS-Au nanostar-nanoparticle heterodimers with oxalic acid while novel cap-like Au nanoparticles were obtained by etching with hydrochloric acid. The obtained heterodimeric nanostructures and cap-like nanoparticles are promising candidates for anisotropic nanoscale building blocks for the controllable assembly of useful, complex architectures.

  14. Photovoltaic performance enhancement of CdS quantum dot-sensitized TiO{sub 2} photoanodes with plasmonic gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Aiping, E-mail: liuaiping1979@gmail.com [Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Ren, Qinghua; Zhao, Ming; Xu, Tao; Yuan, Ming; Zhao, Tingyu [Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Tang, Weihua [State Key Laboratory of Information Photonics and Optical Communication, Beijing University Posts and Telecommunications, Beijing 100876 (China)

    2014-03-15

    Highlights: • CdS QD-sensitized TiO{sub 2} porous photoanode with plasmonic gold. • A prominent light absorption enhancement of hybrid was attained by gold plasmon. • The photovoltaic response of hybrid was tunable by CdS amount. • The Au/TiO{sub 2}/CdS hybrid had a potential application in energy conversion devices. -- Abstract: The CdS quantum dot-sensitized TiO{sub 2} films with plasmonic gold nanoparticles were designed as photoanodes by the electrodeposition of gold combined with the “successive ionic layer adsorption and reaction” (SILAR) method for CdS deposition on porous TiO{sub 2} films. A prominent enhancement in light absorption of Au/TiO{sub 2}/CdS hybrid was attained by efficient light scattering of gold plasmons as sub-wavelength antennas and concentrators. The photogenerated electron formed in the near-surface region of TiO{sub 2} and CdS were facilitated to transfer to the plasmonic gold, resulting in the enhancement of photocurrent and incident photon-to-current conversion efficiency of hybrid photoanode upon photoirradiation. Furthermore, the photovoltaic response of hybrid was highly tunable with respect to the number of SILAR cycles applied to deposit CdS. The thicker absorber layer with less porous structure and larger CdS crystals might limit the electrolyte diffusion into the hybrid electrode and impose a barrier for electron tunneling and transferring. The highly versatile and tunable properties of Au/TiO{sub 2}/CdS photoanodes demonstrated their potential application in energy conversion devices.

  15. Synthesis of Mn doped ZnO nanoparticles with biocompatible capping

    International Nuclear Information System (INIS)

    Sharda; Jayanthi, K.; Chawla, Santa

    2010-01-01

    Free standing nanoparticles of ZnO doped with transition metal ion Mn have been prepared by solid state reaction method at 500 deg. C. X-ray diffraction (XRD) analysis confirmed high quality monophasic wurtzite hexagonal structure with particle size of 50 nm and no signature of dopant as separate phase. Incorporation of Mn has been confirmed with EDS. Bio-inorganic interface was created by capping the nanoparticles with heteromultifunctional organic stabilizer mercaptosuccinic acid (MSA). The surface morphological studies by scanning electron microscopy (SEM) showed formation of spherical particles and the nanoballs grow in size uniformly with MSA capping. MSA capping has been confirmed with thermo gravimetric analysis (TGA) and FTIR. Photoluminescence (PL) studies show that the ZnO:Mn 2+ particles are excitable by blue light and emits in orange and red. Occurrence of room temperature ferromagnetism in Mn doped ZnO makes such biocompatible luminescent magnetic nanoparticles very promising material.

  16. Photoluminescence of urea- and urea/rhodamine B-capped TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalo-Juan, I., E-mail: gonzalo@materials.tu-darmstadt.de; Macé, L.; Tengeler, S.; Mosallem, A.; Nicoloso, N.; Riedel, R.

    2016-07-01

    Urea- and rhodamine B (RhB)-capped TiO{sub 2} nanoparticles (NPs) have been prepared by solvothermal synthesis and characterized by HRTEM, XRD, FTIR, XPS, optical absorption and photoemission. The urea and urea/RhB ligands are capped to the surface of the TiO{sub 2} NPs for the first time through carbamate bonding. The band gap of TiO{sub 2} is slightly reduced from 3.1 eV to 3.0 eV in the urea capped TiO{sub 2} NPs (TU) and 2.9 eV for the NPs capped with urea/RhB (TUR). The generation of new trapping states in TU and TUR at the conduction band edges (surface oxygen vacancies) has been confirmed by the Urbach law providing tail state energies of 180 meV and 270 meV, respectively. These tail states are considered to be responsible for the strong reduction of the photoluminescence at ≈400 nm and the increased emission at ≈600 nm in TU and TUR. The findings suggest that urea- and RhB-capped TiO{sub 2} NPs could have potential applications as photocatalysts, opto-electronic devices, sensors, biological labels and anti-bacterial agents. - Highlights: • Urea- and urea/rhodamine B (RhB)-capped TiO{sub 2} nanoparticles preparation. • Characterization of optical properties of urea- and urea/rhodamine B (RhB)-capped TiO{sub 2} nanoparticles. • The recombination of electrons and holes is significantly reduced in the capped TiO{sub 2} nanoparticles, in comparison with TiO{sub 2}.

  17. CdS nanoparticles immobilized on porous carbon polyhedrons derived from a metal-organic framework with enhanced visible light photocatalytic activity for antibiotic degradation

    Science.gov (United States)

    Yang, Cao; Cheng, Jianhua; Chen, Yuancai; Hu, Yongyou

    2017-10-01

    The CdS/MOF-derived porous carbon (MPC) composite as an efficient visible-light-driven photocatalyst was prepared through the pyrolysis of ZIF-8 and subsequent growth of CdS. The porous and functionalized MPC enables intimate and discrete growth of CdS nanoparticles. This unique structure not only reduces the bulk recombination owing to nano-size effect of CdS, but also suppresses the surface recombination due to the discrete growth of CdS nanoparticles on MPC polyhedrons, which facilitates electron transfer and charge separation. Moreover, such a composite material possessed good adsorption ability toward the antibiotic pollutants because of the amino-functionalized surface. As a result, the as-prepared CdS/MPC composites showed excellent photocatalytic performance for the antibiotic degradation, significantly improving the photoactivity of CdS. Importantly, the CdS/MPC composite with the CdS loading of 20 wt% exhibited the highest photocatalytic efficiency of approximately 91% and apparent rate constant of 0.024 min-1.

  18. Fullerenol-Capped Porous Silica Nanoparticles for pH-Responsive Drug Delivery

    Directory of Open Access Journals (Sweden)

    Nikola Ž. Knežević

    2015-01-01

    Full Text Available Novel nanocomposite containing fullerenol nanoparticles (FNP and porous silica nanoparticles (PSNs was constructed and characterized. The capability of FNP to serve as a pore-capping agent and for entrapping 9-aminoacridine (9-AA inside the pores of the PSN material was also demonstrated. Nitrogen sorption measurements evidence the successful capping of the silica pores while thermogravimetric analysis of FNP loaded PSN indicates the existence of pore-loaded fullerenol molecules. Higher amount of the drug release was noted by exposing the material to weakly acidic conditions in comparison to physiological pH, which may find application in targeted treatment of weakly acidic tumor tissues.

  19. Spectral properties of ultrasmall CdS nanoparticles Stabilized by mercaptoacids and hydrazine

    International Nuclear Information System (INIS)

    Solonenko, Dmytro I.; Rayevska, Oleksandra Ye.; Stroyuk, Oleksandr L.; Kuchmiy, Stepan Ya.

    2013-01-01

    Ultrasmall colloidal CdS quantum dots (QDs) were synthesized in water at room temperature by using a combination of two low-molecular-weight stabilizers - hydrazine and a mercaptoacid, particularly, mercaptoacetic and mercaptopropionic-2 acids. The average size of QDs was found to depend on the Cd-to-S ratio at the synthesis and be as small as 2,5 nm at 80% cadmium(II) excess. The CdS QDs emit broadband photoluminescence in the visible spectrum range with a relative quantum yield of around 5% and the radiative life time of around 100 ns. (authors)

  20. Visible Light-Induced Degradation of Methylene Blue in the Presence of Photocatalytic ZnS and CdS Nanoparticles

    Directory of Open Access Journals (Sweden)

    Parisa Vaziri

    2012-09-01

    Full Text Available ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles after 6 h irradiation time was about 73% with a reaction rate of 3.61 × 10−3 min−1. Higher degradation efficiency and reaction rate were achieved by increasing the amount of photocatalyst and initial pH of the solution.

  1. Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method.

    Science.gov (United States)

    Malashchonak, Mikalai V; Mazanik, Alexander V; Korolik, Olga V; Streltsov, Еugene А; Kulak, Anatoly I

    2015-01-01

    The photoelectrochemical properties of nanoheterostructures based on the wide band gap oxide substrates (ZnO, TiO2, In2O3) and CdS nanoparticles deposited by the successive ionic layer adsorption and reaction (SILAR) method have been studied as a function of the CdS deposition cycle number (N). The incident photon-to-current conversion efficiency (IPCE) passes through a maximum with the increase of N, which is ascribed to the competition between the increase in optical absorption and photocarrier recombination. The maximal IPCE values for the In2O3/CdS and ZnO/CdS heterostructures are attained at N ≈ 20, whereas for TiO2/CdS, the appropriate N value is an order of magnitude higher. The photocurrent and Raman spectroscopy studies of CdS nanoparticles revealed the occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (E U), spectral width of the CdS longitudinal optical (LO) phonon band and the relative intensity of the surface optical (SO) phonon band in the Raman spectra. Maximal values of E U (100-120 meV) correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A notable variation in the degree of disorder of CdS nanoparticles is observed only in the initial stages of CdS growth (several tens of deposition cycles), indicating the preservation of the nanocrystalline state of CdS over a wide range of SILAR cycles.

  2. Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR method

    Directory of Open Access Journals (Sweden)

    Mikalai V. Malashchonak

    2015-11-01

    Full Text Available The photoelectrochemical properties of nanoheterostructures based on the wide band gap oxide substrates (ZnO, TiO2, In2O3 and CdS nanoparticles deposited by the successive ionic layer adsorption and reaction (SILAR method have been studied as a function of the CdS deposition cycle number (N. The incident photon-to-current conversion efficiency (IPCE passes through a maximum with the increase of N, which is ascribed to the competition between the increase in optical absorption and photocarrier recombination. The maximal IPCE values for the In2O3/CdS and ZnO/CdS heterostructures are attained at N ≈ 20, whereas for TiO2/CdS, the appropriate N value is an order of magnitude higher. The photocurrent and Raman spectroscopy studies of CdS nanoparticles revealed the occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (EU, spectral width of the CdS longitudinal optical (LO phonon band and the relative intensity of the surface optical (SO phonon band in the Raman spectra. Maximal values of EU (100–120 meV correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A notable variation in the degree of disorder of CdS nanoparticles is observed only in the initial stages of CdS growth (several tens of deposition cycles, indicating the preservation of the nanocrystalline state of CdS over a wide range of SILAR cycles.

  3. INTERACTION OF SILVER MOLECULAR CLUSTERS, INTRODUCED BY LOW-TEMPERATURE ION EXCHANGE METHOD, WITH NANOPARTICLES OF CdS IN FLUORINE PHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    N. D. Grazhdanov

    2015-09-01

    Full Text Available Glasses with metallic and semi-conductive nano-particles appear to be perspective non-linear and luminescent materials of photonics. It was shown in theory that composite optical materials containing semi-conductive CdS-core with Ag shell (or vice versa are optimal for enhancement of non-linear Kerr effect. Interaction of such an ensemble of particles leads to the forming of Ag island structures on the CdS particle, and formation of acanthite Ag2S on the two phases border (CdS-Ag is minimal. In glasses synthesis of CdS quantum dots occurred due to thermal treatment close to glass transition temperature; introduction of silver was realized by low-temperature ion exchange (LIE. The main object of this work is investigation of Ag+ -LIE effect on the growth of CdS nano-particles. Two glasses were explored in this work: without CdS (glass 1 and with CdS (glass 2, processed by LIE at the temperature of 320°С for 10, 20 and 30 minutes and subsequent heat treatment at temperatures of 410°С and 420°С. In case of glass 1, intensive luminescence appears as a result of LIE, and subsequent heat treatment results in surface resonance at λ=410 nm. In case of glass 2, absorbance spectra change appears that is specific for formation of acanthite and weak luminescence shifting to long-wavelength region (from 550 to 700 nm as a result of applying LIE and heat treatment. It indicates the growth of CdS quantum dots. Experiment has shown that quantum efficiency increases to 70% for glass 2 containing CdS quantum dots without LIE, while glass that contains silver shows steep decrease of quantum efficiency to 0%. That decrease is caused by formation of acanthite Ag2S on the surface of CdS quantum dot.

  4. Adsorption kinetics of alkanethiol-capped gold nanoparticles at the hexane–water interface

    International Nuclear Information System (INIS)

    Ferdous, Sultana; Ioannidis, Marios A.; Henneke, Dale

    2011-01-01

    The pendant drop technique was used to characterize the adsorption behavior of n-dodecane-1-thiol and n-hexane-1-thiol-capped gold nanoparticles at the hexane–water interface. The adsorption process was studied by analyzing the dynamic interfacial tension versus nanoparticle concentration, both at early times and at later stages (i.e., immediately after the interface between the fluids is made and once equilibrium has been established). A series of gold colloids were made using nanoparticles ranging in size from 1.60 to 2.85 nm dissolved in hexane for the interfacial tension analysis. Following free diffusion of nanoparticles from the bulk hexane phase, adsorption leads to ordering and rearrangement of the nanoparticles at the interface and formation of a dense monolayer. With increasing interfacial coverage, the diffusion-controlled adsorption for the nanoparticles at the interface was found to change to an interaction-controlled assembly and the presence of an adsorption barrier was experimentally verified. At the same bulk concentration, different sizes of n-dodecane-1-thiol nanoparticles showed different absorption behavior at the interface, in agreement with the findings of Kutuzov et al. (Phys Chem Chem Phys 9:6351–6358, 2007). The experiments additionally demonstrated the important role played by the capping agent. At the same concentration, gold nanoparticles stabilized by n-hexane-1-thiol exhibited greater surface activity than gold nanoparticles of the same size stabilized by n-dodecane-1-thiol. These findings contribute to the design of useful supra-colloidal structures by the self-assembly of alkane-thiol-capped gold nanoparticles at liquid–liquid interfaces.

  5. Sum Frequency Generation Vibrational Spectroscopy of Colloidal Platinum Nanoparticle Catalysts: Disordering versus Removal of Organic Capping

    KAUST Repository

    Krier, James M.

    2012-08-23

    Recent work with nanoparticle catalysts shows that size and shape control on the nanometer scale influences reaction rate and selectivity. Sum frequency generation (SFG) vibrational spectroscopy is a powerful tool for studying heterogeneous catalysis because it enables the observation of surface intermediates during catalytic reactions. To control the size and shape of catalytic nanoparticles, an organic ligand was used as a capping agent to stabilize nanoparticles during synthesis. However, the presence of an organic capping agent presents two major challenges in SFG and catalytic reaction studies: it blocks a significant fraction of active surface sites and produces a strong signal that prevents the detection of reaction intermediates with SFG. Two methods for cleaning Pt nanoparticles capped with poly (vinylpyrrolidone) (PVP) are examined in this study: solvent cleaning and UV cleaning. Solvent cleaning leaves more PVP intact and relies on disordering with hydrogen gas to reduce the SFG signal of PVP. In contrast, UV cleaning depends on nearly complete removal of PVP to reduce SFG signal. Both UV and solvent cleaning enable the detection of reaction intermediates by SFG. However, solvent cleaning also yields nanoparticles that are stable under reaction conditions, whereas UV cleaning results in aggregation during reaction. The results of this study indicate that solvent cleaning is more advantageous for studying the effects of nanoparticle size and shape on catalytic selectivity by SFG vibrational spectroscopy. © 2012 American Chemical Society.

  6. Uncaria gambir Roxb. mediated green synthesis of silver nanoparticles using diethanolamine as capping agent

    Science.gov (United States)

    Labanni, A.; Zulhadjri; Handayani, D.; Arief, S.

    2018-01-01

    Studies of silver nanoparticles preparation has been developed increasingly due to the wide application in various areas and field, such as medicine, energy, catalysis, and electronic. An environmental-friendly method is needed to fabricate biocompatible silver nanoparticles without producing hazardous materials to the environment. In this study, we synthesized silver nanoparticles by green synthesis method, using leaf extract of gambir (Uncaria gambir Roxb.) as bioreducing agent and aqueous diethanolamine (DEA) solution as capping agents. The AgNO3/DEA molar ratio was varied to investigate the effect of DEA concentration to the properties of silver nanoparticles. The formation of silver nanoparticles was indicated by colour changes to yellowish brown and confirmed by result of UV-Vis spectrophotometer analysis which shown absorption band at 400 to 410 nm. The absorbance was increased to the reaction time of 24 hours, and was decrease by the increasing of DEA concentration in reaction. TEM analysis showed that prepared silver nanoparticles were spherical in shape with diameter of 3,5 - 45,5 nm. The diameter of DEA capped silver nanoparticles was 13 nm, smaller than uncapped silver nanoparticles which was 26 nm It exhibited good stability to time reaction of one month which was potential to be developed in some fields.

  7. Influence of thiol capping on the photoluminescence properties of L-cysteine-, mercaptoethanol- and mercaptopropionic acid-capped ZnS nanoparticles.

    Science.gov (United States)

    Tiwari, A; Dhoble, S J; Kher, R S

    2015-11-01

    Mercaptoethanol (ME), mercaptopropionic acid (MPA) and L-cysteine (L-Cys) having -SH functional groups were used as surface passivating agents for the wet chemical synthesis of ZnS nanoparticles. The effect of the thiol group on the optical and photoluminescence (PL) properties of ZnS nanoparticles was studied. L-Cysteine-capped ZnS nanoparticles showed the highest PL intensity among the studied capping agents, with a PL emission peak at 455 nm. The PL intensity was found to be dependent on the concentration of Zn(2+) and S(2-) precursors. The effect of buffer on the PL intensity of L-Cys-capped ZnS nanoparticles was also studied. UV/Vis spectra showed blue shifting of the absorption edge. Copyright © 2015 John Wiley & Sons, Ltd.

  8. 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.

  9. 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

  10. Anionic 11-mercaptoundecanoic acid capped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Šimšíková, Michaela, E-mail: michaela.simsikova@ceitec.vutbr.cz [CEITEC BUT, Brno University of Technology, Technická 10, 616 69 Brno (Czech Republic); Antalík, Marián [Department of Biochemistry, Faculty of Science, P.J. Šafárik University, Šrobárova 2, 041 54 Košice (Slovakia); Department of Biophysics, Institute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice (Slovakia); Kaňuchová, Mária; Škvarla, Jiří [Institute of Montaneous Sciences and Environmental Protection, Faculty of Mining, Ecology, Process Control and Geotechnologies, Technical University of Košice, Park Komenského 19, 043 84 Košice (Slovakia)

    2013-10-01

    The anionic zinc oxide nanoparticles have been prepared at room temperature by a precipitation method using ZnCl{sub 2} and NaOH and surface modification with 11-mercaptoundecanoic acid (MUA). Atomic force microscopy (AFM) was used for definition of morphology and size of prepared nanoparticles which was proved by measurements of particle size distribution using Zetasizer. Successful coating with MUA as surfactant was acknowledged by X-ray photoelectron spectroscopy and ATR FT-IR spectroscopy. The isoelectric point (IEP) of ZnO–MUA nanoparticles was obtained by measurements of zeta potential and FT-IR dependence on pH; the obtained value was approximately 3.58. The value of exchanged protons was 2.88 which indicates a positive binding cooperativity of modified nanoparticles.

  11. Capped Mesoporous Silica Nanoparticles for the Selective and Sensitive Detection of Cyanide.

    Science.gov (United States)

    Sayed, Sameh El; Licchelli, Maurizio; Martínez-Máñez, Ramón; Sancenón, Félix

    2017-10-18

    The development of easy and affordable methods for the detection of cyanide is of great significance due to the high toxicity of this anion and the potential risks associated with its pollution. Herein, optical detection of cyanide in water has been achieved by using a hybrid organic-inorganic nanomaterial. Mesoporous silica nanoparticles were loaded with [Ru(bipy) 3 ] 2+ , functionalized with macrocyclic nickel(II) complex subunits, and capped with a sterically hindering anion (hexametaphosphate). Cyanide selectively induces demetallation of nickel(II) complexes and the removal of capping anions from the silica surface, allowing the release of the dye and the consequent increase in fluorescence intensity. The response of the capped nanoparticles in aqueous solution is highly selective and sensitive towards cyanide with a limit of detection of 2 μm. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. In situ growth of CdS nanoparticles on UiO-66 metal-organic framework octahedrons for enhanced photocatalytic hydrogen production under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jian-Jian; Wang, Rong; Liu, Xin-Ling; Peng, Fu-Min [School of Chemistry and Chemical Engineering and Innovation Lab for Clean Energy & Green Catalysis, Anhui University, Hefei 230601 (China); Li, Chuan-Hao, E-mail: chuanhao.li@yale.edu [School of Chemistry and Chemical Engineering and Innovation Lab for Clean Energy & Green Catalysis, Anhui University, Hefei 230601 (China); Department of Chemical & Environmental Engineering, Yale University, New Haven 06511 (United States); Teng, Fei [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Yuan, Yu-Peng, E-mail: yupengyuan@ahu.edu.cn [School of Chemistry and Chemical Engineering and Innovation Lab for Clean Energy & Green Catalysis, Anhui University, Hefei 230601 (China); Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2015-08-15

    Graphical abstract: Enhanced photocatalytic hydrogen generation was achieved though constructing the CdS/UiO-66 MOF hybrids. In addition, the resultant hybrids show excellent photostability for hydrogen generation. - Highlights: • CdS nanoparticles were hydrothermally grown on UiO-66 octahedrons. • The resultant CdS/UiO-66 hybrids show enhanced photocatalytic H{sub 2} generation under visible light irradiation. • CdS/UiO-66 hybrids possess excellent photostability for long-term hydrogen generation. - Abstract: CdS nanoparticles acting as photosensitizer was grown in situ upon UiO-66 metal-organic framework octahedrons through a hydrothermal process. The resultant CdS/UiO-66 hybrid photocatalysts show remarkably active hydrogen evolution under visible light irradiation as compared to CdS and UiO-66 alone. The optimum hybrid with 16 wt% CdS loading shows a hydrogen production rate of 235 μmol h{sup −1}, corresponding to 1.2% quantum efficiency at 420 nm. The improved photocatalytic hydrogen production over hybrid CdS/UiO-66 is ascribed to the efficient interfacial charge transfer from CdS to UiO-66, which effectively suppresses the recombination of photogenerated electron-hole pairs and thereby enhancing the photocatalytic efficiency.

  13. Robust Synthesis of Ciprofloxacin-Capped Metallic Nanoparticles and Their Urease Inhibitory Assay.

    Science.gov (United States)

    Nisar, Muhammad; Khan, Shujaat Ali; Qayum, Mughal; Khan, Ajmal; Farooq, Umar; Jaafar, Hawa Z E; Zia-Ul-Haq, Muhammad; Ali, Rashid

    2016-03-25

    The fluoroquinolone antibacterial drug ciprofloxacin (cip) has been used to cap metallic (silver and gold) nanoparticles by a robust one pot synthetic method under optimized conditions, using NaBH₄ as a mild reducing agent. Metallic nanoparticles (MNPs) showed constancy against variations in pH, table salt (NaCl) solution, and heat. Capping with metal ions (Ag/Au-cip) has significant implications for the solubility, pharmacokinetics and bioavailability of fluoroquinolone molecules. The metallic nanoparticles were characterized by several techniques such as ultraviolet visible spectroscopy (UV), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) methods. The nanoparticles synthesized using silver and gold were subjected to energy dispersive X-ray tests in order to show their metallic composition. The NH moiety of the piperazine group capped the Ag/Au surfaces, as revealed by spectroscopic studies. The synthesized nanoparticles were also assessed for urease inhibition potential. Fascinatingly, both Ag-cip and Au-cip NPs exhibited significant urease enzyme inhibitory potential, with IC50 = 1.181 ± 0.02 µg/mL and 52.55 ± 2.3 µg/mL, compared to ciprofloxacin (IC50 = 82.95 ± 1.62 µg/mL). MNPs also exhibited significant antibacterial activity against selected bacterial strains.

  14. Growth and optical characterization of colloidal CdTe nanoparticles capped by a bifunctional molecule

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-sadek, M.S., E-mail: el_sadek_99@email.co [Nanomaterial Laboratory, Physics Department, Faculty of Science, South Valley University, Qena-83523 (Egypt); Crystal Growth Centre, Anna University Chennai, Chennai-600025 (India); Moorthy Babu, S. [Crystal Growth Centre, Anna University Chennai, Chennai-600025 (India)

    2010-08-15

    Thiol-capped CdTe nanoparticles were synthesized in aqueous solution by wet chemical route. CdTe nanoparticles with bifunctional molecule mercaptoacetic acid as a stabilizer were synthesized at pH{approx}11.2 and using potassium tellurite as tellurium source. The effect of refluxing time on the preparation of these samples was measured using UV-vis absorption and photoluminescence analysis. By increasing the refluxing time the UV-vis absorption and photoluminescence results show that the band edge emission is redshifted. The synthesized thiol-capped CdTe were characterized with FT-IR, TEM and TG-DTA. The particle size was calculated by the effective mass approximation (EMA). The role of precursors, their composition, pH and reaction procedure on the development of nanoparticles are analyzed.

  15. Studies on ligand exchange reaction of functionalized mercaptothiadiazole compounds onto citrate capped gold nanoparticles

    International Nuclear Information System (INIS)

    Kalimuthu, Palraj; John, S. Abraham

    2010-01-01

    Mercaptothiadiazole ligands functionalized with thiol (2,5-dimercapto-1,3,4-thiadiazole (DMT)) and methyl (5-methyl-2-mercapto-1,3,4-thiadiazole (MMT)) groups capped onto citrate capped gold nanoparticles (C-AuNPs) by ligand exchange reaction was investigated by UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM) techniques. The surface plasmon resonance band at 522 nm for C-AuNPs was shifted to 530 nm after capping with DMT whereas an additional band was observed at 630 nm due to aggregation in addition to a shift in the band at 522 nm after capping of MMT onto C-AuNPs. Thus, capping of DMT onto C-AuNPs leads to the formation of stable AuNPs while capping of MMT leads to the formation of unstable AuNPs. FT-IR studies show that the citrate ions were completely replaced by both DMT and MMT ligands from the AuNPs. TEM images indicate that the size and shape of the AuNPs remain same after capping of these ligands.

  16. Prolonged reorganization of thiol-capped Au nanoparticles layered structures

    Directory of Open Access Journals (Sweden)

    Sarathi Kundu

    2013-09-01

    Full Text Available Prolonged reorganization behaviour of mono-, di-, tri- and multi-layer films of Au nanoparticles prepared by Langmuir-Blodgett method on hydrophobic Si(001 substrates have been studied by using X-ray scattering techniques. Out-of-plane study shows that although at the initial stage the reorganization occurs through the compaction of the films keeping the layered structure unchanged but finally all layered structures modify to monolayer structure. Due to this reorganization the Au density increases within the nanometer thick films. In-plane study shows that inside the reorganized films Au nanoparticles are distributed randomly and the particle size modifies as the metallic core of Au nanoparticles coalesces.

  17. Laser-fabricated castor oil-capped silver nanoparticles.

    Science.gov (United States)

    Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

    2011-01-01

    Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.

  18. Rapid synthesis of gold and silver nanoparticles using tryptone as a reducing and capping agent

    Science.gov (United States)

    Mehta, Sourabh M.; Sequeira, Marilyn P.; Muthurajana, Harries; D'Souza, Jacinta S.

    2018-02-01

    Due to its eco-friendliness, recent times have seen an immense interest in the green synthesis of metallic nanoparticles. We present here, a protocol for the rapid and cheap synthesis of Au and Ag nanoparticles (NPs) using 1 mg/ml tryptone (trypsinized casein) as a reducing and capping agent. These nanoparticles are spherical, 10 nm in diameter and relatively monodispersed. The atoms of these NPs are arranged in face-centered cubic fashion. Further, when tested for their cytotoxic property against HeLa and VERO cell lines, gold nanoparticles were more lethal than silver nanoparticles, with a more or less similar trend observed against both Gram-positive and Gram-negative bacteria. On the other hand, the NPs were least cytotoxic against a unicellular alga, Chlamydomonas reinhardtii implying their eco-friendly property.

  19. Quaternized Chitosan-Capped Mesoporous Silica Nanoparticles as Nanocarriers for Controlled Pesticide Release.

    Science.gov (United States)

    Cao, Lidong; Zhang, Huirong; Cao, Chong; Zhang, Jiakun; Li, Fengmin; Huang, Qiliang

    2016-06-28

    Nanotechnology-based pesticide formulations would ensure effective utilization of agricultural inputs. In the present work, mesoporous silica nanoparticles (MSNs) with particle diameters of ~110 nm and pore sizes of ~3.7 nm were synthesized via a liquid crystal templating mechanism. A water-soluble chitosan (CS) derivative ( N -(2-hydroxyl)propyl-3-trimethyl ammonium CS chloride, HTCC) was successfully capped on the surface of pyraclostrobin-loaded MSNs. The physicochemical and structural analyses showed that the electrostatic interactions and hydrogen bonding were the major forces responsible for the formation of HTCC-capped MSNs. HTCC coating greatly improved the loading efficiency (LC) (to 40.3%) compared to using bare MSNs as a single encapsulant (26.7%). The microstructure of the nanoparticles was revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The pyraclostrobin-loaded nanoparticles showed an initial burst and subsequent sustained release behavior. HTCC-capped MSNs released faster than bare MSNs in the initial stage. Pyraclostrobin-loaded HTCC-capped MSNs with half doses of pyraclostrobin technical demonstrated almost the same fungicidal activity against Phomopsis asparagi (Sacc.), which obviously reduced the applied pesticide and enhanced the utilization efficiency. Therefore, HTCC-decorated MSNs demonstrated great potential as nanocarriers in agrochemical applications.

  20. Quaternized Chitosan-Capped Mesoporous Silica Nanoparticles as Nanocarriers for Controlled Pesticide Release

    Directory of Open Access Journals (Sweden)

    Lidong Cao

    2016-06-01

    Full Text Available Nanotechnology-based pesticide formulations would ensure effective utilization of agricultural inputs. In the present work, mesoporous silica nanoparticles (MSNs with particle diameters of ~110 nm and pore sizes of ~3.7 nm were synthesized via a liquid crystal templating mechanism. A water-soluble chitosan (CS derivative (N-(2-hydroxylpropyl-3-trimethyl ammonium CS chloride, HTCC was successfully capped on the surface of pyraclostrobin-loaded MSNs. The physicochemical and structural analyses showed that the electrostatic interactions and hydrogen bonding were the major forces responsible for the formation of HTCC-capped MSNs. HTCC coating greatly improved the loading efficiency (LC (to 40.3% compared to using bare MSNs as a single encapsulant (26.7%. The microstructure of the nanoparticles was revealed by scanning electron microscopy (SEM and transmission electron microscopy (TEM. The pyraclostrobin-loaded nanoparticles showed an initial burst and subsequent sustained release behavior. HTCC-capped MSNs released faster than bare MSNs in the initial stage. Pyraclostrobin-loaded HTCC-capped MSNs with half doses of pyraclostrobin technical demonstrated almost the same fungicidal activity against Phomopsis asparagi (Sacc., which obviously reduced the applied pesticide and enhanced the utilization efficiency. Therefore, HTCC-decorated MSNs demonstrated great potential as nanocarriers in agrochemical applications.

  1. Structural and luminescent properties of Fe3+ doped PVA capped CdTe nanoparticles

    Directory of Open Access Journals (Sweden)

    Ravindranadh K.

    2017-07-01

    Full Text Available During recent decades, magnetic and semiconductor nanoparticles have attracted significant attention of scientists in various fields of engineering, physics, chemistry, biology and medicine. Fe3+ doped PVA capped CdTe nanoparticles were prepared by co-precipitation method and characterized by powder X-ray diffraction, SEM, TEM, FT-IR, optical, EPR and PL techniques to collect the information about the crystal structure, coordination/local site symmetry of doped Fe3+ ions in the host lattice and the luminescent properties of prepared sample. Powder XRD data revealed that the crystal structure belongs to a cubic system and its lattice cell parameters were evaluated. The average crystallite size was estimated to be 8 nm. The morphology of prepared samples was analyzed by using SEM and TEM investigations. Functional groups of the prepared sample were observed in FT-IR spectra. Optical absorption and EPR studies have shown that on doping, Fe3+ ions enter the host lattice in octahedral site symmetry. PL studies of Fe3+ doped PVA capped CdTe nanoparticles revealed UV and blue emission bands. CIE chromaticity coordinates were also calculated from the emission spectrum of Fe3+ doped PVA capped CdTe nanoparticles.

  2. Growth of hydroxyapatite on physiologically clotted fibrin capped gold nanoparticles

    International Nuclear Information System (INIS)

    Sastry, T P; Sundaraseelan, J; Swarnalatha, K; Sobhana, S S Liji; Makheswari, M Uma; Sekar, S; Mandal, A B

    2008-01-01

    The growth of hydroxyapatite (HAp) on physiologically clotted fibrin (PCF)-gold nanoparticles is presented for the first time by employing a wet precipitation method. Fourier transform infrared (FTIR) spectroscopy confirmed the characteristic functionalities of PCF and HAp in the PCF-Au-HAp nanocomposite. Scanning electron microscopy (SEM) images have shown cuboidal nanostructures having a size in the range of 70-300 nm of HAp, whereas 2-50 nm sized particles were visualized in high-resolution transmission electron microscopy (TEM). Energy-dispersive x-ray (EDX) and x-ray diffraction (XRD) studies have confirmed the presence of HAp. These results show that gold nanoparticles with PCF acted as a matrix for the growth of HAp, and that PCF-Au-HAp nanocomposite is expected to have better osteoinductive properties

  3. Synthesis, characterization and biocompatibility of cadmium sulfide nanoparticles capped with dextrin for in vivo and in vitro imaging application.

    Science.gov (United States)

    Reyes-Esparza, Jorge; Martínez-Mena, Alberto; Gutiérrez-Sancha, Ivonne; Rodríguez-Fragoso, Patricia; de la Cruz, Gerardo Gonzalez; Mondragón, R; Rodríguez-Fragoso, Lourdes

    2015-11-17

    The safe use in biomedicine of semiconductor nanoparticles, also known as quantum dots (QDs), requires a detailed understanding of the biocompatibility and toxicity of QDs in human beings. The biological characteristics and physicochemical properties of QDs entail new challenges regarding the management of potential adverse health effects following exposure. At certain concentrations, the synthesis of semiconductor nanoparticles of CdS using dextrin as capping agent, at certain concentration, to reduce their toxicity and improves their biocompatibility. This study successfully synthesized and characterized biocompatible dextrin-coated cadmium sulfide nanoparticles (CdS-Dx/QDs). The results show that CdS-Dx/QDs are cytotoxic at high concentrations (>2 μg/mL) in HepG2 and HEK293 cells. At low concentrations (nanoparticles only induced cell death by apoptosis in HEK293 cells at 1 μg/mL concentrations. The in vitro results showed that the cells efficiently took up the CdS-Dx/QDs and this resulted in strong fluorescence. The subcellular localization of CdS-Dx/QDs were usually small and apparently unique in the cytoplasm in HeLa cells but, in the case of HEK293 cells it were more abundant and found in cytoplasm and the nucleus. Animals treated with 100 μg/kg of CdS-Dx/QDs and sacrificed at 3, 7 and 18 h showed a differential distribution in their organs. Intense fluorescence was detected in lung and kidney, with moderate fluorescence detected in liver, spleen and brain. The biocompatibility and toxicity of CdS-Dx/QDs in animals treated daily with 100 μg/kg for 1 week showed the highest level of fluorescence in kidney, liver and brain. Less fluorescence was detected in lung and spleen. There was also evident presence of fluorescence in testis. The histopathological and biochemical analyses showed that CdS-Dx/QDs were non-toxic for rodents. The in vitro and in vivo studies confirmed the effective cellular uptake and even distribution pattern of CdS-Dx/QDs in tissues

  4. Uniformly dispersed CdS nanoparticles sensitized TiO{sub 2} nanotube arrays with enhanced visible-light photocatalytic activity and stability

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lingjuan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei 230009 (China); Lv, Jun, E-mail: lvjun117@126.com [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei 230009 (China); Xu, Guangqing; Wang, Yan; Xie, Kui [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei 230009 (China); Chen, Zhong [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798 (Singapore); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices, Hefei 230009 (China)

    2013-12-15

    In this study, TiO{sub 2} nanotube arrays (TiO{sub 2}-NTs) with various intertube spaces were fabricated in the electrolyte with different water contents and the CdS nanoparticles (CdS NPs) were further deposited onto the TiO{sub 2}-NTs as a sensitizer via a sequential chemical bath deposition (S-CBD) method. The FE-SEM, TEM, XRD and XPS results demonstrated that the CdS NPs were uniformly deposited onto the surface of TiO{sub 2}-NTs. It was found that higher water content in electrolyte was in favor of large intertube space and pore size and the uniform deposition of CdS NPs. The photocatalytic degradation of methyl orange was tested with the as-prepared CdS/TiO{sub 2}-NTs under visible light (λ>400 nm). It was found that the photodegradation rate reached as high as 96.7% under visible irradiation for 180 min. In addition, a reasonable degradation rate of 75.8% was achieved even after 5 cycles, suggesting a good photocatalytic stability of the as-prepared CdS/TiO{sub 2}-NTs. - Graphical abstract: The whole sheet of CdS NPs sensitized TiO{sub 2}-NTs with the Ti subtract was used for degradation of methyl orange under visible light (λ>400 nm) on a XPA-7 photochemical reactor. - Highlights: • Intertube space, pore size were controlled by changing water content in electrolyte. • CdS nanoparticles were uniformly deposited onto the surface of TiO{sub 2} nanotubes. • The catalyst with Ti substrate used as a whole was very convenient for recycling. • Visible-light photocatalytic activity and stability were highly enhanced.

  5. Towards single crystalline, highly monodisperse and catalytically active gold nanoparticles capped with probiotic Lactobacillus plantarum derived lipase

    Science.gov (United States)

    Khan, Imran; Nagarjuna, Ravikiran; Ray Dutta, Jayati; Ganesan, Ramakrishnan

    2018-03-01

    Owing to the eco-friendly nature of biomolecules, there lies a huge interest in exploring them as capping agents for nanoparticles to achieve stability and biocompatibility. Lipase extracted from the probiotic Lactobacillus plantarum is utilized for the first time to study its efficacy in capping gold nanoparticles (GNPs) in the room temperature synthesis using HAuCl4. The synthesized lipase-capped GNPs are characterized using UV-visible spectroscopy, FT-IR, HR-TEM, DLS and zeta potential measurements. Importantly, selected area electron diffraction (SAED) studies with HR-TEM have revealed the effect of lipase capping in tuning the polycrystallinity of the GNPs. The lipase-capped GNPs are explored for their catalytic efficiency towards an environmentally and industrially important conversion of 4-nitrophenol to 4-aminophenol. Exploiting the amine functional groups in the protein, the recoverability and reusability of the GNPs have been demonstrated through immobilization over amine-functionalized Fe3O4 nanoparticles.

  6. Synthesis and characterization of magnetic Co nanoparticles: A comparison study of three different capping surfactants

    International Nuclear Information System (INIS)

    Lu Yu; Lu Xianmao; Mayers, Brian T.; Herricks, Thurston; Xia Younan

    2008-01-01

    This paper compares the performance of three long-chain acids-oleic and elaidic (both olefinic) and stearic (aliphatic)-as a capping agent in the synthesis of magnetic Co nanoparticles. The particles were formed through thermal decomposition of dicobalt octacarbonyl in toluene in the presence of the long-chain acid, and characterized by TEM, high-resolution TEM, and SQUID measurements. Infrared spectra revealed that some of the added olefinic acid was transformed from cis- to trans-configuration (for oleic acid) or from trans- to cis- (for elaidic acid) to facilitate the formation of a densely packed monolayer on the surface of Co nanoparticles. As compared to aliphatic acids, olefinic acids are advantageous for dense packing on small particles with high surface curvatures due to a bent shape of the cis-isomer. The presence of an olefinic acid is able to control particle growth, stabilize the colloidal suspension, and prevent the final product from oxidation by air. Our results indicate that oleic acid, elaidic acid, and a mixture of oleic/stearic acids or elaidic/stearic acids have roughly the same performance in serving as a capping agent for the synthesis of Co nanoparticles with a spherical shape and narrow size distribution. - Graphical abstract: Magnetic Co nanoparticles were synthesized in the presence of different capping agents and the effect of their molecular structures on the morphology of Co nanoparticles was analyzed. The transformation between cis- and trans-isomers of olefinic acids was critical to the formation of a densely packed monolayer on the surface of small nanoparticles characterized by high curvatures

  7. ZnS, CdS and HgS nanoparticles via alkyl-phenyl dithiocarbamate complexes as single source precursors.

    Science.gov (United States)

    Onwudiwe, Damian C; Ajibade, Peter A

    2011-01-01

    The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively.

  8. ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2011-08-01

    Full Text Available The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm, 2.91 eV (426 nm and 4.27 eV (290 nm for the ZnS, CdS and HgS samples respectively.

  9. Electrostatic assembly of CTAB-capped silver nanoparticles along predefined λ-DNA template

    International Nuclear Information System (INIS)

    Wei Gang; Wang Li; Zhou Hualan; Liu Zhiguo; Song Yonghai; Li Zhuang

    2005-01-01

    Cetyltrimethylammonium bromide (CTAB)-capped positively-charged silver nanoparticles synthesized in water-ethanol system was electrostatic assembled on predefined aligned λ-DNA template. Silver nanowire can be obtained by changing the reaction time and the particles concentration. In our work, the length of the silver nanowire obtained is about 10 μm, and the dimension of the wires is about 20 nm. AFM data reveal that the assembly of CTAB-capped silver nanoparticles on DNA is ordered, but there is space between two particles absorbed on the DNA template. X-ray photoelectron spectroscopy (XPS) was applied to characterize the linear silver clusters, which provides an additional proof that the silver particles were assembled onto DNA template with fine order

  10. Synthesis and characterization of TGA-capped CdTe nanoparticles embedded in PVA matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K.; Kaur, Ramneek; Sharma, Mamta [Panjab University, Department of Physics, Center of Advanced Study in Physics, Chandigarh (India)

    2014-10-25

    This paper reports the synthesis and characterization of TGA-capped CdTe nanoparticles and its nanocomposite in a PVA matrix prepared by ex situ technique. The crystallite sizes of the CdTe nanoparticles and nanocomposite calculated from X-ray diffraction patterns are 6.07 and 7.75 nm with hexagonal structure, respectively. The spherical nature of the CdTe nanoparticles is confirmed from transmission electron microscopy measurements. Fourier transform infrared spectroscopy shows good interaction between the CdTe nanoparticles and PVA matrix. The absorption and emission spectra have also been studied. The stability of the TGA-capped CdTe nanoparticles increases after dispersion in a PVA matrix. In electrical measurements, the dark conductivity and the steady-state photoconductivity of CdTe nanocomposite thin films have been studied. The effect of temperature and intensity on the transient photoconductivity of CdTe nanocomposite is also studied. The values of differential life time have been calculated from the decay of photocurrent with time. The non-exponential decay of photoconductivity is observed indicating that the traps exist at all the energies in the band gap, making these materials suitable for various optoelectronic devices. (orig.)

  11. Synthesis and characterization of TGA-capped CdTe nanoparticles embedded in PVA matrix

    International Nuclear Information System (INIS)

    Tripathi, S.K.; Kaur, Ramneek; Sharma, Mamta

    2015-01-01

    This paper reports the synthesis and characterization of TGA-capped CdTe nanoparticles and its nanocomposite in a PVA matrix prepared by ex situ technique. The crystallite sizes of the CdTe nanoparticles and nanocomposite calculated from X-ray diffraction patterns are 6.07 and 7.75 nm with hexagonal structure, respectively. The spherical nature of the CdTe nanoparticles is confirmed from transmission electron microscopy measurements. Fourier transform infrared spectroscopy shows good interaction between the CdTe nanoparticles and PVA matrix. The absorption and emission spectra have also been studied. The stability of the TGA-capped CdTe nanoparticles increases after dispersion in a PVA matrix. In electrical measurements, the dark conductivity and the steady-state photoconductivity of CdTe nanocomposite thin films have been studied. The effect of temperature and intensity on the transient photoconductivity of CdTe nanocomposite is also studied. The values of differential life time have been calculated from the decay of photocurrent with time. The non-exponential decay of photoconductivity is observed indicating that the traps exist at all the energies in the band gap, making these materials suitable for various optoelectronic devices. (orig.)

  12. Biocompatibility study of protein capped and uncapped silver nanoparticles on human hemoglobin

    Science.gov (United States)

    Bhunia, Amit Kumar; Kanti Samanta, Pijus; Aich, Debasish; Saha, Satyajit; Kamilya, Tapanendu

    2015-06-01

    The interactions of human hemoglobin with protein capped silver nanoparticles and bare silver nanoparticles were studied to understand fundamental perspectives about the biocompatibility of protein capped silver nanoparticles compared with bare silver nanoparticles. Bare silver (Ag) nanoparticles (NPs) were prepared by the chemical reduction method. High resolution transmission electron microscopy (HRTEM) analysis along with absorption at ~390 nm indicated the formation of bare Ag NPs. Protein coated Ag NPs were prepared by a green synthesis method. Absorption at ~440 nm along with ~280 nm indicated the formation of protein coated Ag NPs. The biocompatibility of the above mentioned Ag NPs was studied by interaction with human hemoglobin (Hb) protein. In presence of bare Ag NPs, the Soret band of Hb was red shifted. This revealed the distortion of iron from the heme pockets of Hb. Also, the fluorescence peak of Hb was quenched and red shifted which indicated that Hb became unfolded in the presence of bare Ag NPs. No red shift of the absorption of Soret, along with no shift and quenching of the fluorescence peak of Hb were observed in the presence of protein coated Ag NPs. A hemolysis assay suggested that protein coated Ag NPs were more biocompatible than bare one.

  13. Two-phase synthesis of hydrophobic ionic liquid-capped gold nanoparticles and their application for sensing cholesterol

    International Nuclear Information System (INIS)

    Dong, Mingjun; Nan, Zhihan; Liu, Panpan; Zhang, Yanjun; Xue, Zhonghua; Lu, Xiaoquan; Liu, Xiuhui

    2014-01-01

    Highlights: • A novel cholesterol biosensor was constructed based on ChOx-IL-capped-AuNPs/GCE. • IL-capped-AuNPs was synthesized using two-phase synthesis and employed as a conducting matrix to immobilize ChOx. • Direct electrochemistry of ChOx on the electrode was obtained. • The ChOx-IL-capped-AuNPs/GCE exhibit remarkable performance for cholesterol detection. - Abstract: A novel scheme for fabrication of hydrophobic ionic liquid-capped gold nanoparticles (IL-capped AuNPs) modified electrode is presented and its application potential for cholesterol biosensor is investigated. Highly stable gold nanoparticles were characterized by UV–vis absorption spectroscopy and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that IL-capped AuNPs nanocomposites showed excellent electrical conductivity. Furthermore, cholesterol oxidase (ChOx) was directly immobilized on the IL-capped AuNPs nanocomposite, and then the direct electrochemistry of ChOx on the modified glass carbon electrode (GCE) was obtained. As a new platform in cholesterol analysis, ChOx-IL-capped AuNPs/GCE exhibited a linear response to cholesterol in the range of 0.1–50 μM with a detection limit of 0.033 μM. Therefore, hydrophobic ionic liquid-capped gold nanoparticles would serve as a good candidate material to construct the related enzyme biosensors

  14. Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

    Science.gov (United States)

    Saha, Saswati; Gupta, Bhaskar; Gupta, Kamala; Chaudhuri, Mahua Ghosh

    2016-11-01

    Integration of biology with nanotechnology is now becoming attention-grabbing area of research. The antimicrobial potency of silver has been eminent from antiquity. Due to the recent desire for the enhancement of antibacterial efficacy of silver, various synthesis methods of silver in their nano dimensions are being practiced using a range of capping material. The present work highlights a facile biomimetic approach for production of silver nanoparticle being capped and stabilized by putrescine, possessing a diameter of 10-25 ± 1.5 nm. The synthesized nanoparticles have been analyzed spectrally and analytically. Morphological studies are carried out by high-resolution transmission electron microscopy and crystallinity by selected area electron diffraction patterns. Moreover, the elemental composition of the capped nanoparticles was confirmed by energy-dispersive X-ray spectroscopy analysis. A comparative study (zone of inhibition and minimum inhibitory concentration) regarding the interactions and antibacterial potentiality of the capped silver nanoparticles with respect to the bare ones reveal the efficiency of the capped one over the bare one. The bacterial kinetic study was executed to monitor the interference of nanoparticles with bacterial growth rate. The results also highlight the efficacy of putrescine-capped silver nanoparticles as effective growth inhibitors against multi-drug resistant human pathogenic bacterial strains, which may, thus, potentially be applicable as an effective antibacterial control system to fight diseases.

  15. The reactivity study of peptide A3-capped gold and silver nanoparticles with heavy metal ions

    International Nuclear Information System (INIS)

    Yang, Hongyu; Tang, Zhenghua; Wang, Likai; Zhou, Weijia; Li, Ligui; Zhang, Yongqing; Chen, Shaowei

    2016-01-01

    Highlights: • Apparent color change upon the addition of Hg"2"+ or As"3"+ ions into A3-AuNPs solution. • Distinct color change of A3-AgNPs solution only in the presence of Hg"2"+ ions. • The Hg"2"+ concentration limit of A3-AgNPs about 40 times lower than A3-AuNPs. • Based on the DLS, TEM and XPS results, two reaction mechanisms have been proposed. - Abstract: Peptide A3-capped gold and silver nanoparticles were prepared by chemical reduction of metal salt precursors. The nanoparticles exhibited apparent but distinctly different color changes upon the addition of selected heavy metal ions. For gold nanoparticles, the solution color was found to change from red to blue in the presence of Hg"2"+ or As"3"+ ions, accompanied with broadening and a red-shift of the surface plasmon resonance peak. In contrast, silver nanoparticles showed an apparent color change from yellow to colorless only in the presence of Hg"2"+, along with a blue-shift and diminishment of the surface plasmon resonance peak. The Hg"2"+ reaction concentration limit of silver nanoparticle was about 40 times lower than that of gold nanoparticle. Based on the dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopic results, the reaction mechanism has been proposed. Such a sensitive variation of the nanoparticle optical properties to selective ions might be exploited for ion detection for potential applications.

  16. CdS nanoparticles/CeO{sub 2} nanorods composite with high-efficiency visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    You, Daotong; Pan, Bao; Jiang, Fan; Zhou, Yangen; Su, Wenyue, E-mail: suweny@fzu.edu.cn

    2016-02-15

    Graphical abstract: Coupling CdS with CeO{sub 2} can effectively improve the light-harvesting ability of wide-band gap CeO{sub 2} NRs as the photoinduced electrons on the conduction band of CdS are transfered to the conduction band of CeO{sub 2}. - Highlights: • Coupling CdS can effectively improve the light-harvesting ability of wide-band gap CeO{sub 2}. • CdS/CeO{sub 2} composites show high photocatalytic activity under visible light irradiation. • The mechanism of photocatalytic H{sub 2} evolution over CdS/CeO{sub 2} was proposed. - Abstract: Different mole ratios of CdS nanoparticles (NPs)/CeO{sub 2} nanorods (NRs) composites with effective contacts were synthesized through a two-step hydrothermal method. The crystal phase, microstructure, optical absorption properties, electrochemical properties and photocatalytic H{sub 2} production activity of these composites were investigated. It was concluded that the photogenerated charge carriers in the CdS NPs/CeO{sub 2} NRs composite with a proper mole ratio (1:1) exhibited the longest lifetime and highest separation efficiency, which was responsible for the highest H{sub 2}-production rate of 8.4 mmol h{sup −1} g{sup −1} under visible-light irradiation (λ > 420 nm). The superior photocatalytic H{sub 2} evolution properties are attributed to the transfer of visible-excited electrons of CdS NPs to CeO{sub 2} NRs, which can effectively extend the light absorption range of wide-band gap CeO{sub 2} NRs. This work provides feasible routes to develop visible-light responsive CeO{sub 2}-based nanomaterial for efficient solar utilization.

  17. Synthesis and characterization of arsenic-doped cysteine-capped thoria-based nanoparticles

    International Nuclear Information System (INIS)

    Pereira, F. J.; Díez, M. T.; Aller, A. J.

    2013-01-01

    Thoria materials have been largely used in the nuclear industry. Nonetheless, fluorescent thoria-based nanoparticles provide additional properties to be applied in other fields. Thoria-based nanoparticles, with and without arsenic and cysteine, were prepared in 1,2-ethanediol aqueous solutions by a simple precipitation procedure. The synthesized thoria-based nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (ED-XRS), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and fluorescence microscopy. The presence of arsenic and cysteine, as well as the use of a thermal treatment facilitated fluorescence emission of the thoria-based nanoparticles. Arsenic-doped and cysteine-capped thoria-based nanoparticles prepared in 2.5 M 1,2-ethanediol solutions and treated at 348 K showed small crystallite sizes and strong fluorescence. However, thoria nanoparticles subjected to a thermal treatment at 873 K also produced strong fluorescence with a very narrow size distribution and much smaller crystallite sizes, 5 nm being the average size as shown by XRD and TEM. The XRD data indicated that, even after doping of arsenic in the crystal lattice of ThO 2 , the samples treated at 873 K were phase pure with the fluorite cubic structure. The Raman and FT-IR spectra shown the most characteristics vibrational peaks of cysteine together with other peaks related to the bonds of this molecule to thoria and arsenic when present

  18. Agglomeration behavior of lipid-capped gold nanoparticles

    Science.gov (United States)

    Ranjan, Rajeev; Kirillova, Maria A.; Esimbekova, Elena N.; Zharkov, Sergey M.; Kratasyuk, Valentina A.

    2018-04-01

    The current investigation deciphers aggregation pattern of gold nanoparticles (AuNPs) and lipid-treated AuNPs when subjected to aqueous sodium chloride solution with increasing ionic strengths (100-400 nM). AuNPs were synthesized using 0.29 mM chloroauric acid and by varying the concentrations of trisodium citrate (AuNP1 1.55 mM, AuNP2 3.1 mM) and silver nitrate (AuNP3 5.3 μM, AuNP4 10.6 μM) with characteristic LSPR peaks in the range of 525-533 nm. TEM analysis revealed AuNPs to be predominantly faceted nanocrystals with the average size of AuNP1 to be 35 ± 5 nm, AuNP2 15 ± 5 nm, AuNP3 30 ± 5 nm, and AuNP4 30 ± 5 nm and the zeta-average for AuNPs were calculated to be 31.23, 63.80, 26.08, and 28 nm respectively. Induced aggregation was observed within 10 s in all synthesized AuNPs while lipid-treated AuNP2 (AuNP2-L) was found to withstand ionic interferences at all concentration levels. However, lipid-treated AuNPs synthesized using silver nitrate and 1.55 mM trisodium citrate (AuNP3, AuNP4) showed much lower stability. The zeta potential values of lipid-treated AuNPs (AuNP1-L-1 x/200, - 17.93 ± 1.02 mV; AuNP2-L-1 x/200, - 21.63 ± 0.70; AuNP3-L-1 x/200, - 14.54 ± 0.90; AuNP3-L-1 x/200 - 13.77 ± 0.83) justified these observations. To summarize, AuNP1 and AuNP2 treated with lipid mixture 1 equals or above 1 x/200 or 1 x/1000 respectively showed strong resistance against ionic interferences (up to 400 mM NaCl). Use of lipid mixture 1 for obtaining highly stable AuNPs also provided functional arms of various lengths which can be used for covalent coupling. [Figure not available: see fulltext.

  19. Chitosan Capped Silver Nanoparticles as Colorimetric Sensor for the Determination of Iron(III

    Directory of Open Access Journals (Sweden)

    Javad Tashkhourian

    2017-12-01

    Full Text Available A selective, simple and low-cost method for the colorimetric determination of Fe3+ ions based on chitosan capped silver nanoparticles (Chit-AgNPs was presented. Chitosan is a cationic polyelectrolyte and possesses amino and hydroxy groups which make it widely used as a capping agent for Ag NPs. The synthesized chitosan capped silver nanoparticles with excellent colloidal stability were characterized by UV–Visible spectrometry, transmission electron microscopy, Fourier transform infrared, X-ray diffraction. Chit-AgNPs exhibit a strong surface plasmon resonance band which disappears in the presence of increasing concentrations of Fe3+ ions. This system showed a visually detectable color change from brownish-yellow to colorless for the selective determination of Fe3+. The method can be applied for the determination of Fe3+ ions in the concentration range of 1.0×10-6 to 5.0×10-4 M. The detection limit was determined from three times the standard deviation of the blank signal (3σ/slope as 5.3 × 10−7 M. The developed method was successfully applied for the determination of Fe3+in real samples

  20. MoS_2/reduced graphene oxide hybrid with CdS nanoparticles as a visible light-driven photocatalyst for the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Peng, Wen-chao; Chen, Ying; Li, Xiao-yan

    2016-01-01

    Highlights: • MoS_2/rGO hybrid is synthesized using a one-step hydrothermal method. • MoS_2/rGO hybrid is used as the support and cocatalyst for CdS nanoparticles. • CdS-MoS_2/rGO composite is effective photocatalyst for 4-NP reduction in visible light. • Ammonium formate is an effective sacrificial agent for 4-NP photocatalytic reduction. - Abstract: Photocatalytic reduction of nitroaromatic compounds to aromatic amines using visible light is an attractive process that utilizes sunlight as the energy source for the chemical conversions. Herewith we synthesized a composite material consisting of CdS nanoparticles grown on the surface of MoS_2/reduced graphene oxide (rGO) hybrid as a novel photocatalyst for the reduction of 4-nitrophenol (4-NP). The CdS-MoS_2/rGO composite is shown as a high-performance visible light-driven photocatalyst. Even without a noble-metal cocatalyst, the catalyst exhibited a great activity under visible light irradiation for the reduction of 4-NP to much less toxic 4-aminophenol (4-AP) with ammonium formate as the sacrificial agent. Composite CdS-0.03(MoS_2/0.01rGO) was found to be the most effective photocatalyst for 4-NP reduction. The high photocatalytic performance is apparently resulted from the synergetic functions of MoS_2 and graphene in the composite, i.e. the cocatalysts serve as both the active adsorption sites for 4-NP and electron collectors for the separation of electron-hole pairs generated by CdS nanoparticles. The laboratory results show that the CdS-MoS_2/rGO composite is a low-cost and stable photocatalyst for effective reduction and detoxification of nitroaromatic compounds using solar energy.

  1. Hydrothermal synthesis of functionalized CdS nanoparticles and their application as fluorescence probes in the determination of uracil and thymine

    International Nuclear Information System (INIS)

    Lu Yaxiang; Li Li; Ding Yaping; Zhang Fenfen; Wang Yaping; Yu Weijun

    2012-01-01

    A novel, sensitive, and convenient method for the determination of uracil and thymine by functionalized CdS nanoparticles (NPs) was proposed. CdS NPs were prepared by hydrothermal process and modified with thioglycollic acid (TGA) in aqueous solution. The fluorescence intensity of functionalized CdS NPs was quenched in the presence of uracil or thymine. Under optimal conditions, the relative fluorescence intensity (F 0 /F) was proportional to the concentration in the range of 9.0x10 -6 -1.0x10 -4 mol/L for uracil (r=0.9985) and 8.8x10 -7 -1.5x10 -4 mol/L for thymine (r=0.9960). The corresponding detection limits were 9.6x10 -7 mol/L and 3.2x10 -7 mol/L, respectively. In addition, the possible quenching mechanism was also discussed. - Highlights: → Nano-CdS fluorescence probes were synthesized with good optical properties. → Uracil and thymine were successfully detected by CdS fluorescence probes. → Wide linear ranges and low detection limits were obtained.

  2. Structural, optical, XPS and magnetic properties of Zn particles capped by ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Iu.G., E-mail: yugmor@hotmail.com [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Ortega, D., E-mail: daniel.ortega@imdea.org [Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049, Madrid (Spain); Mafina, M.-K., E-mail: m.k.mafina@qmul.ac.uk [School of Engineering and Materials Science, Queen Mary University of London, Mile End, Eng, 231, London E1 4NS (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-06-05

    Highlights: • Levitation-jet aerosol synthesis of Zn particles capped by ZnO nanoparticles (NPs). • TEM, XRD, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between unit-cell volume of crystal lattice and maximum magnetization. - Abstract: Spherical zinc particles ranging from 42 to 760 nm in average size and capped with plate-like zinc oxide particles of 10–30 nm in sizes have been prepared by levitation-jet aerosol synthesis through condensation of zinc vapor in an inert/oxidizer gas flow. The nanoparticles have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), BET measurements, ultra violet visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray electron spectroscopy (XPS), superconducting quantum interference device (SQUID), and vibrating-sample magnetometer (VSM). Magnetic and XRD data indicate that the observed ferromagnetic ordering related to the changes in unit-cell volume of Zn in the Zn/ZnO interface of the nanoparticles. These results are in good correlation with the optical measurements data.

  3. Gallotannin-Capped Gold Nanoparticles: Green Synthesis and Enhanced Morphology of AFM Images.

    Science.gov (United States)

    Kim, Jaehyung; Yhim, Won Been; Park, Jong-Won; Lee, Sang-Hyeon; Kim, Tae Yoon; Cha, Song-Hyun; Kim, Hyun-Seok; Jang, Hong-Lae; Cho, Miyeon; Park, Youmie; Cho, Seonho

    2016-06-01

    Gold nanoparticles (AuNPs) were synthesized by a green method using a plant secondary metabolite, gallotannin. Gallotannin was used as a reducing and capping agent to convert gold ions into AuNPs for the generation of gallotannin-capped AuNPs (GT-AuNPs). This synthetic route is ecofriendly and eliminates the use of toxic chemical reducing agents. The characteristic surface plasmon resonance of the GT-AuNPs was observed at 536 nm in the UV-visible spectra. The face-centered cubic structure of GT-AuNPs was verified by X-ray diffraction analysis. The majority of the GT-AuNPs had a spherical shape with an average diameter of 15.93 ± 8.60 nm. Fourier transform infrared spectra suggested that the hydroxyl functional groups of gallotannin were involved in the synthesis of GT-AuNPs. The size and shape of nanoparticles can have a crucial impact on their biological, mechanical, and structural properties. Herein, we developed a modified anisotropic diffusion equation to selectively remove nanoscale experimental noise while preserving nanoscale intrinsic geometry information. To demonstrate the performance of the developed method, the ridge and valley lines were plotted by utilizing the principle curvatures. Compared to the original anisotropic diffusion and raw atomic force microscopy (AFM) experimental data, the developed modified anisotropic diffusion shows excellent performance in nanoscale noise removal while preserving the intrinsic aeometry of the nanoparticles.

  4. Cellular imaging and folate receptor targeting delivery of gum kondagogu capped gold nanoparticles in cancer cells.

    Science.gov (United States)

    Kumar, Sathish Sundar Dhilip; Mahesh, Ayyavu; Antoniraj, M Gover; Rathore, Hanumant Singh; Houreld, N N; Kandasamy, Ruckmani

    2018-04-01

    In this study, the green synthesis of gum kondagogu capped gold nanoparticles (GK-GNPs) was prepared using a naturally available polysaccharide. The anionic gum capped GK-GNPs enabled the successful coupling of folic acid (FA) and fluorescein isothiocyanate (FITC) to produce a fluorescently labelled GNP (F2-GNP). F2-GNPs were further characterized using different physicochemical methods Cellular viability, cellular imaging, and targeted delivery of F2-GNPs were further evaluated in both folate receptor positive (MCF-7) and folate receptor negative (A549) cancer cells. Physicochemical characterization revealed a nanoparticle with a small size (37 nm), smooth surface (surface charge of -23.7 mV), crystallinity of gold nanoparticles and existence of gum kondagogu in the F2-GNPs. Cellular uptake of F2-GNPs indicated a greater affinity towards folate receptor positive cells. This study shows that the F2-GNPs is as an effective nanocarrier for targeted drug delivery and cellular imaging via folate receptors. Copyright © 2017. Published by Elsevier B.V.

  5. Solvent-assisted in situ synthesis of cysteamine-capped silver nanoparticles

    Science.gov (United States)

    Oliva, José M.; Ríos de la Rosa, Julio M.; Sayagués, María J.; Sánchez-Alcázar, José A.; Merkling, Patrick J.; Zaderenko, Ana P.

    2018-03-01

    Silver nanoparticles offer a huge potential for biomedical applications owing to their exceptional properties and small size. Specifically, cysteamine-capped silver nanoparticles could form the basis for new anticancer therapies combining the cytotoxic effect of the silver core with the inherent antitumor activity of cysteamine, which inhibit cancer cell proliferation and suppress invasion and metastasis. In addition, the capability of the cysteamine coating monolayer to couple a variety of active principles and targeting (bio)molecules of interest proves key to the tailoring of this platform in order to exploit the pathophysiology of specific tumor types. Nevertheless, the chain length and conformational flexibility of cysteamine, together with its ability to attach to the surface of silver nanoparticles via both the thiol and the amine group, have made the in situ synthesis of these particles an especially challenging task. Herein we report a solvent-assisted in situ synthesis method that solves this problem. The obtained nanoparticles have been fully characterized by UV-visible absorption spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, electron diffraction measurement, high resolution transmission electron microscopy, scanning transmission electron microscopy, energy dispersive x-ray spectroscopy nanoanalysis, and dynamic light scattering measurement. Our synthesis method achieves extremely high yield and surface coating ratio, and colloidal stability over a wide range of pH values including physiological pH. Additionally, we have demonstrated that cysteamine-capped nanoparticles obtained by this method can be conjugated to an antibody for active targeting of the epidermal growth factor receptor, which plays an important role in the pathogenesis and progression of a wide variety of tumors, and induce cell death in human squamous carcinoma cells. We believe this method can be readily extended to combinations of noble

  6. Preparation and Properties of Nanoparticles of Calcium Phosphates With Various Ca/P Ratios.

    Science.gov (United States)

    Sun, Limin; Chow, Laurence C; Frukhtbeyn, Stanislav A; Bonevich, John E

    2010-01-01

    This study aimed at preparing and studying the properties of nanoparticles of calcium phosphate (nCaP) with Ca/P ratios ranging from 1.0 to 1.67 using a spray-drying technique. Micro-structural analyses suggested that the nCaPs with Ca/P ratios of 1.67 to 1.33 were nano-sized amorphous calcium phosphate (ACP) containing varying amounts of acid phosphate and carbonate. The nCaP with Ca/P ratio of 1 contained only nano-sized low crystalline dicalcium phosphate (DCP). BET measurements of the nCaPs showed specific surface areas of (12 ± 2 to 50 ± 1) m(2)/g, corresponding to estimated equivalent spherical diameters of (38 to 172) nm. However, dynamic light scattering measurements revealed much larger particles of (380 ± 49 to 768 ± 111) nm, owing to agglomeration of the smaller primary nano particles as revealed by Scanning Electron Microscopy (SEM). Thermodynamic solubility measurements showed that the nCaPs with Ca/P ratio of 1.33 - 1.67 all have similar solubility behavior. The materials were more soluble than the crystalline hydroxyapatite (HA) at pH greater than about 4.7, and more soluble than β-tricalcium phosphate (β-TCP), octacalcium phosphate (OCP) and DCP at pH above 5.5. Their solubility approached that of α-tricalcium phosphate (α-TCP) at about pH 7. These nCaPs, which cannot be readily prepared by other currently available methods for nanoparticle preparation, have potential biomedical applications.

  7. The reactivity study of peptide A3-capped gold and silver nanoparticles with heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hongyu [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Tang, Zhenghua, E-mail: zhht@scut.edu.cn [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Wang, Likai; Zhou, Weijia; Li, Ligui [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Zhang, Yongqing [Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Chen, Shaowei, E-mail: shaowei@ucsc.edu [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2016-08-15

    Highlights: • Apparent color change upon the addition of Hg{sup 2+} or As{sup 3+} ions into A3-AuNPs solution. • Distinct color change of A3-AgNPs solution only in the presence of Hg{sup 2+} ions. • The Hg{sup 2+} concentration limit of A3-AgNPs about 40 times lower than A3-AuNPs. • Based on the DLS, TEM and XPS results, two reaction mechanisms have been proposed. - Abstract: Peptide A3-capped gold and silver nanoparticles were prepared by chemical reduction of metal salt precursors. The nanoparticles exhibited apparent but distinctly different color changes upon the addition of selected heavy metal ions. For gold nanoparticles, the solution color was found to change from red to blue in the presence of Hg{sup 2+} or As{sup 3+} ions, accompanied with broadening and a red-shift of the surface plasmon resonance peak. In contrast, silver nanoparticles showed an apparent color change from yellow to colorless only in the presence of Hg{sup 2+}, along with a blue-shift and diminishment of the surface plasmon resonance peak. The Hg{sup 2+} reaction concentration limit of silver nanoparticle was about 40 times lower than that of gold nanoparticle. Based on the dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopic results, the reaction mechanism has been proposed. Such a sensitive variation of the nanoparticle optical properties to selective ions might be exploited for ion detection for potential applications.

  8. Direct colorimetric detection of unamplified pathogen DNA by dextrin-capped gold nanoparticles.

    Science.gov (United States)

    Baetsen-Young, Amy M; Vasher, Matthew; Matta, Leann L; Colgan, Phil; Alocilja, Evangelyn C; Day, Brad

    2018-03-15

    The interaction between gold nanoparticles (AuNPs) and nucleic acids has facilitated a variety of diagnostic applications, with further diversification of synthesis match bio-applications while reducing biotoxicity. However, DNA interactions with unique surface capping agents have not been fully defined. Using dextrin-capped AuNPs (d-AuNPs), we have developed a novel unamplified genomic DNA (gDNA) nanosensor, exploiting dispersion and aggregation characteristics of d-AuNPs, in the presence of gDNA, for sequence-specific detection. We demonstrate that d-AuNPs are stable in a five-fold greater salt concentration than citrate-capped AuNPs and the d-AuNPs were stabilized by single stranded DNA probe (ssDNAp). However, in the elevated salt concentrations of the DNA detection assay, the target reactions were surprisingly further stabilized by the formation of a ssDNAp-target gDNA complex. The results presented herein lead us to propose a mechanism whereby genomic ssDNA secondary structure formation during ssDNAp-to-target gDNA binding enables d-AuNP stabilization in elevated ionic environments. Using the assay described herein, we were successful in detecting as little as 2.94 fM of pathogen DNA, and using crude extractions of a pathogen matrix, as few as 18 spores/µL. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles.

    Science.gov (United States)

    Grzelczak, Marcin P; Danks, Stephen P; Klipp, Robert C; Belic, Domagoj; Zaulet, Adnana; Kunstmann-Olsen, Casper; Bradley, Dan F; Tsukuda, Tatsuya; Viñas, Clara; Teixidor, Francesc; Abramson, Jonathan J; Brust, Mathias

    2017-12-26

    Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported.

  10. Chondroitin sulfate-capped super-paramagnetic iron oxide nanoparticles as potential carriers of doxorubicin hydrochloride.

    Science.gov (United States)

    Mallick, Neha; Anwar, Mohammed; Asfer, Mohammed; Mehdi, Syed Hassan; Rizvi, Mohammed Moshahid Alam; Panda, Amulya Kumar; Talegaonkar, Sushama; Ahmad, Farhan Jalees

    2016-10-20

    Chondroitin-4-sulfate (CS), a glycosaminoglycan, was used to prepare CS-capped super-paramagnetic iron oxide nanoparticles, which were further employed for loading a water-soluble chemotherapeutic agent (doxorubicin hydrochloride, DOX). CS-capped SPIONs have potential biomedical application in cancer targeting. The optimized formulation had a hydrodynamic size of 91.2±0.8nm (PDI; 0.228±0.004) and zeta potential of -49.1±1.66mV. DOX was loaded onto the formulation up to 2% (w/w) by physical interaction with CS. TEM showed nano-sized particles having a core-shell structure. XRD confirmed crystal phase of iron oxide. FT-IR conceived the interaction of iron oxide with CS as bidentate chelation and also confirmed DOX loading. Vibration sample magnetometry confirmed super-paramagnetic nature of nanoparticles, with saturation magnetization of 0.238emug(-1). In vitro release profile at pH 7.4 showed that 96.67% of DOX was released within 24h (first order kinetics). MTT assay in MCF7 cells showed significantly higher (p<0.0001) cytotoxicity for DOX in SPIONs than DOX solution (IC50 values 6.294±0.4169 and 11.316±0.1102μgmL(-1), respectively). Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Synthesis of organically-capped metallic zinc nanoparticles using electrical explosion of wires (EEW) coupled with PIERMEN

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkader, Elseddik M.; Jelliss, Paul A., E-mail: jellissp@slu.edu; Buckner, Steven W., E-mail: buckners@slu.edu

    2015-01-15

    In this study zinc nanoparticles (ZNPs) were produced using electrical explosion of wires (EEW) with NP size around 100 nm. The explosion chamber was constructed from Teflon to withstand the shockwave, to allow growth and reaction of the incipient ZNPs in various organic solvents, and to allow a constant flow of argon creating an inert atmosphere. We utilized polymerization initiation by electron-rich metallic nanoparticles (PIERMEN) as the capping technique for the reactive ZNPs. Epoxides and alkenes served as the capping monomers. Epoxide caps underwent oligomerization on the surface of the NPs to form a protective polyether cap which renders the particles stable, non-pyrophoric in air, and dispersible in organic solvents. We investigated various Zn to monomer molar ratios varying from 1:1 to 10:1. Polyethylene glycol was also used as a capping agent and was found to give the smallest average Zn core sizes with the metal core diameters varying from 15 to 20 nm. Several solvents were used to study differences in resultant particle size and we observe toluene to give the smallest metal cores. Transmission electron microscopy shows the spherical particles with the metallic core embedded in a polymer matrix. The sample consists of predominantly smaller particles, but there was also a broad size distribution giving a range of 20–150 nm. Powder X-ray diffraction (PXRD) was used to confirm the identity of the metallic NPs. The capping agents were characterized using both attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) and Raman spectroscopies. There was no evidence for formation of zinc oxide with appropriate organic capping agents and solvent combinations; thus, this is the first report of production of pure metallic zinc nanoparticles with an organic cap using EEW. - Highlights: • Organically-capped Zn metal nanoparticles are produced by EEW in organic solution. • Incipient Zn metal nanoparticles initiate oligomerization of epoxide and

  12. Photodegradation of luminescence in organic-ligand-capped Eu3+:LaF3 nano-particles

    International Nuclear Information System (INIS)

    King, Gavin G. G.; Taylor, Luke R.; Longdell, Jevon J.; Clarke, David J.; Quilty, J. W.

    2014-01-01

    The luminescence from europium doped lanthanum trifluoride (Eu 3+ :LaF 3 ) nano-crystals can be greatly enhanced by capping with β-diketonate organic ligands. Here, we report on photo-stability measurements for the case of nano-crystals capped with thenoyltrifluroacetone (TTA) and compared with those capped with an inactive ligand, oleic acid. With exposure to UV pump light, we observed significant decrease in fluorescence and change in emission spectrum of the TTA-capped nano-particles whilst the fluorescence lifetime remained approximately constant. After a dose of order 70 kJ cm −2 , the luminescence level was similar to that of oleic acid capped nano-crystals. We discuss possible mechanisms

  13. Porous TiO{sub 2} nanofibers decorated CdS nanoparticles by SILAR method for enhanced visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Fengyu; Hou, Dongfang, E-mail: dfhouok@126.com; Hu, Fuchao; Xie, Kui; Qiao, Xiuqing; Li, Dongsheng, E-mail: lidongsheng1@126.com

    2017-01-01

    Graphical abstract: A heterojunction photocatalyst with CdS Nanoparticles self-assembled via SILAR Method at surfaces of electrospun TiO2 nanofibers shows enhanced visible-light photocatalytic activities. - Highlights: • Combined electrospinning and successive ionic layer adsorption and reaction process. • Pouous TiO{sub 2} nanofibers decorated CdS nanoparticles. • Synergetic effect of photosensitization and heterojunction. - Abstract: 1D porous CdS nanoparticles/TiO{sub 2} nanofibers heterostructure has been fabricated via simple electrospinning and a successive ionic layer adsorption and reaction (SILAR) process. The morphology, composition, and optical properties of the resulting CdS/TiO{sub 2} heterostructures can be rationally tailored through changing the SILAR cycles. The photocatalytic hydrogen evolution and decomposition of rhodamine B (RhB) of the as-synthesized heterostructured photocatalysts were investigated under visible light irradiation. Compared to TiO{sub 2} nanofibers,the as-obtained CdS/TiO{sub 2} heterostructures exhibit enhanced photocatalytic activity for hydrogen production and decomposition of RhB under visible-light irradiation. The heterojunction system performs best with H{sub 2} generation rates of 678.61 μmol h{sup −1} g{sup −1} under visible light irradiation which benefits from the two effects: (a) the 1D porous nanofibrous morphology contributes to not only more active sites but also more efficient transfer of the photogenerated charges (b) the synergetic effect of heterojunction and photosensitization reducing the recombination of photogenerated electrons and holes.

  14. Porous TiO_2 nanofibers decorated CdS nanoparticles by SILAR method for enhanced visible-light-driven photocatalytic activity

    International Nuclear Information System (INIS)

    Tian, Fengyu; Hou, Dongfang; Hu, Fuchao; Xie, Kui; Qiao, Xiuqing; Li, Dongsheng

    2017-01-01

    Graphical abstract: A heterojunction photocatalyst with CdS Nanoparticles self-assembled via SILAR Method at surfaces of electrospun TiO2 nanofibers shows enhanced visible-light photocatalytic activities. - Highlights: • Combined electrospinning and successive ionic layer adsorption and reaction process. • Pouous TiO_2 nanofibers decorated CdS nanoparticles. • Synergetic effect of photosensitization and heterojunction. - Abstract: 1D porous CdS nanoparticles/TiO_2 nanofibers heterostructure has been fabricated via simple electrospinning and a successive ionic layer adsorption and reaction (SILAR) process. The morphology, composition, and optical properties of the resulting CdS/TiO_2 heterostructures can be rationally tailored through changing the SILAR cycles. The photocatalytic hydrogen evolution and decomposition of rhodamine B (RhB) of the as-synthesized heterostructured photocatalysts were investigated under visible light irradiation. Compared to TiO_2 nanofibers,the as-obtained CdS/TiO_2 heterostructures exhibit enhanced photocatalytic activity for hydrogen production and decomposition of RhB under visible-light irradiation. The heterojunction system performs best with H_2 generation rates of 678.61 μmol h"−"1 g"−"1 under visible light irradiation which benefits from the two effects: (a) the 1D porous nanofibrous morphology contributes to not only more active sites but also more efficient transfer of the photogenerated charges (b) the synergetic effect of heterojunction and photosensitization reducing the recombination of photogenerated electrons and holes.

  15. Determination of gold nanoparticles in environmental water samples by second-order optical scattering using dithiotreitol-functionalized CdS quantum dots after cloud point extraction

    International Nuclear Information System (INIS)

    Mandyla, Spyridoula P.; Tsogas, George Z.; Vlessidis, Athanasios G.; Giokas, Dimosthenis L.

    2017-01-01

    Highlights: • A new method has been developed to determine gold nanoparticles in water samples. • Extraction was achieved by cloud point extraction. • A nano-hybrid assembly between AuNPs and dithiol-coated quantum dots was formulated. • Detection was accomplished at pico-molar levels by second-order light scattering. • The method was selective against ionic gold and other nanoparticle species. - Abstract: This work presents a new method for the sensitive and selective determination of gold nanoparticles in water samples. The method combines a sample preparation and enrichment step based on cloud point extraction with a new detection motif that relies on the optical incoherent light scattering of a nano-hybrid assembly that is formed by hydrogen bond interactions between gold nanoparticles and dithiotreitol-functionalized CdS quantum dots. The experimental parameters affecting the extraction and detection of gold nanoparticles were optimized and evaluated to the analysis of gold nanoparticles of variable size and surface coating. The selectivity of the method against gold ions and other nanoparticle species was also evaluated under different conditions reminiscent to those usually found in natural water samples. The developed method was applied to the analysis of gold nanoparticles in natural waters and wastewater with satisfactory results in terms of sensitivity (detection limit at the low pmol L −1 levels), recoveries (>80%) and reproducibility (<9%). Compared to other methods employing molecular spectrometry for metal nanoparticle analysis, the developed method offers improved sensitivity and it is easy-to-operate thus providing an additional tool for the monitoring and the assessment of nanoparticles toxicity and hazards in the environment.

  16. Determination of gold nanoparticles in environmental water samples by second-order optical scattering using dithiotreitol-functionalized CdS quantum dots after cloud point extraction

    Energy Technology Data Exchange (ETDEWEB)

    Mandyla, Spyridoula P.; Tsogas, George Z.; Vlessidis, Athanasios G.; Giokas, Dimosthenis L., E-mail: dgiokas@cc.uoi.gr

    2017-02-05

    Highlights: • A new method has been developed to determine gold nanoparticles in water samples. • Extraction was achieved by cloud point extraction. • A nano-hybrid assembly between AuNPs and dithiol-coated quantum dots was formulated. • Detection was accomplished at pico-molar levels by second-order light scattering. • The method was selective against ionic gold and other nanoparticle species. - Abstract: This work presents a new method for the sensitive and selective determination of gold nanoparticles in water samples. The method combines a sample preparation and enrichment step based on cloud point extraction with a new detection motif that relies on the optical incoherent light scattering of a nano-hybrid assembly that is formed by hydrogen bond interactions between gold nanoparticles and dithiotreitol-functionalized CdS quantum dots. The experimental parameters affecting the extraction and detection of gold nanoparticles were optimized and evaluated to the analysis of gold nanoparticles of variable size and surface coating. The selectivity of the method against gold ions and other nanoparticle species was also evaluated under different conditions reminiscent to those usually found in natural water samples. The developed method was applied to the analysis of gold nanoparticles in natural waters and wastewater with satisfactory results in terms of sensitivity (detection limit at the low pmol L{sup −1} levels), recoveries (>80%) and reproducibility (<9%). Compared to other methods employing molecular spectrometry for metal nanoparticle analysis, the developed method offers improved sensitivity and it is easy-to-operate thus providing an additional tool for the monitoring and the assessment of nanoparticles toxicity and hazards in the environment.

  17. Antifungal activity of wide band gap Thioglycolic acid capped ZnS:Mn semiconductor nanoparticles against some pathogenic fungi

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Isam M.; Ali, Iftikhar M. [Department of physics, College of Science, Baghdad University, Baghdad (Iraq); Dheeb, Batol Imran [Department of Biology, College of Education, Iraqia University, Baghdad (Iraq); Abas, Qayes A. [Department of physics, College of Education, University of Anbar, Anbar (Iraq); Asmeit Ramizy, E-mail: asmat_hadithi@yahoo.com [Department of physics, College of Science, University of Anbar, Anbar (Iraq); Renewable energy Research Center, University of Anbar, Anbar (Iraq); Eisa, M.H. [Department of physics, College of Science, Sudan University of Science Technology, Khartoum 11113 (Sudan); Department of physics, College of Science, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11623 (Saudi Arabia); Aljameel, A.I. [Department of physics, College of Science, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11623 (Saudi Arabia)

    2017-04-01

    The manganese doped zinc sulfide nanoparticles were synthesized by simple aqueous chemical reaction of manganese chloride, zinc acetate and thioacitamide in aqueous solution. Thioglycolic acid is used as capping agent for controlling the nanoparticle size. The main advantage of the ZnS:Mn nanoparticles of diameter ~ 2.73 nm is that the sample is prepared by using non-toxic precursors in a cost effective and eco-friendly way. The structural, morphological and chemical composition of the nanoparticles have been investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with energy dispersion spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy. The nanosize of the prepared nanoparticles was elucidated by Scanning Electron Microscopy (SEM). FTIR result ensures that Thioglycolic acid is well bonded on the surface of ZnS:Mn NPs. The antifungal effects of Thioglycolic acid capped ZnS:Mn nanoparticles exhibited a potent antifungal activity against tested fungal strains, so deserving further investigation for clinical applications. The antifungal property of manganese doped zinc sulphide nanoparticles is attributed to the generation of reactive oxygen species due to the interaction of nanoparticles with water. Additionally, the presence of Zn and S in the zone of inhibition area leads to perturbation of fungi cell membranes resulting in growth inhibition. - Highlights: • The manganese doped zinc sulfide nanoparticles were synthesized. • Thioglycolic acid is used as capping agent for controlling the nanoparticle size. • The structural, morphological and chemical composition of the nanoparticles has been investigated. • The presence of Zn and S in the zone of inhibition area leads to perturbation of fungi cell membranes.

  18. Antifungal activity of wide band gap Thioglycolic acid capped ZnS:Mn semiconductor nanoparticles against some pathogenic fungi

    International Nuclear Information System (INIS)

    Ibrahim, Isam M.; Ali, Iftikhar M.; Dheeb, Batol Imran; Abas, Qayes A.; Asmeit Ramizy; Eisa, M.H.; Aljameel, A.I.

    2017-01-01

    The manganese doped zinc sulfide nanoparticles were synthesized by simple aqueous chemical reaction of manganese chloride, zinc acetate and thioacitamide in aqueous solution. Thioglycolic acid is used as capping agent for controlling the nanoparticle size. The main advantage of the ZnS:Mn nanoparticles of diameter ~ 2.73 nm is that the sample is prepared by using non-toxic precursors in a cost effective and eco-friendly way. The structural, morphological and chemical composition of the nanoparticles have been investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with energy dispersion spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy. The nanosize of the prepared nanoparticles was elucidated by Scanning Electron Microscopy (SEM). FTIR result ensures that Thioglycolic acid is well bonded on the surface of ZnS:Mn NPs. The antifungal effects of Thioglycolic acid capped ZnS:Mn nanoparticles exhibited a potent antifungal activity against tested fungal strains, so deserving further investigation for clinical applications. The antifungal property of manganese doped zinc sulphide nanoparticles is attributed to the generation of reactive oxygen species due to the interaction of nanoparticles with water. Additionally, the presence of Zn and S in the zone of inhibition area leads to perturbation of fungi cell membranes resulting in growth inhibition. - Highlights: • The manganese doped zinc sulfide nanoparticles were synthesized. • Thioglycolic acid is used as capping agent for controlling the nanoparticle size. • The structural, morphological and chemical composition of the nanoparticles has been investigated. • The presence of Zn and S in the zone of inhibition area leads to perturbation of fungi cell membranes.

  19. {sup 6}LiF oleic acid capped nanoparticles entrapment in siloxanes for thermal neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Carturan, S., E-mail: sara.carturan@lnl.infn.it; Maggioni, G., E-mail: Gianluigi.maggioni@lnl.infn.it [Department of Physics and Astronomy, University of Padova, Via Marzolo 8, 35100 Padova (Italy); INFN, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro (Italy); Marchi, T.; Gramegna, F.; Cinausero, M. [INFN, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro (Italy); Quaranta, A. [Department of Industrial Engineering, University of Trento, Trento (Italy); INFN, Tifpa, Trento (Italy); Palma, M. Dalla [INFN, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro (Italy); Department of Industrial Engineering, University of Trento, Trento (Italy)

    2016-07-07

    The good light output of siloxane based scintillators as displayed under γ-rays and α particles has been exploited here to obtain clear and reliable response toward thermal neutrons. Sensitization towards thermal neutrons has been pursued by adding {sup 6}LiF, in form of nanoparticles. Aiming at the enhancement of compatibility between the inorganic nanoparticles and the low polarity, siloxane based surrounding medium, oleic acid-capped {sup 6}LiF nanoparticles have been synthesized by thermal decomposition of Li trifluoroacetate. Thin pellets siloxane scintillator maintained their optical transmittance up to weight load of 2% of {sup 6}Li. Thin samples with increasing {sup 6}Li concentration and thicker ones with fixed {sup 6}Li amount have been prepared and tested with several sources (α, γ-rays, moderated neutrons). Light output as high as 80% of EJ212 under α irradiation was measured with thin samples, and negligible changes have been observed as a result of {sup 6}LiF addition. In case of thick samples, severe light loss has been observed, as induced by opacity. Nevertheless, thermal neutrons detection has been assessed and the data have been compared with GS20, based on Li glass, taken as a reference material.

  20. Surface capped fluorescent semiconductor nanoparticles: radiolytic synthesis and some of its biological applications

    International Nuclear Information System (INIS)

    Saha, A.

    2006-01-01

    Semiconductor nanocrystals or colloidal quantum dots (QD's) have generated great research interest because of their unusual properties arising out of quantum confinement effects. Many researchers in the field of nanotechnology focus on the 'high quality' semiconductor quantum dots. A good synthetic route should yield nanoparticles with narrow size distribution, good crystallinity, high photostability, desired surface properties and high photoluminescence quantum efficiency. In the domain of colloidal chemistry, reverse micellar synthesis, high temperature thermolysis using organometallic precursors and synthesis in aqueous media using polyphosphates or thiols as stabilizers are the most prominent ones. In contrast, γ-radiation assisted synthesis can offer a simplified approach to prepare size-controlled nanoparticles at room temperature. Syntheses of thiol-capped II-VI nanoparticles by radiolytic method, its characterization and some of its luminescence-based applications of biological relevance will be presented. The versatility of thiols (RSH) can be emphasized here as changing the R-group imparts different functionality to the particles and thus chemical behavior of the particles can be manipulated according to the application intended for. (authors)

  1. Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

    International Nuclear Information System (INIS)

    Wang Baiqi; Jing Liqiang; Qu Yichun; Li Shudan; Jiang Baojiang; Yang Libin; Xin Baifu; Fu Honggang

    2006-01-01

    TiO 2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO 2 nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO 2 nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO 2 mass weight, respectively, and the linkage between DBS groups and TiO 2 surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO 2 obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO 2 is also related to the increase in the capability for adsorbing RhB

  2. RSM optimized Moringa oleifera peel extract for green synthesis of M. oleifera capped palladium nanoparticles with antibacterial and hemolytic property.

    Science.gov (United States)

    Surendra, T V; Roopan, Selvaraj Mohana; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah; Rayalu, G Mokesh

    2016-09-01

    Palladium nanoparticles (Pd NPs) are the very good catalytic agents in many coupling reactions, also these are very well biological agents against bacteria and fungus. M. oleifera capped Pd NPs were synthesized from microwave assisted methanolic extract of M. oleifera peel. To optimize the extraction process RSM (Response Surface Methodology) was applied. To get a good extraction yield BBD (Box-Behnken Design) was employed. The better optimized conditions for the extraction was found as 400W, 25mL of CH3OH at 65°C for 2min. We observed 61.66mg of extract yield from this method. Eco-friendly M. oleifera capped Pd NPs were synthesized using M. oleifera peel extract and confirmed using the different characterization techniques like UV- Vis spectroscopy, XRD, SEM and HR-TEM analysis. We found the size of the M. oleifera capped Pd NPs nanoparticles as 27±2nm and shape of the particles as spherical through the TEM analysis. M. oleifera capped Pd NPs exhibits good antibacterial activity against S. aureus (Staphylococcus aureus) and E. coli (Escherichia coli) bacterial strains and we found the zone inhibition as 0.6 and 0.7mm. The synthesized M. oleifera capped Pd NPs are screened for hemolytic activity and it proved the M. oleifera capped Pd NPs are non-toxic on RBCs cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Colorimetric and visual determination of dicyandiamide using gallic acid-capped gold nanoparticles

    International Nuclear Information System (INIS)

    Liu, Junfeng; Zhang, Xiaofang; Xiao, Can; Yang, Ankang; Zhao, Hong; He, Yujian; Li, Xiangjun; Yuan, Zhuobin

    2015-01-01

    A new method is presented for the visual detection of dicyandiamide (DCD). Gold nanoparticles (AuNPs) capped with gallic acid (GA) were synthesized in a single step at room temperature, using GA as both the reducing agent and stabilizer. In the presence of DCD, the hydrogen-bonding interaction between GA and DCD induces the aggregation of AuNPs, associated with a color change from red to gray that can be observed with bare eye. DCD could be quantified by photometry as the red shift of the maximal absorption band is linearly related to the logarithm of concentration of DCD in the 0.1 to 500 μM concentration range, with a regression coefficient of 0.9987 and a 80 nM detection limit (at an SNR of 3). The proposed method was successfully applied to the detection of DCD in spiked dairy samples. (author)

  4. 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.

  5. Novel two-step synthesis of gold nanoparticles capped with bile acid conjugates

    International Nuclear Information System (INIS)

    Noponen, Virpi; Bhat, Shreedhar; Sievaenen, Elina; Kolehmainen, Erkki

    2008-01-01

    Bile acids and their conjugates are physiologically important molecules. Syntheses and structure elucidation combined with investigation of properties and applications of bile acids and their derivatives are of academic interest. The concept of using bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects. In this article, an easy and simple route for obtaining N-lithocholyl-L-(cysteine ethyl ester) (3), capable of effectively capping and stabilizing metal nanoparticles, is described. The whole synthetic route needs only two steps giving a moderate to good yield. The gold NPs are characterized by elemental analysis, UV spectroscopy, and TEM. Additionally, 13 C CP/MAS NMR studies for different ligand/Au ratios have been performed

  6. Green synthesis of chondroitin sulfate-capped silver nanoparticles: characterization and surface modification.

    Science.gov (United States)

    Cheng, Kuang-ming; Hung, Yao-wen; Chen, Cheng-cheung; Liu, Cheng-che; Young, Jenn-jong

    2014-09-22

    A one-step route for the green synthesis of highly stable and nanosized silver metal particles with narrow distribution is reported. In this environmentally friendly synthetic method, silver nitrate was used as silver precursor and biocompatible chondroitin sulfate (ChS) was used as both reducing agent and stabilizing agent. The reaction was carried out in a stirring aqueous medium at the room temperature without any assisted by microwave, autoclave, laser irradiation, γ-ray irradiation or UV irradiation. The transparent colorless solution was converted to the characteristics light red then deep red-brown color as the reaction proceeds, indicating the formation of silver nanoparticles (Ag NPs). The Ag NPs were characterized by UV-visible spectroscopy (UV-vis), photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were Ag NPs capped with ChS. In this report, dynamic light scattering (DLS) was used as a routinely analytical tool for measuring size and distribution in a liquid environment. The effects of the reaction time, reaction temperature, concentration and the weight ratio of ChS/Ag+ on the particle size and zeta potential were investigated. The TEM image clearly shows the morphology of the well-dispersed ChS-capped Ag NPs are spherical in shape, and the average size (propyl] chitosan chloride (HTCC) were prepared by an ionic gelation method and the surface charge of Ag NPs was switched from negative to positive. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Effect of Particle Size on the Magnetic Properties of Ni Nanoparticles Synthesized with Trioctylphosphine as the Capping Agent

    Directory of Open Access Journals (Sweden)

    Toshitaka Ishizaki

    2016-09-01

    Full Text Available Magnetic cores of passive components are required to have low hysteresis loss, which is dependent on the coercive force. Since it is well known that the coercive force becomes zero at the superparamagnetic regime below a certain critical size, we attempted to synthesize Ni nanoparticles in a size-controlled fashion and investigated the effect of particle size on the magnetic properties. Ni nanoparticles were synthesized by the reduction of Ni acetylacetonate in oleylamine at 220 °C with trioctylphosphine (TOP as the capping agent. An increase in the TOP/Ni ratio resulted in the size decrease. We succeeded in synthesizing superparamagnetic Ni nanoparticles with almost zero coercive force at particle size below 20 nm by the TOP/Ni ratio of 0.8. However, the saturation magnetization values became smaller with decrease in the size. The saturation magnetizations of the Ni nanoparticles without capping layers were calculated based on the assumption that the interior atoms of the nanoparticles were magnetic, whereas the surface-oxidized atoms were non-magnetic. The measured and calculated saturation magnetization values decreased in approximately the same fashion as the TOP/Ni ratio increased, indicating that the decrease could be mainly attributed to increases in the amounts of capping layer and oxidized surface atoms.

  8. Synthesis, Structural and Optical Properties of TOPO and HDA Capped Cadmium Sulphide Nanocrystals, and the Effect of Capping Ligand Concentration

    Directory of Open Access Journals (Sweden)

    Damian C. Onwudiwe

    2015-01-01

    Full Text Available The thermal decomposition of bis(N,N-diallyldithiocarbamatoCd(II in a “one-pot” synthesis in tri-n-octylphosphine oxide (TOPO and hexadecylamine (HDA afforded CdS (TOPO-CdS and HDA-CdS of varying optical properties and morphologies. The influence of the ratio of the precursor concentration to the capping molecule, as a factor affecting the morphology and size of the nanoparticles, was investigated. The particles varied in shape from spheres to rods and show quantum size effects in their optical spectra with clear differences in the photoluminescence (PL spectra. The PL spectrum of the HDA capped CdS nanoparticles has an emission maximum centred at 468, 472, and 484 nm for the precursor to HDA concentration ratio of 1 : 10, 1 : 15, and 1 : 20, respectively, while the TOPO capped nanoparticles show emission peaks at 483, 494, and 498 nm at the same concentration ratio. Powdered X-ray diffraction (p-XRD shows the nanoparticles to be hexagonal. The crystallinity of the nanoparticles was evident from high resolution transmission electron microscopy (HRTEM which gave well-defined images of particles with clear lattice fringes.

  9. 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.

  10. Study on growth kinetics of hexadecylamine capped CdSe nanoparticles using its electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Oluwafemi, S.O., E-mail: tobi_55@yahoo.co [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa 3886 (South Africa); Revaprasadu, N. [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa 3886 (South Africa)

    2009-05-01

    The growth kinetics of hexadecylamine (HDA) capped CdSe synthesised via a novel, mild, effective, and facile non-organometallic route was studied using its electronic properties. The emission and optical maxima of all the nanoparticles synthesised are blue-shifted as the reaction time increases indicating decrease in particle size. The UV spectra show distinct excitonic features which can be attributed to the first electronic transition [1S{sub 3/2}(h)-1S(e)] occurring in CdSe nanoparticles with band-edge luminescence in their emission spectra. The extinction coefficient was determined for convenient and accurate measurements of the concentration of the nanocrystals. Nucleation is very fast and well separated from particle growth under this reaction condition. Two distinguishable stages of growth were observed: an early stage 0-10 min characterised by fast growth, with narrow size distribution and the late stage characterised by slow growth with slight defocusing of size distribution and large particle sizes. The diameter of the size ranges from 2.2 to 3.0 nm. About 94% of the available monomer concentration was consumed during the growth and the solubility of 3.0 nm CdSe in hexadecylamine is measured to be 9.216x10{sup -7} M{sup 2} at 433 deg. K.

  11. Sum frequency generation and catalytic reaction studies of the removal of the organic capping agents from Pt nanoparticles by UV-ozone treatment

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, Cesar; Park, Jeong Y.; Yamada, Yusuke; Lee, Hyun Sook; Tsung, Chia-Kuang; Yang, Peidong; Somorjai, Gabor A.

    2009-12-10

    We report the structure of the organic capping layers of platinum colloid nanoparticles and their removal by UV-ozone exposure. Sum frequency generation vibrational spectroscopy (SFGVS) studies identify the carbon-hydrogen stretching modes on poly(vinylpyrrolidone) (PVP) and tetradecyl tributylammonium bromide (TTAB)-capped platinum nanoparticles. We found that the UV-ozone treatment technique effectively removes the capping layer on the basis of several analytical measurements including SFGVS, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The overall shape of the nanoparticles was preserved after the removal of capping layers, as confirmed by transmission electron microscopy (TEM). SFGVS of ethylene hydrogenation on the clean platinum nanoparticles demonstrates the existence of ethylidyne and di-{sigma}-bonded species, indicating the similarity between single-crystal and nanoparticle systems.

  12. Microbial glycolipoprotein-capped silver nanoparticles as emerging antibacterial agents against cholera.

    Science.gov (United States)

    Gahlawat, Geeta; Shikha, Sristy; Chaddha, Baldev Singh; Chaudhuri, Saumya Ray; Mayilraj, Shanmugam; Choudhury, Anirban Roy

    2016-02-01

    With the increased number of cholera outbreaks and emergence of multidrug resistance in Vibrio cholerae strains it has become necessary for the scientific community to devise and develop novel therapeutic approaches against cholera. Recent studies have indicated plausibility of therapeutic application of metal nano-materials. Among these, silver nanoparticles (AgNPs) have emerged as a potential antimicrobial agent to combat infectious diseases. At present nanoparticles are mostly produced using physical or chemical techniques which are toxic and hazardous. Thus exploitation of microbial systems could be a green eco-friendly approach for the synthesis of nanoparticles having similar or even better antimicrobial activity and biocompatibility. Hence, it would be worth to explore the possibility of utilization of microbial silver nanoparticles and their conjugates as potential novel therapeutic agent against infectious diseases like cholera. The present study attempted utilization of Ochrobactrum rhizosphaerae for the production of AgNPs and focused on investigating their role as antimicrobial agents against cholera. Later the exopolymer, purified from the culture supernatant, was used for the synthesis of spherical shaped AgNPs of around 10 nm size. Further the exopolymer was characterized as glycolipoprotein (GLP). Antibacterial activity of the novel GLP-AgNPs conjugate was evaluated by minimum inhibitory concentration, XTT reduction assay, scanning electron microscopy (SEM) and growth curve analysis. SEM studies revealed that AgNPs treatment resulted in intracellular contents leakage and cell lysis. The potential of microbially synthesized nanoparticles, as novel therapeutic agents, is still relatively less explored. In fact, the present study first time demonstrated that a glycolipoprotein secreted by the O. rhizosphaerae strain can be exploited for production of AgNPs which can further be employed to treat infectious diseases. Although this type of polymer has

  13. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Science.gov (United States)

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-07-01

    A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV-vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhBaq-visible light system was O2-rad ; nevertheless, h+ and rad OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the reusability of 1.5-CdS/MIL composite was also studied.

  14. Synthesis and optical properties of CdS/ZnS coreshell nanoparticles

    International Nuclear Information System (INIS)

    Saraswathi Amma, B.; Manzoor, K.; Ramakrishna, K.; Pattabi, Manjunatha

    2008-01-01

    Synthesis and optical properties of manganese (Mn 2+ )-doped, polyvinyl pyrrolidone (PVP)-capped cadmium sulphide (CdS) nanoparticles coated with zinc sulphide (ZnS) are reported. Colloidal solution of Mn 2+ -doped CdS nanoparticles capped with PVP is synthesized using methanol as solvent. PVP is used to control the particle size and to prevent agglomeration. Mn 2+ doping is expected to help in increasing the CdS band edge photoluminescence (PL) emission. Addition of zinc nitrate and sodium sulphide alternately to the Mn 2+ -doped, PVP-stabilized CdS colloid led to the formation of ZnS-coated CdS coreshell nanoparticles. Photoluminescence emission spectra recorded for (CdS-PVP)Mn nanoparticles showed two emission peaks, one at 416 nm and the other weaker peak at 586 nm which is attributed to Mn 2+ emission. Intensity of Mn 2+ peak increased with increase in the Mn 2+ content. Mn 2+ emission disappears when ZnS is coated over the CdS core, resulting in pure CdS band edge emission

  15. Glucose capped silver nanoparticles induce cell cycle arrest in HeLa cells.

    Science.gov (United States)

    Panzarini, Elisa; Mariano, Stefania; Vergallo, Cristian; Carata, Elisabetta; Fimia, Gian Maria; Mura, Francesco; Rossi, Marco; Vergaro, Viviana; Ciccarella, Giuseppe; Corazzari, Marco; Dini, Luciana

    2017-06-01

    This study aims to determine the interaction (uptake and biological effects on cell viability and cell cycle progression) of glucose capped silver nanoparticles (AgNPs-G) on human epithelioid cervix carcinoma (HeLa) cells, in relation to amount, 2×10 3 or 2×10 4 NPs/cell, and exposure time, up to 48h. The spherical and well dispersed AgNPs (30±5nm) were obtained by using glucose as reducing agent in a green synthesis method that ensures to stabilize AgNPs avoiding cytotoxic soluble silver ions Ag + release. HeLa cells take up abundantly and rapidly AgNPs-G resulting toxic to cells in amount and incubation time dependent manner. HeLa cells were arrested at S and G2/M phases of the cell cycle and subG1 population increased when incubated with 2×10 4 AgNPs-G/cell. Mitotic index decreased accordingly. The dissolution experiments demonstrated that the observed effects were due only to AgNPs-G since glucose capping prevents Ag + release. The AgNPs-G influence on HeLa cells viability and cell cycle progression suggest that AgNPs-G, alone or in combination with chemotherapeutics, may be exploited for the development of novel antiproliferative treatment in cancer therapy. However, the possible influence of the cell cycle on cellular uptake of AgNPs-G and the mechanism of AgNPs entry in cells need further investigation. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Liposomal flucytosine capped with gold nanoparticle formulations for improved ocular delivery

    Directory of Open Access Journals (Sweden)

    Salem HF

    2016-01-01

    Full Text Available Heba F Salem,1 Sayed M Ahmed,2 Mahmoud M Omar3 1Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt; 2Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, Egypt; 3Department of Industrial Pharmacy, Faculty of Pharmacy, Deraya University, El-Minia, Egypt Abstract: Nanoliposomes have an organized architecture that provides versatile functions. In this study, liposomes were used as an ocular carrier for nanogold capped with flucytosine antifungal drug. Gold nanoparticles were used as a contrasting agent that provides tracking of the drug to the posterior segment of the eye for treating fungal intraocular endophthalmitis. The nanoliposomes were prepared with varying molar ratios of lecithin, cholesterol, Span 60, a positive charge inducer (stearylamine, and a negative charge inducer (dicetyl phosphate. Formulation F6 (phosphatidylcholine, cholesterol, Span 60, and stearylamine at a molar ratio of 1:1:1:0.15 demonstrated the highest extent of drug released, which reached 7.043 mg/h. It had a zeta potential value of 42.5±2.12 mV and an average particle size approaching 135.1±12.0 nm. The ocular penetration of the selected nanoliposomes was evaluated in vivo using a computed tomography imaging technique. It was found that F6 had both the highest intraocular penetration depth (10.22±0.11 mm as measured by the computed tomography and the highest antifungal efficacy when evaluated in vivo using 32 infected rabbits’ eyes. The results showed a strong correlation between the average intraocular penetration of the nanoparticles capped with flucytosine and the percentage of the eyes healed. After 4 weeks, all the infected eyes (n=8 were significantly healed (P<0.01 when treated with liposomal formulation F6. Overall, the nanoliposomes encapsulating flucytosine have been proven efficient in treating the infected rabbits’ eyes, which proves the efficiency of the

  17. Mesoporous CdS via Network of Self-Assembled Nanocrystals: Synthesis, Characterization and Enhanced Photoconducting Property.

    Science.gov (United States)

    Patra, Astam K; Banerjee, Biplab; Bhaumik, Asim

    2018-01-01

    Semiconduction nanoparticles are intensively studied due to their huge potential in optoelctronic applications. Here we report an efficient chemical route for hydrothermal synthesis of aggregated mesoporous cadmium sulfide (CdS) nanoparticles using supramolecular-assembly of ionic and water soluble sodium salicylate as the capping agent. The nanostructure, mesophase, optical property and photoconductivity of these mesoporous CdS materials have been characterized by using small and wide angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2-sorption, Raman analysis, Fourier transformed infrared (FT-IR), UV-Visible DSR spectroscopy, and photoconductivity measurement. Wide angle XRD pattern and high resolution TEM image analysis suggested that the particle size of the materials is within 10 nm and the nanoparticles are in well-crystallized cubic phase. Mesoporous CdS nanoparticles showed drastically enhanced photoelectrochemical response under visible light irradiation on entrapping a photosensitizer (dye) molecule in the interparticle spaces. Efficient synthesis strategy and the enhanced photo response in the mesoporous CdS material could facilitate the designing of other porous semiconductor oxide/sulfide and their applications in photon-to-electron conversion processes.

  18. X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles

    International Nuclear Information System (INIS)

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M.A.; Haskel, D.; te Velthuis, S.G.E; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian Fernandez, C.; Garcia, M.A.

    2009-01-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 · 10 -4 was found at the Au L 3 edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M s , of 0.06 emu/g Au . SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences

  19. X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; te Velthuis, S. G. E; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian Fernandez, C.; Garcia, M. A.; Univ.Complutense de Madrid; Inst. de Magnetismo Aplicado; Univ. of Pisa; Lab. di Magnetismo Molecolare

    2009-01-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  20. X-ray magnetic circular dichroism and small angle neutron scattering study of thiol capped gold nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; Pinel, E. F.; te Velthuis, S. G. E.; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian, C.; Garcia, M. A.; Univ. Complutense de Madrid; Inst. de Magnetismo Aplicado UCM; Univ. Pisa; Univ. di Padova

    2009-11-01

    X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

  1. Investigations on structural and optical properties of starch capped ZnS nanoparticles synthesized by microwave irradiation method

    Science.gov (United States)

    Lalithadevi, B.; Mohan Rao, K.; Ramananda, D.

    2018-05-01

    Following a green synthesis method, zinc sulfide (ZnS) nanoparticles were prepared by chemical co-precipitation technique using starch as capping agent. Microwave irradiation was used as heating source. X-ray diffraction studies indicated that nanopowders obtained were polycrystalline possessing ZnS simple cubic structure. Transmission electron microscopic studies indicated that starch limits the agglomeration by steric stabilization. Interaction between ZnS and starch was confirmed by Fourier transform infrared spectroscopy as well as Raman scattering studies. Quantum size effects were observed in optical absorption studies while quenching of defect states on nanoparticles was improved with increase in starch addition as indicated by photoluminescence spectra.

  2. Synthesis of PEG-Iodine-Capped Gold Nanoparticles and Their Contrast Enhancement in In Vitro and In Vivo for X-Ray/CT

    International Nuclear Information System (INIS)

    Sun-Hee, K.; Eun-Mi, K.; Chang-Moon, L.; Dong, W.K.; Seok, T.L.; Myung-Hee, S.; Hwan-Jeong, J.

    2012-01-01

    We designed gold nanoparticles (AuNPs) capped with iodine and polyethylene glycol (PEG) to provide effective enhancement for X-ray CT imaging. The methoxy PEG-iodine-capped AuNPs were prepared through the chemisorption of iodine and substitution of methoxy PEG-SH onto the surface of gold nanoparticles, and severe aggregation in TEM was not observed. The binding energies of Au 4f 7/2 and I 3d 5/2 of the methoxy PEG-iodine-capped AuNPs were obtained as 84.1 eV and 619.3 eV, respectively. The binding energy shift of methoxy PEG-iodine-capped AuNPs would be resulted from the chemisorption between gold nanoparticles and iodine atoms. The methoxy PEG-iodine-capped AuNPs have higher enhancement compared to PEG-capped gold nanoparticles in the same amount of gold in vitro. After postinjection of methoxy PEG-iodine-capped AuNPs into the mice, dramatic contrast enhancement at the heart, aorta, liver, and kidney was observed, this was maintained up to 5 days, and there was no evidence of apparent toxicity. In conclusion, methoxy PEG-iodine-capped AuNPs might be a good candidate as a CT contrast agent for blood pool imaging, and this will also contribute to the prolongation of a blood circulation time for X-ray CT imaging.

  3. Amidase-responsive controlled release of antitumoral drug into intracellular media using gluconamide-capped mesoporous silica nanoparticles

    Science.gov (United States)

    Candel, Inmaculada; Aznar, Elena; Mondragón, Laura; Torre, Cristina De La; Martínez-Máñez, Ramón; Sancenón, Félix; Marcos, M. Dolores; Amorós, Pedro; Guillem, Carmen; Pérez-Payá, Enrique; Costero, Ana; Gil, Salvador; Parra, Margarita

    2012-10-01

    MCM-41 silica nanoparticles were used as inorganic scaffolding to prepare a nanoscopic-capped hybrid material S1, which was able to release an entrapped cargo in the presence of certain enzymes, whereas in the absence of enzymes, a zero release system was obtained. S1 was prepared by loading nanoparticles with Safranine O dye and was then capped with a gluconamide derivative. In the absence of enzymes, the release of the dye from the aqueous suspensions of S1 was inhibited as a result of the steric hindrance imposed by the bulky gluconamide derivative, the polymerized gluconamide layer and the formation of a dense hydrogen-bonded network around the pore outlets. Upon the addition of amidase and pronase enzymes, delivery of Safranine O dye was observed due to the enzymatic hydrolysis of the amide bond in the anchored gluconamide derivative. S1 nanoparticles were not toxic for cells, as demonstrated by cell viability assays using HeLa and MCF-7 cell lines, and were associated with lysosomes, as shown by confocal microscopy. Finally, the S1-CPT material loaded with the cytotoxic drug camptothecin and capped with the gluconamide derivative was prepared. The HeLa cells treated with S1-CPT underwent cell death as a result of material internalization, and of the subsequent cellular enzyme-mediated hydrolysis and aperture of the molecular gate, which induced the release of the camptothecin cargo.

  4. Effect of capping agents on the cytotoxicity of silver nanoparticles in human normal and cancer skin cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Netchareonsirisuk, Ponsawan [Chulalongkorn University, Program in Biotechnology, Faculty of Science (Thailand); Puthong, Songchan [Chulalongkorn University, Antibody Production Research Unit, Institute of Biotechnology and Genetic Engineering (Thailand); Dubas, Stephan [Chulalongkorn University, Petroleum and Petrochemical College (Thailand); Palaga, Tanapat [Chulalongkorn University, Department of Microbiology, Faculty of Science (Thailand); Komolpis, Kittinan, E-mail: kittinan.k@chula.ac.th [Chulalongkorn University, Antibody Production Research Unit, Institute of Biotechnology and Genetic Engineering (Thailand)

    2016-11-15

    Silver nanoparticles (AgNPs) are among the most widely used nanomaterials in medical and consumer products. However, safety in the uses of AgNPs is still controversial. The toxicity of AgNPs toward various cell types has been reported to depend on the surface properties of the nanoparticles. In this study, the effect of AgNPs with the average size of 5–15 nm on the viability of the CCD-986SK human normal skin fibroblast cell line and A375 human malignant melanoma cell line was evaluated. Comparative toxicity studies, based on MTT assay, were performed by using either sodium alginate or poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) as capping agent in the nanoparticle preparation. The cytotoxicity tests revealed that AgNO{sub 3} alone was highly toxic to both cell types while both alginate and PSSMA alone were not toxic. AgNPs capped with alginate were selectively toxic to the cancer cell line but not to the normal cell line while AgNPs capped with PSSMA were toxic to both cancer and normal cell lines. Judging from the 50 % inhibition concentration (IC{sub 50}), it was found that the cancer cell line was more sensitive to AgNPs than the normal cell line. Study on the mode of cell death by annexin V and propidium iodide staining revealed that AgNPs induced more apoptotic cell death (84–90 %) than necrosis (8–12 %) in the skin cancer cell line. These results suggest that the toxicity of AgNPs depended on the type of capping agent and the type of cell line.

  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

    2017-08-01

    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.

  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

    2017-08-14

    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.

  7. The effect of reducing agents on the electronic, magnetic and electrocatalytic properties of thiol-capped Pt/Co and Pt/Ni nanoparticles

    CSIR Research Space (South Africa)

    Mathe, NR

    2015-05-01

    Full Text Available The electronic, magnetic and electrocatalytic properties of bimetallic thiol-capped Pt/Co and Pt/Ni nanoparticles were synthesised using two reducing agents, NaBH(sub4) and N(sub2)H(sub4). X-ray diffraction analysis of the nanoparticles showed Pt...

  8. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Longxing, E-mail: hulxhhhb@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Deng, Guihua [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Lu, Wencong [College of Sciences, Shanghai University, Shanghai 200444 (China); Pang, Siwei; Hu, Xing [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2017-07-15

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB{sub aq}-visible light system was O{sub 2}{sup −}·; nevertheless, h{sup +} and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs

  9. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    International Nuclear Information System (INIS)

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-01-01

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB aq -visible light system was O 2 − ·; nevertheless, h + and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the

  10. UV-induced photochemical transformations of citrate-capped silver nanoparticle suspensions

    International Nuclear Information System (INIS)

    Gorham, Justin M.; MacCuspie, Robert I.; Klein, Kate L.; Fairbrother, D. Howard; Holbrook, R. David

    2012-01-01

    Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300 nm ultraviolet (UV) light on (20, 40, 60 and 80) nm citrate-capped AgNP suspensions has been investigated. As a consequence of irradiation, the initial yellow hue of the AgNP suspensions is transformed towards a near colorless solution due to the loss of the surface plasmon resonance (SPR) absorbance. The decrease in SPR absorbance followed a first-order decay process for all particle sizes with a rate constant that increased linearly with the AgNP specific surface area and non-linearly with light intensity. The rate of loss of the SPR absorbance decreased with increasing citrate concentration, suggesting a surface-mediated transformation. Absorbance, atomic force microscopy, and dynamic light scattering results all indicated that AgNP photolysis was accompanied by a diameter decrease and occasional aggregation. Furthermore, in situ transmission electron microscopy imaging using a specialized liquid cell also showed a decrease in the particle size and the formation of a core–shell structure in UV-exposed AgNPs. X-ray photoelectron spectroscopy analysis suggested that this shell consisted of oxidized silver. The SPR in UV-exposed AgNP suspensions could be regenerated by addition of a strong reducing agent (NaBH 4 ), supporting the idea that oxidized silver is present after photolysis. Evidence for UV-enhanced dissolution and the production of silver ions was obtained with the Donnan membrane technique. This study reveals that the physico-chemical properties of aqueous AgNP suspensions will change significantly upon exposure to UV light, with implications for environmental health and safety risk assessments.

  11. pH-dependent immobilization of urease on glutathione-capped gold nanoparticles.

    Science.gov (United States)

    Garg, Seema; De, Arnab; Mozumdar, Subho

    2015-05-01

    Urease is a nickel-dependent metalloenzyme that catalyzes the hydrolysis of urea to form ammonia and carbon dioxide. Although the enzyme serves a significant role in several detoxification and analytical processes, its usability is restricted due to high cost, availability in small amounts, instability, and a limited possibility of economic recovery from a reaction mixture. Hence, there is a need to develop an efficient, simple, and reliable immobilization strategy for the enzyme. In this study, the carboxyl terminated surface of glutathione-capped gold nanoparticles have been utilized as a solid support for the covalent attachment of urease. The immobilization has been carried out at different pH conditions so as to elucidate its effect on the immobilization efficiency and enzyme bioactivity. The binding of the enzyme has been quantitatively and qualitatively analyzed through techniques like ultraviolet-visible spectroscopy, intrinsic steady state fluorescence, and circular dichorism. The bioactivity of the immobilized enzyme was investigated with respect to the native enzyme under different thermal conditions. Recyclability and shelf life studies of the immobilized enzyme have also been carried out. Results reveal that the immobilization is most effective at pH of 7.4 followed by that in an acidic medium and is least in alkaline environment. The immobilized enzyme also exhibits enhance activity in comparison to the native form at physiological temperature. The immobilized urease (on gold glutathione nanoconjugates surface) can be effectively employed for biosensor fabrication, immunoassays and as an in vivo diagnostic tool in the future. © 2014 Wiley Periodicals, Inc.

  12. Rapid and selective detection of cysteine based on its induced aggregates of cetyltrimethylammonium bromide capped gold nanoparticles

    International Nuclear Information System (INIS)

    Wang Jian; Li Yuanfang; Huang Chengzhi; Wu Tong

    2008-01-01

    A detection method of cysteine is reported in this contribution with water-soluble positively charged gold nanoparticles (Au-NPs) that were prepared by seed-mediated method and capped with cetyltrimethylammonium bromide (CTAB). In aqueous medium of pH 4.2, the CTAB-capped Au-NPs display greatly different features from those of generally prepared citrate-coated Au-NPs. It was found that in a medium of high salt concentration, the presence of cysteine could induce aggregation of CTAB-capped Au-NPs, while citrate-coated Au-NPs could get aggregation soon even if without the presence of cysteine. The cysteine-induced aggregates of CTAB-capped Au-NPs display strong plasmon resonance light scattering (PRLS) signals characterized at 566.0 nm when excited by a light beam, and the PRLS intensities of the aggregates are in proportion to the concentration of cysteine in the range of 0.01-0.40 μg mL -1 with the limit of detection (3σ) being 2.9 ng mL -1 . No amino acids in the samples interfere with the detection, and cysteine in artificial samples could be detected with the recovery between 95.3% and 105.9%, and R.S.D. is less than 3.6%

  13. Evolution of the microstructure, chemical composition and magnetic behaviour during the synthesis of alkanethiol-capped gold nanoparticles

    International Nuclear Information System (INIS)

    Guerrero, E.; Rojas, T.C.; Multigner, M.; Crespo, P.; Munoz-Marquez, M.A.; Garcia, M.A.; Hernando, A.; Fernandez, A.

    2007-01-01

    In the present paper, we show an exhaustive microstructural characterization of thiol-capped gold nanoparticles (NPs) with two different average particle sizes. These samples are compared with the polymer-like Au(I) phase formed as a precursor during the synthesis of the thiol-capped gold NPs. The set of analysed samples shows different microstructures at the nanoscale with different proportions of Au atoms bonded either to S or to Au atoms. It has been experimentally shown that the presence of a ferromagnetic-like behaviour is associated to the formation of NPs with simultaneous presence of Au-Au and Au-S bonds. In order to explain such magnetic behaviour a possible model is proposed based on the spin-orbit coupling so that localized charges and/or spins (Au-S bonds) can trap conduction electrons (Au-Au bonds) in orbits

  14. Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanoparticles and their Colloidal Stability in Phosphate Buffer

    Science.gov (United States)

    2015-01-01

    Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (Mn = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (Mn = 2000) and biotin-terminated PEG (Mn = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir2012, 28, 12861−1287022906305) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline. PMID:24898128

  15. Functional PEG-PAMAM-tetraphosphonate capped NaLnF₄ nanoparticles and their colloidal stability in phosphate buffer.

    Science.gov (United States)

    Zhao, Guangyao; Tong, Lemuel; Cao, Pengpeng; Nitz, Mark; Winnik, Mitchell A

    2014-06-17

    Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (M(n) = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (M(n) = 2000) and biotin-terminated PEG (M(n) = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000-PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir 2012, 28, 12861-12870) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline.

  16. Effect of capping agent on the morphology, size and optical properties of In{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Latha, Ch. Kanchana; Aparna, Y. [Department of Physics, Jawaharlal Nehru Technological University Hyderabad (JNTUH), College of Engineering Hyderabad (CEH), Telangana (India); Raghasudha, Mucherla; Veerasomaiah, P., E-mail: raghasudha_m@yahoo.co.in [Department of Chemistry, University College of Science, Osmania University, Hyderabad, Telangana (India); Ramchander, M. [Department of Bio Chemistry, Mahatma Gandhi University, Nalgonda, Telangana (India); Ravinder, D. [Department of Physics, Osmania University, Hyderabad, Telangana (India); Jaipal, K. [Inorganic & Physical Chemistry Division, Indian Institute of Chemical Technology (IICT), Hyderabad, Telangana (India); Shridhar, D. [Department of Physics, Khairatabad Government Degree College, Hyderabad, Telangana (India)

    2017-01-15

    The Indium Oxide (In{sub 2}O{sub 3}) nanoparticles were synthesized through Acacia gum mediated method with the surfactants CTAB (Cetyl Trimethyl Ammonium Bromide) and SDBS (Sodium Docecyl Benzene Sulfonate). The characterization of the synthesized In{sub 2}O{sub 3} nanoparticles was carried out by XRD, FTIR, RAMAN, TEM, SEM, EDAX, UV-Vis and PL techniques. TG-DTA analysis was performed to know the calcination temperature of In{sub 2}O{sub 3} nanoparticles. XRD analysis confirmed the crystalline nature of the synthesized In{sub 2}O{sub 3} nanoparticles. The morphology and chemical composition were characterized by TEM, SEM and EDAX respectively. It was observed that morphology and size of synthesized nanoparticles measured by TEM and SEM analysis were dependent on the type of capping agent (surfactant) used. Raman and UV-Vis spectral analysis confirmed that the band gap value of CTAB capped In{sub 2}O{sub 3} particles were larger than the SDBS capped In{sub 2}O{sub 3} particles. FTIR analysis indicated that the bands were stretched in In{sub 2}O{sub 3} particles capped by SDBS than by CTAB. From the photoluminescence studies (PL technique), a blue shift in the emission peaks of CTAB and SDBS capped In{sub 2}O{sub 3} particles was observed that indicates larger optical band gap than the bulk. (author)

  17. Synthesis and structural, optical and thermal properties of CdS:Zn2+ nanoparticles

    Science.gov (United States)

    Muruganandam, S.; Anbalagan, G.; Murugadoss, G.

    2014-12-01

    Undoped and Zn (1-5, 10 %) -doped CdS nanoparticles were successfully synthesized by chemical method and polyvinylpyrrolidone was used as capping agent. The morphology and crystalline structure of the samples were studied by transmission electron microscopy and X-ray diffraction. The average particle size of the spherical nanoparticles determined by these techniques was of the order of 2.5-6 nm. The functional groups of the capping agent on CdS:Zn2+ surface were identified by FT-IR study. The band gap of the nanoparticles was calculated using UV-visible absorption spectra and the result showed that the band gap values were dramatically blue shifted from the bulk CdS. The optimum concentration of the doping ions was selected through absorption study. Photoluminescence of the CdS:Zn2+ nanoparticle showed strong blue and green emission. The thermal properties of the nanoparticles were analyzed by thermogravimetric-differential thermal analysis.

  18. One dimensional CdS nanowire@TiO2 nanoparticles core-shell as high performance photocatalyst for fast degradation of dye pollutants under visible and sunlight irradiation.

    Science.gov (United States)

    Arabzadeh, Abbas; Salimi, Abdollah

    2016-10-01

    In this study, one-dimensional CdS nanowires@TiO2 nanoparticles core-shell structures (1D CdS NWs@TiO2 NPs) were synthesized by a facile wet chemical-solvothermal method. The different aspects of the properties of CdS NWs@TiO2 NPs were surveyed by using a comprehensive range of characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, scanning electron microscopy (SEM), fluorescence spectroscopy, energy dispersive X-ray spectroscopy (EDX), Cyclic Voltammetry (CV) and amperometry. The as-prepared nanostructure was applied as an effective photocatalyst for degradation of methyl orange (MO), methylene blue (MB) and rhodamine B (Rh B) under visible and sunlight irradiation. The results indicated significantly enhanced photocatalytic activity of CdS NWs@TiO2 NPs for degradation of MO, MB and Rh B compared to CdS NWs. The enhanced photocatalytic activity could be attributed to the enhanced sunlight absorbance and the efficient charge separation of the formed heterostructure between CdS NWs and TiO2. The results showed that MO, Rh B and MB were almost completely degraded after 2, 2 and 3min of exposure to sunlight, respectively; while under visible light irradiation (3W blue LED lamp) the dyes were decomposed with less half degradation rate. The catalytic activity was retained even after three degradation cycles of organic dyes, demonstrating that the proposed nanocomposite can be effectively used as efficient photocatalyst for removal of environmental pollutions caused by organic dyes under sunlight irradiation and it could be an important addition to the field of wastewater treatment. We hope the present study may open a new window of such 1-D semiconductor nanocomposites to be used as visible light photocatalysts in the promising field of organic dyes degradation. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Structural, spectroscopic and anti-microbial inspection of PEG capped ZnO nanoparticles for biomedical applications

    Science.gov (United States)

    Meshram, J. V.; Koli, V. B.; Kumbhar, S. G.; Borde, L. C.; Phadatare, M. R.; Pawar, S. H.

    2018-04-01

    Zinc oxide (ZnO) nanoparticles (NPs) have a wide range of biomedical applications. Present study demonstrates the new methodology in sol-gel technology for synthesizing Polyethylene glycol (PEG) capped ZnO NPs and its size effect on anti-microbial activity. The reaction time was increased from 1 h to 5 h for the synthesis of ZnO NPs at 130 °C. The size of PEG capped ZnO NPs is increased from 10 to 84 nm by increasing the reaction upto 5 h. The x-ray diffraction studies and transmission electron microscopy analysis reveals the phase purity and hexagonal wurtzite crystal structure with uniform PEG capping on the surface of ZnO NPs. UV–visible spectroscopy exhibits the peak at 366 nm which is attributed to ZnO NPs. No adverse effect is observed in case of absorbance spectroscopy. Further, Fourier transforms infrared spectroscopy and thermo gravimetric analysis depicts the adsorption of PEG molecules on the ZnO NPs surface. The anti-microbial activities for both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria were studied by optical density (OD) mesurement. The remarkable anti-microbial activity was observed for PEG capped ZnO NPs synthesized at 1 h reaction time showing higher activity in comparison with that synthesized from 2 h to 5 h reaction time. The microbial growth was found to be inhibited after 10 h OD measurement for both the bacteria. The anti-microbial activity may be attributed to the generation of ROS and H2O2. However, these generated species plays a vital role in inhibition of microbial growth. Hence, PEG capped ZnO NPs has promising biomedical applications.

  20. Properties of electrospun CdS and CdSe filled poly(methyl methacrylate) (PMMA) nanofibres

    Energy Technology Data Exchange (ETDEWEB)

    Mthethwa, T.P. [University of Johannesburg, Department of Chemical Technology, P.O. Box 17011, Doornfontein 2028 (South Africa); Moloto, M.J., E-mail: mmoloto@uj.ac.za [University of Johannesburg, Department of Chemical Technology, P.O. Box 17011, Doornfontein 2028 (South Africa); De Vries, A.; Matabola, K.P. [CSIR Materials Science and Manufacturing, 4 Gomery avenue, Summerstrand, Port Elizabeth 6000 (South Africa)

    2011-04-15

    Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: {yields} TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. {yields} The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. {yields} The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. {yields} Both TEM images for nanoparticles and SEM for fibres shows the morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the

  1. Properties of electrospun CdS and CdSe filled poly(methyl methacrylate) (PMMA) nanofibres

    International Nuclear Information System (INIS)

    Mthethwa, T.P.; Moloto, M.J.; De Vries, A.; Matabola, K.P.

    2011-01-01

    Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: → TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. → The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. → The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. → Both TEM images for nanoparticles and SEM for fibres shows the morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the polymer fibres at low

  2. Synthesis and biological studies of highly concentrated lisinopril-capped gold nanoparticles for CT tracking of angiotensin converting enzyme (ACE)

    Science.gov (United States)

    Ghann, William E.; Aras, Omer; Fleiter, Thorsten; Daniel, Marie-Christine

    2011-05-01

    For patients with a history of heart attack or stroke, the prevention of another cardiovascular or cerebrovascular event is crucial. The development of cardiac and pulmonary fibrosis has been associated with overexpression of tissue angiotensin-converting enzyme (ACE). Recently, gold nanoparticles (GNPs) have shown great potential as X-ray computed tomography (CT) contrast agents. Since lisinopril is an ACE inhibitor, it has been used as coating on GNPs for targeted imaging of tissue ACE in prevention of fibrosis. Herein, lisinopril-capped gold nanoparticles (LIS-GNPs) were synthesized up to a concentration of 55 mgAu/mL. Their contrast was measured using CT and the results were compared to Omnipaque, a commonly used iodine-based contrast agent. The targeting ability of these LIS-GNPs was also assessed.

  3. Pouous TiO2 nanofibers decorated CdS nanoparticles by SILAR method for enhanced visible-light-driven photocatalytic activity

    Science.gov (United States)

    Tian, Fengyu; Hou, Dongfang; Hu, Fuchao; Xie, Kui; Qiao, Xiuqing; Li, Dongsheng

    2017-01-01

    1D porous CdS nanoparticles/TiO2 nanofibers heterostructure has been fabricated via simple electrospinning and a successive ionic layer adsorption and reaction (SILAR) process. The morphology, composition, and optical properties of the resulting CdS/TiO2 heterostructures can be rationally tailored through changing the SILAR cycles. The photocatalytic hydrogen evolution and decomposition of rhodamine B (RhB) of the as-synthesized heterostructured photocatalysts were investigated under visible light irradiation. Compared to TiO2 nanofibers,the as-obtained CdS/TiO2 heterostructures exhibit enhanced photocatalytic activity for hydrogen production and decomposition of RhB under visible-light irradiation. The heterojunction system performs best with H2 generation rates of 678.61 μmol h-1 g-1 under visible light irradiation which benefits from the two effects: (a) the 1D porous nanofibrous morphology contributes to not only more active sites but also more efficient transfer of the photogenerated charges (b) the synergetic effect of heterojunction and photosensitization reducing the recombination of photogenerated electrons and holes.

  4. Melanoma-Targeted Chemothermotherapy and In Situ Peptide Immunotherapy through HSP Production by Using Melanogenesis Substrate, NPrCAP, and Magnetite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kowichi Jimbow

    2013-01-01

    Full Text Available Exploitation of biological properties unique to cancer cells may provide a novel approach to overcome difficult challenges to the treatment of advanced melanoma. In order to develop melanoma-targeted chemothermoimmunotherapy, a melanogenesis substrate, N-propionyl-4-S-cysteaminylphenol (NPrCAP, sulfur-amine analogue of tyrosine, was conjugated with magnetite nanoparticles. NPrCAP was exploited from melanogenesis substrates, which are expected to be selectively incorporated into melanoma cells and produce highly reactive free radicals through reacting with tyrosinase, resulting in chemotherapeutic and immunotherapeutic effects by oxidative stress and apoptotic cell death. Magnetite nanoparticles were conjugated with NPrCAP to introduce thermotherapeutic and immunotherapeutic effects through nonapoptotic cell death and generation of heat shock protein (HSP upon exposure to alternating magnetic field (AMF. During these therapeutic processes, NPrCAP was also expected to provide melanoma-targeted drug delivery system.

  5. The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles

    Science.gov (United States)

    Onwudiwe, Damian C.; Strydom, Christien A.

    2015-01-01

    Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML12L2] (M = Cd(II), Zn(II); L1 = N-phenyldithiocarbamate, L2 = 2,2‧ bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M = Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained.

  6. Zeta potential and Raman studies of PVP capped Bi2S3 nanoparticles synthesized by polyol method

    Science.gov (United States)

    Tarachand, Sathe, Vasant G.; Okram, Gunadhor S.

    2018-05-01

    Here we report the synthesis and characterisation of polyvinylpyrrolidone (PVP) capped Bi2S3 nanoparticles via one step catalyst-free polyol method. Raman spectroscopy, dynamic light scattering and zeta potential analysis were performed on it. Rietveld refinement of powder XRD of PVP capped samples confirmed the formation of single phase orthorhombic Bi2S3 for all PVP capped samples. The presence of eight obvious Raman modes further confirmed the formation of stoichiometric Bi2S3. Dynamic light scattering (DLS) studies show a clear increase in hydrodynamic diameter for samples made with increasing PVP concentration. Particle size obtained from DLS and XRD (using Scherrer's formula) combine with change in full width half maxima of Raman modes collectively suggest overall improvement in crystallinity and quality of product on introducing PVP. In zeta potential (ζ) measurement, steric hindrance of carbon chains plays very crucial role and a systematic reduction of ζ value is observed for samples made with decreasing PVP concentration. An isoelectric point is obtained for sample made with low PVP (1g). Present results are likely to open a window for its medical and catalytic applications.

  7. Eco-friendly synthesis of Solanum trilobatum extract-capped silver nanoparticles is compatible with good antimicrobial activities

    Science.gov (United States)

    Ramanathan, Santheraleka; Gopinath, Subash C. B.; Anbu, Periasamy; Lakshmipriya, Thangavel; Kasim, Farizul Hafiz; Lee, Choul-Gyun

    2018-05-01

    This study focused on the evaluation of antimicrobial activity of silver nanoparticles (AgNPs) after their green synthesis by means of a Solanum trilobatum bark extract. The obtained product with an intense surface plasmon resonance band at ∼442 nm with UV-visible spectroscopic analysis indicated the formation of AgNPs. The morphology of AgNPs was observed under transmission electron microscopy and field emission scanning electron microscopy, displayed that the eco-friendly synthesized AgNPs have a spherical shape with an average size of ∼25 nm in diameter. X-ray powder diffraction and selected area electron diffraction analyses confirmed that the AgNPs are crystalline in nature. Fourier transform infrared spectroscopy indicated that the AgNPs capped with active ingredients of the bark extract. X-ray photoelectron spectroscopy revealed elemental composition of the AgNPs. The performance of S. trilobatum bark extract-capped AgNPs in terms of inhibition of microbial growth was studied by disc diffusion and well diffusion assays. Eco-friendly synthesized S. trilobatum extract-capped AgNPs were found to possess enhanced antimicrobial properties: growth inhibition of gram-negative and gram-positive bacteria and of fungal species. These results demonstrated the potential applications of the indigenous medicinal plants to the field of nanotechnology.

  8. Sodium hydroxide as pretreatment and fluorosurfactant-capped gold nanoparticles as sensor for the highly selective detection of cysteine.

    Science.gov (United States)

    Wu, Hsin-Pin; Huang, Chia-Chi; Cheng, Tian-Lu; Tseng, Wei-Lung

    2008-07-15

    A sensor for detecting cysteine (Cys) in a solution of fluorosurfactant (FSN)-capped gold nanoparticles (AuNPs) has been developed. Under acidic conditions, FSN-capped AuNPs are aggregated in the presence of homocysteine (HCys) and Cys but not in the presence of cysteinylglycine, glutathione, and gamma-glutamycysteine. When adding NaOH to a solution of HCys, the five-membered ring transition state is formed through intramolecular hydrogen abstraction. By contrast, it is difficult for Cys to form a four-membered ring transition state after Cys has been pretreated with NaOH. As a result, the HCys-induced aggregation of the FSN-capped AuNPs is suppressed because the five-membered ring transition state exhibits relatively larger steric hindrance and has stronger interaction with the FSN molecules. Thus, we can discriminate between Cys and HCys on the basis of different aggregation kinetics. Under the optimum condition, the selectivity of the probe for Cys in aqueous solutions is remarkably high over the other aminthiols. Note that HCys and Cys have very similar structure and pK(a) value. We have validated the applicability of our method through the analyses of Cys in urine samples. It is believed that this approach has great potential for the detection of Cys in biological samples.

  9. Study of the synthesis of copper nanoparticles: the role of capping and kinetic towards control of particle size and stability

    Energy Technology Data Exchange (ETDEWEB)

    Granata, Giuseppe, E-mail: giuseppe.granata@aoni.waseda.jp; Yamaoka, Taishi [Waseda University, School of Creative Science and Engineering (Japan); Pagnanelli, Francesca [Sapienza University of Rome, Department of Chemistry (Italy); Fuwa, Akio [Waseda University, School of Creative Science and Engineering (Japan)

    2016-05-15

    The synthesis of copper nanoparticles (CuNPs) by surfactant-assisted chemical reduction method was studied aiming to identify and quantify the role of kinetic and capping on particle size distribution. The use of a strong and a mild reducing agent (hydrazine, d-glucose) has been investigated as well as the use of three different capping agents: cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP). Experimental tests were arranged according to factorial designs. CuNPs were characterized by XRD, FE-SEM and UV–Vis spectrophotometry. Particle size distribution was determined by image analysis and significance of investigated factors was statistically assessed by analysis of variance. Under the investigated conditions, CTAB was found capable of preventing oxidation but it had a significant positive effect on nanoparticle size (about 40 and 30 nm); SDS determined a good size control but no stabilization, whilst PVP could provide both size control (significant negative effect of about 15 and 25 nm) and stability. Average size of CuNPs can be significantly reduced of about 50 nm by replacing d-glucose with hydrazine.Graphical Abstract.

  10. Eco-friendly synthesis of gelatin-capped bimetallic Au-Ag nanoparticles for chemiluminescence detection of anticancer raloxifene hydrochloride.

    Science.gov (United States)

    Alarfaj, Nawal A; El-Tohamy, Maha F

    2016-09-01

    This study described the utility of green analytical chemistry in the synthesis of gelatin-capped silver, gold and bimetallic gold-silver nanoparticles (NPs). The preparation of nanoparticles was based on the reaction of silver nitrate or chlorauric acid with a 1.0 wt% aqueous gelatin solution at 50°C. The gelatin-capped silver, gold and bimetallic NPs were characterized using transmission electron microscopy, UV-vis, X-ray diffraction and Fourier transform infrared spectroscopy, and were used to enhance a sensitive sequential injection chemiluminescence luminol-potassium ferricyanide system for determination of the anticancer drug raloxifene hydrochloride. The developed method is eco-friendly and sensitive for chemiluminescence detection of the selected drug in its bulk powder, pharmaceutical injections and biosamples. After optimizing the conditions, a linear relationship in the range of 1.0 × 10(-9) to 1.0 × 10(-1)  mol/L was obtained with a limit of detection of 5.0 × 10(-10)  mol/L and a limit of quantification of 1.0 × 10(-9)  mol/L. Statistical treatment and method validation were performed based on ICH guidelines. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Esterase- and pH-responsive poly(β-amino ester)-capped mesoporous silica nanoparticles for drug delivery

    Science.gov (United States)

    Fernando, Isurika R.; Ferris, Daniel P.; Frasconi, Marco; Malin, Dmitry; Strekalova, Elena; Yilmaz, M. Deniz; Ambrogio, Michael W.; Algaradah, Mohammed M.; Hong, Michael P.; Chen, Xinqi; Nassar, Majed S.; Botros, Youssry Y.; Cryns, Vincent L.; Stoddart, J. Fraser

    2015-04-01

    Gating of mesoporous silica nanoparticles (MSNs) with the stimuli-responsive poly(β-amino ester) has been achieved. This hybrid nanocarrier releases doxorubicin (DOX) under acidic conditions or in the presence of porcine liver esterase. The DOX loaded poly(β-amino ester)-capped MSNs reduce cell viability when tested on MDA-MB-231 human breast cancer cells.Gating of mesoporous silica nanoparticles (MSNs) with the stimuli-responsive poly(β-amino ester) has been achieved. This hybrid nanocarrier releases doxorubicin (DOX) under acidic conditions or in the presence of porcine liver esterase. The DOX loaded poly(β-amino ester)-capped MSNs reduce cell viability when tested on MDA-MB-231 human breast cancer cells. Electronic supplementary information (ESI) available: Experimental details relating to (i) the synthesis and characterisation of the surface-functionalised MSN and POL (ii) cargo-loading and release studies in solution, (iii) cellular internalisation of nanomaterials, and (iv) cell viability tests. See DOI: 10.1039/c4nr07443b

  12. CERN Document Server (CDS): Introduction

    CERN Multimedia

    CERN. Geneva; Costa, Flavio

    2017-01-01

    A short online tutorial introducing the CERN Document Server (CDS). Basic functionality description, the notion of Revisions and the CDS test environment. Links: CDS Production environment CDS Test environment  

  13. Antibacterial Efficacy of Polysaccharide Capped Silver Nanoparticles Is Not Compromised by AcrAB-TolC Efflux Pump

    Directory of Open Access Journals (Sweden)

    Mitali Mishra

    2018-05-01

    Full Text Available Antibacterial therapy is of paramount importance in treatment of several acute and chronic infectious diseases caused by pathogens. Over the years extensive use and misuse of antimicrobial agents has led to emergence of multidrug resistant (MDR and extensive drug resistant (XDR pathogens. This drastic escalation in resistant phenotype has limited the efficacy of available therapeutic options. Thus, the need of the hour is to look for alternative therapeutic approaches to mitigate healthcare concerns caused due to MDR bacterial infections. Nanoparticles have gathered much attention as potential candidates for antibacterial therapy. Equipped with advantages of, wide spectrum bactericidal activity at very low dosage, inhibitor of biofilm formation and ease of permeability, nanoparticles have been considered as leading therapeutic candidates to curtail infections resulting from MDR bacteria. However, substrate non-specificity of efflux pumps, particularly those belonging to resistance nodulation division super family, have been reported to reduce efficacy of many potent antibacterial therapeutic drugs. Previously, we had reported antibacterial activity of polysaccharide-capped silver nanoparticles (AgNPs toward MDR bacteria. We showed that AgNPs inhibits biofilm formation and alters expression of cytoskeletal proteins FtsZ and FtsA, with minimal cytotoxicity toward mammalian cells. In the present study, we report no reduction in antibacterial efficacy of silver nanoparticles in presence of AcrAB-TolC efflux pump proteins. Antibacterial tests were performed according to CLSI macrobroth dilution method, which revealed that both silver nanoparticles exhibited bactericidal activity at very low concentrations. Further, immunoblotting results indicated that both the nanoparticles modulate the transporter AcrB protein expression. However, expression of the membrane fusion protein AcrA did show a significant increase after exposure to AgNPs. Our results

  14. A comparative study on CdS: PEO and CdS: PMMA nanocomposite solid films

    International Nuclear Information System (INIS)

    Padmaja, S.; Jayakumar, S.; Balaji, R.; Vaideki, K.

    2016-01-01

    Cadmium Sulphide (CdS) nanoparticles were reinforced in Poly(ethylene Oxide) (PEO) and Poly(methyl methacrylate) (PMMA) matrices by in situ technique. The presence of CdS in PEO and PMMA matrix was confirmed using X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared spectroscopy (FTIR) analysis disclosed the co-ordination of CdS in the matrices. Thermal analysis of the nanocomposites was carried out using Differential Scanning calorimetric studies (DSC). The optical studies using UV–vis spectroscopy were carried out to find the band gap of the materials and the absorption onset. The CdS particle size in the matrices was found by Effective Mass Approximation (EMA) model using the band gap values and was confirmed by TEM studies. The surface trapped emissions of the nanocomposites were observed from the photoluminescence (PL) spectra. The distribution of CdS particles in the polymer matrices were presented by Atomic force microscopic studies (AFM).

  15. A comparative study on CdS: PEO and CdS: PMMA nanocomposite solid films

    Energy Technology Data Exchange (ETDEWEB)

    Padmaja, S. [Thin film centre, PSG College of Technology, Coimbatore (India); Jayakumar, S., E-mail: s_jayakumar_99@yahoo.com [Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore (India); Balaji, R.; Vaideki, K. [Thin film centre, PSG College of Technology, Coimbatore (India)

    2016-08-15

    Cadmium Sulphide (CdS) nanoparticles were reinforced in Poly(ethylene Oxide) (PEO) and Poly(methyl methacrylate) (PMMA) matrices by in situ technique. The presence of CdS in PEO and PMMA matrix was confirmed using X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared spectroscopy (FTIR) analysis disclosed the co-ordination of CdS in the matrices. Thermal analysis of the nanocomposites was carried out using Differential Scanning calorimetric studies (DSC). The optical studies using UV–vis spectroscopy were carried out to find the band gap of the materials and the absorption onset. The CdS particle size in the matrices was found by Effective Mass Approximation (EMA) model using the band gap values and was confirmed by TEM studies. The surface trapped emissions of the nanocomposites were observed from the photoluminescence (PL) spectra. The distribution of CdS particles in the polymer matrices were presented by Atomic force microscopic studies (AFM).

  16. Citrate-capped gold nanoparticle electrophoretic heat production in response to a time-varying radiofrequency electric-field.

    Science.gov (United States)

    Corr, Stuart J; Raoof, Mustafa; Mackeyev, Yuri; Phounsavath, Sophia; Cheney, Matthew A; Cisneros, Brandon T; Shur, Michael; Gozin, Michael; McNally, Patrick J; Wilson, Lon J; Curley, Steven A

    2012-11-15

    The evaluation of heat production from gold nanoparticles (AuNPs) irradiated with radiofrequency (RF) energy has been problematic due to Joule heating of their background ionic buffer suspensions. Insights into the physical heating mechanism of nanomaterials under RF excitations must be obtained if they are to have applications in fields such as nanoparticle-targeted hyperthermia for cancer therapy. By developing a purification protocol which allows for highly-stable and concentrated solutions of citrate-capped AuNPs to be suspended in high-resistivity water, we show herein, for the first time, that heat production is only evident for AuNPs of diameters ≤ 10 nm, indicating a unique size-dependent heating behavior not previously observed. Heat production has also shown to be linearly dependent on both AuNP concentration and total surface area, and severely attenuated upon AuNP aggregation. These relationships have been further validated using permittivity analysis across a frequency range of 10 MHz to 3 GHz, as well as static conductivity measurements. Theoretical evaluations suggest that the heating mechanism can be modeled by the electrophoretic oscillation of charged AuNPs across finite length scales in response to a time-varying electric field. It is anticipated these results will assist future development of nanoparticle-assisted heat production by RF fields for applications such as targeted cancer hyperthermia.

  17. Investigations of UV photolysis of PVP-capped silver nanoparticles in the presence and absence of dissolved organic carbon

    International Nuclear Information System (INIS)

    Poda, Aimee R.; Kennedy, Alan J.; Cuddy, Michael F.; Bednar, Anthony J.

    2013-01-01

    This study investigated the effect of UV irradiation on the characteristics and toxicity of 50 nm (nominal diameter) polyvinylpyrrolidone-capped silver nanoparticles (AgNPs) in the presence and absence of dissolved organic carbon (DOC). The photolysis resulted in a decrease in average particle size as measured by field flow fractionation interfaced with inductively coupled plasma mass spectrometry. The decrease in size was attributed to the photo-induced oxidation of the PVP and dissolution of metallic silver. Moreover, photolysis of the AgNPs in solutions containing DOC appeared to give rise to small nanoparticles (∼5 nm) formed via reduction of dissolved silver ions. These results were consistent with photolysis of AgNO 3 solutions initially devoid of nanoparticles. Thus, the carbon-containing constituents of DOC serve as reducing agents for Ag + , primarily under conditions of UV irradiation. The standard zooplankton model, Daphnia magna, indicated that the toxicity of nanosilver was significantly reduced when the AgNPs have been exposed to UV light. Observed toxicity was further reduced when AgNPs in DOC-containing solutions were exposed to UV. These results suggest that environmentally relevant conditions such as DOC and UV light are important mitigating factors that mediate the aquatic toxicity of AgNPs.

  18. Graphite-supported 2,2′-bipyridine-capped ultrafine tin nanoparticles for anodes of lithium-ion batteries

    International Nuclear Information System (INIS)

    Nabais, Catarina; Schneider, Raphaël; Willmann, Patrick; Billaud, Denis

    2012-01-01

    Highlights: ► 2,2′-bipyridine capped Sn nanoparticles as anode materials for Li-ion batteries. ► High dispersion of Sn nanoparticles at the surface of the graphite matrix. ► The introduction of 2,2′-bipyridine improves the capacity and cycling stability. ► A stable reversible capacity of ca. 480 mA h g −1 after 20 cycles was observed. - Abstract: Monodisperse and small tin nanoparticles were prepared from a 2,2′-bipyridine–tin(+2) chloride complex using sodium borohydride as reducing agent. When the synthesis was conducted in the presence of graphite, Sn particles with an average diameter of ca. 29 nm well-dispersed at the surface of graphite were obtained. Electrochemical lithium insertion was carried out in these materials. A stable reversible capacity of ca. 480 mA h g −1 , value 37% higher than that of pure graphite, was found.

  19. CdS Nanoparticle-Modified α-Fe2O3/TiO2 Nanorod Array Photoanode for Efficient Photoelectrochemical Water Oxidation.

    Science.gov (United States)

    Yin, Ruiyang; Liu, Mingyang; Tang, Rui; Yin, Longwei

    2017-09-02

    In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe 2 O 3 /TiO 2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe 2 O 3 /TiO 2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance. Importantly, for the designed abnormal type-II heterostructure between Fe 2 O 3 /TiO 2 , the conduction band position of Fe 2 O 3 is higher than that of TiO 2 , the photogenerated electrons from Fe 2 O 3 will rapidly recombine with the photogenerated holes from TiO 2 , thus leads to an efficient separation of photogenerated electrons from Fe 2 O 3 /holes from TiO 2 at the Fe 2 O 3 /TiO 2 interface, greatly improving the separation efficiency of photogenerated holes within Fe 2 O 3 and enhances the photogenerated electron injection efficiency in TiO 2 . Working as the photoanodes of PEC water oxidation, CdS/α-Fe 2 O 3 /TiO 2 heterostucture electrode exhibits improved photocurrent density of 0.62 mA cm - 2 at 1.23 V vs. reversible hydrogen electrode (RHE) in alkaline electrolyte, with an obviously negatively shifted onset potential of 80 mV. This work provides promising methods to enhance the PEC water oxidation performance of the TiO 2 -based heterostructure photoanodes.

  20. High temperature stability of surfactant capped CoFe2O4 nanoparticles

    International Nuclear Information System (INIS)

    Ayyappan, S.; Panneerselvam, G.; Antony, M.P.; Philip, John

    2011-01-01

    Highlights: → Self-assembled molecular layers of surfactant on nanoparticles are often used to modify surface properties. → We demonstrate that a surfactant nanolayer on CoFe 2 O 4 nanoparticles can act as a strong reducing agent under high temperature vacuum annealing. → We propose a possible reduction mechanism of CoFe 2 O 4 nanoparticles under air and vacuum annealing. → Our results are important in the understanding of the stability of nanoparticles at high temperatures. - Abstract: We investigate the effect of adsorbed surfactant on the structural stability of CoFe 2 O 4 nanoparticles during vacuum thermal annealing. In-situ high temperature X-ray diffraction studies show a reduction of oleic acid coated CoFe 2 O 4 nanoparticles into α-Fe and CoO under annealing at 800 deg. C. On the contrary, the uncoated CoFe 2 O 4 nanoparticles remains stable, with its cubic phase intact, even at 1000 deg. C. Thermo-gravimetric analysis coupled mass spectra reveals that the evolved carbon from the surfactant aids the removal of oxygen atom from CoFe 2 O 4 lattice thereby reducing it to α-Fe and CoO phases. These results are important in tailoring stable CoFe 2 O 4 nanostructures for various applications.

  1. Synthesis of Alkanethiolate-Capped Metal Nanoparticles Using Alkyl Thiosulfate Ligand Precursors: A Method to Generate Promising Reagents for Selective Catalysis

    Directory of Open Access Journals (Sweden)

    Khin Aye San

    2018-05-01

    Full Text Available Evaluation of metal nanoparticle catalysts functionalized with well-defined thiolate ligands can be potentially important because such systems can provide a spatial control in the reactivity and selectivity of catalysts. A synthetic method utilizing Bunte salts (sodium S-alkylthiosulfates allows the formation of metal nanoparticles (Au, Ag, Pd, Pt, and Ir capped with alkanethiolate ligands. The catalysis studies on Pd nanoparticles show a strong correlation between the surface ligand structure/composition and the catalytic activity and selectivity for the hydrogenation/isomerization of alkenes, dienes, trienes, and allylic alcohols. The high selectivity of Pd nanoparticles is driven by the controlled electronic properties of the Pd surface limiting the formation of Pd–alkene adducts (or intermediates necessary for (additional hydrogenation. The synthesis of water soluble Pd nanoparticles using ω-carboxylate-S-alkanethiosulfate salts is successfully achieved and these Pd nanoparticles are examined for the hydrogenation of various unsaturated compounds in both homogeneous and heterogeneous environments. Alkanethiolate-capped Pt nanoparticles are also successfully synthesized and further investigated for the hydrogenation of various alkynes to understand their geometric and electronic surface properties. The high catalytic activity of activated terminal alkynes, but the significantly low activity of internal alkynes and unactivated terminal alkynes, are observed for Pt nanoparticles.

  2. Evaluation of the photophysicochemical properties and photodynamic therapy activity of nanoconjugates of zinc phthalocyanine linked to glutathione capped Au and Au3Ag1 nanoparticles

    CSIR Research Space (South Africa)

    Oluwole, DA

    2018-03-01

    Full Text Available , Charles Maphanga, Saturnin Ombinda-Lemboumba, Patience Mthunzi-Kufa, Tebello Nyokong ABSTRACT: We report on the synthesis of glutathione capped gold (AuNPs–GSH) and gold– silver (Au3Ag1NPs–GSH) nanoparticles and their covalent attachment to Zn...

  3. Sum Frequency Generation Vibrational Spectroscopy of Colloidal Platinum Nanoparticle Catalysts: Disordering versus Removal of Organic Capping

    KAUST Repository

    Krier, James M.; Michalak, William D.; Baker, L. Robert; An, Kwangjin; Komvopoulos, Kyriakos; Somorjai, Gabor A.

    2012-01-01

    Recent work with nanoparticle catalysts shows that size and shape control on the nanometer scale influences reaction rate and selectivity. Sum frequency generation (SFG) vibrational spectroscopy is a powerful tool for studying heterogeneous

  4. Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria

    Science.gov (United States)

    2014-01-01

    In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) revealed the presence of spherical silver nanoparticles of the size range 5 to 40 nm, most of these being 16 to 20 nm in diameter. X-ray diffraction (XRD) spectrum of the nanoparticles exhibited 2θ values corresponding to silver nanoparticles. These nanoparticles were found to be naturally protein coated. SDS-PAGE analysis showed the presence of an 85-kDa protein band responsible for capping and stabilization of the silver nanoparticles. Antimicrobial activities of the silver nanoparticles against human as well as plant pathogenic multidrug-resistant bacteria were assayed. The particles showed inhibitory effect on the growth kinetics of human and plant bacteria. Furthermore, the genotoxic potential of the silver nanoparticles with increasing concentrations was evaluated by DNA fragmentation studies using plasmid DNA. PMID:25114655

  5. Preparation, properties and anticancer effects of mixed As4S4/ZnS nanoparticles capped by Poloxamer 407

    International Nuclear Information System (INIS)

    Bujňáková, Z.; Baláž, M.; Zdurienčíková, M.; Sedlák, J.; Čaplovičová, M.; Čaplovič, Ľ.; Dutková, E.; Zorkovská, A.; Turianicová, E.; Baláž, P.; Shpotyuk, O.

    2017-01-01

    Arsenic sulfide compounds have a long history of application in a traditional medicine. In recent years, realgar has been studied as a promising drug in cancer treatment. In this study, the arsenic sulfide (As 4 S 4 ) nanoparticles combined with zinc sulfide (ZnS) ones in different molar ratio have been prepared by a simple mechanochemical route in a planetary mill. The successful synthesis and structural properties were confirmed and followed via X-ray diffraction and high-resolution transmission electron microscopy measurements. The morphology of the particles was studied via scanning electron microscopy and transmission electron microscopy methods and the presence of nanocrystallites was verified. For biological tests, the prepared As 4 S 4 /ZnS nanoparticles were further milled in a circulation mill in a water solution of Poloxamer 407 (0.5 wt%), in order to cover the particles with this biocompatible copolymer and to obtain stable nanosuspensions with unimodal distribution. The average size of the particles in the nanosuspensions (~ 120 nm) was determined by photon cross-correlation spectroscopy method. Stability of the nanosuspensions was determined via particle size distribution and zeta potential measurements, confirming no physico-chemical changes for several months. Interestingly, with the increasing amount of ZnS in the sample, the stability was improved. The anti-cancer effects were tested on two melanoma cell lines, A375 and Bowes, with promising results, confirming increased efficiency of the samples containing both As 4 S 4 and ZnS nanocrystals. - Highlights: • Mixed As 4 S 4 /ZnS nanoparticles were prepared by dry milling in the first stage • Stable nanosuspensions of As 4 S 4 /ZnS nanoparticles capped by Poloxamer 407 were prepared by wet milling in the second stage • ZnS in the samples is beneficial: higher values of S A , stability, solubility and anticancer activity were improved

  6. The role of aqueous leaf extract of Tinospora crispa as reducing and capping agents for synthesis of gold nanoparticles

    Science.gov (United States)

    Apriandanu, D. O. B.; Yulizar, Y.

    2017-04-01

    Environmentally friendly method for green synthesis of Au nanoparticles (AuNP) using aqueous leaf extract of Tinospora crispa (TLE) was reported. TLE has the ability for reducing and capping AuNP. Identification of active compounds in aqueous leaf extract was obtained by phytochemical analysis and Fourier transform infrared spectroscopy (FTIR). The AuNP-TLE growth was characterized using UV-Vis spectrophotometer. The particle size and the distribution of AuNP were confirmed by particle size analyzer (PSA). AuNP-TLE formation was optimized by varying the extract concentration and time of the synthesis process. UV-Vis absorption spectrum of optimum AuNP formation displayed by the surface plasmon resonance at maximum wavelength of λmax 536 nm. The PSA result showed that AuNP has size distribution of 80.60 nm and stable up to 21 days. TEM images showed that the size of the AuNP is ± 25 nm.

  7. 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.

  8. Localized-Surface-Plasmon Enhanced the 357 nm Forward Emission from ZnMgO Films Capped by Pt Nanoparticles

    Directory of Open Access Journals (Sweden)

    Song XM

    2009-01-01

    Full Text Available Abstract The Pt nanoparticles (NPs, which posses the wider tunable localized-surface-plasmon (LSP energy varying from deep ultraviolet to visible region depending on their morphology, were prepared by annealing Pt thin films with different initial mass-thicknesses. A sixfold enhancement of the 357 nm forward emission of ZnMgO was observed after capping with Pt NPs, which is due to the resonance coupling between the LSP of Pt NPs and the band-gap emission of ZnMgO. The other factors affecting the ultraviolet emission of ZnMgO, such as emission from Pt itself and light multi-scattering at the interface, were also discussed. These results indicate that Pt NPs can be used to enhance the ultraviolet emission through the LSP coupling for various wide band-gap semiconductors.

  9. Revisiting magnetism of capped Au and ZnO nanoparticles: Surface band structure and atomic orbital with giant magnetic moment

    Energy Technology Data Exchange (ETDEWEB)

    Hernando, Antonio; Crespo, Patricia [Instituto de Magnetismo Aplicado, UCM-CSIC-ADIF, Las Rozas. P.O. Box 155, 28230 Madrid (Spain); Dept. Fisica de Materiales, Universidad Complutense, Madrid (Spain); Garcia, Miguel Angel [Instituto de Ceramica y Vidrio, CSIC, C/ Kelsen, 5, Madrid 28049 (Spain); Coey, Michael [Trinity College Dublin, Dublin (Ireland); Ayuela, Andres; Echenique, Pedro Miguel [Centro de Fisica de Materiales, CFM-MPC CSIC-UPV/EHU, Donostia International Physics Center (DIPC), 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Fac. de Quimicas, Universidad del Pais Vasco UPV-EHU, 20018 San Sebastian (Spain)

    2011-10-15

    In this article we review the exotic magnetism of nanoparticles (NPs) formed by substances that are not magnetic in bulk as described with generality in Section 1. In particular, the intrinsic character of the magnetism observed on capped Au and ZnO NPs is analysed. X-ray magnetic circular dichroism (XMCD) analysis has shown that the magnetic moments are intrinsic and lie in the Au and Zn atoms, respectively, as analysed in Section 2, where the general theoretical ideas are also revisited. Since impurity atoms bonded to the surface act as donor or acceptor of electrons that occupy the surface states, the anomalous magnetic response is analysed in terms of the surface band in Section 3. Finally, Section 4 summarizes our last theoretical proposal. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Hybrid polymer-CdS solar cell active layers formed by in situ growth of CdS nanoparticles

    International Nuclear Information System (INIS)

    Masala, S.; Del Gobbo, S.; Borriello, C.; Bizzarro, V.; La Ferrara, V.; Re, M.; Pesce, E.; Minarini, C.; De Crescenzi, M.; Di Luccio, T.

    2011-01-01

    The integration of semiconductor nanoparticles (NPs) into a polymeric matrix has the potential to enhance the performance of polymer-based solar cells taking advantage of the physical properties of NPs and polymers. We synthesize a new class of CdS-NPs-based active layer employing a low-cost and low temperature route compatible with large-scale device manufacturing. Our approach is based on the controlled in situ thermal decomposition of a cadmium thiolate precursor in poly(3-hexylthiophene) (P3HT). The casted P3HT:precursor solid foils were heated up from 200 to 300 °C to allow the precursor decomposition and the CdS-NP formation within the polymer matrix. The CdS-NP growth was controlled by varying the annealing temperature. The polymer:precursor weight ratio was also varied to investigate the effects of increasing the NP volume fraction on the solar cell performances. The optical properties were studied by using UV–Vis absorption and photoluminescence (PL) spectroscopy at room temperature. To investigate the photocurrent response of P3HT:CdS nanocomposites, ITO/P3HT:CdS/Al solar cell devices were realized. We measured the external quantum efficiency (EQE) as a function of the wavelength. The photovoltaic response of the devices containing CdS-NPs showed a variation compared with the devices with P3HT only. By changing the annealing temperature the EQE is enhanced in the 400–600 nm spectral region. By increasing the NPs volume fraction remarkable changes in the EQE spectra were observed. The data are discussed also in relation to morphological features of the interfaces studied by Focused Ion Beam technique.

  11. Multifunctional properties of cotton fabrics coated with in situ synthesis of zinc oxide nanoparticles capped with date seed extract.

    Science.gov (United States)

    El-Naggar, Mehrez E; Shaarawy, S; Hebeish, A A

    2018-02-01

    In situ formation of zinc oxide nanoparticles (ZnO-NPs) was studied within the framework of several factors. variables examined include (i) innovation of a new capping agent; (ii) nature of the cotton fabric related to its processing; (iii) formation of Zinc hydroxide (Zn(OH) 2 ) due to reduction of zinc acetate with sodium hydroxide (iv) treatment of the differently processed cotton fabrics with (Zn(OH) 2 ) functionalized dispersion as per the exhaustion method, (v) further treatment of the cotton fabrics with (Zn(OH) 2 ) dispersion according to the pad-dry-cure method and (Vi) conversion of (Zn(OH) 2 ) to ZnO-NPs during the curing step in the latter method. Results depict that the incorporation of the bio-extract obtained from date seed waste works effectively as capping material which stabilize ZnO-NPs. Mercerized bleached cotton fabric proves to be a better candidate than mercerized loomstate cotton fabric in conferring sustainable bactericidal and UV blocking. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Quantification of captopril in urine through surface-assisted laser desorption/ionization mass spectrometry using 4-mercaptobenzoic acid-capped gold nanoparticles as an internal standard.

    Science.gov (United States)

    Chen, Wen-Tsen; Chiang, Cheng-Kang; Lin, Yang-Wei; Chang, Huan-Tsung

    2010-05-01

    We have developed a new internal standard method for the determination of the concentration of captopril (CAP) through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using gold nanoparticles (Au NPs). This approach provided linearity for CAP over the concentration range 2.5-25 microM (R(2) = 0.987), with a limit of detection (signal-to-noise ratio = 3) of 1.0 microM. The spot-to-spot variations in the concentration of CAP through SALDI-MS analyses performed in the absence and presence of the internal standard were 26% and 9%, respectively (15 measurements). This approach provides simplicity, accuracy, precision, and great reproducibility to the determination of the levels of CAP in human urine samples. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  13. New method for preparation of polyoxometalate-capped gold nanoparticles, and their assembly on an indium-doped tin oxide electrode

    International Nuclear Information System (INIS)

    Cheng, Y.; Zheng, J.; Wang, Z.; Liu, L.; Wu, Y.; Yang, J.

    2011-01-01

    Functionalized gold nanoparticles capped with polyoxometalates were prepared by a simple photoreduction technique where phosphododecamolybdates serve as reducing reagents, photocatalysts, and as stabilizers. TEM images of the resulting gold nanoparticles show the particles to have a relative narrow size distribution. Monolayer and multilayer structures of the negatively charged capped gold nanoparticles were deposited on a poly(vinyl pyridine)-derivatized indium-doped tin oxide (ITO) electrode via the layer-by-layer technique. The surface plasmon resonance band of the gold nanoparticles displays a blue shift on the surface of the ITO electrode. This is due to the substrate-induced charge redistribution in the gold nanoparticles and a change in the electromagnetic coupling between the assembled nanoparticles. The modified electrode exhibits the characteristic electrochemical behavior of surface-confined phosphododecamolybdate and excellent electrocatalytic activity. The catalysis of the modified electrode towards the model compound iodate was systematically studied. The heterogeneous catalytic rate constant for the electrochemical reduction of iodate was determined by chronoamperometry to be ca. 1. 34 x 10 5 mol -1 .L.s -1 . The amperometric method gave a linear range from 2. 5 x 10 -6 to 1. 5 x 10 -3 M and a detection limit of 1. 0 x 10 -6 M. We believe that the functionalized gold nanoparticles prepared by this photoreduction technique are advantageous in terms of fabrication of sensitive and stable redox electrodes. (author)

  14. PEG capped methotrexate silver nanoparticles for efficient anticancer activity and biocompatibility.

    Science.gov (United States)

    Muhammad, Zarmina; Raza, Abida; Ghafoor, Sana; Naeem, Ayesha; Naz, Syeda Sohaila; Riaz, Sundus; Ahmed, Wajiha; Rana, Nosheen Fatima

    2016-08-25

    Nanocarriers endow tremendous benefits to the drug delivery systems depending upon the specific properties of either component. These benefits include, increase in the drug blood retention time, reduced efflux, additional toxicity and targeted delivery. Methotrexate (MTX) is clinically used for cancer treatment. Higher dosage of MTX results in hepatic and renal toxicity. In this study methotrexate silver nanoparticles (Ag-MTX) coated with polyethylene glycol (PEG) are synthesized and characterized. Their anticancer activity and biocompatibility is also evaluated. Ag-MTX nanoparticles are synthesized by chemical reduction method. They are characterized by Ultraviolet-Visible Spectroscopy and Fourier Transform Infrared Spectroscopy. Average size of PEG coated Ag-MTX nanoparticles (PEG-Ag-MTX nanoparticles) is 12nm. These particles exhibited improved anticancer activity against MCF-7 cell line. Hemolytic activity of these particles was significantly less than MTX. PEG-Ag-MTX nanoparticles are potential nanocarrier of methotrexate which may offer MTX based cancer treatment with reduced side effects. In-vivo investigations should be carried out to explore them in detail. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Green Synthesis and Characterization of SmVO4 Nanoparticles in the Presence of Carbohydrates As Capping Agents with Investigation of Visible-Light Photocatalytic Properties

    Science.gov (United States)

    Eghbali-Arani, Mohammad; Sobhani-Nasab, Ali; Rahimi-Nasrabadi, Mehdi; Pourmasoud, Saeid

    2018-03-01

    SmVO4 nanoparticles were synthesized through a fast and simple procedure (green method). The effects of three parameters including temperature, type of capping agent, and concentration on the size and morphology behavior of SmVO4 nanoparticles were explored. The analysis of SmVO4 nanoparticles was performed through some techniques including, Fourier transform infrared spectroscopy, x-ray diffraction, energy dispersive x-ray microanalysis, scanning electron microscopy, transmission electron microscopy, thermogravimetry, differential thermal analysis, ultraviolet-visible spectroscopy, and vibrating sample magnetometers. The study of photocatalytic behaviour of the SmVO4 nanoparticles in various conditions has been carried out. The impacts of different factors such as dosage, grain size, and kind of pollutant (methylene blue = MB and methyl orange = MO) on the photocatalytic property of SmVO4 nanoparticles were assessed. The photocatalytic activities of SmVO4 catalysts were studied for the degradation of dye under visible light (λ > 400 nm).

  16. Preparation and Characterization of ZnS, CdS and HgS/Poly(methyl methacrylate Nanocomposites

    Directory of Open Access Journals (Sweden)

    Johannes Z. Mbese

    2014-09-01

    Full Text Available The synthesis and characterization of ZnS/PMMA (poly(methyl methacrylate, CdS/PMMA and HgS/PMMA nanocomposites are presented. Hexadecylamine (HDA-capped ZnS, CdS and HgS nanoparticles were synthesized using dithiocarbamate single molecule precursors at 180 °C. FTIR (Fourier transform infrared spectroscopy spectra measurement confirmed the dispersion of the metal sulfide nanoparticles in the PMMA matrices to form the metal sulfides/PMMA nanocomposites. Powder X-ray diffraction confirmed the presence of the amorphous PMMA in the nanocomposites. The ZnS and HgS particles were indexed to the cubic phase, while the HgS particles correspond to the hexagonal phase. Thermogravimetric analyses showed that the metal sulfide nanocomposites are thermally more stable than their corresponding precursor complexes. The TEM (Transmission electron microscope analyses revealed that the ZnS nanoparticles have a particle size of 3–5 nm; the crystallite size of the CdS nanoparticles is 6–12 nm, and HgS nanoparticles are 6–12 nm.

  17. Permanent magnetism in phosphine- and chlorine-capped gold: from clusters to nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Marquez, Miguel A., E-mail: miguel.angel@icmse.csic.es; Guerrero, Estefania; Fernandez, Asuncion [Instituto de Ciencia de Materiales de Sevilla (CSIC-US) (Spain); Crespo, Patricia; Hernando, Antonio [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC) (Spain); Lucena, Raquel; Conesa, Jose C. [Instituto de Catalisis y Petroleoquimica (CSIC) (Spain)

    2010-05-15

    Magnetometry results have shown that gold NPs ({approx}2 nm in size) protected with phosphine and chlorine ligands exhibit permanent magnetism. When the NPs size decreases down to the subnanometric size range, e.g. undecagold atom clusters, the permanent magnetism disappears. The near edge structure of the X-ray absorption spectroscopy data points out that charge transfer between gold and the capping system occurs in both cases. These results strongly suggest that nearly metallic Au bonds are also required for the induction of a magnetic response. Electron paramagnetic resonance observations indicate that the contribution to magnetism from eventual iron impurities can be disregarded.

  18. Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

    Science.gov (United States)

    Stevanović, Magdalena; Kovačević, Branimir; Petković, Jana; Filipič, Metka; Uskoković, Dragan

    2011-01-01

    Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-α, γ, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species. PMID:22131829

  19. Optical properties and extinction spectroscopy to characterize the synthesis of amine capped silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roldan, Maria Virginia [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina)], E-mail: vroldan@fceia.unr.edu.ar; Scaffardi, Lucia B. [CIOp - CONICET, CIC, c.c. 124, 1900 La Plata (Argentina) and Area Departamental de Ciencias Basicas, Facultad de Ingenieria, Universidad Nacional de La Plata, La Plata (Argentina); Sanctis, Oscar de [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina); Pellegri, Nora [Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, UNR, Rosario (Argentina)], E-mail: pellegri@fceia.unr.edu.ar

    2008-12-20

    The present work describes a method for preparation of Ag nanoparticles from chemical reduction of AgNO{sub 3} in ethanol with ATS [N-[3-(trimethoxysilyl)propyl] diethylenetriamine] as surface modifier. We study the influence of different parameters such as concentration, time, temperature and reductor agents on the size and shape of the nanoparticles. We present the morphologic and structural characterization of samples by UV-vis extinction spectroscopy, Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Particularly, using optical extinction spectroscopy, the present work shows the analysis of size evolution in the fabrication process of spherical silver nanoparticles. This evolution is studied as a function of the time elapsed between the beginning of the reaction and the extraction of the sample (temporal delayed synthesis), and as a function of the temperature during the chemical reaction. In both the cases, we propose the study of the plasmon width as a useful, simple and inexpensive method for analysis of the mean radius, specially, for values below 6 nm.

  20. Optical properties and extinction spectroscopy to characterize the synthesis of amine capped silver nanoparticles

    International Nuclear Information System (INIS)

    Roldan, Maria Virginia; Scaffardi, Lucia B.; Sanctis, Oscar de; Pellegri, Nora

    2008-01-01

    The present work describes a method for preparation of Ag nanoparticles from chemical reduction of AgNO 3 in ethanol with ATS [N-[3-(trimethoxysilyl)propyl] diethylenetriamine] as surface modifier. We study the influence of different parameters such as concentration, time, temperature and reductor agents on the size and shape of the nanoparticles. We present the morphologic and structural characterization of samples by UV-vis extinction spectroscopy, Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Particularly, using optical extinction spectroscopy, the present work shows the analysis of size evolution in the fabrication process of spherical silver nanoparticles. This evolution is studied as a function of the time elapsed between the beginning of the reaction and the extraction of the sample (temporal delayed synthesis), and as a function of the temperature during the chemical reaction. In both the cases, we propose the study of the plasmon width as a useful, simple and inexpensive method for analysis of the mean radius, specially, for values below 6 nm

  1. From oleic acid-capped iron oxide nanoparticles to polyethyleneimine-coated single-particle magnetofectins

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Acuña, Melissa [University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering (United States); Maldonado-Camargo, Lorena [University of Florida, Department of Chemical Engineering (United States); Dobson, Jon; Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering (United States)

    2016-09-15

    Various inorganic nanoparticle designs have been developed and used as non-viral gene carriers. Magnetic gene carriers containing polyethyleneimine (PEI), a well-known transfection agent, have been shown to improve DNA transfection speed and efficiency in the presence of applied magnetic field gradients that promote particle–cell interactions. Here we report a method to prepare iron oxide nanoparticles conjugated with PEI that: preserves the narrow size distribution of the nanoparticles, conserves magnetic properties throughout the process, and results in efficient transfection. We demonstrate the ability of the particles to electrostatically bind with DNA and transfect human cervical cancer (HeLa) cells by the use of an oscillating magnet array. Their transfection efficiency is similar to that of Lipofectamine 2000™, a commercial transfection reagent. PEI-coated particles were subjected to acidification, and acidification in the presence of salts, before DNA binding. Results show that although these pre-treatments did not affect the ability of particles to bind DNA they did significantly enhanced transfection efficiency. Finally, we show that these magnetofectins (PEI-MNP/DNA) complexes have no effect on the viability of cells at the concentrations used in the study. The systematic preparation of magnetic vectors with uniform physical and magnetic properties is critical to progressing this non-viral transfection technology.

  2. Photoelectrochemical detection of copper ions by modulating the growth of CdS quantum dots.

    Science.gov (United States)

    Grinyte, Ruta; Barroso, Javier; Díez-Buitrago, Beatriz; Saa, Laura; Möller, Marco; Pavlov, Valeri

    2017-09-15

    We discovered that copper ions (Cu 2+ ) catalyze the oxidation of cysteine (CSH) by oxygen (O 2 ) to modulate the growth of CSH-capped cadmium sulfide (CdS) nanoparticles (NPs). This new chemical process was applied to sensitive fluorogenic and photoelectrochemical (PEC) detection of Cu 2+ ions in real samples of mineral and tap water using the photocatalytic activity of the resulting NPs. Disposable screen-printed electrodes (SPCEs) modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP) by cyclic voltammetry (CV) were employed for PEC analytical system. CdS NPs formed during the assay photocatalyze oxidation of 1-thioglycerol (TG) upon application of 0.3 V vs. Ag/AgCl to SPCEs. Os-PVP complex mediated the electron transfer between the electrode surface and CdS NPs. We proved that our assays did not suffer from interference from other ions accompanying Cu 2+ and the sensitivity of our assays covers the European Union standard limit of Cu 2+ ions in drinking water. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Safe Haven CDS Premiums

    DEFF Research Database (Denmark)

    Klingler, Sven; Lando, David

    Credit Default Swaps can be used to lower capital requirements of dealer banks who enter into uncollateralized derivatives positions with sovereigns. We show in a model that the regulatory incentive to obtain capital relief makes CDS contracts valuable to dealer banks and empirically that...... support that CDS contracts are used for capital relief....

  4. Chitosan and carboxymethyl-chitosan capping ligands: Effects on the nucleation and growth of hydroxyapatite nanoparticles for producing biocomposite membranes.

    Science.gov (United States)

    Dumont, Vitor C; Mansur, Alexandra A P; Carvalho, Sandhra M; Medeiros Borsagli, Fernanda G L; Pereira, Marivalda M; Mansur, Herman S

    2016-02-01

    Synthetic biomaterials based on calcium phosphates (CaP) have been widely studied for bone tissue reconstruction therapies, but no definitive solution that fulfills all of the required properties has been identified. Thus, this study reports the synthesis of composite membranes based on nanohydroxyapatite particles (nHA) embedded in chitosan (CHI) and O-carboxymethyl chitosan (CMC) matrices produced using a one-step co-precipitation method in water media. Biopolymers were used as capping ligands for simultaneously controlling the nucleation and growth of the nHA particles during the precipitation process and also to form the polymeric network of the biocomposites. The bionanocomposites were extensively characterized using light microscopy (LM), scanning and transmission electron microscopy (SEM/TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray micro-CT analysis (μCT), andMTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazoliumbromide) cell proliferation assays for cell cytotoxicity. The results demonstrated that the ligands used during the synthesis highly affected the composites produced, primarily due the changes in the mechanisms and kinetics of nucleation and growth of the HA particles at the nanoscale level. The SEMimages revealed that the use of carboxyl-functionalized chitosan (CMC) ligands significantly reduced the average size of theHA nanoparticles and caused the formation of a narrower size distribution (90±20nm) compared to theHAnanoparticles producedwith chitosan ligands (220±50nm). The same trend was verified by the AFM analysis,where the nHA particles were formed evenly dispersed in the polymer matrix. However, the CMC-based composites were more homogeneously distributed, which was endorsed by the images collected via X-ray micro-CT. The FTIR spectra and the XRD analysis indicated that nanosized hydroxyapatite was the predominant calcium

  5. Citrate-coated silver nanoparticles interactions with effluent organic matter: influence of capping agent and solution conditions

    KAUST Repository

    Gutierrez, Leonardo

    2015-07-31

    Fate and transport studies of silver nanoparticles (AgNPs) discharged from urban wastewaters containing effluent organic matter (EfOM) into natural waters represent a key knowledge gap. In this study, EfOM interfacial interactions with AgNPs and their aggregation kinetics were investigated by atomic force microscopy (AFM) and time-resolved dynamic light scattering (TR-DLS), respectively. Two well-characterized EfOM isolates, i.e., wastewater humic (WW humic) and wastewater colloids (WW colloids, a complex mixture of polysaccharides-proteins-lipids), and a River humic isolate of different characteristics were selected. Citrate-coated AgNPs were selected as representative capped-AgNPs. Citrate-coated AgNPs showed a considerable stability in Na+ solutions. However, Ca2+ ions induced aggregation by cation bridging between carboxyl groups on citrate. Although the presence of River humic increased the stability of citrate-coated AgNPs in Na+ solutions due to electrosteric effects, they aggregated in WW humic-containing solutions, indicating the importance of humics characteristics during interactions. Ca2+ ions increased citrate-coated AgNPs aggregation rates in both humic solutions, suggesting cation bridging between carboxyl groups on their structures as a dominant interacting mechanism. Aggregation of citrate-coated AgNPs in WW colloids solutions was significantly faster than those in both humic solutions. Control experiments in urea solution indicated hydrogen bonding as the main interacting mechanism. During AFM experiments, citrate-coated AgNPs showed higher adhesion to WW humic than to River humic, evidencing a consistency between TR-DLS and AFM results. Ca2+ ions increased citrate-coated AgNPs adhesion to both humic isolates. Interestingly, strong WW colloids interactions with citrate caused AFM probe contamination (nanoparticles adsorption) even at low Na+ concentrations, indicating the impact of hydrogen bonding on adhesion. These results suggest the importance

  6. Room-temperature sol–gel synthesis of organic ligand-capped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zobel, Mirijam, E-mail: mirijam.zobel@fau.de; Chatterjee, Haimantee [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany); Matveeva, Galina; Kolb, Ute [Johannes Gutenberg-Universität, Institut für Physikalische Chemie (Germany); Neder, Reinhard B., E-mail: reinhard.neder@fau.de [Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik (Germany)

    2015-05-15

    Powders of zinc oxide nanoparticles with individual particle sizes below 10 nm in diameter are readily produced in base-induced sol–gel processes from ethanolic solutions of zinc acetate dihydrate. These particles are covered with acetate molecules and without further stabilization, they grow when stored as a powder. Here, we present three organic ligands, which reproducibly stabilize individual particle sizes <5 nm within the agglomerated powders for extended periods of time, up to months. Citric acid and 1,5-diphenyl-1,3,5-pentanetrione result in average diameters of 3 nm, whereas dimethyl-L-tartrate stabilizes 2.1 nm. X-ray diffraction and pair distribution function analysis were used to investigate the structural properties of the particles. TEM data confirm the individual particle size and crystallinity and show that the particles are agglomerated without structural coherence. Besides the introduction of these novel ligands for ZnO nanoparticles, we investigated, in particular, the influence of each synthesis step onto the final nanoparticle size in the powder. Previous studies often reported the employed synthesis parameters, but did not motivate the reasoning for their choice based on detailed experimental observations. Herein, we regard separately the steps of (i) the synthesis of the colloids, (ii) their precipitation, and (iii) the drying of the resulting gel to understand the role of the ligands therein. ZnO particles only covered with acetate grow to 5 nm during the drying process, whereas particles with any of the additional ligands retain their colloidal size of 2–3 nm. This clearly shows the efficient binding and effect of the presented ligands.

  7. Chitosan and carboxymethyl-chitosan capping ligands: Effects on the nucleation and growth of hydroxyapatite nanoparticles for producing biocomposite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Vitor C.; Mansur, Alexandra A.P.; Carvalho, Sandhra M.; Medeiros Borsagli, Fernanda G.L.; Pereira, Marivalda M.; Mansur, Herman S., E-mail: hmansur@demet.ufmg.br

    2016-02-01

    Synthetic biomaterials based on calcium phosphates (CaP) have been widely studied for bone tissue reconstruction therapies, but no definitive solution that fulfills all of the required properties has been identified. Thus, this study reports the synthesis of composite membranes based on nanohydroxyapatite particles (nHA) embedded in chitosan (CHI) and O-carboxymethyl chitosan (CMC) matrices produced using a one-step co-precipitation method in water media. Biopolymers were used as capping ligands for simultaneously controlling the nucleation and growth of the nHA particles during the precipitation process and also to form the polymeric network of the biocomposites. The bionanocomposites were extensively characterized using light microscopy (LM), scanning and transmission electron microscopy (SEM/TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray micro-CT analysis (μCT), and MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) cell proliferation assays for cell cytotoxicity. The results demonstrated that the ligands used during the synthesis highly affected the composites produced, primarily due the changes in the mechanisms and kinetics of nucleation and growth of the HA particles at the nanoscale level. The SEM images revealed that the use of carboxyl-functionalized chitosan (CMC) ligands significantly reduced the average size of the HA nanoparticles and caused the formation of a narrower size distribution (90 ± 20 nm) compared to the HA nanoparticles produced with chitosan ligands (220 ± 50 nm). The same trend was verified by the AFM analysis, where the nHA particles were formed evenly dispersed in the polymer matrix. However, the CMC-based composites were more homogeneously distributed, which was endorsed by the images collected via X-ray micro-CT. The FTIR spectra and the XRD analysis indicated that nanosized hydroxyapatite was the

  8. A simple and facile synthesis of MPA capped CdSe and CdSe/CdS core/shell nanoparticles

    Science.gov (United States)

    Sukanya, D.; Sagayaraj, P.

    2015-06-01

    II-VI semiconductor nanostructures, in particular, CdSe quantum dots have drawn a lot of attention because of their promising potential applications in biological tagging, photovoltaic, display devices etc. due to their excellent optical properties, high emission quantum yield, size dependent emission wavelength and high photostability. In this paper, we describe the synthesis and properties of mercaptopropionic acid capped CdSe and CdSe/CdS nanoparticles through a simple and efficient co-precipitation method followed by hydrothermal treatment. The growth process, characterization and the optical absorption as a function of wavelength for the synthesized MPA capped CdSe and CdSe/CdS nanoparticles have been determined using X-ray diffraction study (XRD), Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and High Resolution Transmission Electron Microscopy (HRTEM).

  9. A simple and facile synthesis of MPA capped CdSe and CdSe/CdS core/shell nanoparticles

    International Nuclear Information System (INIS)

    Sukanya, D.; Sagayaraj, P.

    2015-01-01

    II-VI semiconductor nanostructures, in particular, CdSe quantum dots have drawn a lot of attention because of their promising potential applications in biological tagging, photovoltaic, display devices etc. due to their excellent optical properties, high emission quantum yield, size dependent emission wavelength and high photostability. In this paper, we describe the synthesis and properties of mercaptopropionic acid capped CdSe and CdSe/CdS nanoparticles through a simple and efficient co-precipitation method followed by hydrothermal treatment. The growth process, characterization and the optical absorption as a function of wavelength for the synthesized MPA capped CdSe and CdSe/CdS nanoparticles have been determined using X-ray diffraction study (XRD), Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and High Resolution Transmission Electron Microscopy (HRTEM)

  10. Evaluating the antimicrobial, apoptotic, and cancer cell gene delivery properties of protein-capped gold nanoparticles synthesized from the edible mycorrhizal fungus Tricholoma crassum

    Science.gov (United States)

    Basu, Arpita; Ray, Sarmishtha; Chowdhury, Supriyo; Sarkar, Arnab; Mandal, Deba Prasad; Bhattacharjee, Shamee; Kundu, Surekha

    2018-05-01

    Biosynthesis of gold nanoparticles of distinct geometric shapes with highly functional protein coats without additional capping steps is rarely reported. This study describes green synthesis of protein-coated gold nanoparticles for the first time from the edible, mycorrhizal fungus Tricholoma crassum (Berk.) Sacc . The nanoparticles were of the size range 5-25 nm and of different shapes. Spectroscopic analysis showed red shift of the absorption maxima with longer reaction period during production and blue shift with increase in pH. These were characterized with spectroscopy, SEM, TEM, AFM, XRD, and DLS. The particle size could be altered by changing synthesis parameters. These had potent antimicrobial activity against bacteria, fungi, and multi-drug-resistant pathogenic bacteria. These also had inhibitory effect on the growth kinetics of bacteria and germination of fungal spores. These showed apoptotic properties on eukaryotic cells when tested with comet assays. Moreover, the particles are capped with a natural 40 kDa protein which was utilized as attachment sites for genes to be delivered into sarcoma cancer cells. The present work also attempted at optimizing safe dosage of these nanoparticles using hemolysis assays, for application in therapy. Large-scale production of the nanoparticles in fermentors and other possible applications of the particles have been discussed.

  11. Colorimetric detection of riboflavin by silver nanoparticles capped with β-cyclodextrin-grafted citrate.

    Science.gov (United States)

    Ma, Qi; Song, Jinping; Zhang, Sufang; Wang, Meifang; Guo, Yong; Dong, Chuan

    2016-12-01

    β-Cyclodextrin-grafted citrate was used for the first time as a stabilizer and reducer to prepare silver nanoparticles (AgNPs). The as-synthesized AgNPs were further characterized by UV-vis absorption spectroscopy, powder X-ray diffraction spectroscopy, and transmission electron microscopy. The results show that the presence of riboflavin caused severe aggregation of the nanoparticles, thereby inducing a colour change from yellow to red. 1 H NMR further verified the formation of non-inclusion complexes between riboflavin and β-cyclodextrin-grafted citrate. Hydrogen bond was considered the main driving force of the interaction between the riboflavin and external rim of β-cyclodextrin. Based on these observations, the as-synthesized AgNPs were utilized to develop a novel colorimetric sensor for riboflavin detection. This colorimetric probe showed excellent selectivity and high sensitivity for riboflavin with a detection limit of 167nM. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Toxicity of Citrate-Capped Silver Nanoparticles in Common Carp (Cyprinus carpio)

    Science.gov (United States)

    Lee, Byoungcheun; Duong, Cuong Ngoc; Cho, Jaegu; Lee, Jaewoo; Kim, Kyungtae; Seo, Youngrok; Kim, Pilje; Choi, Kyunghee; Yoon, Junheon

    2012-01-01

    Juvenile common carp (Cyprinus carpio) were used as a model to investigate acute toxicity and oxidative stress caused by silver nanoparticles (Ag-NPs). The fish were exposed to different concentrations of Ag-NPs for 48 h and 96 h. After exposure, antioxidant enzyme levels were measured, including glutathione-S-transferase (GST), superoxidase dismutase, and catalase (CAT). Other biochemical parameters and histological abnormalities in different tissues (i.e., the liver, gills, and brain) were also examined. The results showed that Ag-NPs agglomerated in freshwater used during the exposure experiments, with particle size remaining <100 nm. Ag-NPs had no lethal effect on fish after 4 days of exposure. Biochemical analysis showed that enzymatic activities in the brain of the fish exposed to 200 μg/L of Ag-NPs were significantly reduced. Varied antioxidant enzyme activity was recorded in the liver and gills. Varied antioxidant enzyme activity was recorded for CAT in the liver and GST in the gills of the fish. However, the recovery rate of fish exposed to 200 μg/L of Ag-NPs was slower than when lower particle concentrations were used. Other biochemical indices showed no significant difference, except for NH3 and blood urea nitrogen concentrations in fish exposed to 50 μg/L of Ag-NPs. This study provides new evidence about the effects of nanoparticles on aquatic organisms. PMID:23093839

  13. Toxicity of Citrate-Capped Silver Nanoparticles in Common Carp (Cyprinus carpio

    Directory of Open Access Journals (Sweden)

    Byoungcheun Lee

    2012-01-01

    Full Text Available Juvenile common carp (Cyprinus carpio were used as a model to investigate acute toxicity and oxidative stress caused by silver nanoparticles (Ag-NPs. The fish were exposed to different concentrations of Ag-NPs for 48 h and 96 h. After exposure, antioxidant enzyme levels were measured, including glutathione-S-transferase (GST, superoxidase dismutase, and catalase (CAT. Other biochemical parameters and histological abnormalities in different tissues (i.e., the liver, gills, and brain were also examined. The results showed that Ag-NPs agglomerated in freshwater used during the exposure experiments, with particle size remaining <100 nm. Ag-NPs had no lethal effect on fish after 4 days of exposure. Biochemical analysis showed that enzymatic activities in the brain of the fish exposed to 200 g/L of Ag-NPs were significantly reduced. Varied antioxidant enzyme activity was recorded in the liver and gills. Varied antioxidant enzyme activity was recorded for CAT in the liver and GST in the gills of the fish. However, the recovery rate of fish exposed to 200 g/L of Ag-NPs was slower than when lower particle concentrations were used. Other biochemical indices showed no significant difference, except for NH3 and blood urea nitrogen concentrations in fish exposed to 50 g/L of Ag-NPs. This study provides new evidence about the effects of nanoparticles on aquatic organisms.

  14. Boron-capped tris(glyoximato) cobalt clathrochelate as a precursor for the electrodeposition of nanoparticles catalyzing H2 evolution in water.

    Science.gov (United States)

    Anxolabéhère-Mallart, Elodie; Costentin, Cyrille; Fournier, Maxime; Nowak, Sophie; Robert, Marc; Savéant, Jean-Michel

    2012-04-11

    Electrochemical investigation of a boron-capped tris(glyoximato)cobalt clathrochelate complex in the presence of acid reveals that the catalytic activity toward hydrogen evolution results from an electrodeposition of cobalt-containing nanoparticles on the electrode surface at a modest cathodic potential. The deposited particles act as remarkably active catalysts for H(2) production in water at pH 7. © 2012 American Chemical Society

  15. Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Stevanović M

    2011-11-01

    Full Text Available Magdalena Stevanović1, Branimir Kovačević2, Jana Petković3, Metka Filipič3, Dragan Uskoković11Institute of Technical Sciences of Serbian Academy of Sciences and Arts, 2Institute of General and Physical Chemistry, Belgrade, Serbia; 3Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, SloveniaAbstract: Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly- α, γ, L-glutamic acid (PGA, a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species.Keywords: silver nanoparticles, poly-α, γ, L-glutamic, green synthesis, morphology, cytotoxicity

  16. Cervical Cap

    Science.gov (United States)

    ... Videos for Educators Search English Español The Cervical Cap KidsHealth / For Teens / The Cervical Cap What's in ... Call the Doctor? Print What Is a Cervical Cap? A cervical cap is a small cup made ...

  17. The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles.

    Science.gov (United States)

    Onwudiwe, Damian C; Strydom, Christien A

    2015-01-25

    Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML(1)2L(2)] (M=Cd(II), Zn(II); L(1)=N-phenyldithiocarbamate, L(2)=2,2' bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M=Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Improving SERS Detection of Bacillus thuringiensis Using Silver Nanoparticles Reduced with Hydroxylamine and with Citrate Capped Borohydride

    International Nuclear Information System (INIS)

    Felix-Rivera, H.; Gonzalez, R.; Rodriguez, G.D.M.; Oliva, M. P.; Hernandez-Rivera, S.P.; Rios-Velazquez, C.

    2011-01-01

    The development of techniques that could be useful in fields other than biological warfare agents countermeasures such as medical diagnostics, industrial microbiology, and environmental applications have become a very important subject of research. Raman spectroscopy can be used in near field or at long distances from the sample to obtain fingerprinting information of chemical composition of microorganisms. In this research, biochemical components of the cell wall and endospores of Bacillus thuringiensis (Bt) were identified by surface-enhanced Raman scattering (SERS) spectroscopy using silver (Ag) nanoparticles (NPs) reduced by hydroxylamine and borohydride capped with sodium citrate. Activation of hot spots, aggregation and surface charge modification of the NPs, was studied and optimized to obtain signal enhancements from Bt by SERS. Slight aggregation of the NPs as well as surface charge modification to a more acidic ambient was induced using small-size borohydride-reduced NPs in the form of metallic suspensions aimed at increasing the Ag NP-Bt interactions. Hydroxylamine-reduced NPs required slight aggregation and no pH modifications in order to obtain high spectral quality results in bringing out SERS signatures of Bt.

  19. Improving SERS Detection of Bacillus thuringiensis Using Silver Nanoparticles Reduced with Hydroxylamine and with Citrate Capped Borohydride

    Directory of Open Access Journals (Sweden)

    Hilsamar Félix-Rivera

    2011-01-01

    Full Text Available The development of techniques that could be useful in fields other than biological warfare agents countermeasures such as medical diagnostics, industrial microbiology, and environmental applications have become a very important subject of research. Raman spectroscopy can be used in near field or at long distances from the sample to obtain fingerprinting information of chemical composition of microorganisms. In this research, biochemical components of the cell wall and endospores of Bacillus thuringiensis (Bt were identified by surface-enhanced Raman scattering (SERS spectroscopy using silver (Ag nanoparticles (NPs reduced by hydroxylamine and borohydride capped with sodium citrate. Activation of “hot spots”, aggregation and surface charge modification of the NPs, was studied and optimized to obtain signal enhancements from Bt by SERS. Slight aggregation of the NPs as well as surface charge modification to a more acidic ambient was induced using small-size borohydride-reduced NPs in the form of metallic suspensions aimed at increasing the Ag NP-Bt interactions. Hydroxylamine-reduced NPs required slight aggregation and no pH modifications in order to obtain high spectral quality results in bringing out SERS signatures of Bt.

  20. Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties.

    Science.gov (United States)

    Bu, Hang-Beom; Kikunaga, Hayato; Shimura, Kunio; Takahasi, Kohji; Taniguchi, Taichi; Kim, DaeGwi

    2013-02-28

    Water soluble nanoparticles (NPs) with a high emission property were synthesized via hydrothermal routes. In this report, we chose thiol ligand N-acetyl-L-cysteine as the ideal stabilizer and have successfully employed it to synthesize readily size-controllable CdTe NPs in a reaction of only one step. Hydrothermal synthesis of CdTe NPs has been carried out in neutral or basic conditions so far. We found out that the pH value of precursor solutions plays an important role in the uniformity of the particle size. Actually, high quality CdTe NPs were synthesized under mild acidic conditions of pH 5. The resultant NPs indicated good visible light-emitting properties and stability. Further, the experimental results showed that the reaction temperature influenced significantly the growth rate and the maximum size of the NPs. The CdTe NPs with a high photoluminescence quantum yield (the highest value: 57%) and narrower half width at half maximum (the narrowest value: 33 nm) were attained in very short time, within 40 minutes, reaching diameters of 2.3 to 4.3 nm. The PL intensity was increased with an increase in the reaction time, reflecting the suppression of nonradiative recombination processes. Furthermore, the formation of CdTe/CdS core-shell structures was discussed from the viewpoint of PL dynamics and X-ray diffraction studies.

  1. Biocidal Activity of Plasma Modified Electrospun Polysulfone Mats Functionalized with Polyethyleneimine-Capped Silver Nanoparticles

    KAUST Repository

    Schiffman, Jessica D.

    2011-11-01

    The incorporation of silver nanoparticles (AgNPs) into polymeric nanofibers has attracted a great deal of attention due to the strong antimicrobial activity that the resulting fibers exhibit. However, bactericidal efficacy of AgNP-coated electrospun fibrous mats has not yet been demonstrated. In this study, polysulfone (PSf) fibers were electrospun and surface-modified using an oxygen plasma treatment, which allowed for facile irreversible deposition of cationically charged polyethyleneimine (PEI)-AgNPs via electrostatic interactions. The PSf-AgNP mats were characterized for relative silver concentration as a function of plasma treatment time using ICP-MS and changes in contact angle. Plasma treatment of 60 s was the shortest time required for maximum loss of bacteria (Escherichia coli) viability. Time-dependent bacterial cytotoxicity studies indicate that the optimized PSf-AgNP mats exhibit a high level of inactivation against both Gram negative bacteria, Escherichia coli, and Gram positive bacteria, Bacillus anthracis and Staphylococcus aureus. © 2011 American Chemical Society.

  2. Positively charged gold nanoparticles capped with folate quaternary chitosan: Synthesis, cytotoxicity, and uptake by cancer cells.

    Science.gov (United States)

    Yen, Hui-Ju; Young, Yen-An; Tsai, Tsung-Neng; Cheng, Kuang-Ming; Chen, Xin-An; Chen, Ying-Chuan; Chen, Cheng-Cheung; Young, Jenn-Jong; Hong, Po-da

    2018-03-01

    In this study, we synthesized various quaternary chitosan derivatives and used them to stabilize gold nanoparticles (AuNPs). These chitosan derivatives comprised N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), folate-HTCC, galactosyl-HTCC, and their fluorescein isothiocyanate-conjugated derivatives. Various positively surface-charged AuNPs were prepared under alkaline conditions using glucose as a reducing agent in the presence of the HTCC derivatives (HTCCs). The effects of the concentration of NaOH, glucose, and HTCCs on the particles size, zeta potential, and stability were studied in detail. Cell cycle assays verify that none of the HTCCs or HTCCs-AuNPs was cytotoxic to human umbilical vein endothelial cells. Flow cytometry analysis showed that the folate HTCC-AuNPs were internalized in Caco-2, HepG2, and HeLa cancer cells to a significantly greater extent than AuNPs without folate. But, galactosyl HTCC-AuNPs only showed high cell uptake by HepG2 cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Chitosan-capped gold nanoparticles for selective and colorimetric sensing of heparin

    International Nuclear Information System (INIS)

    Chen, Zhanguang; Wang, Zhen; Chen, Xi; Xu, Haixiong; Liu, Jinbin

    2013-01-01

    In this contribution, novel chitosan-stabilized gold nanoparticles (AuNPs) were prepared by mixing chitosan with citrate-reductive AuNPs under appropriate conditions. The as-prepared chitosan-stabilized AuNPs were positively charged and highly stably dispersed in aqueous solution. They exhibited weak resonance light scattering (RLS) intensity and a wine red color. In addition, the chitosan-stabilized AuNPs were successfully utilized as novel sensitive probes for the detection of heparin for the first time. It was found that the addition of heparin induced a strong increase of RLS intensity for AuNPs and the color change from red to blue. The increase in RLS intensity and the color change of chitosan-stabilized AuNPs caused by heparin allowed the sensitive detection of heparin in the range of 0.2–60 μM (∼6.7 U/mL). The detection limit for heparin is 0.8 μM at a signal-to-noise ratio of 3. The present sensor for heparin detection possessed a low detection limit and wide linear range. Additionally, the proposed method was also applied to the detection of heparin in biological media with satisfactory results

  4. Chitosan-capped gold nanoparticles for selective and colorimetric sensing of heparin

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhanguang, E-mail: kqlu@stu.edu.cn; Wang, Zhen; Chen, Xi [Shantou University, Department of Chemistry (China); Xu, Haixiong [Shantou Central Hospital, Affiliated Shantou Hospital of SUN YAT-SEN University (China); Liu, Jinbin [University of Texasat Dallas, Department of Chemistry (United States)

    2013-09-15

    In this contribution, novel chitosan-stabilized gold nanoparticles (AuNPs) were prepared by mixing chitosan with citrate-reductive AuNPs under appropriate conditions. The as-prepared chitosan-stabilized AuNPs were positively charged and highly stably dispersed in aqueous solution. They exhibited weak resonance light scattering (RLS) intensity and a wine red color. In addition, the chitosan-stabilized AuNPs were successfully utilized as novel sensitive probes for the detection of heparin for the first time. It was found that the addition of heparin induced a strong increase of RLS intensity for AuNPs and the color change from red to blue. The increase in RLS intensity and the color change of chitosan-stabilized AuNPs caused by heparin allowed the sensitive detection of heparin in the range of 0.2-60 {mu}M ({approx}6.7 U/mL). The detection limit for heparin is 0.8 {mu}M at a signal-to-noise ratio of 3. The present sensor for heparin detection possessed a low detection limit and wide linear range. Additionally, the proposed method was also applied to the detection of heparin in biological media with satisfactory results.

  5. Antibacterial activity of biochemically capped iron oxide nanoparticles: A view towards green chemistry.

    Science.gov (United States)

    Irshad, Rabia; Tahir, Kamran; Li, Baoshan; Ahmad, Aftab; R Siddiqui, Azka; Nazir, Sadia

    2017-05-01

    A green approach to fabricate nanoparticles has been evolved as a revolutionary discipline. Eco-compatible reaction set ups, use of non-toxic materials and production of highly active biological and photocatalytic products are few benefits of this greener approach. Here, we introduce a green method to synthesize Fe oxide NPs using Punica granatum peel extract. The formation of Fe oxide NPs was optimized using different concentrations of peel extract (20mL, 40mL and 60mL) to achieve small size and better morphology. The results indicate that the FeNPs, obtained using 40mL concentration of peel extract possess the smallest size. The morphology, size and crystallinity of NPs was confirmed by implementing various techniques i.e. UV-Vis spectroscopy, X-ray diffraction, Scanning Electron Microscopy and Electron Diffraction Spectroscopy. The bio-chemicals responsible for reduction and stabilization of FeNPs were confirmed by FT-IR analysis. The biogenic FeNPs were tested for their size dependent antibacterial activity. The biogenic FeNPs prepared in 40mL extract concentrations exhibited strongest antibacterial activity against Pseudomonas aeruginosa i.e. 22 (±0.5) mm than FeNPs with 20mL and 60mL extract concentrations i.e. 18 (±0.4) mm and 14 (±0.3) mm respectively. The optimized FeNPs with 40mL peel extract are not only highly active for ROS generation but also show no hemolytic activity. Thus, FeNPs synthesized using the greener approach are found to have high antibacterial activity along with biocompatibility. This high antibacterial activity can be referred to small size and large surface area. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Fluorosurfactant-capped gold nanoparticles-enhanced chemiluminescence from hydrogen peroxide-hydroxide and hydrogen peroxide-bicarbonate in presence of cobalt(II)

    Science.gov (United States)

    Li, Jinge; Li, Qianqian; Lu, Chao; Zhao, Lixia; Lin, Jin-Ming

    2011-02-01

    Nonionic fluorosurfactant (FSN)-capped gold nanoparticles (GNPs) remain excellently stable at a wider pH range and high ionic strength, which is useful to investigate some CL systems involved in high salt and a strict pH range. In this study, we utilized FSN-capped GNPs of different sizes to distinguish the emitting species from H 2O 2-Co 2+-NaOH and H 2O 2-Co 2+-NaHCO 3 systems. When the pH of FSN-capped gold colloidal solution was adjusted to 10.2 by dropwise addition of 0.05 M NaOH, the CL intensity of H 2O 2-Co 2+-NaHCO 3 system was enhanced 6-fold or 60-fold respectively in the presence of FSN-capped 14 nm or 69 nm GNPs with comparison to H 2O 2-Co 2+-NaOH. The variation of CL spectra and UV-vis spectra, as well as the quenching effect of reactive oxygen species scavengers were studied in detail to understand the CL enhancement mechanisms of FSN-capped GNPs on the two systems. For H 2O 2-Co 2+-NaOH system, the gold(I) complexes intermediate and singlet oxygen dimol species were proposed as the emitting species. The excited states of the carbon dioxide dimers and singlet oxygen dimol species were considered responsible for the light emission of H 2O 2-Co 2+-NaHCO 3 system. To our knowledge, this work is the first time to study the two CL systems simultaneously using nanoparticles.

  7. Fungus-Mediated Preferential Bioleaching of Waste Material Such as Fly - Ash as a Means of Producing Extracellular, Protein Capped, Fluorescent and Water Soluble Silica Nanoparticles

    Science.gov (United States)

    Khan, Shadab Ali; Uddin, Imran; Moeez, Sana; Ahmad, Absar

    2014-01-01

    In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Energy dispersive analysis of X-rays (EDAX). PMID:25244567

  8. Fungus-mediated preferential bioleaching of waste material such as fly - ash as a means of producing extracellular, protein capped, fluorescent and water soluble silica nanoparticles.

    Directory of Open Access Journals (Sweden)

    Shadab Ali Khan

    Full Text Available In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL, Transmission electron microscopy (TEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and Energy dispersive analysis of X-rays (EDAX.

  9. In vitro studies on radiosensitization effect of glucose capped gold nanoparticles in photon and ion irradiation of HeLa cells

    International Nuclear Information System (INIS)

    Kaur, Harminder; Pujari, Geetanjali; Semwal, Manoj K.; Sarma, Asitikantha; Avasthi, Devesh Kumar

    2013-01-01

    Highlights: ► Glucose capped gold nanoparticles (Glu-AuNPs) are synthesized for internalization in HeLa cells (cervical cancer cells). ► Internalization of Glu-AuNPs in HeLa cells is confirmed by cross section TEM of cells. ► Irradiation (by C ion or γ-rays) of HeLa cells with internalized Glu-AuNPs results in enhanced radiosensitization. ► There is about 30% reduction in radiation dose for 90% cell killing of HeLa cells, when internalized by Glu-AuNPs. ► The enhanced radiosensitization due to Glu-AuNPs is of interest for researchers in nanobiotechnology and radiation biology. -- Abstract: Noble metal nanoparticles are of great interest due to their potential applications in diagnostics and therapeutics. In the present work, we synthesized glucose capped gold nanoparticle (Glu-AuNP) for internalization in the HeLa cell line (human cervix cancer cells). The capping of glucose on Au nanoparticle was confirmed by Raman spectroscopy. The Glu-AuNP did not show any toxicity to the HeLa cell. The γ-radiation and carbon ion irradiation of HeLa cell with and without Glu-AuNP were performed to evaluate radiosensitization effects. The study revealed a significant reduction in radiation dose for killing the HeLa cells with internalized Glu-AuNPs as compared to the HeLa cells without Glu-AuNP. The Glu-AuNP treatment resulted in enhancement of radiation effect as evident from increase in relative biological effectiveness (RBE) values for carbon ion irradiated HeLa cells

  10. Gold nanoparticles capped with benzalkonium chloride and poly (ethylene imine) for enhanced loading and skin permeability of 5-fluorouracil.

    Science.gov (United States)

    Safwat, Mohamed A; Soliman, Ghareb M; Sayed, Douaa; Attia, Mohamed A

    2017-11-01

    To enhance 5-fluorouracil (5-FU) permeability through the skin by loading onto gold nanoparticles (GNPs) capped with two cationic ligands, benzalkonium chloride (BC) or poly (ethylene imine) (PEI). Whereas 5-FU has excellent efficacy against many cancers, its poor permeability through biological membranes and several adverse effects limit its clinical benefits. BC and PEI were selected to stabilize GNPs and to load 5-FU through ionic interactions. 5-FU/BC-GNPs and 5-FU/PEI-GNPs were prepared at different 5-FU/ligand molar ratios and different pH values and were evaluated using different techniques. GNPs stability was tested as a function of salt concentration and storage time. 5-FU release from BC- and PEI-GNPs was evaluated as a function of solution pH. Ex vivo permeability studies of different 5-FU preparations were carried out using mice skin. 5-FU-loaded GNPs size and surface charge were dependent on the 5-FU/ligand molar ratios. 5-FU entrapment efficiency and loading capacity were dependent on the used ligand, 5-FU/ligand molar ratio and solution pH. Maximum drug entrapment efficiency of 59.0 ± 1.7% and 46.0 ± 1.1% were obtained for 5-FU/BC-GNPs and 5-FU/PEI-GNPs, respectively. 5-FU-loaded GNPs had good stability against salinity and after storage for 4 months at room temperature and at 4 °C. In vitro 5-FU release was pH- and ligand-dependent where slower release was observed at higher pH and for 5-FU/BC-GNPs. 5-FU permeability through mice skin was significantly higher for drug-loaded GNPs compared with drug-ligand complex or drug aqueous solution. Based on these results, BC- and PEI-GNPs might find applications as effective topical delivery systems of 5-FU.

  11. Picric acid capped silver nanoparticles as a probe for colorimetric sensing of creatinine in human blood and cerebrospinal fluid samples.

    Science.gov (United States)

    Parmar, Ankita K; Valand, Nikunj N; Solanki, Kalpesh B; Menon, Shobhana K

    2016-02-21

    Creatinine is the most important parameter to be determined in the diagnosis of renal, muscular and thyroid function. The most common method for the determination of creatinine is Jaffe's reaction, a routine practice for blood and urine analysis. However, in cases of icteric and haemolyzed blood samples, interference occurs during the estimation of creatinine by other constituents present in the blood like bilirubin, creatine, and urea, which lead to wrong diagnosis. To overcome such difficulty, we have developed a silver nanoparticle (Ag NPs) based sensor for the selective determination of creatinine. In this study, a new approach has been given to the traditional Jaffe's reaction, by coating Ag NPs with picric acid (PA) to form an assembly that can selectively detect creatinine. The Ag NPs based sensor proficiently and selectively recognizes creatinine due to the ability of picric acid to bind with it and form a complex. The nanoassembly and the interactions were investigated by transmission electron microscopy (TEM), dynamic light scattering (DLS) analysis, UV-Vis spectroscopy, FT-IR spectroscopy and ESI-MS, which demonstrated the binding affinity of creatinine with PA-capped Ag NPs. A linear correlation was obtained in the range of 0.01 μM-1 μM with an R(2) value of 0.9998 and a lower detection limit of 8.4 nM. The sensor was successfully applied to different types of blood and CSF samples for the determination of creatinine, and the results were compared to that of the Jaffe's method. With the advantages of high sensitivity, selectivity and low sample volume, this method is potentially suitable for the on-site monitoring of creatinine.

  12. Cervical Cap

    Science.gov (United States)

    ... giving birth vaginally, which means the cervical cap may not fit as well. Inconsistent or incorrect use of the cervical cap increases your risk of pregnancy. For example, you may get pregnant when using the cervical cap if: ...

  13. Synthesis and Characterization of Fe3O4 Nanoparticles using Polyvinyl Alcohol (PVA) as Capping Agent and Glutaraldehyde (GA) as Crosslinker

    Science.gov (United States)

    Budi Hutami Rahayu, Lale; Oktavia Wulandari, Ika; Herry Santjojo, Djoko; Sabarudin, Akhmad

    2018-01-01

    The use of polyvinyl alcohol (PVA) as a capping agent and glutaraldehyde (GA) as a crosslinker for a synthesis of magnetite (Fe3O4) nanoparticles is able to reduce agglomeration of produced Fe3O4. Additionally, oxidation of Fe3O4 by air could be avoided. The synthesis is carried out in two steps: first step, magnetite (Fe3O4) nanoparticles were prepared by dissolving the FeCl3.6H2O and FeCl2.4H2O in alkaline media (NH3.H2O). The second step, magnetite nanoparticles were coated with polyvinyl alcohol (PVA) and glutaraldehyde (GA) to obtain Fe3O4-PVA-GA. The latter material was then characterized by FTIR to determine the typical functional groups of magnetite coated with PVA-GA. X-ray Diffraction analysis was used to determine structure and size of crystal as well as the percentage of magnetite produced. It was found that the produced nanoparticles have crystal sizes around 4-9 nm with the cubic crystal structure. The percentage of magnetite phase increases when the amount of glutaraldehyde increased. SEM-EDX was employed to assess the surface morphology and elemental composition of the resulted nanoparticles. The magnetic character of the magnetite and Fe3O4- PVA-GA were studied using Electron Spin Resonance.

  14. Synthesis of carboxyl-capped and bright YVO4:Eu,Bi nanoparticles and their applications in immunochromatographic test strip assay

    International Nuclear Information System (INIS)

    Luo, Min; Sun, Tian-Ying; Wang, Jia-Hong; Yang, Peng; Gan, Liang; Liang, Li-Lei; Yu, Xue-Feng; Gong, Xing-Hou

    2013-01-01

    Graphical abstract: - Highlights: • The morphology and properties of YVO 4 :Eu,Bi nanoparticles were investigated. • YVO 4 :Eu,Bi were coupled with IgG for bioprobes due to their good properties. • YVO 4 :Eu,Bi were applied to immunochromatographic test strip assay. - Abstract: Carboxyl-capped YVO 4 :Eu,Bi nanoparticles with average diameter of ∼10 nm were synthesized via a copolymer of phosphono and carboxylic acid mediated hydrothermal method. Under a 350 nm ultraviolet light excitation, the YVO 4 :Eu,Bi NPs exhibit sharp and bright red emission peaked at 615 nm and with highest quantum yield of ∼43%. Furthermore, the nanoparticles show good water/buffer stability and feasible bioconjugation benefiting from the carboxylic groups on their surface. Based on these kind optical and surface properties of the YVO 4 :Eu,Bi nanoparticles, an immunochromatographic test strip assay for quantitative determination of human IgG was achieved. This protocol can be extended to other rare-earth nanoparticles with the purpose of developing bioprobes for desired applications

  15. Capped CuInS2 quantum dots for H2 evolution from water under visible light illumination

    International Nuclear Information System (INIS)

    Li, Tzung-Luen; Cai, Cheng-Da; Yeh, Te-Fu; Teng, Hsisheng

    2013-01-01

    Highlights: ► Dispersed CuInS 2 quantum dots showed remarkable photosynthetic activity using visible light. ► Photogenerated electrons in CuInS 2 were effective in H 2 production from aqueous solution. ► The bifunctional capping reagent effectively transported photogenerated electrons for reaction. ► Ru-loaded CuInS 2 quantum dots showed a quantum efficiency of 4.7% in H 2 evolution. ► Attaching CuInS 2 to TiO 2 with CdS passivation achieved a quantum efficiency of 41%. - Abstract: This study demonstrates H 2 evolution from water decomposition catalyzed by capped CuInS 2 quantum dots (QDs) that are highly dispersed in a polysulfide aqueous solution. The CuInS 2 QDs, which are obtained from solvothermal synthesis, have a size of 4.3 nm and a band gap of 1.97 eV. For photosynthetic H 2 evolution in the aqueous solution, the QDs are capped with a multidentate ligand (3-mercaptopropionic acid), which has a thiol end for attaching the QDs and a hydrophilic carboxylic end for dispersion in water. The capped QDs exhibit low activity in catalyzing H 2 evolution under visible illumination. After photodepositing 0.5 wt.% Ru, the capped QDs are active in producing H 2 with illumination. This demonstrates that the photogenerated electrons travel through the capping reagent to generate deposited Ru, which subsequently serves as an electron trap for H 2 evolution. A heterostructure formed by attaching the capped QDs on TiO 2 nanoparticles, followed by coating CdS with photodeposition, exhibits a high quantum efficiency of 41% for H 2 evolution from the polysulfide solution. These results demonstrate the potential for photosynthesis and phototherapy in biologic in vivo or microfluidic systems based on this capped QD material.

  16. Preparation, characterization and evaluation of water-soluble L-cysteine-capped-CdS nanoparticles as fluorescence probe for detection of Hg(II) in aqueous solution

    International Nuclear Information System (INIS)

    Cai Zhaoxia; Yang Hong; Zhang Yi; Yan Xiuping

    2006-01-01

    Water-soluble L-cysteine-capped-CdS nanoparticles were prepared in aqueous solution at room temperature through a straightforward one-pot process by using safe and low-cost inorganic salts as precursors, and characterized by transmission electron microscopy, X-ray diffraction spectrometry, Fourier transform infrared spectrometry, spectrofluorometry and ultraviolet-visible spectrometry. The prepared L-cysteine-capped-CdS nanoparticles were evaluated as fluorescence probe for Hg(II) detection. The fluorescence quenching of the L-cysteine-capped-CdS nanoparticles depended on the concentration and pH of Hg(II) solution. Maximum fluorescence quenching was observed at pH 7.4 with the excitation and emission wavelengths of 360 nm and 495 nm, respectively. Quenching of its fluorescence due to Hg(II) at the 20 nmol l -1 level was unaffected by the presence of 5 x 10 6 -fold excesses of Na(I) and K(I), 5 x 10 5 -fold excesses of Mg(II), 5 x 10 4 -fold excesses of Ca(II), 500-fold excesses of Al(III), 91-fold excesses of Mn(II), 23.5-fold excesses of Pb(II), 25-fold excesses of Fe(III), 25-fold excesses of Ag(I), 8.5-fold excesses of Ni(II) and 5-fold excesses of Cu(II). Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Hg(II) ranging from 16 nmol l -1 to 112 nmol l -1 . The limit of detection for Hg(II) was 2.4 nmol l -1 . The developed method was applied to the detection of trace Hg(II) in aqueous solutions

  17. Ultrasonic/surfactant assisted of CdS nano hollow sphere synthesis and characterization

    International Nuclear Information System (INIS)

    Rafati, Amir Abbas; Borujeni, Ahmad Reza Afraz; Najafi, Mojgan; Bagheri, Ahmad

    2011-01-01

    CdS hollow nanospheres with diameters ranging from 40 to 150 nm have been synthesized by a surfactant-assisted sonochemical route. The successful vesicle templating indicates that the outer leaflet of the bilayer is the receptive surface in the controlled growth of CdS nanoparticles which provide the unique reactor for the nucleation and mineralization growth of CdS nanoparticles. The CdS nanostructures obtained were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and photoluminescence spectroscopy. Structural characterization of hollow CdS nanospheres indicates that these products packed with square subunits having sizes between 5 and 7 nm in diameter. The formation of the hollow nanostructure was explained by a vesicle template mechanism, in which sonication and surfactant play important roles. The band-edge emission and surface luminescence of the CdS nanoparticles were observed. -Research Highlights: → CdS hollow nanospheres with diameters of 40-150 nm were synthesized. → Nanoparticles were characterized by UV/Vis and photoluminescence. → Nanospheres are composed of smaller nanocrystals with the average size of 6.8 nm. → The band gap energy of the CdS nanoparticles is higher than its bulk value.

  18. Clinical Decision Support (CDS) Inventory

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Clinical Decision Support (CDS) Inventory contains descriptions of past and present CDS projects across the Federal Government. It includes Federal projects,...

  19. Superior magnetic properties of Ni ferrite nanoparticles synthesized by capping agent-free one-step coprecipitation route at different pH values

    Science.gov (United States)

    Iranmanesh, P.; Tabatabai Yazdi, Sh.; Mehran, M.; Saeednia, S.

    2018-03-01

    In this work, well-dispersed nanoparticles of NiFe2O4 with diameters less than 10 nm and good crystallinity and excellent magnetic properties were synthesized via a simple one-step capping agent-free coprecipitation route from metal chlorides. The ammonia was used as the precipitating agent and also the solution basicity controller. The effect of pH value during the coprecipitation process was investigated by details through microstructural, optical and magnetic characterizations of the synthesized particles using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-vis spectroscopy, and vibrating sample magnetometer. The results showed that the particle size, departure from the inverse spinel structure, the band gap value and the magnetization of Ni ferrite samples increase with pH value from 9 to 11 indicating the more pronounced surface effects in the smaller nanoparticles.

  20. Improving conversion efficiency of CdS quantum dots-sensitized TiO{sub 2} nanotube arrays by doping with Zn{sup 2+} and decorating with ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chong, E-mail: chongchen@henu.edu.cn [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Wang, Lei; Li, Fumin; Ling, Lanyu [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2014-08-01

    The Zn-doped TiO{sub 2} nanotube arrays (TNTs) decorated with ZnO nanoparticles have been prepared via electrochemical anodization and immersing method. Furthermore, the CdS quantum dots (QDs) were deposited on the prepared Zn-doped TNTs-ZnO thin films by chemical bath deposition (CBD) method to fabricate the CdS QDs-sensitized Zn-doped TNTs-ZnO photoelectrodes. The nanostructure, morphology, optical properties and electrochemical properties of the CdS/Zn-doped TNTs-ZnO photoelectrode with comparison to those of the CdS/TNTs photoelectrodes were investigated. It has been found that the Zn-doped TNTs-ZnO photoelectrodes significantly increased the UV–vis light absorption of the CdS/Zn-doped TNTs-ZnO photoelectrodes and reduced the charge recombination at the surfaces of the CdS/Zn-doped TNTs-ZnO photoelectrodes. As a consequence, when the Zn-doped TNTs-ZnO film was adopted instead of the plain TNTs film, the light-chemical energy conversion efficiency of the CdS/Zn-doped TNTs-ZnO photoelectrode was much improved compared with the CdS/TNTs photoelectrode. A maximum energy conversion efficiency achieved for the CdS/Zn-doped TNTs-ZnO photoelectrode is 3.86%, which is a 17% improvement compared with the maximum energy conversion efficiency of 3.29% achieved for the CdS/TNTs photoelectrodes. - Highlights: • The CdS/Zn-doped TNTs-ZnO photoelectrodes were synthesized. • The optical properties and photochemical properties were investigated. • The energy conversion efficiency depends on the Zn doping concentration. • The energy conversion efficiency was improved by the Zn doping.

  1. ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors

    OpenAIRE

    Onwudiwe, Damian C.; Ajibade, Peter A.

    2011-01-01

    The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescen...

  2. CdS loaded on coal based activated carbon nanofibers with enhanced photocatalytic property

    Science.gov (United States)

    Guo, Jixi; Guo, Mingxi; Jia, Dianzeng; Song, Xianli; Tong, Fenglian

    2016-08-01

    The coal based activated carbon nanofibers (CBACFs) were prepared by electrospinning a mixture of polyacrylonitrile (PAN) and acid treated coal. Cadmium sulfide (CdS) nanoparticles loaded on CBACFs were fabricated by solvothermal method. The obtained samples were characterized by FESEM, TEM, and XRD. The results reveal that the CdS nanoparticles are homogeneously dispersed on the surfaces of CBACFs. The CdS/CBACFs nanocomposites exhibited higher photoactivity for photodegradation of methyl blue (MB) under visible light irradiation than pure CdS nanoparticles. CBACFs can be used as low cost support materials for the preparation of nanocomposites with high photocatalytic activity.

  3. 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.

  4. Green synthesis and antibacterial effects of aqueous colloidal solutions of silver nanoparticles using camomile terpenoids as a combined reducing and capping agent.

    Science.gov (United States)

    Parlinska-Wojtan, Magdalena; Kus-Liskiewicz, Małgorzata; Depciuch, Joanna; Sadik, Omowunmi

    2016-08-01

    Green synthesis method using camomile extract was applied to synthesize silver nanoparticles to tune their antibacterial properties merging the synergistic effect of camomile and Ag. Scanning transmission electron microscopy revealed that camomile extract (CE) consisted of porous globular nanometer sized structures, which were a perfect support for Ag nanoparticles. The Ag nanoparticles synthesized with the camomile extract (AgNPs/CE) of 7 nm average sizes, were uniformly distributed on the CE support, contrary to the pure Ag nanoparticles synthesized with glucose (AgNPs/G), which were over 50 nm in diameter and strongly agglomerated. The energy dispersive X-ray spectroscopy chemical analysis showed that camomile terpenoids act as a capping and reducing agent being adsorbed on the surface of AgNPs/CE enabling their reduction from Ag(+) and preventing them from agglomeration. Fourier transform infrared and ultraviolet-visible spectroscopy measurements confirmed these findings, as the spectra of AgNPs/CE, compared to pure CE, did not contain the 1109 cm(-1) band, corresponding to -C-O groups of terpenoids and the peaks at 280 and 320 nm, respectively. Antibacterial tests using four bacteria strains showed that the AgNPs/CE performed five times better compared to CE AgNPs/G samples, reducing totally all the bacteria in 2 h.

  5. Comparative studies of upconversion luminescence characteristics and cell bioimaging based on one-step synthesized upconversion nanoparticles capped with different functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, Ming-Kiu [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China); Chan, Chi-Fai; Wong, Ka-Leung [Department of Chemistry, Hong Kong Baptist University (Hong Kong); Hao, Jianhua, E-mail: jh.hao@polyu.edu.hk [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2015-01-15

    Herein, three types of upconverting NaGdF{sub 4}:Yb/Er nanoparticles (UCNPs) have been synthesized via one-step hydrothermal synthesis with polyethylene glycol (PEG), polyethylenimine (PEI) and 6-aminocapronic acid (6AA) functionalization. To evident the presence of these groups, FTIR spectra and ζ-potentials were measured to support the successful capping of PEG, PEI and 6AA on the UCNPs. The regular morphology and cubic phase of these functionalized UCNPs were attributed to the capping effect of the surfactants. Tunable upconversion luminescence (UCL) from red to green were observed under 980 nm laser excitation and the UCL tuning was attributed to the presence of various surface ligands. Moreover, surface group dependent UCL bioimaging was performed in HeLa cells. The enhanced UCL bioimaging demonstrated by PEI functionalized UCNPs evident high cell uptake. The significant cell uptake is explained by the electrostatic attraction between the amino groups (–NH{sub 2}) and the cell membrane. Moreover, the functionalized UCNPs demonstrated low cytotoxicity in MTT assay. Additional, paramagnetic property was presented by these UCNPs under magnetic field. - Highlights: • Tunable upconversion emission by capped functional groups under fixed composition. • Surface dependent upconversion luminescence bioimaging in HeLa cells. • Low cytotoxicity. • Additional paramagnetic property due to Gd{sup 3+} ions.

  6. Facile synthesis of mPEG-luteolin-capped silver nanoparticles with antimicrobial activity and cytotoxicity to neuroblastoma SK-N-SH cells.

    Science.gov (United States)

    Qing, Weixia; Wang, Yong; Li, Xiao; Lu, Minghua; Liu, Xiuhua

    2017-12-01

    We firstly report a facile route for the green synthesis of mPEG-luteolin-capped silver nanoparticles (mPEG-luteolin-AgNPs) using mPEG-luteolin as both the reducer and stabilizer. The reaction was carried out in a stirred aqueous solution at 50°C without additional poisonous reagents. The prepared mPEG-luteolin-AgNPs was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), zeta potential and UV-vis (UV-vis) spectrum, respectively. The proportions of mPEG-luteolin capped silver nanoparticles is about 89.9%, and the content of silver is 6.65%. The mPEG-luteolin-AgNPs was evaluated the antimicrobial effects on Staphlococcus aureus, Extended spectrum β-Lactamases Staphlococcus aureus, Escherichia Coli and Extended spectrum β-Lactamases Escherichia Coli using drilling hole method. The results showed that both gram-positive and gram-negative bacteria were killed by the mPEG-luteolin-AgNPs at low concentration. Meanwhile, the cell viability assay demonstrated that mPEG-luteolin-AgNPs had toxic effects on human neuroblastoma SK-N-SH cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Preparation and characterization of layer-by-layer self-assembled polyelectrolyte multilayer films doped with surface-capped SiO2 nanoparticles.

    Science.gov (United States)

    Yang, Guangbin; Ma, Hongxia; Yu, Laigui; Zhang, Pingyu

    2009-05-15

    SiO(2) nanoparticles capped with gamma-aminopropyltrimethoxysilane were doped into polyelectrolyte (poly(allylamine hydrochloride), PAH, and poly(acrylic acid), PAA) multilayer films via spin-assisted layer-by-layer self-assembly. The resulting as-prepared multilayer films were heated at a proper temperature to generate cross-linked composite films with increased adhesion to substrates. The tribological behavior of the multilayer films was evaluated on a microtribometer. It was found that SiO(2)-doped composite films had better wear resistance than pure polyelectrolyte multilayers, possibly because doped SiO(2) nanoparticles were capable of enhancing load-carrying capacity and had "miniature ball bearings" effect. Moreover, heat-treatment had significant effect on the morphology of the composite films. Namely, heat-treated (SiO(2)/PAA)(9) film had a larger roughness than the as-prepared one, due to heat-treatment-induced agglomeration of SiO(2) nanoparticles and initiation of defects. However, heat-treated (PAH/PAA)(3)/(SiO(2)/PAA)(3)(PAH/PAA)(3) film had greatly reduced roughness than the as-prepared one, and it showed considerably improved wear resistance as well. This could be closely related to the "sandwich-like" structure of the composite multilayer film. Namely, the outermost strata of composite multilayer film were able to eliminate defects associated with the middle strata, allowing nanoparticles therein to maintain strength and robustness while keeping soft and fluid-like exposed surface. And the inner strata were well anchored to substrate and acted as an initial "bed" for SiO(2) nanoparticles to be inhabited, resulting in good antiwear ability.

  8. Nanoniobia modification of CdS photoanode for an efficient and stable photoelectrochemical cell.

    Science.gov (United States)

    Pareek, Alka; Paik, Pradip; Borse, Pramod H

    2014-12-30

    Herein we report the surface modification of a CdS film by niobia nanoparticles via thioglycerol as an organic linker and thus fabricate an efficient and a stable photoanode for a photoelectrochemical (PEC) cell. We have synthesized three differenly sized (∼3, ∼6 ,and ∼9 nm) niobia nanoparticles by a hydrothermal synthesis approach and have further investigated the particle-size-dependent PEC performance of the nanoparticle-modified CdS photoanode. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirm the formation of Nb2O5 nanoparticles that are prepared via decomposition of the niobium peroxo complex during the hydrothermal reaction and reveal the presence of surface OH(-) groups over niobia nanoparticles that impart a high catalytic property to a material. The nano-Nb2O5-modified photoanode displayed a 23-fold higher power conversion efficiency compared to that of CdS. This modified structure increases the open circuit voltage (OCV) from 0.65 to 0.77 V, which is attributed to the nano-Nb2O5-induced surface passivation effect over bare CdS. Linking of nanoparticles on the CdS surface improves the photocorrosion stability of the CdS photoanode for even longer than 4 h in contrast to the tens of minutes for the base CdS surface. The uniform coverage of the CdS photoanode surface by niobia nanoparticles is thus found to be the controlling parameter for achieving a higher PEC performance and stability of the photoanode. This finding directed us to design an improved CdS photoanode for efficient and prolonged PEC hydrogen generation from a PEC cell.

  9. Dual stimuli-responsive nano-vehicles for controlled drug delivery: mesoporous silica nanoparticles end-capped with natural chitosan.

    Science.gov (United States)

    Hakeem, Abdul; Duan, Ruixue; Zahid, Fouzia; Dong, Chao; Wang, Boya; Hong, Fan; Ou, Xiaowen; Jia, Yongmei; Lou, Xiaoding; Xia, Fan

    2014-11-11

    Herein, we report natural chitosan end-capped MCM-41 type MSNPs as novel, dual stimuli, responsive nano-vehicles for controlled anticancer drug delivery. The chitosan nanovalves tightly close the pores of the MSNPs to control premature cargo release under physiological conditions but respond to lysozyme and acidic media to release the trapped cargo.

  10. Citrate-coated silver nanoparticles interactions with effluent organic matter: influence of capping agent and solution conditions

    KAUST Repository

    Gutierrez, Leonardo; Aubry, Cyril; Cornejo, Mauricio; Croue, Jean Philippe

    2015-01-01

    Fate and transport studies of silver nanoparticles (AgNPs) discharged from urban wastewaters containing effluent organic matter (EfOM) into natural waters represent a key knowledge gap. In this study, EfOM interfacial interactions with Ag

  11. Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

    Energy Technology Data Exchange (ETDEWEB)

    Das, D., E-mail: ddasphy014@gmail.com; Hussain, A. M. P. [Department of Physics, Cotton College, Guwahati, Assam, India- 781001 (India)

    2016-05-06

    Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectra and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.

  12. Modulatory effects of Zn2+ ions on the toxicity of citrate- and PVP-capped gold nanoparticles towards freshwater algae, Scenedesmus obliquus.

    Science.gov (United States)

    Iswarya, V; Johnson, J B; Parashar, Abhinav; Pulimi, Mrudula; Chandrasekaran, N; Mukherjee, Amitava

    2017-02-01

    Gold nanoparticles (GNPs) are widely used for medical purposes, both in diagnostics as well as drug delivery, and hence are prone to release and distribution in the environment. Thus, we have explored the effects of GNPs with two distinct surface capping (citrate and PVP), and three different sizes (16, 27, and 37 nm) at 0.01-, 0.1-, and 1-mg L -1 concentrations on a predominant freshwater alga Scenedesmus obliquus in the sterile freshwater matrix. We have also investigated how an abundant metal ion from freshwater, i.e., Zn 2+ ions may modulate the effects of the selected GNPs (40 nm, citrate, and PVP capped). Preliminary toxicity results revealed that gold nanoparticles were highly toxic in comparison to zinc ions alone. A significant modulation in the toxicity of Zn ions was not noticed in the presence of GNPs. In contrast, zinc ions minimized the toxicity produced by GNPs (both CIT-37 and PVP-37), despite its individual toxicity. Approximately, about 42, 33, and 25% toxicity reduction was noted at 0.05-, 0.5-, and 5-mg L -1 Zn ions, respectively, for CIT-37 GNPs, while 31% (0.05 mg L -1 ), 24% (0.5 mg L -1 ), and 9% (5 mg L -1 ) of toxicity reduction were noted for PVP-37 GNPs. Maximum toxicity reduction was seen at 0.05 mg L -1 of Zn ions. Abbott modeling substantiated antagonistic effects offered by Zn 2+ ions on GNPs. Stability and sedimentation data revealed that the addition of zinc ions gradually induced the aggregation of NPs and in turn significantly reduced the toxicity of GNPs. Thus, the naturally existing ions like Zn 2+ have an ability to modulate the toxicity of GNPs in a real-world environment scenario.

  13. Polyvinylpyrrolidone-Capped Silver Nanoparticle Inhibits Infection of Carbapenem-Resistant Strain of Acinetobacter baumannii in the Human Pulmonary Epithelial Cell

    Directory of Open Access Journals (Sweden)

    Vishvanath Tiwari

    2017-08-01

    Full Text Available Acinetobacter baumannii, an opportunistic ESKAPE pathogen, causes respiratory and urinary tract infections. Its prevalence increases gradually in the clinical setup. Pathogenicity of Acinetobacter is significantly influenced by its ability to infect and survive in human pulmonary cells. Therefore, it is important to study the infection of A. baumannii in human pulmonary host cell (A-549, monitoring surface interacting and internalized bacteria. It was found that during infection of A. baumannii, about 40% bacteria adhered to A-549, whereas 20% got internalized inside pulmonary cell and induces threefold increase in the reactive oxygen species production. We have synthesized polyvinylpyrrolidone (PVP-capped AgNPs using chemical methods and tested its efficacy against carbapenem-resistant strain of A. baumannii. PVP-capped silver nanoparticles (PVP-AgNPs (30 µM have shown antibacterial activity against carbapenem-resistant strain of A. baumannii and this concentration does not have any cytotoxic effect on the human pulmonary cell line (IC50 is 130 µM. Similarly, PVP-AgNPs treatment decreases 80% viability of intracellular bacteria, decreases adherence of A. baumannii to A-549 (40 to 2.2%, and decreases intracellular concentration (20 to 1.3% of A. baumannii. This concludes that PVP-AgNPs can be developed as a substitute for carbapenem to control the infection caused by carbapenem-resistant A. baumannii.

  14. Molecular beacon based biosensor for the sequence-specific detection of DNA using DNA-capped gold nanoparticles-streptavidin conjugates for signal amplification

    International Nuclear Information System (INIS)

    Fang, Xian; Jiang, Wei; Han, Xiaowei; Zhang, Yuzhong

    2013-01-01

    We describe a highly sensitive and selective molecular beacon-based electrochemical impedance biosensor for the sequence-specific detection of DNA. DNA-capped conjugates between gold nanoparticles (Au-NPs) and streptavidin are used for signal amplification. The molecular beacon was labeled with a thiol at its 5′ end and with biotin at its 3′ end, and then immobilized on the surface of a bare gold electrode through the formation of Au-S bonds. Initially, the molecular beacon is present in the “closed” state, and this shields the biotin from being approached by streptavidin due to steric hindrance. In the presence of the target DNA, the target DNA molecules hybridize with the loop and cause a conformational change that moves the biotin away from the surface of the electrode. The biotin thereby becomes accessible for the reporter (the DNA-streptavidin capped Au-NPs), and this results in a distinct increase in electron transfer resistance. Under optimal conditions, the increase in resistance is linearly related to the logarithm of the concentration of complementary target DNA in the range from 1.0 fM to 0.1 μM, with a detection limit of 0.35 fM (at an S/N of 3). This biosensor exhibits good selectivity, and acceptable stability and reproducibility. (author)

  15. CDS User survey

    CERN Multimedia

    CERN Document Service

    2011-01-01

      The CERN Document Server is launching a user survey in order to collect information relative to its search engine, submission interfaces, collaborative features and content organisation. With the view of re-shaping its collections and interfaces and to better integrate with the new INSPIRE platform that serves all HEP literature, CERN Document Server team invites you to take part in the survey. Your input is essential to provide us with useful information before setting up the new service and improve your interactions with CDS. Thanks for participating !  

  16. Identification of the formation of metal-vinylidene interfacial bonds of alkyne-capped platinum nanoparticles by isotopic labeling.

    Science.gov (United States)

    Hu, Peiguang; Chen, Limei; Deming, Christopher P; Bonny, Lewis W; Lee, Hsiau-Wei; Chen, Shaowei

    2016-10-07

    Stable platinum nanoparticles were prepared by the self-assembly of 1-dodecyne and dodec-1-deuteroyne onto bare platinum colloid surfaces. The nanoparticles exhibited consistent core size and optical properties. FTIR and NMR measurements confirmed the formation of Pt-vinylidene (Pt[double bond, length as m-dash]C[double bond, length as m-dash]CH-) interfacial linkages rather than Pt-acetylide (Pt-C[triple bond, length as m-dash]C-) and platinum-hydride (Pt-H) bonds.

  17. Safe-haven CDS Premia

    DEFF Research Database (Denmark)

    Klingler, Sven; Lando, David

    We argue that Credit Default Swap (CDS) premia for safe-haven sovereigns, like Germany and the United States, are driven to a large extent by regulatory requirements under which derivatives dealing banks have an incentive to buy CDS to hedge counterparty credit risk of their counterparties. We...

  18. One-pot solvothermal route to self-assembly of cauliflower-shaped CdS microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Ge Ming [Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071 (China); Cui Yao [Institute of New Energy Material Chemistry, and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Liu Lu, E-mail: liul@nankai.edu.cn [Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071 (China); Zhou Zhen, E-mail: zhouzhen@nankai.edu.cn [Institute of New Energy Material Chemistry, and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China)

    2011-05-15

    Nearly monodispersed cauliflower-shaped CdS microspheres were prepared through a simple one-step solvothermal route on a large scale by employing sodium dodecyl sulfate (SDS) as the surfactant. Images by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) indicate that cauliflower-shaped CdS microspheres with diameters in the range from 1.3 to 4.5 {mu}m are assembled by nanoparticles with an average diameter of approximately 30 nm. The possible formation mechanism of the cauliflower-shaped CdS microspheres was also proposed. The photovoltaic activity of cauliflower-shaped CdS architectures has been investigated, indicating that the as-obtained CdS microspheres exhibited higher photovoltaic performance in comparison with CdS nanoparticles.

  19. In situ growth of capping-free magnetic iron oxide nanoparticles on liquid-phase exfoliated graphene

    NARCIS (Netherlands)

    Tsoufis, T.; Syrgiannis, Z.; Akhtar, N.; Prato, M.; Katsaros, F.; Sideratou, Z.; Kouloumpis, A.; Gournis, D.; Rudolf, P.

    2015-01-01

    We report a facile approach for the in situ synthesis of very small iron oxide nanoparticles on the surface of high-quality graphene sheets. Our synthetic strategy involved the direct, liquid-phase exfoliation of highly crystalline graphite (avoiding any oxidation treatment) and the subsequent

  20. Dialkylamide as Both Capping Agent and Surfactant in a Direct Solvothermal Synthesis of Magnetite and Titania Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Cara, C.; Musinu, A.; Mameli, V.; Ardu, A.; Nižňanský, D.; Buršík, Josef; Scorciapino, M. A.; Manzo, G.; Cannas, C.

    2015-01-01

    Roč. 15, č. 5 (2015), s. 2364-2372 ISSN 1528-7483 R&D Projects: GA ČR(CZ) GA14-18392S Institutional support: RVO:61388980 Keywords : Nanomagnetics * Nanoparticles * Nuclear magnetic resonance * Fourier transform infrared spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 4.425, year: 2015

  1. Development, optimization, and in vitro characterization of dasatinib-loaded PEG functionalized chitosan capped gold nanoparticles using Box-Behnken experimental design.

    Science.gov (United States)

    Adena, Sandeep Kumar Reddy; Upadhyay, Mansi; Vardhan, Harsh; Mishra, Brahmeshwar

    2018-03-01

    The purpose of this research study was to develop, optimize, and characterize dasatinib loaded polyethylene glycol (PEG) stabilized chitosan capped gold nanoparticles (DSB-PEG-Ch-GNPs). Gold (III) chloride hydrate was reduced with chitosan and the resulting nanoparticles were coated with thiol-terminated PEG and loaded with dasatinib (DSB). Plackett-Burman design (PBD) followed by Box-Behnken experimental design (BBD) were employed to optimize the process parameters. Polynomial equations, contour, and 3D response surface plots were generated to relate the factors and responses. The optimized DSB-PEG-Ch-GNPs were characterized by FTIR, XRD, HR-SEM, EDX, TEM, SAED, AFM, DLS, and ZP. The results of the optimized DSB-PEG-Ch-GNPs showed particle size (PS) of 24.39 ± 1.82 nm, apparent drug content (ADC) of 72.06 ± 0.86%, and zeta potential (ZP) of -13.91 ± 1.21 mV. The responses observed and the predicted values of the optimized process were found to be close. The shape and surface morphology studies showed that the resulting DSB-PEG-Ch-GNPs were spherical and smooth. The stability and in vitro drug release studies confirmed that the optimized formulation was stable at different conditions of storage and exhibited a sustained drug release of the drug of up to 76% in 48 h and followed Korsmeyer-Peppas release kinetic model. A process for preparing gold nanoparticles using chitosan, anchoring PEG to the particle surface, and entrapping dasatinib in the chitosan-PEG surface corona was optimized.

  2. Electrical bistability in conductive hybrid composites of doped polyaniline nanofibers-gold nanoparticles capped with dodecane thiol.

    Science.gov (United States)

    Borriello, A; Agoretti, P; Cassinese, A; D'Angelo, P; Mohanraj, G T; Sanguigno, L

    2009-11-01

    A novel electrical bistable hybrid nanocomposite based on doped Polyaniline nanofibers with 1-Dodecanethiol-protected Gold nanoparticle (PAni.AuDT), 3-4 nm in size, as the conductive component and polystyrene as polymer matrix was prepared. The structural morphology of the composite and the dispersion of nanoparticles inside it were evaluated using Transmission Electron Microscopy (TEM). The thermal stability and the ratio Polyaniline/Gold nanoparticles in the composite were determined by using thermogravimetric analysis. The electrical bistability of the PAni.AuDT-PS composite, the influence of the dispersion of the PAni.AuDT conductive network and the basic operation mechanism, have been assessed by measuring the electrical response of planar device architectures, also as a function of the environmental temperature (in the range 200 K K). The basic operation mechanism of the hybrid compound has been then correlated to the combined action of the thermally-induced scattering of charge carriers and the thermal contraction of the hosting polymeric matrix. Moreover, the right compromise between these two effects in terms of the most efficient bistability has been studied, founding the concentration of the conductive component which optimizes the device on-off ratio (I(on)/ I(off)).

  3. Strasbourg Astronomical Data Center (CDS

    Directory of Open Access Journals (Sweden)

    F Genova

    2013-01-01

    Full Text Available The Centre de Donnees astronomiques de Strasbourg (CDS, created in 1972, has been a pioneer in the dissemination of digital scientific data. Ensuring sustainability for several decades has been a major issue because science and technology evolve continuously and the data flow increases endlessly. The paper briefly describes CDS activities, major services, and its R&D strategy to take advantage of new technologies. The next frontiers for CDS are the new Web 2.0/3.0 paradigm and, at a more general level, global interoperability of astronomical on-line resources in the Virtual Observatory framework.

  4. Preparation, properties and anticancer effects of mixed As{sub 4}S{sub 4}/ZnS nanoparticles capped by Poloxamer 407

    Energy Technology Data Exchange (ETDEWEB)

    Bujňáková, Z., E-mail: bujnakova@saske.sk [Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia); Baláž, M. [Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia); Zdurienčíková, M.; Sedlák, J. [Cancer Research Institute, BMC Slovak Academy of Sciences, Dúbravská 9, 84505 Bratislava (Slovakia); Čaplovičová, M. [STU Centre for Nanodiagnostics, Slovak University of Technology, Vazovova 5, 81243 Bratislava (Slovakia); Čaplovič, Ľ. [Faculty of Materials Science and Technology, Slovak University of Technology, Paulínska 16, 91724 Trnava (Slovakia); Dutková, E.; Zorkovská, A.; Turianicová, E.; Baláž, P. [Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia); Shpotyuk, O. [Scientific Research Company “Carat”, Stryjska 202, 79031 Lviv (Ukraine); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15., 42200 Czestochowa (Poland); and others

    2017-02-01

    Arsenic sulfide compounds have a long history of application in a traditional medicine. In recent years, realgar has been studied as a promising drug in cancer treatment. In this study, the arsenic sulfide (As{sub 4}S{sub 4}) nanoparticles combined with zinc sulfide (ZnS) ones in different molar ratio have been prepared by a simple mechanochemical route in a planetary mill. The successful synthesis and structural properties were confirmed and followed via X-ray diffraction and high-resolution transmission electron microscopy measurements. The morphology of the particles was studied via scanning electron microscopy and transmission electron microscopy methods and the presence of nanocrystallites was verified. For biological tests, the prepared As{sub 4}S{sub 4}/ZnS nanoparticles were further milled in a circulation mill in a water solution of Poloxamer 407 (0.5 wt%), in order to cover the particles with this biocompatible copolymer and to obtain stable nanosuspensions with unimodal distribution. The average size of the particles in the nanosuspensions (~ 120 nm) was determined by photon cross-correlation spectroscopy method. Stability of the nanosuspensions was determined via particle size distribution and zeta potential measurements, confirming no physico-chemical changes for several months. Interestingly, with the increasing amount of ZnS in the sample, the stability was improved. The anti-cancer effects were tested on two melanoma cell lines, A375 and Bowes, with promising results, confirming increased efficiency of the samples containing both As{sub 4}S{sub 4} and ZnS nanocrystals. - Highlights: • Mixed As{sub 4}S{sub 4}/ZnS nanoparticles were prepared by dry milling in the first stage • Stable nanosuspensions of As{sub 4}S{sub 4}/ZnS nanoparticles capped by Poloxamer 407 were prepared by wet milling in the second stage • ZnS in the samples is beneficial: higher values of S{sub A}, stability, solubility and anticancer activity were improved.

  5. Porphyran-capped gold nanoparticles modified carbon paste electrode: a simple and efficient electrochemical sensor for the sensitive determination of 5-fluorouracil

    Science.gov (United States)

    Lima, Dhésmon; Calaça, Giselle Nathaly; Viana, Adriano Gonçalves; Pessôa, Christiana Andrade

    2018-01-01

    The application of carbon paste electrodes modified with porphyran-capped gold nanoparticles (CPE/AuNps-PFR) to detect an important anticancer drug, 5-fluorouracil (5-FU), is described. Gold nanoparticles (AuNps) were synthesized through a green one-pot route, by using porphyran (PFR) (a sulfated polysaccharide extracted from red seaweed) as reducing and stabilizing agent. The reaction temperature and the concentrations of AuCl4- and PFR for AuNps-PFR synthesis were optimized by using a 23 full factorial design with central point assayed in triplicate. The smallest particle size (128.7 nm, obtained by DLS) was achieved by employing a temperature of 70 °C and AuCl4- and PFR concentrations equal to 2.5 mmol L-1 and 0.25 mg mL-1, respectively. The AuNps-PFR nanocomposite was characterized by UV-vis spectroscopy, FTIR, DLS, TEM, XRD and zeta potential, which proved that PFR was effective at reducing and capping the AuNps. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments showed that the nanocomposite could enhance the electrochemical performance of the electrodes, as a consequence of the high conductivity and large surface area presented by the AuNps. The CPE/AuNps-PFR was able to electrocatalyze the oxidation of 5-FU by CV and differential pulse voltammetry (DPV). A linear relationship between the DPV peak currents and 5-FU concentration was verified in the range from 29.9 to 234 μmol L-1 in 0.04 mol L-1 BR buffer solution pH 8.0. Detection and quantification limits were found to be 0.66 and 2.22 μmol L-1, respectively. Besides the good sensitivity, CPE/AuNps-PFR showed reproducibility and did not suffer significant interference from potentially electroative biological compounds. The good analytical performance of the modified electrode was confirmed for determining 5-FU in pharmaceutical formulations, with good percent recoveries (ranging from 96.6 to 101.4%) and an acceptable relative standard deviation (RSD = 2.80%).

  6. A new approach for bisphenol A detection employing fluorosurfactant-capped gold nanoparticle-amplified chemiluminescence from cobalt(II) and peroxymonocarbonate.

    Science.gov (United States)

    Pan, Feng; Liu, Lin; Dong, Shichao; Lu, Chao

    2014-07-15

    In this work, we utilized the nonionic fluorosurfactant-capped gold nanoparticles (GNPs) as a novel chemiluminescence (CL) probe for the determination of trace bisphenol A. Bisphenol A can induce a sharp decrease in CL intensity from the GNP-Co(2+)-peroxymonocarbonate (HCO4(-)) system. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the logarithm of concentration of bisphenol A in the range of 0.05-50 μM (R(2) = 0.9936), and the detection limit at a signal-to-noise ratio of 3 for bisphenol A was 10 nM. The applicability of the proposed method has been validated by determining bisphenol A in real polycarbonate samples with satisfactory results. The recoveries for bisphenol A in spiked samples were found to be between 94.4% and 105.0%. The relative standard deviation (RSD) for 12 repeated measurements of 0.5 μM bisphenol A was 2.2%. The proposed method described herein was simple, selective and obviated the need of extensive sample pretreatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Direct electron transfer of glucose oxidase and biosensing for glucose based on PDDA-capped gold nanoparticle modified graphene/multi-walled carbon nanotubes electrode.

    Science.gov (United States)

    Yu, Yanyan; Chen, Zuanguang; He, Sijing; Zhang, Beibei; Li, Xinchun; Yao, Meicun

    2014-02-15

    In this work, poly (diallyldimethylammonium chloride) (PDDA)-capped gold nanoparticles (AuNPs) functionalized graphene (G)/multi-walled carbon nanotubes (MWCNTs) nanocomposites were fabricated. Based on the electrostatic attraction, the G/MWCNTs hybrid material can be decorated with AuNPs uniformly and densely. The new hierarchical nanostructure can provide a larger surface area and a more favorable microenvironment for electron transfer. The AuNPs/G/MWCNTs nanocomposite was used as a novel immobilization platform for glucose oxidase (GOD). Direct electron transfer (DET) was achieved between GOD and the electrode. Field emission scanning electron microscopy (FESEM), UV-vis spectroscopy and cyclic voltammetry (CV) were used to characterize the electrochemical biosensor. The glucose biosensor fabricated based on GOD electrode modified with AuNPs/G/MWCNTs demonstrated satisfactory analytical performance with high sensitivity (29.72mAM(-1)cm(-2)) and low limit of detection (4.8 µM). The heterogeneous electron transfer rate constant (ΚS) and the apparent Michaelis-Menten constant (Km) of GOD were calculated to be 11.18s(-1) and 2.09 mM, respectively. With satisfactory selectivity, reproducibility, and stability, the nanostructure we proposed offered an alternative for electrode fabricating and glucose biosensing. © 2013 Elsevier B.V. All rights reserved.

  8. Protein-gold clusters-capped mesoporous silica nanoparticles for high drug loading, autonomous gemcitabine/doxorubicin co-delivery, and in-vivo tumor imaging

    KAUST Repository

    Croissant, Jonas G.; Zhang, Dingyuan; Alsaiari, Shahad K.; Lu, Jie; Deng, Lin; Tamanoi, Fuyuhiko; Zink, Jeffrey I.; Khashab, Niveen M.

    2016-01-01

    Functional nanocarriers capable of transporting high drug contents without premature leakage and to controllably deliver several drugs are needed for better cancer treatments. To address this clinical need, gold cluster bovine serum albumin (AuNC@BSA) nanogates were engineered on mesoporous silica nanoparticles (MSN) for high drug loadings and co-delivery of two different anticancer drugs. The first drug, gemcitabine (GEM, 40 wt%), was loaded in positively-charged ammonium-functionalized MSN (MSN-NH3+). The second drug, doxorubicin (DOX, 32 wt%), was bound with negatively-charged AuNC@BSA electrostatically-attached onto MSN-NH3+, affording highly loaded pH-responsive MSN-AuNC@BSA nanocarriers. The co-delivery of DOX and GEM was achieved for the first time via an inorganic nanocarrier, possessing a zero-premature leakage behavior as well as drug loading capacities seven times higher than polymersome NPs. Besides, unlike the majority of strategies used to cap the pores of MSN, AuNC@BSA nanogates are biotools and were applied for targeted red nuclear staining and in-vivo tumor imaging. The straightforward non-covalent combination of MSN and gold-protein cluster bioconjugates thus leads to a simple, yet multifunctional nanotheranostic for the next generation of cancer treatments.

  9. Protein-gold clusters-capped mesoporous silica nanoparticles for high drug loading, autonomous gemcitabine/doxorubicin co-delivery, and in-vivo tumor imaging

    KAUST Repository

    Croissant, Jonas G.

    2016-03-23

    Functional nanocarriers capable of transporting high drug contents without premature leakage and to controllably deliver several drugs are needed for better cancer treatments. To address this clinical need, gold cluster bovine serum albumin (AuNC@BSA) nanogates were engineered on mesoporous silica nanoparticles (MSN) for high drug loadings and co-delivery of two different anticancer drugs. The first drug, gemcitabine (GEM, 40 wt%), was loaded in positively-charged ammonium-functionalized MSN (MSN-NH3+). The second drug, doxorubicin (DOX, 32 wt%), was bound with negatively-charged AuNC@BSA electrostatically-attached onto MSN-NH3+, affording highly loaded pH-responsive MSN-AuNC@BSA nanocarriers. The co-delivery of DOX and GEM was achieved for the first time via an inorganic nanocarrier, possessing a zero-premature leakage behavior as well as drug loading capacities seven times higher than polymersome NPs. Besides, unlike the majority of strategies used to cap the pores of MSN, AuNC@BSA nanogates are biotools and were applied for targeted red nuclear staining and in-vivo tumor imaging. The straightforward non-covalent combination of MSN and gold-protein cluster bioconjugates thus leads to a simple, yet multifunctional nanotheranostic for the next generation of cancer treatments.

  10. 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.

  11. Magnetodielectric effect in CdS nanosheets grown within Na-4 mica

    Science.gov (United States)

    Mandal, Amrita; Mitra, Sreemanta; Datta, Anindya; Banerjee, Sourish; Chakravorty, Dipankar

    2012-04-01

    CdS nanosheets of thickness 0.6 nm were grown within the interlayer spaces of Na-4 mica. Magnetization measurements carried out in the temperature range 2-300 K showed the composites to have weak ferromagnetic-like properties even at room temperature. The saturation magnetization (MS) at room temperature was found to be higher than that reported for CdS nanoparticles. The higher value of MS may be ascribed to the presence of a large number defects in the present CdS system, due to a large surface to volume ratio in the nanosheets as compared to that of CdS nanoparticles. The nanocomposites exhibited a magnetodielectric effect with a dielectric constant change of 5.3% for a magnetic field of 0.5 T. This occurred due to a combination of magnetoresistance and Maxwell-Wagner effect as delineated in the model developed by Catalan.

  12. Preparation, properties and anticancer effects of mixed As4S4/ZnS nanoparticles capped by Poloxamer 407.

    Science.gov (United States)

    Bujňáková, Z; Baláž, M; Zdurienčíková, M; Sedlák, J; Čaplovičová, M; Čaplovič, Ľ; Dutková, E; Zorkovská, A; Turianicová, E; Baláž, P; Shpotyuk, O; Andrejko, S

    2017-02-01

    Arsenic sulfide compounds have a long history of application in a traditional medicine. In recent years, realgar has been studied as a promising drug in cancer treatment. In this study, the arsenic sulfide (As 4 S 4 ) nanoparticles combined with zinc sulfide (ZnS) ones in different molar ratio have been prepared by a simple mechanochemical route in a planetary mill. The successful synthesis and structural properties were confirmed and followed via X-ray diffraction and high-resolution transmission electron microscopy measurements. The morphology of the particles was studied via scanning electron microscopy and transmission electron microscopy methods and the presence of nanocrystallites was verified. For biological tests, the prepared As 4 S 4 /ZnS nanoparticles were further milled in a circulation mill in a water solution of Poloxamer 407 (0.5wt%), in order to cover the particles with this biocompatible copolymer and to obtain stable nanosuspensions with unimodal distribution. The average size of the particles in the nanosuspensions (~120nm) was determined by photon cross-correlation spectroscopy method. Stability of the nanosuspensions was determined via particle size distribution and zeta potential measurements, confirming no physico-chemical changes for several months. Interestingly, with the increasing amount of ZnS in the sample, the stability was improved. The anti-cancer effects were tested on two melanoma cell lines, A375 and Bowes, with promising results, confirming increased efficiency of the samples containing both As 4 S 4 and ZnS nanocrystals. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Effect of PVP as a capping agent in single reaction synthesis of nanocomposite soft/hard ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, H.A. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saiden, N.M., E-mail: nlaily@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saion, E.; Azis, R.S.; Mamat, M.S. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Hashim, M. [Advanced Material and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia)

    2017-04-15

    Nanocomposite magnets consist of soft and hard ferrite phases are known as an exchange spring magnet when they are sufficiently spin exchange coupled. Hard and soft ferrites offer high value of coercivity, H{sub c} and saturation magnetization, M{sub s} respectively. In order to obtain a better permanent magnet, both soft and hard ferrite phases need to be “exchange coupled”. The nanoparticles were prepared by a simple one-pot technique of 80% soft phase and 20% hard phase. This technique involves a single reaction mixture of metal nitrates and aqueous solution of varied amounts of polyvinylpyrrolidone (PVP). The heat treatment applied was at 800 °C for 3 h. The synthesized composites were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infra-red (FT-IR), Energy Dispersive X-Ray (EDX), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM). The coexistence of two phases, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and SrFe{sub 12}O{sub 19} were observed by XRD patterns. It also verified by the EDX that no impurities detected. The magnetic properties of nanocomposite ferrites for 0.06 g/ml PVP gives a better properties of H{sub c} 932 G and M{sub s} 39.0 emu/g with average particle size obtained from FESEM was 49.2 nm. The concentration of PVP used gives effect on the magnetic properties of the samples. - Highlights: • Amount of PVP play important roles in controlling the particle size distribution and magnetic properties. • This is a novel technique to produce nanocomposite ferrites effectively. • This study contributes better understanding on magnetic properties in nanoparticle composite magnets.

  14. Cradle Cap (For Parents)

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Cradle Cap (Infantile Seborrheic Dermatitis) KidsHealth / For Parents / Cradle Cap ( ... many babies develop called cradle cap. About Cradle Cap Cradle cap is the common term for seborrheic ...

  15. Microwave Synthesized Monodisperse CdS Spheres of Different Size and Color for Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Carlos A. Rodríguez-Castañeda

    2015-01-01

    Full Text Available Monodisperse CdS spheres of size of 40 to 140 nm were obtained by microwave heating from basic solutions. It is observed that larger CdS spheres were formed at lower solution pH (8.4–8.8 and smaller ones at higher solution pH (10.8–11.3. The color of CdS products changed with solution pH and reaction temperature; those synthesized at lower pH and temperature were of green-yellow color, whereas those formed at higher pH and temperature were of orange-yellow color. A good photovoltage was observed in CdS:poly(3-hexylthiophene solar cells with spherical CdS particles. This is due to the good dispersion of CdS nanoparticles in P3HT solution that led to a large interface area between the organic and inorganic semiconductors. Higher photocurrent density was obtained in green-yellow CdS particles of lower defect density. The efficient microwave chemistry accelerated the hydrolysis of thiourea in pH lower than 9 and produced monodisperse spherical CdS nanoparticles suitable for solar cell applications.

  16. {sup 99m}Tc-labelled gold nanoparticles capped with HYNIC-peptide/mannose for sentinel lymph node detection

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo-Garcia, Blanca E. [Instituto Nacional de Investigaciones Nucleares, Estado de Mexico (Mexico); Universidad Autonoma del Estado de Mexico, Estado de Mexico (Mexico); Ramirez, Flor de M. [Instituto Nacional de Investigaciones Nucleares, Estado de Mexico (Mexico); Ferro-Flores, Guillermina, E-mail: ferro_flores@yahoo.com.m [Instituto Nacional de Investigaciones Nucleares, Estado de Mexico (Mexico); De Leon-Rodriguez, Luis M. [Universidad de Guanajuato, Guanajuato (Mexico); Santos-Cuevas, Clara L.; Morales-Avila, Enrique [Instituto Nacional de Investigaciones Nucleares, Estado de Mexico (Mexico); Universidad Autonoma del Estado de Mexico, Estado de Mexico (Mexico); Arteaga de Murphy, Consuelo; Pedraza-Lopez, Martha [Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City (Mexico); Medina, Luis A. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Instituto Nacional de Cancerologia, Mexico City (Mexico); Camacho-Lopez, Marco A. [Universidad Autonoma del Estado de Mexico, Estado de Mexico (Mexico)

    2011-01-15

    The aim of this research was to prepare a multifunctional system of technetium-99m-labelled gold nanoparticles conjugated to HYNIC-GGC/mannose and to evaluate its biological behaviour as a potential radiopharmaceutical for sentinel lymph node detection (SLND). Methods: Hydrazinonicotinamide-Gly-Gly-Cys-NH{sub 2} (HYNIC-GGC) peptide and a thiol-triazole-mannose derivative were synthesized, characterized and conjugated to gold nanoparticles (AuNP, 20 nm) to prepare a multifunctional system of HYNIC-GGC-AuNP-mannose by means of spontaneous reaction of the thiol (Cys) present in HYNIC-GGC sequence and in the thiol-mannose derivative. The nanoconjugate was characterized by transmission electron microscopy (TEM), IR, UV-Vis, Raman, fluorescence and X-ray photoelectron spectroscopy (XPS). Technetium-99m labelling was carried out using EDDA/tricine as coligands and SnCl{sub 2} as reducing agent with further size-exclusion chromatography purification. Radiochemical purity was determined by size-exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in rat liver homogenized tissue (mannose-receptor positive tissue). Biodistribution studies were accomplished in Wistar rats and images obtained using a micro-SPECT/CT system. Results: TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with HYNIC-GGC-NH{sub 2} and thiol-mannose through interactions with thiol groups and the N-terminal amine of cysteine. Radio-chromatograms showed radiochemical purity higher than 95%. {sup 99m}Tc-EDDA/HYNIC-GGC-AuNP-mannose ({sup 99m}Tc-AuNP-mannose) showed specific recognition for mannose receptors in rat liver tissue. After subcutaneous administration of {sup 99m}Tc-AuNP-mannose in rats (footpad), radioactivity levels in the popliteal and inguinal lymph nodes revealed that 99% of the activity was extracted by the first lymph node (popliteal extraction). Biodistribution studies and in vivo micro-SPECT/CT images in Wistar rats showed an evident

  17. 99mTc-labelled gold nanoparticles capped with HYNIC-peptide/mannose for sentinel lymph node detection

    International Nuclear Information System (INIS)

    Ocampo-Garcia, Blanca E.; Ramirez, Flor de M.; Ferro-Flores, Guillermina; De Leon-Rodriguez, Luis M.; Santos-Cuevas, Clara L.; Morales-Avila, Enrique; Arteaga de Murphy, Consuelo; Pedraza-Lopez, Martha; Medina, Luis A.; Camacho-Lopez, Marco A.

    2011-01-01

    The aim of this research was to prepare a multifunctional system of technetium-99m-labelled gold nanoparticles conjugated to HYNIC-GGC/mannose and to evaluate its biological behaviour as a potential radiopharmaceutical for sentinel lymph node detection (SLND). Methods: Hydrazinonicotinamide-Gly-Gly-Cys-NH 2 (HYNIC-GGC) peptide and a thiol-triazole-mannose derivative were synthesized, characterized and conjugated to gold nanoparticles (AuNP, 20 nm) to prepare a multifunctional system of HYNIC-GGC-AuNP-mannose by means of spontaneous reaction of the thiol (Cys) present in HYNIC-GGC sequence and in the thiol-mannose derivative. The nanoconjugate was characterized by transmission electron microscopy (TEM), IR, UV-Vis, Raman, fluorescence and X-ray photoelectron spectroscopy (XPS). Technetium-99m labelling was carried out using EDDA/tricine as coligands and SnCl 2 as reducing agent with further size-exclusion chromatography purification. Radiochemical purity was determined by size-exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in rat liver homogenized tissue (mannose-receptor positive tissue). Biodistribution studies were accomplished in Wistar rats and images obtained using a micro-SPECT/CT system. Results: TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with HYNIC-GGC-NH 2 and thiol-mannose through interactions with thiol groups and the N-terminal amine of cysteine. Radio-chromatograms showed radiochemical purity higher than 95%. 99m Tc-EDDA/HYNIC-GGC-AuNP-mannose ( 99m Tc-AuNP-mannose) showed specific recognition for mannose receptors in rat liver tissue. After subcutaneous administration of 99m Tc-AuNP-mannose in rats (footpad), radioactivity levels in the popliteal and inguinal lymph nodes revealed that 99% of the activity was extracted by the first lymph node (popliteal extraction). Biodistribution studies and in vivo micro-SPECT/CT images in Wistar rats showed an evident lymph node uptake (11.58±1

  18. Influences of the CdS nanoparticles grown strategies on CdTe nanorods array films: A comparison between successive ionic layer absorption and reaction and chemical bath deposition

    International Nuclear Information System (INIS)

    Wang, Jun; Zhou, Xiaoming; Lv, Pin; Yang, Lihua; Ding, Dong; Niu, Jiasheng; Liu, Li; Li, Xue; Fu, Wuyou; Yang, Haibin

    2016-01-01

    The cadmium sulfide (CdS) film is deposited on the surface of cadmium telluride (CdTe) nanorods (NRs) by two different methods, successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) techniques. The influence of the deposition parameters on the properties of the films is investigated. Compared to SILAR, CBD is a simple and time saving technique, which can ensure full coverage and better growth of CdS on the surface of CdTe NRs. The photovoltaic characteristics of CdS sensitized CdTe films are also investigated. It is found that the CdTe/CBD-CdS thin film demonstrates excellent photoelectrical properties, which is ascribed to the large absorption coefficient of the material, indicating the potential applications in solar cells.

  19. Effects of bacteria on CdS thin films used in technological devices

    Science.gov (United States)

    Alpdoğan, S.; Adıgüzel, A. O.; Sahan, B.; Tunçer, M.; Metin Gubur, H.

    2017-04-01

    Cadmium sulfide (CdS) thin films were fabricated on glass substrates by the chemical bath deposition method at 70 {}^\\circ \\text{C} considering deposition times ranging from 2 h to 5 h. The optical band gaps of CdS thin films were found to be in the 2.42-2.37 eV range. CdS thin films had uniform spherical nano-size grains which had polycrystalline, hexagonal and cubic phases. The films had a characteristic electrical resistivity of the order of {{10}5} Ω \\text{cm} and n-type conductivity at room condition. CdS thin films were incubated in cultures of B.domonas aeruginosa and Staphylococcus aureus, which exist abundantly in the environment, and form biofilms. SEM images showed that S. aureus and K. pneumonia were detected significantly on the film surfaces with a few of P. aeruginosa and B. subtilis cells attached. CdS thin film surface exhibits relatively good resistance to the colonization of P. aeruginosa and B. subtilis. Optical results showed that the band gap of CdS thin films which interacted with the bacteria is 2.42 \\text{eV} . The crystal structure and electrical properties of CdS thin films were not affected by bacterial adhesion. The antimicrobial effect of CdS nanoparticles was different for different bacterial strains.

  20. Layered sphere-shaped TiO₂ capped with gold nanoparticles on structural defects and their catalysis of formaldehyde oxidation.

    Science.gov (United States)

    Ma, Chunyan; Pang, Guanglong; He, Guangzhi; Li, Yang; He, Chi; Hao, Zhengping

    2016-01-01

    We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials, which were formed by layered deposition of multiple anatase TiO2 nanosheets. The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet, including crystal steps and edges, thereby fixing the Au-TiO2 perimeter interface. Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface. The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface. Such vacancies are essential for generating active oxygen species (*O(-)) on the TiO2 surface and Ti(3+) ions in bulk TiO2. These ions can then form Ti(3+)-O(-)-Ti(4+) species, which are known to enhance the catalytic activity of formaldehyde (HCHO) oxidation. These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials. Copyright © 2015. Published by Elsevier B.V.

  1. Effect of temperature on the optical and structural properties of hexadecylamine capped ZnS nanoparticles using Zinc(II) N-ethyl-N-phenyldithiocarbamate as single source precursor

    Energy Technology Data Exchange (ETDEWEB)

    Onwudiwe, Damian C., E-mail: dconwudiwe@webmail.co.za [Chemical Resource Beneficiation, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Strydom, Christien [Chemical Resource Beneficiation, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Oluwafemi, Oluwatobi S., E-mail: oluwafemi.oluwatobi@gmail.com [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag X1, Mthatha (South Africa); Songca, Sandile P. [Faculty of Science, Engineering and Technology, Walter Sisulu University, P.O. Box 19712, Tecoma, East London (South Africa)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► HDA-capped ZnS nanoparticles were synthesized via thermolysis of a single source precursor. ► Zinc(II) N-ethyl-N-phenyldithiocarbamate was used as the single source precursor. ► The growth temperature was varied to study the optical properties of the nanocrystals. ► Change in growth temperature affects the structural properties of the ZnS nanoparticles. ► Hexagonal wurtzite phase was obtained at lower temperatures while cubic sphalerite phase was obtained at higher growth temperatures. -- Abstract: Reported in this work is the synthesis of HDA (hexadecylamine)-capped ZnS nanoparticles by a single source route using Zinc(II) N-ethyl-N-phenyldithiocarbamate as a precursor. By varying the growth temperature, the temporal evolution of the optical properties and morphology of the nanocrystals were investigated. The as-synthesized nanoparticles were characterized using UV–vis absorption and photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). All the particles exhibited quantum confinement in their optical properties with band edge emission at the early stage of the reaction. The XRD showed transition from hexagonal wurtzite phase to cubic sphalerite phase as the growth temperature increases. The TEM image showed that the particles are small and spherical in shape while the HRTEM image confirmed the crystalline nature of the material.

  2. In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent.

    Science.gov (United States)

    Escárcega-González, Carlos Enrique; Garza-Cervantes, J A; Vázquez-Rodríguez, A; Montelongo-Peralta, Liliana Zulem; Treviño-González, M T; Díaz Barriga Castro, E; Saucedo-Salazar, E M; Chávez Morales, R M; Regalado Soto, D I; Treviño González, F M; Carrazco Rosales, J L; Cruz, Rocío Villalobos; Morones-Ramírez, José Rubén

    2018-01-01

    One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells. In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo. The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet-visible, and Fourier transform infrared. We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative ( Escherichia coli , Pseudomonas aeruginosa , and a clinical multidrug-resistant strain of P. aeruginosa ) and Gram-positive ( Bacillus subtilis ) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the

  3. Synthesis and photoluminescence enhancement of PVA capped Mn2+ doped ZnS nanoparticles and observation of tunable dual emission: A new approach

    International Nuclear Information System (INIS)

    Viswanath, R.; Bhojya Naik, H.S.; Yashavanth Kumar, G.S.; Prashanth Kumar, P.N.; Harish, K.N.; Prabhakara, M.C.; Praveen, R.

    2014-01-01

    Highlights: • Synthesis of PVA capped Mn 2+ doped ZnS nanoparticles by chemical precipitation method in air atmosphere. • Characterized by the spectral techniques. • Study on their optical properties. • Calculation of particle size by different techniques. • Investigation of the increased luminescence characteristics (UV to IR region) of Mn 2+ doped ZnS ions at room temperature and the origin of the luminescence observed. - Abstract: This paper reports the enhanced photoluminescence (PL) property of polyvinyl alcohol (PVA) capped Mn 2+ doped ZnS nanocrystals prepared by chemical precipitation method. The surface-modified Mn 2+ doped ZnS nanocrystals resulted in the multi-color property. The morphology and crystallite size were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The crystallite size was estimated to be 5 nm from HRTEM and calculated as 2–4 nm from peak broadening of the X-ray diffraction (XRD) pattern with cubic zincblende structure. Increase in the band gap with decrease in the crystallite size was observed from the UV–visible absorption spectrum, which confirms the quantum confinement effect. The room temperature photoluminescence (PL) emission measurements revealed the presence of blue (427 nm) and near IR reddish–orange (752 nm) emission bands in addition to the typical yellow–orange (585 nm) bands in all the Mn 2+ doped samples, which were attributed due to transition within the 3ds configuration of Mn 2+ ions incorporation in ZnS host under UV excitation at 320 nm. As far as we know, the reddish–orange bands at 752 nm near IR region along with the blue and yellow–orange colored PL are reported for the first time. In this way, the PL color from these ZnS nanocrystals can be tuned from UV to near infrared region (IR). The synthesized ZnS:Mn NPs can be further functionalized for using them as biolabels

  4. Synthesis and photoluminescence enhancement of PVA capped Mn{sup 2+} doped ZnS nanoparticles and observation of tunable dual emission: A new approach

    Energy Technology Data Exchange (ETDEWEB)

    Viswanath, R. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Bhojya Naik, H.S., E-mail: hsb_naik@rediffmail.com [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Yashavanth Kumar, G.S.; Prashanth Kumar, P.N.; Harish, K.N. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Prabhakara, M.C. [Department of P.G. Studies and Research in Industrial Chemistry, Sir. M.V. Government Science College, Bommanakatte, Shimoga, Bhadravathi, Karnataka, 577302 (India); Praveen, R. [Department of Technical Education, Automobile Technology Branch HMS Polytechnic (Government Aided), Tumkur, Karnataka, 572102 (India)

    2014-05-01

    Highlights: • Synthesis of PVA capped Mn{sup 2+} doped ZnS nanoparticles by chemical precipitation method in air atmosphere. • Characterized by the spectral techniques. • Study on their optical properties. • Calculation of particle size by different techniques. • Investigation of the increased luminescence characteristics (UV to IR region) of Mn{sup 2+} doped ZnS ions at room temperature and the origin of the luminescence observed. - Abstract: This paper reports the enhanced photoluminescence (PL) property of polyvinyl alcohol (PVA) capped Mn{sup 2+} doped ZnS nanocrystals prepared by chemical precipitation method. The surface-modified Mn{sup 2+} doped ZnS nanocrystals resulted in the multi-color property. The morphology and crystallite size were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The crystallite size was estimated to be 5 nm from HRTEM and calculated as 2–4 nm from peak broadening of the X-ray diffraction (XRD) pattern with cubic zincblende structure. Increase in the band gap with decrease in the crystallite size was observed from the UV–visible absorption spectrum, which confirms the quantum confinement effect. The room temperature photoluminescence (PL) emission measurements revealed the presence of blue (427 nm) and near IR reddish–orange (752 nm) emission bands in addition to the typical yellow–orange (585 nm) bands in all the Mn{sup 2+} doped samples, which were attributed due to transition within the 3ds configuration of Mn{sup 2+} ions incorporation in ZnS host under UV excitation at 320 nm. As far as we know, the reddish–orange bands at 752 nm near IR region along with the blue and yellow–orange colored PL are reported for the first time. In this way, the PL color from these ZnS nanocrystals can be tuned from UV to near infrared region (IR). The synthesized ZnS:Mn NPs can be further functionalized for

  5. Visual detection of copper(II) ions in blood samples by controlling the leaching of protein-capped gold nanoparticles.

    Science.gov (United States)

    Lee, Yen-Fei; Deng, Ting-Wei; Chiu, Wei-Jane; Wei, Tsao-Yen; Roy, Prathik; Huang, Chih-Ching

    2012-04-21

    We have developed a simple, low-cost, paper-based probe for the selective colorimetric detection of copper ions (Cu(2+)) in aqueous solutions. The bovine serum albumin (BSA)-modified 13.3-nm Au nanoparticle (BSA-Au NP) probe was designed to detect Cu(2+) ions using lead ions (Pb(2+)) and 2-mercaptoethanol (2-ME) as leaching agents in a glycine-NaOH (pH 12.0) solution. In addition, a nitrocellulose membrane (NCM) was used to trap the BSA-Au NPs, leading to the preparation of a nanocomposite film consisting of a BSA-Au NP-decorated membrane (BSA-Au NPs/NCM). The BSA-Au NPs probe operates on the principle that Cu deposition on the surface of the BSA-Au NPs inhibits their leaching ability, which is accelerated by Pb(2+) ions in the presence of 2-ME. Under optimal solution conditions (5 mM glycine-NaOH (pH 12.0), Pb(2+) (50 μM), and 2-ME (1.0 M)), the Pb(2+)/2-ME-BSA-Au NPs/NCM enabled the detection of Cu(2+) at nanomolar concentrations in aqueous solutions by the naked eye with high selectivity (at least 100-fold over other metal ions). In addition, this cost-effective probe allowed for the rapid and simple determination of Cu(2+) ions in not only natural water samples but also in a complex biological sample (in this case, blood sample).

  6. Death cap

    DEFF Research Database (Denmark)

    Rudbæk, Torsten R; Kofoed, Pernille Bouteloup; Bove, Jeppe

    2014-01-01

    Death cap (Amanita phalloides) is commonly found and is one of the five most toxic fungi in Denmark. Toxicity is due to amatoxin, and poisoning is a serious medical condition, causing organ failure with potential fatal outcome. Acknowledgement and clarification of exposure, symptomatic and focused...

  7. Uniform deposition of water-soluble CdS quantum dots on TiO2 nanotube arrays by cyclic voltammetric electrodeposition: Effectively prevent aggregation and enhance visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhang, Xiaojiao; Lin, Shiwei; Liao, Jianjun; Pan, Nengqian; Li, Danhong; Cao, Xiankun; Li, Jianbao

    2013-01-01

    Highlights: • Water-soluble CdS QDs were deposited on the TNTAs by DC electrodeposition, CV electrodeposition, and SILAR. • The CV method could effectively prevent the aggregation and uniformly deposit CdS QDs onto the TNTAs. • The CTAB/CdS/TNTAs prepared by the CV method exhibited superior photoelectrical properties and photocatalytic activity. -- Abstract: Water-soluble CdS quantum dots (QDs) covered with cationic surfactant-cetyltrimethylammonium bromide (CTAB) were deposited on the highly ordered TiO 2 nanotube arrays (TNTAs) by various methods, such as direct current (DC) electrodeposition, cyclic voltammetric (CV) electrodeposition, and successive ionic layer adsorption reaction (SILAR). The morphology measurements show that CTAB capping could well control the QD size and the CV method could effectively prevent the nanoparticle aggregation and uniformly deposit QDs onto TNTAs. Among all the deposition methods studied, the sample prepared by the CV method possesses superior photoelectrical properties and photocatalytic activity. A maximum photoconversion efficiency of 2.81% is achieved for the CdS/TNTAs prepared by CV electrodeposition, which exhibits about 17 times enhancement over the efficiency of the sample prepared by DC electrodeposition. And the photocatalytic degradation of methyl orange under visible-light irradiation demonstrates that the rate constant of the sample prepared by the CV method is almost seven times of that of the untreated TNTAs. Moreover, the underlying mechanism for the improving properties has been discussed

  8. Co-sensitization of quantum dot sensitized solar cells composed of TiO2 nanocrystalline photoanode with CdS and PbS nanoparticles and effect of PbS on the performance of solar cell

    Directory of Open Access Journals (Sweden)

    Maziar Marandi

    2017-09-01

    Full Text Available In this research, CdS and PbS quantum dots were applied as the light sensitizers in TiO2 based nanostructured solar cells. The PbS quantum dots could absorb a wide range of the sunlight spectrum on earth due to their low bandgap energy. As a result, the cell sensitization is more effective by application of both CdS and PbS quantum dots sensitizers. The TiO2 nanocrystals were synthesized through a hydrothermal process and deposited on FTO glass substrates as the photoanode scaffold. Then PbS quantum dots were grown on the surface of this nanocrystalline layer by a successive ionic layer adsorption and reaction (SILAR method. The CdS quantum dots were over-grown in the next step through a similar deposition method. Finally this sensitized layer was applied as the photoelectrode of the corresponding quantum dot sensitized solar cells. The results demonstrated that the maximum efficiency was achieved for the cell with a photoanode made of co-sensitization through 2 and 6 cycles of PbS and CdS deposition, respectively. The photovoltaic parameters of this cell were measured as Jsc of 10.81 mA/cm2, Voc of 590 mv and energy conversion efficiency of 2.7+0.2%.

  9. Enriching The Metadata On CDS

    CERN Document Server

    Chhibber, Nalin

    2014-01-01

    The project report revolves around the open source software package called Invenio. It provides the tools for management of digital assets in a repository and drives CERN Document Server. Primary objective is to enhance the existing metadata in CDS with data from other libraries. An implicit part of this task is to manage disambiguation (within incoming data), removal of multiple entries and handle replications between new and existing records. All such elements and their corresponding changes are integrated within Invenio to make the upgraded metadata available on the CDS. Latter part of the report discuss some changes related to the Invenio code-base itself.

  10. Enhancing the Antibacterial Activity of Light-Activated Surfaces Containing Crystal Violet and ZnO Nanoparticles: Investigation of Nanoparticle Size, Capping Ligand, and Dopants.

    Science.gov (United States)

    Sehmi, Sandeep K; Noimark, Sacha; Pike, Sebastian D; Bear, Joseph C; Peveler, William J; Williams, Charlotte K; Shaffer, Milo S P; Allan, Elaine; Parkin, Ivan P; MacRobert, Alexander J

    2016-09-30

    Healthcare-associated infections pose a serious risk for patients, staff, and visitors and are a severe burden on the National Health Service, costing at least £1 billion annually. Antimicrobial surfaces significantly contribute toward reducing the incidence of infections as they prevent bacterial adhesion and cause bacterial cell death. Using a simple, easily upscalable swell-encapsulation-shrink method, novel antimicrobial surfaces have been developed by incorporating metal oxide nanoparticles (NPs) and crystal violet (CV) dye into medical-grade polyurethane sheets. This study compares the bactericidal effects of polyurethane incorporating ZnO, Mg-doped ZnO, and MgO. All metal oxide NPs are well defined, with average diameters ranging from 2 to 18 nm. These materials demonstrate potent bactericidal activity when tested against clinically relevant bacteria such as Escherichia coli and Staphylococcus aureus . Additionally, these composites are tested against an epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) that is rife in hospitals throughout the UK. Furthermore, we have tested these materials using a low light intensity (∼500 lx), similar to that present in many clinical environments. The highest activity is achieved from polymer composites incorporating CV and ∼3 nm ZnO NPs, and the different performances of the metal oxides have been discussed.

  11. Synthesis and characterization of water-dispersed CdSe/CdS core-shell quantum dots prepared via Layer-by-layer Method capped with carboxylic-functionalized poly(vinyl alcohol)

    Energy Technology Data Exchange (ETDEWEB)

    Ramanery, Fabio Pereira; Mansur, Alexandra Ancelmo Piscitelli; Mansur, Herman Sander, E-mail: hmansur@demet.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Metalurgia e Engenharia dos Materiais. Centro de Nanociencia, Nanotecnologia e Inovacao

    2014-08-15

    The main goal of this work was to synthesize CdSe/CdS (core-shell) nanoparticles stabilized by polymer ligand using entirely aqueous colloidal chemistry at room temperature. First, the CdSe core was prepared using precursors and acid-functionalized poly(vinyl alcohol) as the capping ligand. Next, a CdS shell was grown onto the CdSe core via the layer-by-layer technique. The CdS shell was formed by two consecutive monolayers, as estimated by empirical mathematical functions. The nucleation and growth of CdSe quantum dots followed by CdS shell deposition were characterized by UV-vis spectroscopy, photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). The results indicated a systematic red-shift of the absorption and emission spectra after the deposition of CdS, indicating the shell growth onto the CdSe core. TEM coupled with electron diffraction analysis revealed the presence of CdSe/CdS with an epitaxial shell growth. Therefore, it may be concluded that CdSe/CdS quantum dots with core-shell nanostructure were effectively synthesized.(author)

  12. An improved pyrolysis route to synthesize carbon-coated CdS quantum dots with fluorescence enhancement effect

    International Nuclear Information System (INIS)

    Zhang Kejie; Liu Xiaoheng

    2011-01-01

    Well-dispersed carbon-coated CdS (CdS-C) quantum dots were successfully prepared via the improved pyrolysis of bis(1-dodecanethiol)-cadmium(II) under nitrogen atmosphere. This simple method effectively solved the sintered problem resulted from conventional pyrolysis process. The experimental results indicated that most of the as-prepared nanoparticles displayed well-defined core-shell structures. The CdS cores with diameter of ∼5 nm exhibited hexagonal crystal phase, the carbon shells with thickness of ∼2 nm acted as a good dispersion medium to prevent CdS particles from aggregation, and together with CdS effectively formed a monodisperse CdS-Carbon nanocomposite. This composite presented a remarkable fluorescence enhancement effect, which indicated that the prepared nanoparticles might be a promising photoresponsive material or biosensor. This improved pyrolysis method might also offer a facile way to prepare other carbon-coated semiconductor nanostructures. - Graphical abstract: We demonstrated a facile approach to synthesize well-dispersed carbon-coated CdS quantum dots. The as-prepared nanoparticles presented remarkable fluorescence enhancement effect. Highlights: → Carbon-coated CdS quantum dots were synthesized by an one-step pyrolysis method. → Well-dispersed CdS-carbon nanoparticles were obtained by an acid treatment process. → As-prepared nanoparticles presented remarkable fluorescence enhancement effect.

  13. ORF Sequence: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >gnl|CMER|CME069C hypothetical protein MQSGSSEERVSSHMEARDSAPTASSMPSLRLTATATATATAR...LTYAHVSRPRPPAHLPRSDAYGGSPSASTTSSSTATARPTCAHEAAHPPQVHHLGSGACGGSPSASTTSSSTATARPTCAHEAAHPPQVHHLGSGACDGSPSASTTSSSTATAR...PTCAHEAAHPPQVHRLGSGACGGSPSASTTSSSTATARPTCAHEAAHPPQVHRLGSGACGGSPSASTTSSSTATARPTCAHEADHPPQVHRQGSDVSHINHTTKKLLSLWLLARPTATVKATVKVLRSDARRCGPDLSTTAEQARCNCREQCRSRTHR

  14. ORF Sequence: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available KGSWTFYIMLLASFRIFFGLGLSLSPMESWTIMNVVHAGVTFIVFHWIKGNPFHTPWVDMMGKGEKQTWWEQIDGSVQNTPSRKFLICVVVFLYLAAVHSTPFERQFFFVHAVNLIAFLVVFVAKLPFMHGVRIFGINR ... cds gnl|CMER >gnl|CMER|CMQ020C hypothetical protein, conserved MQSGHGETRFDVGVEWLRA

  15. Apical cap

    International Nuclear Information System (INIS)

    McLoud, T.C.; Isler, R.J.; Novelline, R.A.; Putman, C.E.; Simeone, J.; Stark, P.

    1981-01-01

    Apical caps, either unilateral or bilateral, are a common feature of advancing age and are usually the result of subpleural scarring unassociated with other diseases. Pancoast (superior sulcus) tumors are a well recognized cause of unilateral asymmetric apical density. Other lesions arising in the lung, pleura, or extrapleural space may produce unilateral or bilateral apical caps. These include: (1) inflammatory: tuberculosis and extrapleural abscesses extending from the neck; (2) post radiation fibrosis after mantle therapy for Hodgkin disease or supraclavicular radiation in the treatment of breast carcinoma; (3) neoplasm: lymphoma extending from the neck or mediastinum, superior sulcus bronchogenic carcinoma, and metastases; (4) traumatic: extrapleural dissection of blood from a ruptured aorta, fractures of the ribs or spine, or hemorrhage due to subclavian line placement; (5) vascular: coarctation of the aorta with dilated collaterals over the apex, fistula between the subclavian artery and vein; and (6) miscellaneous: mediastinal lipomatosis with subcostal fat extending over the apices

  16. Optimal Financing with CDS Markets

    NARCIS (Netherlands)

    Matta, R.

    2013-01-01

    One could argue that CDSs improve risk sharing, hence credit supply and financing terms for firms. Accordingly, one would expect risky borrowers to benefit the most from CDS insurance. This is in contrast, however, with recent empirical evidence (Ashcraft and Santos (2009) and Hirtle (2009)). This

  17. Group 12 dithiocarbamate complexes: Synthesis, spectral studies and their use as precursors for metal sulfides nanoparticles and nanocomposites

    Science.gov (United States)

    Ajibade, Peter A.; Ejelonu, Benjamin C.

    2013-09-01

    Zn(II), Cd(II) and Hg(II) dithiocarbamate complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, UV-Vis, FTIR, 1H- and 13C NMR spectroscopy. The complexes were thermolysed at 180 °C and used as single molecule precursors for the synthesis of HDA capped ZnS, CdS and HgS nanoparticles and polymethylmethacrylate (PMMA) nanocomposites. The optical and structural properties of the nanoparticles and nanocomposites were studied by UV-Vis, PL, XRD and SEM. The crystallites sizes of the nanoparticles varied between 3.03 and 23.45 nm. SEM and EDX analyses of the nanocomposites confirmed the presence of the nanoparticles in the polymer matrix.

  18. Chemical synthesis of highly size-confined triethylamine-capped ...

    Indian Academy of Sciences (India)

    2018-03-23

    Mar 23, 2018 ... TiO2 nanoparticles and its dye-sensitized solar cell performance .... Figure 5. Formation mechanism of TEA-capped and uncapped TiO2 nanoparticles. ... this research work, synthesized TEA-capped TiO2 nanopar- ticles were ...

  19. Hexagonal pencil-like CdS nanorods: Facile synthesis and enhanced visible light photocatalytic performance

    Science.gov (United States)

    An, Liang; Wang, Guanghui; Zhao, Lei; Zhou, Yong; Gao, Fang; Cheng, Yang

    2015-07-01

    In the present study, hexagonal pencil-like CdS nanorods have been successfully synthesized through a typical facile and economical one-step hydrothermal method without using any surfactant or template. The product was characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and energy dispersive analysis of X-ray (EDX). The results revealed that the prepared CdS photocatalyst consisted of a large quantity of straight and smooth solid hexagonal nanorods and a few nanoparticles. The photocatalytic activities of CdS nanorods and commercial CdS powders were investigated by the photodegradation of Orange II (OII) in aqueous solution under visible light, and the CdS nanorods presented the highest photocatalytic activity. Its photocatalytic efficiency enhancement was attributed to the improved transmission of photogenerated electron-hole pairs in the CdS nanostructures. The present findings may provide a facile approach to synthesize high efficient CdS photocatalysts.

  20. Photoelectrochemical and Raman characterization of nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Kozytskiy, A.V. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Stroyuk, O.L., E-mail: stroyuk@inphyschem-nas.kiev.ua [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Kuchmiy, S.Ya. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Mazanik, A.V.; Poznyak, S.K. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Streltsov, E.A., E-mail: streltea@bsu.by [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Kulak, A.I., E-mail: kulak@igic.bas-net.by [Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Surganova str., 9/1, Minsk 220072 (Belarus); Korolik, O.V. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Dzhagan, V.M., E-mail: dzhagan@isp.kiev.ua [V.E. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, 41 Nauky Av., 03028 Kyiv (Ukraine)

    2014-07-01

    Properties of CdS nanoparticles (NPs) grown by successive ionic layer adsorption and reaction (SILAR) method on the surface of electrodeposited ZnO films were studied by Raman, photocurrent and UV–Vis absorption spectroscopies. The CdS nanoparticles deposited at a SILAR cycle number (N) from 5 to 10 exhibit a broadening of the band gap (E{sub g}) by 0.17–0.31 eV as compared with that of the CdS particles grown at N = 30. The size quantization of the interband transition energy in CdS nanoparticles is in accordance with the Raman spectroscopic data demonstrating a considerable increase in the LO peak intensity with increasing the N from 5 to 10 as a result of transition to resonant light scattering. The spectral width of the LO peak decreases from 50 to 15 cm{sup −1} as the N increases from 5 to 30 reflecting a less pronounced effect of the nanoparticle surface on the phonon scattering. A large spectral width of the Raman peaks is assumed to originate from a complex structure of the CdS nanoparticles comprising crystallinity domains that can affect the phonon confinement. The photocurrent spectroscopy of ZnO/CdS heterostructures showed that the band gap of CdS NPs deposited at N > 20 is smaller by ∼ 0.08 eV than that of bulk cadmium sulfide. It was concluded that this effect is not associated with photoexcitation of structural defects but rather reflects intrinsic electronic properties of SILAR-deposited CdS nanoparticles. - Highlights: • Visible-light-sensitive ZnO/CdS heterostructures were prepared by SILAR. • A large Raman peak width originates from a complex structure of CdS nanoparticles. • Vibrational properties of CdS nanoparticles depend on SILAR cycle number.

  1. Photoelectrochemical and Raman characterization of nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

    International Nuclear Information System (INIS)

    Kozytskiy, A.V.; Stroyuk, O.L.; Kuchmiy, S.Ya.; Mazanik, A.V.; Poznyak, S.K.; Streltsov, E.A.; Kulak, A.I.; Korolik, O.V.; Dzhagan, V.M.

    2014-01-01

    Properties of CdS nanoparticles (NPs) grown by successive ionic layer adsorption and reaction (SILAR) method on the surface of electrodeposited ZnO films were studied by Raman, photocurrent and UV–Vis absorption spectroscopies. The CdS nanoparticles deposited at a SILAR cycle number (N) from 5 to 10 exhibit a broadening of the band gap (E g ) by 0.17–0.31 eV as compared with that of the CdS particles grown at N = 30. The size quantization of the interband transition energy in CdS nanoparticles is in accordance with the Raman spectroscopic data demonstrating a considerable increase in the LO peak intensity with increasing the N from 5 to 10 as a result of transition to resonant light scattering. The spectral width of the LO peak decreases from 50 to 15 cm −1 as the N increases from 5 to 30 reflecting a less pronounced effect of the nanoparticle surface on the phonon scattering. A large spectral width of the Raman peaks is assumed to originate from a complex structure of the CdS nanoparticles comprising crystallinity domains that can affect the phonon confinement. The photocurrent spectroscopy of ZnO/CdS heterostructures showed that the band gap of CdS NPs deposited at N > 20 is smaller by ∼ 0.08 eV than that of bulk cadmium sulfide. It was concluded that this effect is not associated with photoexcitation of structural defects but rather reflects intrinsic electronic properties of SILAR-deposited CdS nanoparticles. - Highlights: • Visible-light-sensitive ZnO/CdS heterostructures were prepared by SILAR. • A large Raman peak width originates from a complex structure of CdS nanoparticles. • Vibrational properties of CdS nanoparticles depend on SILAR cycle number

  2. Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression through suppression of p300 stabilization and NFκB/c-Jun activation in breast cancer MDA-MB-231 cells

    International Nuclear Information System (INIS)

    Chen, Ying-Jung; Lee, Yuan-Chin; Huang, Chia-Hui; Chang, Long-Sen

    2016-01-01

    Triple-negative breast cancers (TNBCs) are highly invasive and have a higher rate of distant metastasis. Matrix metalloproteinase-9 (MMP-9) plays a crucial role in EGF/EGFR-mediated malignant progression and metastasis of TNBCs. Various studies have revealed that treatment with gallic acid down-regulates MMP-9 expression in cancer cells, and that conjugation of phytochemical compounds with gold nanoparticles (AuNPs) increases the anti-tumor activity of the phytochemical compounds. Thus, the effect of gallic acid-capped AuNPs (GA-AuNPs) on MMP-9 expression in EGF-treated TNBC MDA-MB-231 cells was analyzed in the present study. The so-called green synthesis of AuNPs by means of gallic acid was performed at pH 10, and the resulting GA-AuNPs had spherical shape with an average diameter of approximately 50 nm. GA-AuNPs notably suppressed migration and invasion of EGF-treated cells, and inhibited EGF-induced MMP-9 up-regulation. GA-AuNPs abrogated EGF-induced Akt/p65 and ERK/c-Jun phosphorylation, leading to down-regulation of MMP-9 mRNA and protein expression in EGF-treated cells. Meanwhile, EGF-induced p300 stabilization was found to be involved in MMP-9 expression, whereas GA-AuNPs inhibited the EGF-promoted stability of the p300 protein. Although GA-AuNPs and gallic acid suppressed EGF-induced MMP-9 up-regulation via the same signaling pathway, the effective concentration of gallic acid was approximately 100-fold higher than that of GA-AuNPs for inhibition of MMP-9 expression in EGF-treated cells to a similar extent. Collectively, our data indicate that, in comparison with gallic acid, GA-AuNPs have a superior ability to inhibit EGF/EGFR-mediated MMP-9 expression in TNBC MDA-MB-231 cells. Our findings also point to a way to improve the anti-tumor activity of gallic acid. - Highlights: • Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression. • EGF-induced MMP-9 expression via p300 stabilization and NFκB/c-Jun activation. • Gallic acid-capped

  3. Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression through suppression of p300 stabilization and NFκB/c-Jun activation in breast cancer MDA-MB-231 cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ying-Jung; Lee, Yuan-Chin; Huang, Chia-Hui [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Chang, Long-Sen, E-mail: lschang@mail.nsysu.edu.tw [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2016-11-01

    Triple-negative breast cancers (TNBCs) are highly invasive and have a higher rate of distant metastasis. Matrix metalloproteinase-9 (MMP-9) plays a crucial role in EGF/EGFR-mediated malignant progression and metastasis of TNBCs. Various studies have revealed that treatment with gallic acid down-regulates MMP-9 expression in cancer cells, and that conjugation of phytochemical compounds with gold nanoparticles (AuNPs) increases the anti-tumor activity of the phytochemical compounds. Thus, the effect of gallic acid-capped AuNPs (GA-AuNPs) on MMP-9 expression in EGF-treated TNBC MDA-MB-231 cells was analyzed in the present study. The so-called green synthesis of AuNPs by means of gallic acid was performed at pH 10, and the resulting GA-AuNPs had spherical shape with an average diameter of approximately 50 nm. GA-AuNPs notably suppressed migration and invasion of EGF-treated cells, and inhibited EGF-induced MMP-9 up-regulation. GA-AuNPs abrogated EGF-induced Akt/p65 and ERK/c-Jun phosphorylation, leading to down-regulation of MMP-9 mRNA and protein expression in EGF-treated cells. Meanwhile, EGF-induced p300 stabilization was found to be involved in MMP-9 expression, whereas GA-AuNPs inhibited the EGF-promoted stability of the p300 protein. Although GA-AuNPs and gallic acid suppressed EGF-induced MMP-9 up-regulation via the same signaling pathway, the effective concentration of gallic acid was approximately 100-fold higher than that of GA-AuNPs for inhibition of MMP-9 expression in EGF-treated cells to a similar extent. Collectively, our data indicate that, in comparison with gallic acid, GA-AuNPs have a superior ability to inhibit EGF/EGFR-mediated MMP-9 expression in TNBC MDA-MB-231 cells. Our findings also point to a way to improve the anti-tumor activity of gallic acid. - Highlights: • Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression. • EGF-induced MMP-9 expression via p300 stabilization and NFκB/c-Jun activation. • Gallic acid-capped

  4. Surface biofunctionalized CdS and ZnS quantum dot nanoconjugates for nanomedicine and oncology: to be or not to be nanotoxic?

    Directory of Open Access Journals (Sweden)

    Mansur AAP

    2016-09-01

    Full Text Available Alexandra AP Mansur,1 Herman S Mansur,1 Sandhra M de Carvalho,1–3 Zélia IP Lobato,2 Maria IMC Guedes,2 Maria F Leite3 1Center of Nanoscience, Nanotechnology, and Innovation-CeNano2I, Department of Metallurgical and Materials Engineering, 2Department of Preventive Veterinary Medicine, Veterinary School, 3Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil Abstract: Herein, for the first time, we demonstrated that novel biofunctionalized semiconductor nanomaterials made of Cd-containing fluorescent quantum dot nanoconjugates with the surface capped by an aminopolysaccharide are not biologically safe for clinical applications. Conversely, the ZnS-based nanoconjugates proved to be noncytotoxic, considering all the parameters investigated. The results of in vitro cytotoxicity were remarkably dependent on the chemical composition of quantum dot (CdS or ZnS, the nature of the cell (human cancerous and embryonic types, and the concentration and time period of exposure to these nanomaterials, caused by the effects of Cd2+ on the complex nanotoxicity pathways involved in cellular uptake. Unexpectedly, no decisive evidence of nanotoxicity of CdS and ZnS conjugates was observed in vivo using intravenous injections in BALB/c mice for 30 days, with minor localized fluorescence detected in liver tissue specimens. Therefore, these results proved that CdS nanoconjugates could pose an excessive threat for clinical applications due to unpredicted and uncorrelated in vitro and in vivo responses caused by highly toxic cadmium ions at biointerfaces. On the contrary, ZnS nanoconjugates proved that the “safe by design” concept used in this research (ie, biocompatible core–shell nanostructures could benefit a plethora of applications in nanomedicine and oncology. Keywords: fluorescent nanoparticles, semiconductor quantum dots, nanotoxicity, bionanoconjugates, nanoprobes

  5. Synthesis of CdS hollow/solid nanospheres and their chain-structures by membrane technique

    International Nuclear Information System (INIS)

    Duan Shumin; Wu Qingsheng; Jia Runping; Liu Xinbo

    2008-01-01

    CdS hollow/solid nanospheres and their chain-structures were successfully synthesized through supporting liquid membrane (SLM) system with bio-membrane. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, and photoluminescence (PL) spectroscopy have been used for the characterization of the products. The average diameters of CdS solid/hollow spheres are about 10, 40 nm, respectively. The wall of the hollow spheres is about 5 nm. CdS products are all cubic face-centered structure with the cell constant a = 5.830 A. We also explore the morphology, structure and possible synthesis mechanism. A possible template mechanism has been proposed for the production of the hollow CdS nanocrystals, that is, CdS nanoparticles grow along the non-soakage interface between CHCl3 and reactant solution. During this process, the organic functional groups were crucial to the control of crystal morphologies

  6. Luminescence studies of CdS spherical particles via hydrothermal synthesis

    Science.gov (United States)

    Xu, Guo Qin; Liu, Bing; Xu, Shi Jie; Chew, Chwee Har; Chua, Soo Jin; Gana, Leong Ming

    2000-06-01

    The spherical particles of CdS consisting of nanoparticles (∼100 nm) were synthesized by a hydrothermal process. The particle formation and growth depend on the rate of sulfide-ion generation and diffusion-controlled aggregation of nanoparticles. As demonstrated in the profiles of powder X-ray diffraction, the crystalline phases are governed by the reaction temperature. Photoluminescence studies on CdS particles show two emission bands at the room temperature. The red emission at 680 nm is due to sulfur vacancies, and a new infrared red (IR) emission at 760 nm is attributed to self-activated centers. A red shift of IR band with the decrease of temperature was explained with a configurational coordinate model. The different saturation limits for the red and IR bands are discussed in terms of the formation of donor-acceptor pairs and exciton in CdS particles.

  7. Size-dependent photodegradation of CdS particles deposited onto TiO2 mesoporous films by SILAR method

    International Nuclear Information System (INIS)

    Ahmed, Rasin; Will, Geoffrey; Bell, John; Wang Hongxia

    2012-01-01

    The particle size, size distribution and photostability of CdS nanoparticles incorporated onto mesoporous TiO 2 films by a successive ionic layer adsorption and reaction (SILAR) method were investigated by Raman spectroscopy, UV–Visible spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). High-resolution TEM indicated that the synthesized CdS particles were hexagonal phase and the particle sizes were less than 5 nm for up to nine SILAR deposition cycles. Quantum size effect was found with the CdS-sensitized TiO 2 films prepared with up to nine SILAR cycles. The band gap of CdS nanoparticles decreased from 2.65 to 2.37 eV with the increase of the SILAR cycles from 1 to 11. The investigation of the stability of the CdS/TiO 2 films in air under illumination (440.6 μW/cm 2 ) showed that the photodegradation rate was up to 85 % per day for the sample prepared with three SILAR cycles. XPS analysis indicated that the photodegradation was due to the oxidation of CdS, leading to the transformation from sulphide to sulphate (CdSO 4 ). Furthermore, the degradation rate was strongly dependent upon the particle size of CdS. Smaller particles showed faster degradation rate. The size-dependent photo-induced oxidization was rationalized with the variation of size-dependent distribution of surface atoms of CdS particles. Molecular dynamics-based theoretical calculation has indicated that the surface sulphide anion of a large CdS particle such as CdS made with 11 cycles (CdS × 11, average particle size = 5.6 nm) accounts for 9.6 % of the material whereas this value is increased to 19.2 % for (CdS × 3)-based smaller particles (average particle size = 2.7 nm). The photostability of CdS nanoparticles was significantly enhanced when coated with ZnS particles deposited with four SILAR cycles. The growth mechanism of ZnS upon CdS nanoparticles was discussed.

  8. Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria

    OpenAIRE

    Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha

    2014-01-01

    In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon ...

  9. A configurable CDS for the production laboratory

    CERN Document Server

    Meek, Irish

    2003-01-01

    Various aspects of a configurable chromatography data system (CDS) for the production laboratory are discussed. The Atlas CDS can be configured extensively to fit the production laboratory work flow and meet the needs of analysts. The CDS can also be configured to automatically create a sample sequence with the required number of injections and download methods to the dedicated instrument. The Atlas Quick Start wizard offers uses quick way of generating a sequence from a predefined template and starting a run. (Edited abstract).

  10. Morphology, structure and optical properties of hydrothermally synthesized CeO2/CdS nanocomposites

    Science.gov (United States)

    Mohanty, Biswajyoti; Nayak, J.

    2018-04-01

    CeO2/CdS nanocomposites were synthesized using a two-step hydrothermal technique. The effects of precursor concentration on the optical and structural properties of the CeO2/CdS nanoparticles were systematically studied. The morphology, composition and the structure of the CeO2/CdS nanocomposite powder were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectrum analysis (EDXA) and X-ray diffraction (XRD), respectively. The optical properties of CeO2/CdS nanocomposites were studied by UV-vis absorption and photoluminescence (PL) spectroscopy. The optical band gaps of the CeO2/CdS nanopowders ranged from 2.34 eV to 2.39 eV as estimated from the UV-vis absorption. In the room temperature photoluminescence spectrum of CeO2/CdS nanopowder, a strong blue emission band was observed at 400 nm. Since the powder shows strong visible luminescence, it may be used as a blue phosphor in future. The original article published with this DOI was submitted in error. The correct article was inadvertently left out of the original submission. This has been rectified and the correct article was published online on 16 April 2018.

  11. Investigation of the photoluminescence properties of thermochemically synthesized CdS nanocrystals

    Directory of Open Access Journals (Sweden)

    M. Molaei

    2011-03-01

    Full Text Available In this work we have synthesized CdS nanocrystals with thermochemical method. CdSO4 and Na2S2O3 were used as the precursors and thioglycolic acid (TGA was used as capping agent molecule. The structure and optical property of the nanocrystals were characterized by means of XRD, TEM, UV-visible optical spectroscopy and photoluminescence (PL. X-ray diffraction (XRD and TEM analyses demonstrated hexagonal phase CdS nanocrystals with an average size around 2 nm. Synthesized nanocrystals exhibited band gap of about 3.2 eV and showed a broad band emission from 400-750 nm centered at 504 nm with a (0.27, 0.39 CIE coordinate. This emission can be attributed to recombination of an electron in conduction band with a hole trapped in Cd vacancies near to the valance band of CdS. The best attained photoluminescence quantum yield of the nanocrystals was about 12%, this amount is about 20 times higher than that for thioglycerol (TG capped CdS nanocrystals.

  12. One-pot size and shape controlled synthesis of DMSO capped iron

    Indian Academy of Sciences (India)

    https://www.ias.ac.in/article/fulltext/boms/029/06/0617-0621. Keywords. Iron oxide; thermal decomposition; TEM; VSM. Abstract. We report here the capping of iron oxide nanoparticles with dimethyl sulfoxide (DMSO) to make chloroform soluble iron oxide nanoparticles. Size and shape of the capped iron oxide nanoparticles ...

  13. Green wet chemical route to synthesize capped CdSe quantum dots

    Indian Academy of Sciences (India)

    In the present work, we report green synthesis of tartaric acid (TA) and triethanolamine (TEA) capped ... CdSe quantum dots; chemical bath deposition; capping; green chemistry; nanomaterials. 1. .... at high concentration of nanoparticles.

  14. Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT.

    Science.gov (United States)

    Xu, Shoufang; Lu, Hongzhi

    2016-11-15

    A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as "functional monomer" for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as "functional monomer", exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6-95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Characterization and in vitro studies on anticancer, antioxidant activity against colon cancer cell line of gold nanoparticles capped with Cassia tora SM leaf extract

    Science.gov (United States)

    Abel, Ezra Elumalai; John Poonga, Preetam Raj; Panicker, Shirly George

    2016-01-01

    This study was aimed to determine the effectiveness of synthesized gold nanoparticles of an ethnobotanically and medicinally important plant species Cassia tora against colon cancer cells and to find its antibacterial and antioxidant activities. In order to improve the bioavailability of C. tora, we synthesized gold nanoparticles through green synthesis, by simple mixing and stirring of C. tora leaf powder and tetrachloroauric acid (HAuCl4) solution which gave a dispersion of gold nanoparticles conjugate with C. tora secondary metabolites (SMs) with characteristic surface plasmon resonance. It was characterized by Fourier transform infrared spectroscopy, zeta sizer, zeta potential and transmission electron microscopy. Antibacterial activity was carried out for gold nanoparticles conjugated with C. tora SMs, using well-diffusion method. The MTT assay for cell viability and markers such as catalase, nitric oxide and lipid peroxidation was predictable to confirm the cytotoxicity and antioxidant properties. The treatment of gold nanoparticles conjugated with C. tora SMs on Col320 cells showed reduction in the cell viability through MTT assay, and it also significantly suppressed the release of H2O2, LPO and NO production in a dose-dependent manner. C. tora SMs conjugate gold nanoparticles showed enhanced bioavailability, antioxidant and anticancer effect against colon cancer cell line (Col320).

  16. Luminescent nanocomposites of conducting polymers and in-situ grown CdS quantum dots

    International Nuclear Information System (INIS)

    Borriello, C.; Masala, S.; Nenna, G.; Minarini, C.; Di Luccio, T.; Bizzarro, V.; Re, M.; Pesce, E.

    2010-01-01

    Luminescent PVK:CdS and P3HT:CdS nanocomposites with enhanced electrooptical properties have been synthesized. The nucleation and growth of CdS nanoparticles have been obtained by the thermolysis of a single Cd and S precursor dispersed in the polymers. The size distribution and morphology of the nanoparticles have been studied by TEM analyses. Monodispersive and very small nanoparticles of diameter below 3 nm in PVK and 2 nm in P3HT, have been obtained. The application of such nanocomposites as emitting layers in OLED devices is discussed.

  17. Synthesis and characterization of TiO2/CdS core–shell nanorod arrays and their photoelectrochemical property

    International Nuclear Information System (INIS)

    Cao Chunlan; Hu Chenguo; Shen Weidong; Wang, Shuxia; Tian Yongshu; Wang Xue

    2012-01-01

    Highlights: ► TiO 2 /CdS core–shell nanorod arrays were fabricated by spin-SILAR method. ► The enhanced photocurrent was found in the TiO 2 /CdS core–shell nanorod arrays. ► The CdS coated on TiO 2 increases the e-h separation and enlarges light absorption range. - Abstract: TiO 2 /CdS core–shell nanorod arrays have been fabricated via a two-step method. Vertically aligned TiO 2 nanorod arrays (NRs) were synthesized by a facile hydrothermal method, and followed by depositing CdS nanoparticles on TiO 2 NRs by spin-coating successive ion layer adsorption and reaction (spin-SILAR) method. The surface morphology, structure, optical and photoelectrochemical behaviors of the core–shell NRs films are considered. The UV–vis absorption spectrum results suggested that the absorption peak of the TiO 2 /CdS core–shell NRs shifts from the ultraviolet region to the visible region in comparison to that of the pure TiO 2 NRs. The obviously enhanced photoelectrochemical (PEC) performances of the heterojunction NRs were found under illumination of the simulated sunlight in comparison with that of the TiO 2 NRs. The enhanced PEC performance and formation mechanism of TiO 2 /CdS core–shell NRs were discussed in detail.

  18. Photonic sintering of thin film prepared by dodecylamine capped CuIn{sub x}Ga{sub 1−x}Se{sub 2} nanoparticles for printed photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manjeet, E-mail: msitbhu@gmail.com; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-08-28

    In this paper, we report solution phase large scale synthesis of monodisperse phase pure CuIn{sub x}Ga{sub 1−x}Se{sub 2} (CIGS) nanoparticles by using dodecylamine as solvent and dispersant. Various compositions of CIGS nanoparticles with different Ga content are synthesized by simply adding different amounts of Ga precursors. The band gap of CIGS nanoparticles can be tuned by changing Ga content. Effort is given to understand the formation pathway of CIGS phase so as to make the synthesis easier for the desired product. High intensity pulsed light technique, which provides extreme local heating, is used to sinter the thin film prepared using these nanoparticles on a Mo–glass surface. A uniformly conductive and dense CIGS film can be prepared by adjusting the energy of light and exposure time. The high intensity light irradiation of the CIGS film leads to diffusion of smaller CIGS nanoparticles to form a particle with larger grain size and thus enables sintering of particles without using high temperature processing. - Highlights: • Large scale synthesis of CuIn{sub x}Ga{sub 1−x}Se{sub 2} (CIGS) is reported. • Dodecylamine is used as surfactant and solvent. • CIGS phase formation mechanism is described. • High intensity pulsed light technique is used to sinter the CIGS film.

  19. Highly sensitive, colorimetric detection of mercury(II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature.

    Science.gov (United States)

    Liu, Dingbin; Qu, Weisi; Chen, Wenwen; Zhang, Wei; Wang, Zhuo; Jiang, Xingyu

    2010-12-01

    We provide a highly sensitive and selective assay to detect Hg(2+) in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by Hg(2+) that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of Hg(2+) in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 × 10(-8)-1 × 10(-2) M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for Hg(2+).

  20. Solution precursor plasma deposition of nanostructured CdS thin films

    International Nuclear Information System (INIS)

    Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

    2012-01-01

    Highlights: ► Inexpensive process with capability to produce large scale nanostructured coatings. ► Technique can be employed to spray the coatings on any kind of substrates including polymers. ► The CdS coatings developed have good electrical conductivity and optical properties. ► Coatings possess large amount of particulate boundaries and nanostructured grains. -- Abstract: Cadmium sulfide (CdS) films are used in solar cells, sensors and microelectronics. A variety of techniques, such as vapor based techniques, wet chemical methods and spray pyrolysis are frequently employed to develop adherent CdS films. In the present study, rapid deposition of CdS thin films via plasma spray route using a solution precursor was investigated, for the first time. Solution precursor comprising cadmium chloride, thiourea and distilled water was fed into a DC plasma jet via an axial atomizer to create ultrafine droplets for instantaneous and accelerated thermal decomposition in the plasma plume. The resulting molten/semi-molten ultrafine/nanoparticles of CdS eventually propel toward the substrate to form continuous CdS films. The chemistry of the solution precursor was found to be critical in plasma pyrolysis to control the stoichiometry and composition of the films. X-ray diffraction studies confirmed hexagonal α-CdS structure. Surface morphology and microstructures were investigated to compare with other synthesis techniques in terms of process mechanism and structural features. Transmission electron microscopy studies revealed nanostructures in the atomized particulates. Optical measurements indicated a decreasing transmittance in the visible light with increasing the film thickness and band gap was calculated to be ∼2.5 eV. The electrical resistivity of the films (0.243 ± 0.188 × 10 5 Ω cm) was comparable with the literature values. These nanostructured polycrystalline CdS films could be useful in sensing and solar applications.

  1. Solution precursor plasma deposition of nanostructured CdS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan, Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan, Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan, Dearborn, MI 48128 (United States)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Inexpensive process with capability to produce large scale nanostructured coatings. Black-Right-Pointing-Pointer Technique can be employed to spray the coatings on any kind of substrates including polymers. Black-Right-Pointing-Pointer The CdS coatings developed have good electrical conductivity and optical properties. Black-Right-Pointing-Pointer Coatings possess large amount of particulate boundaries and nanostructured grains. -- Abstract: Cadmium sulfide (CdS) films are used in solar cells, sensors and microelectronics. A variety of techniques, such as vapor based techniques, wet chemical methods and spray pyrolysis are frequently employed to develop adherent CdS films. In the present study, rapid deposition of CdS thin films via plasma spray route using a solution precursor was investigated, for the first time. Solution precursor comprising cadmium chloride, thiourea and distilled water was fed into a DC plasma jet via an axial atomizer to create ultrafine droplets for instantaneous and accelerated thermal decomposition in the plasma plume. The resulting molten/semi-molten ultrafine/nanoparticles of CdS eventually propel toward the substrate to form continuous CdS films. The chemistry of the solution precursor was found to be critical in plasma pyrolysis to control the stoichiometry and composition of the films. X-ray diffraction studies confirmed hexagonal {alpha}-CdS structure. Surface morphology and microstructures were investigated to compare with other synthesis techniques in terms of process mechanism and structural features. Transmission electron microscopy studies revealed nanostructures in the atomized particulates. Optical measurements indicated a decreasing transmittance in the visible light with increasing the film thickness and band gap was calculated to be {approx}2.5 eV. The electrical resistivity of the films (0.243 {+-} 0.188 Multiplication-Sign 10{sup 5} {Omega} cm) was comparable with the literature

  2. Dynamic Modeling of CDS Index Tranche Spreads

    DEFF Research Database (Denmark)

    Dorn, Jochen

    This paper provides a Market Model which implies a dynamics for standardized CDS index tranche spreads, i.e. tranches which securitise CDS index series and dispose of predefined subordination. This model is useful for pricing options on tranches with future Issue Dates as well as for modeling...... options on structured credit derivatives. With the upcoming regulation of the CDS market in perspective, the model presented here is also an attempt to face the effects on pricing approaches provoked by an eventual Clearing Chamber . It becomes also possible to calibrate Index Tranche Options with bespoke...... tenors/tranche subordination to market data obtained by more liquid Index Tranche Options with standard characteristics....

  3. Enhanced Photovoltaic Properties of the Solar Cells Based on Cosensitization of CdS and Hydrogenation

    Directory of Open Access Journals (Sweden)

    Hongcai He

    2015-01-01

    Full Text Available The hydrogenated TiO2 porous nanocrystalline film is modified with CdS quantum dots by successive ionic layer adsorption and reaction (SILAR method to prepare the cosensitized TiO2 solar cells by CdS quantum dots and hydrogenation. The structure and topography of the composite photoanode film were confirmed by X-ray diffraction and scanning electron microscopy. With deposited CdS nanoparticles, UV absorption spectra of H:TiO2 photoanode film indicated a considerably enhanced absorption in the visible region. The cosensitized TiO2 solar cell by CdS quantum dots and hydrogenation presents much better photovoltaic properties than either CdS sensitized TiO2 solar cells or hydrogenated TiO2 solar cells, which displays enhanced photovoltaic performance with power conversion efficiency (η of 1.99% (Jsc=6.26 mA cm−2, Voc=0.65 V, and FF = 0.49 under full one-sun illumination. The reason for the enhanced photovoltaic performance of the novel cosensitized solar cell is primarily explained by studying the Nyquist spectrums, IPCE spectra, dark current, and photovoltaic performances.

  4. What do we know about speculation in the CDS market?

    NARCIS (Netherlands)

    L. Norden (Lars); K. Radoeva (Kristina)

    2012-01-01

    textabstractWe measure speculation in the CDS market and investigate its determinants. The CDS volume on a firm that exceeds its outstanding debt (= naked CDS) indicates speculation since hedging can be ruled out. Using weekly CDS trading volume data for actively traded U.S. firms during 2008-2012,

  5. HDR-Clinical Data Service (CDS)

    Data.gov (United States)

    Department of Veterans Affairs — CDS is a SOAP/REST web service interface that supports Create, Retrieve, Update, and Delete (CRUD) operations against HDR data stores over secure Hypertext Transfer...

  6. Improving the Formatting Tools of CDS Invenio

    CERN Document Server

    Caffaro, J; Pu Faltings, Pearl

    2006-01-01

    CDS Invenio is the web-based integrated digital library system developed at CERN. It is a strategical tool that supports the archival and open dissemination of documents produced by CERN researchers. This paper reports on my Master’s thesis work done on BibFormat, a module in CDS Invenio, which formats documents metadata. The goal of this project was to implement a completely new formatting module for CDS Invenio. In this report a strong emphasis is put on the user-centered design of the new BibFormat. The bibliographic formatting process and its requirements are discussed. The task analysis and its resulting interaction model are detailed. The document also shows the implemented user interface of BibFormat and gives the results of the user evaluation of this interface. Finally the results of a small usability study of the formats included in CDS Invenio are discussed.

  7. Amorphous MoS{sub x} on CdS nanorods for highly efficient photocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaofang; Tang, Chaowan; Zheng, Qun; Shao, Yu; Li, Danzhen, E-mail: dzli@fzu.edu.cn

    2017-02-15

    Loading cocatalyst on semiconductors was crucially necessary for improving the photocatalytic hydrogen evolution. Amorphous MoS{sub x} as a novel and noble metal-free cocatalyst was loaded on CdS nanorods by a simple photodeposition method. Efficient hydrogen evolution with amount of 15 mmol h{sup −1} g{sup −1} was observed over the MoS{sub x} modified CdS nanorods, which was about 6 times higher than that by using Pt as cocatalyst. Meanwhile, with MoS{sub x} cocatalyst, the efficiency of CdS nanorods was superior to that of CdS nanoparticles and bulk CdS. No deactivation could be observed in the efficiency of MoS{sub x} modified CdS nanorods under irradiation for successive 10 h. Further experimental results indicated that the efficient electrons transfer, low overpotential of hydrogen evolution and active S atoms over the MoS{sub x} modified CdS nanorods were responsible for the higher efficiency. Our results provided guidance for synthesizing noble metal-free materials as cocatalyst for photocatalytic hydrogen evolution. - Graphical abstract: Photodeposition of amorphous MoS{sub x} on CdS nanorods for highly efficient photocatalytic hydrogen evolution. - Highlights: • Amorphous MoSx cocatalyst was loaded on CdS NRs by a simple photodeposition. • MoS{sub x}/CdS NRs exhibited 6 times higher hydrogen evolution efficiency than Pt/CdS NRs. • The hydrogen evolution of MoS{sub x}/CdS NRs linearly increased with prolonging time. • Lower overpotential and efficient electron transfer were observed over MoS{sub x}/CdS NRs.

  8. The cervical cap (image)

    Science.gov (United States)

    The cervical cap is a flexible rubber cup-like device that is filled with spermicide and self-inserted over the cervix ... left in place several hours after intercourse. The cap is a prescribed device fitted by a health ...

  9. Iron oxide nanoparticles stabilized inside highly ordered ...

    Indian Academy of Sciences (India)

    CdS nanoparticles prepared in reverse micellar system was incorporated into ... The molar ratio of various constituents of the hydrothermal gel was ... other synthesis techniques for the preparation of iron oxide nanocomposites using.

  10. Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA

    Directory of Open Access Journals (Sweden)

    Tao Kong

    2014-10-01

    Full Text Available A pentablock copolymer was prepared via the atom transfer radical polymerization of 2-hydroxyethyl methacrylate (HEMA initiated by 2-bromoisobutyryl end-capped PPO-PEO-PPO as a macroinitiator in DMF. Attaching PHEMA blocks altered the self-assembly process of the pentablock copolymer with γ-CDs in aqueous solution. Before attaching the PHEMA, the macroinitiator was preferentially bent to pass through the inner cavity of γ-CDs to give rise to tight-fit double-chain stranded polypseudorotaxanes (PPRs. After attaching the PHEMA, the resulting pentablock copolymer was single-chain stranded into the interior of γ-CDs to form more stable, loose-fit PPRs. The results of 1H NMR, WXRD, DSC, TGA, 13C CP/MAS NMR and FTIR analyses indicated that γ-CDs can accommodate and slip over PHEMA blocks to randomly distribute along the entire pentablock copolymer chain. This results in unique, single-chain stranded PPRs showing no characteristic channel-type crystal structure.

  11. Cradle Cap: Treatment

    Science.gov (United States)

    Cradle cap Treatment Cradle cap usually doesn't require medical treatment. It clears up on its own within a few months. In the meantime, wash ... tips can help you control and manage cradle cap. Gently rub your baby's scalp with your fingers ...

  12. Size-dependent photodegradation of CdS particles deposited onto TiO{sub 2} mesoporous films by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Rasin; Will, Geoffrey; Bell, John; Wang Hongxia, E-mail: hx.wang@qut.edu.au [Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering (Australia)

    2012-09-15

    The particle size, size distribution and photostability of CdS nanoparticles incorporated onto mesoporous TiO{sub 2} films by a successive ionic layer adsorption and reaction (SILAR) method were investigated by Raman spectroscopy, UV-Visible spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). High-resolution TEM indicated that the synthesized CdS particles were hexagonal phase and the particle sizes were less than 5 nm for up to nine SILAR deposition cycles. Quantum size effect was found with the CdS-sensitized TiO{sub 2} films prepared with up to nine SILAR cycles. The band gap of CdS nanoparticles decreased from 2.65 to 2.37 eV with the increase of the SILAR cycles from 1 to 11. The investigation of the stability of the CdS/TiO{sub 2} films in air under illumination (440.6 {mu}W/cm{sup 2}) showed that the photodegradation rate was up to 85 % per day for the sample prepared with three SILAR cycles. XPS analysis indicated that the photodegradation was due to the oxidation of CdS, leading to the transformation from sulphide to sulphate (CdSO{sub 4}). Furthermore, the degradation rate was strongly dependent upon the particle size of CdS. Smaller particles showed faster degradation rate. The size-dependent photo-induced oxidization was rationalized with the variation of size-dependent distribution of surface atoms of CdS particles. Molecular dynamics-based theoretical calculation has indicated that the surface sulphide anion of a large CdS particle such as CdS made with 11 cycles (CdS Multiplication-Sign 11, average particle size = 5.6 nm) accounts for 9.6 % of the material whereas this value is increased to 19.2 % for (CdS Multiplication-Sign 3)-based smaller particles (average particle size = 2.7 nm). The photostability of CdS nanoparticles was significantly enhanced when coated with ZnS particles deposited with four SILAR cycles. The growth mechanism of ZnS upon CdS nanoparticles was discussed.

  13. Template-directed nucleation and growth of CdS nanocrystal: the role of helical and nonhelical nanofibers on their shape and size

    International Nuclear Information System (INIS)

    Bose, Partha Pratim; Banerjee, Arindam

    2010-01-01

    This study describes the use of chiral nature of synthetic self-assembled nanofibers for nucleation and growth of Cadmium sulfide (CdS) nanocrystals with different sizes and shapes in room temperature. The templates are built by immobilizing a peptide capping agent on the surface of synthetic self-assembled helical or nonhelical nanofibers and CdS nanocrystals were allowed to grow on them. It is observed that there are differences in shapes and sizes of the nanocrystals depending on the chiral nature of the nanofibers on which they were growing. Even the CdS nanocrystals grown on different chiral and achiral nanofibers differ markedly in their photoluminescence properties. Thus, here we introduce a new way of using chirality of nanofibers to nucleate and grow CdS nanocrystals of different shape, size, and optical property.

  14. In situ generated CdS nanostructure induced enhanced photoluminescence from Dy{sup 3+} ions doped dielectric nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Chirantan; Karmakar, Basudeb [Glass Science and Technology Section, Glass Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India)

    2017-08-15

    We report CdS nanostructure induced enhanced photoluminescence (PL) from Dy{sup +3}:CdS co-doped dielectric-nanocomposites synthesized by the conventional melt-quench technique. CdS nanocrystals (NCs) were synthesized as in situ within the dielectric medium and their growth was controlled by heat treatment duration. Nanoparticles were investigated with absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Raman spectroscopy. The experimentally obtained sizes of the NCs are found to increase from 5-11 nm to 50-80 nm. Bandgap enhancement for the carrier confinement was found to alter within the range of 0.20-0.38 eV. Phonon confinement effect has been confirmed by blue shifting of Raman peak for CdS NCs at 303 cm{sup -1}. Enhanced highly intense sharp PL peak at 576 nm was detected, and different parameters associated with the PL enhancement including energy transfer from CdS NCs to Dy{sup 3+} ions have been studied. This PL enhancement was steered by varying CdS NC sizes. Enhanced PL of these nanocomposites finds their potential applications as gain medium in the field of solid state lasers. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Decrease of back recombination rate in CdS quantum dots sensitized solar cells using reduced graphene oxide

    International Nuclear Information System (INIS)

    Badawi Ali

    2015-01-01

    The photovoltaic performance of CdS quantum dots sensitized solar cells (QDSSCs) using the 0.2 wt% of reduced graphene oxide and TiO 2 nanoparticles (RGO+TiO 2 nanocomposite) photoanode is investigated. CdS QDs are adsorbed onto RGO+TiO 2 nanocomposite films by the successive ionic layer adsorption and reaction (SILAR) technique for several cycles. The current density–voltage (J–V) characteristic curves of the assembled QDSSCs are measured at AM1.5 simulated sunlight. The optimal photovoltaic performance for CdS QDSSC was achieved for six SILAR cycles. Solar cells based on the RGO+TiO 2 nanocomposite photoanode achieve a 33% increase in conversion efficiency (η) compared with those based on plain TiO 2 nanoparticle (NP) photoanodes. The electron back recombination rates decrease significantly for CdS QDSSCs based on RGO+TiO 2 nanocomposite photoanodes. The lifetime constant (τ) for CdS QDSSC based on the RGO+TiO 2 nanocomposite photoanode is at least one order of magnitude larger than that based on the bare TiO 2 NPs photoanode. (paper)

  16. Synthesis of CdS flower-like hierarchical microspheres as electrode material for electrochemical performance

    International Nuclear Information System (INIS)

    Kaviyarasu, K.; Manikandan, E.; Maaza, M.

    2015-01-01

    We report in this paper, a facile hydrothermal route for the preparation of CdS nanocrystals at room temperature (RT). Composition, structure and morphology of the products were analyzed and characterized by X-ray diffraction (XRD) confirms that the hydrothermal treatment at 180 °C for periods ranging from 0 to 1440 min caused no significant modification of the long range order structure subjected to hydrothermal treatment. From the XRD analysis the diffraction peaks pertaining to 26.75°, 43.89° and 52.34° are attributed to the (111), (220) and (311) planes of cubic zinc blende structure. The Photoluminescence (PL) spectra are dominated by a strong narrow band edge emission tunable in the blue region of the visible spectra indicating the narrow size distribution of CdS nanocrystals. TEM observation shows that the CdS nanocrystals synthesized by hydrothermal synthesis are well dispersed and the average crystallite size was found to be ∼10 nm. The confocal microscopic studies reveal that each flower like spheres is due to Ostwald's ripening with numerous nanoparticles aggregating a surface. - Highlights: • The adjacent particle coalesces together forming spherical particles. • The average crystalline size of CdS nanoparticles was found to be ∼3 nm. • In the case of spherical crystallite, is given by L = 3/4 D. • The CdS nanocrystal exhibits a direct band gap of 2.4 eV. • The microspheres are dispersed with good monodispersity

  17. TLC-SERS Plates with a Built-In SERS Layer Consisting of Cap-Shaped Noble Metal Nanoparticles Intended for Environmental Monitoring and Food Safety Assurance

    Directory of Open Access Journals (Sweden)

    H. Takei

    2015-01-01

    Full Text Available We report on a thin layer chromatograph (TLC with a built-in surface enhanced Raman scattering (SERS layer for in-situ identification of chemical species separated by TLC. Our goal is to monitor mixture samples or diluted target molecules suspended in a host material, as happens often in environmental monitoring or detection of food additives. We demonstrate that the TLC-SERS can separate mixture samples and provide in-situ SERS spectra. One sample investigated was a mixture consisting of equal portions of Raman-active chemical species, rhodamine 6 G (R6G, crystal violet (CV, and 1,2-di(4-pyridylethylene (BPE. The three components could be separated and their SERS spectra were obtained from different locations. Another sample was skim milk with a trace amount of melamine. Without development, no characteristic peaks were observed, but after development, a peak was observed at 694 cm−1. Unlike previous TLC-SERS whereby noble metal nanoparticles are added after development of a sample, having a built-in SERS layer greatly facilitates analysis as well as maintaining high uniformity of noble metal nanoparticles.

  18. Radioluminescence studies of colloidal oleate-capped β-Na(Gd,Lu)F4:Ln3+ nanoparticles (Ln = Ce, Eu, Tb).

    Science.gov (United States)

    Cooper, Daniel R; Capobianco, John A; Seuntjens, Jan

    2018-04-26

    We report on the synthesis, characterization, and radioluminescence quantification of several new varieties of nanoparticles with the general composition β-NaLnF4, incorporating known luminescent activator/sensitizer pairs. Using Monte Carlo modeling to complement luminescence measurements, we have calculated the radioluminescence yields and intrinsic conversion efficiencies of colloidally-dispersed nanoparticles by comparison to an organic liquid scintillator. While five of the compositions had low to modest radioluminescence yields relative to bulk materials, colloidal β-Na(Lu0.65Gd0.2Tb0.15)F4 displayed a strong output of 39 460 photons per MeV absorbed, comparable to some of the best non-hygroscopic bulk crystal scintillators and X-ray phosphors such as Gd2O2S:Tb. Measurements of β-Na(Lu0.65Gd0.2Tb0.15)F4 powder samples revealed persistent luminescence as well as stable charge trapping, warranting further investigation.

  19. A comparative study of economical separation and aggregation properties of biologically capped and thiol functionalized gold nanoparticles: selecting the eco-friendly trojan horses for biological applications.

    Science.gov (United States)

    Pandey, Sunil; Thakur, Mukeshchand; Shah, Ritu; Oza, Goldie; Mewada, Ashmi; Sharon, Madhuri

    2013-09-01

    We are presenting facile bio-fabrication of extremely stable gold nanoparticles (GNPs) using medicinal plant Azadirachta indica (commonly called Neem) and its comparison with most commonly used glutathione (GSH) protected GNPs in terms of stability under physiological conditions, seperation using density gradient centrifugation and aggregation properties in the solution. There was dual peak at 536 and 662 nm indicating the presence of non-spherical GNPs including triangles, rods and hexagons in case of A. indica mediated GNPs unlike citrate stabilized GNPs which exhibited single sharp peak. Spherical GNPs were separated from the consortium of uniquely shaped nanoparticles bio-fabricated using A. indica leaf extract using sucrose density gradient centrifugation (SDGC).To comprehend the anti-agglomeration potentials of A. indica leaf mediated GNPs and GSH-GNPs under physiological conditions, flocculation parameters (FP) were calculated and found to be least for A. indica leaf mediated GNPs, indicating their exceptional stability. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Shape induced (spherical, sheets and rods) optical and magnetic properties of CdS nanostructures with enhanced photocatalytic activity for photodegradation of methylene blue dye under ultra-violet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Bilal; Kumar, Sachin; Kumar, Sumeet; Ojha, Animesh K., E-mail: animesh@mnnit.ac.in

    2016-09-15

    CdS nanostructures of different shapes such as, nanoparticles (NPs), nanosheets (NS) and nanorods (NRs) have been synthesized by one step chemical solvothermal method. The synthesized samples were characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, UV–visible (UV-VIS) spectroscopy, Raman spectroscopy (RS) and vibrating sample magnetometer (VSM) techniques. The effect of shape on optical and magnetic properties of CdS nanostructures was studied. The optical band gap and emission spectra are found to be shape dependent. CdS NRs were found to have high saturation (Ms) magnetization than that of CdS NPs and NS. The role of shape on photocatalytic performance of CdS NPs, NS and NRs was investigated by monitoring the photodegradation of methylene blue (MB) dye under the UV irradiation of wavelength 365 nm. The lower recombination rate of electron-hole pairs and larger surface area as reactive facets for adsorption of MB dye molecules in CdS NS are mainly lead to the better photocatalytic performance of CdS NS compared to NPs and NRs. - Highlights: • Synthesis of CdS nanostructures with different shapes (spherical, rod and sheet) by easy and low cost solvothermal method. • Shape induced optical and magnetic properties of CdS nanostructures have been investigated. • The shapes of nanostructures play an important role for photocatalytic performance of CdS nanostructures.

  1. NaNO3/NaCl Oxidant and Polyethylene Glycol (PEG) Capped Gold Nanoparticles (AuNPs) as a Novel Green Route for AuNPs Detection in Electrochemical Biosensors.

    Science.gov (United States)

    López-Marzo, Adaris M; Hoyos-de-la-Torre, Raquel; Baldrich, Eva

    2018-03-20

    Gold nanoparticles (AuNPs) have been exploited as signal-producing tags in electrochemical biosensors. However, the electrochemical detection of AuNPs is currently performed using corrosive acid solutions, which may raise health and environmental concerns. Here, oxidant salts, and specifically the environmentally friendly and occupational safe NaNO 3 /NaCl mixture, have been evaluated for the first time as potential alternatives to the acid solutions traditionally used for AuNPs electrooxidation. In addition, a new strategy to improve the sensitivity of the biosensor through PEG-based ligand exchange to produce less compact and easier to oxidize AuNPs immunoconjugates is presented too. As we show, the electrochemical immunosensor using NaNO 3 /NaCl measurement solution for AuNPs electrooxidation and detection, coupled to the employment of PEG-capped nanoimmunoconjugates, produced results comparable to classical HCl detection. The procedure developed was next tested for human matrix metallopeptidase-9 (hMMP9) analysis, exhibiting a 0.18-23 ng/mL linear range, a detection limit of 0.06 ng/mL, and recoveries between 95 and 105% in spiked human plasma. These results show that the procedure developed is applicable to the analysis of protein biomarkers in blood plasma and could contribute to the development of more environmentally friendly AuNP-based electrochemical biosensors.

  2. Investigation of optical properties and the photocatalytic activity of synthesized YbYO4 nanoparticles and YbVO4/NiWO4 nanocomposites by polymeric capping agents

    Science.gov (United States)

    Pourmasoud, Saeid; Sobhani-Nasab, Ali; Behpour, Mohsen; Rahimi-Nasrabadi, Mehdi; Ahmadi, Farhad

    2018-04-01

    YbVO4 nanoparticles YbVO4/NiWO4 nanocomposites were synthesized by simple and new method. The effect of various polymeric capping agents such as Tween 80, Tween 20 and PEG on the shape and size of YbVO4/NiWO4 nanocomposites were investigated. YbVO4/NiWO4 nanocomposites were analyzed through some techniques including, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), thermogravimetry differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), field emission electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV-Vis), and energy-dispersive X-ray spectroscopy (EDX). This attempt is the first study on the photocatalytic performance of the YbVO4/NiWO4 nanocomposites in various conditions such as size of particles and kind of dyes (rhodamine B (Rh B), methylene blue (MB), methyl orange (MO), and phenol red (Ph R)), under visible light.

  3. Non-covalent interactions of cadmium sulphide and gold nanoparticles with DNA

    Science.gov (United States)

    Atay, Z.; Biver, T.; Corti, A.; Eltugral, N.; Lorenzini, E.; Masini, M.; Paolicchi, A.; Pucci, A.; Ruggeri, G.; Secco, F.; Venturini, M.

    2010-08-01

    Mercaptoethanol-capped CdS nanoparticles (CdSnp) and monohydroxy-(1-mercaptoundec-11-yl)tetraethylene-glycol-capped Au nanoparticles (Aunp) were synthesised, characterised and their interactions with DNA were investigated. Aunp are stable in different aqueous solvents, whereas CdSnp do precipitate in 0.1 M NaCl and form two different cluster types in 0.1 M NaNO3. As regards the CdSnp/DNA interaction, absorbance and fluorescence titrations, ethidium bromide displacement assays and gel electrophoresis experiments indicate that a non-covalent interaction between DNA and the CdSnp external surface does take place. The binding constant was evaluated to be equal to (2.2 ± 0.5) × 105 M-1. On the contrary, concerning Aunp, no direct interaction with DNA could be observed. Possible interaction with serum albumin was also checked, but no effects could be observed for either CdSnp or Aunp. Finally, short-time exposure of cultured cells to nanoparticles revealed the ability of CdSnp to enter the cells and allocate both in cytosol and nucleus, thus promoting cell proliferation at low concentration ( p resulted in a significant inhibition of cell growth, accompanied by apoptotic cell death. Aunp neither enter the cells, nor do affect cell proliferation. In conclusion, our data indicate that CdSnp can strongly interact with living cells and nucleic acid while no effects or interactions were observed for Aunp.

  4. Photoacoustic Study of CdS QDs for Application in Quantum-Dot-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    S. Abdallah

    2012-01-01

    Full Text Available The optical properties and photovoltaic characterization of CdS quantum dots sensitized solar cells (QDSSCs were studied. CdS QDs were prepared by the chemical solution deposition (CD technique. Photoacoustic spectroscopy (PA was employed to study the optical properties of the prepared samples. The sizes of the CdS QDs were estimated from transmission electron microscope (TEM micrographs gives radii ranged from 1.57 to 1.92 nm. The current density-voltage (J-V characteristic curves of the assembled QDSSCs were measured. Fluorine doped Tin Oxide (FTO substrates were coated with 20 nm-diameter TiO2 nanoparticles (NPs. Presynthesized colloidal CdS quantum dots of different particles size were deposited on the TiO2-coated substrates using direct adsorption (DA method. The FTO counter electrodes were coated with platinum, while the electroelectrolyte containing I-/I-3 redox species was sandwiched between the two electrodes. The short current density (Jsc and efficiency (η increases as the particle size increases. The values of Jsc increases linearly with increasing the intensities of the sun light which indicates the greater sensitivity of the assembled cells.

  5. Peroxide-Dependent Analyte Conversion by the Heme Prosthetic Group, the Heme Peptide “Microperoxidase-11” and Cytochrome c on Chitosan Capped Gold Nanoparticles Modified Electrodes

    Directory of Open Access Journals (Sweden)

    Frieder W. Scheller

    2012-05-01

    Full Text Available In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds. In order to check whether cyt c has an enzymatic activity in the native state where the protein matrix should suppress the inherent peroxidatic activity of its heme prosthetic group, we applied a biocompatible immobilization matrix and very low concentrations of the co-substrate H2O2. The biocatalysts were entrapped on the surface of a glassy carbon electrode in a biocompatible chitosan layer which contained gold nanoparticles. The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication. The catalytic efficiency of microperoxidase-11 is sufficient for sensors indicating HRP substrates, e.g., p-aminophenol, paracetamol and catechol, but also the hydroxylation of aniline and dehalogenation of 4-fluoroaniline. The lower limit of detection for p-aminophenol is comparable to previously published papers with different enzyme systems. The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

  6. Nucleation and characterization of hydroxyapatite on thioglycolic acid-capped reduced graphene oxide/silver nanoparticles in simplified simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jun; Zhang, Zhaochun, E-mail: zhangzhaochun@shu.edu.cn; Yu, Zhenwei; He, Zhenni; Yang, Shanshan; Jiang, Huiyi

    2014-01-15

    Herein hydroxyapatite (HA) has been synthesized by the nucleation on the surfaces of reduced graphene oxide/silver nanoparticles (rGO/AgNPs) chemisorbed with thioglycolic acid (TGA). The self-assembled monolayer of TGA formed on rGO/AgNPs was immersed in simplified simulated body fluid under gentle growth conditions, forming rGO/AgNPs/TGA/HA biocomposite. The phase structures and functional groups of biocomposite were analyzed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Enhanced Raman spectrum of TGA on prepared rGO/AgNPs was obtained with excitation at 633 nm, showing that TGA was chemisorbed on AgNPs through S atom and TGA molecular plane exhibited a tilted orientation with respect to AgNPs. The morphologies of biocomposite were investigated by means of atomic force microscope and transmission electron microscope coupled with energy dispersive spectrum. Analysis shows that the AgNPs uniformly distributed on the rGO nanosheets with the size of about 15–20 nm and HA formation initiated through Ca{sup 2+}-adsorption upon complexation with -COO{sup −} groups of TGA on AgNPs. The results obtained indicated that the rGO/AgNPs/TGA/HA biocomposite may have immense potential application in bone tissue engineering fields for its outstanding and stable activities.

  7. Nucleation and characterization of hydroxyapatite on thioglycolic acid-capped reduced graphene oxide/silver nanoparticles in simplified simulated body fluid

    Science.gov (United States)

    Zhao, Jun; Zhang, Zhaochun; Yu, Zhenwei; He, Zhenni; Yang, Shanshan; Jiang, Huiyi

    2014-01-01

    Herein hydroxyapatite (HA) has been synthesized by the nucleation on the surfaces of reduced graphene oxide/silver nanoparticles (rGO/AgNPs) chemisorbed with thioglycolic acid (TGA). The self-assembled monolayer of TGA formed on rGO/AgNPs was immersed in simplified simulated body fluid under gentle growth conditions, forming rGO/AgNPs/TGA/HA biocomposite. The phase structures and functional groups of biocomposite were analyzed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Enhanced Raman spectrum of TGA on prepared rGO/AgNPs was obtained with excitation at 633 nm, showing that TGA was chemisorbed on AgNPs through S atom and TGA molecular plane exhibited a tilted orientation with respect to AgNPs. The morphologies of biocomposite were investigated by means of atomic force microscope and transmission electron microscope coupled with energy dispersive spectrum. Analysis shows that the AgNPs uniformly distributed on the rGO nanosheets with the size of about 15-20 nm and HA formation initiated through Ca2+-adsorption upon complexation with sbnd COO- groups of TGA on AgNPs. The results obtained indicated that the rGO/AgNPs/TGA/HA biocomposite may have immense potential application in bone tissue engineering fields for its outstanding and stable activities.

  8. Nucleation and characterization of hydroxyapatite on thioglycolic acid-capped reduced graphene oxide/silver nanoparticles in simplified simulated body fluid

    International Nuclear Information System (INIS)

    Zhao, Jun; Zhang, Zhaochun; Yu, Zhenwei; He, Zhenni; Yang, Shanshan; Jiang, Huiyi

    2014-01-01

    Herein hydroxyapatite (HA) has been synthesized by the nucleation on the surfaces of reduced graphene oxide/silver nanoparticles (rGO/AgNPs) chemisorbed with thioglycolic acid (TGA). The self-assembled monolayer of TGA formed on rGO/AgNPs was immersed in simplified simulated body fluid under gentle growth conditions, forming rGO/AgNPs/TGA/HA biocomposite. The phase structures and functional groups of biocomposite were analyzed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Enhanced Raman spectrum of TGA on prepared rGO/AgNPs was obtained with excitation at 633 nm, showing that TGA was chemisorbed on AgNPs through S atom and TGA molecular plane exhibited a tilted orientation with respect to AgNPs. The morphologies of biocomposite were investigated by means of atomic force microscope and transmission electron microscope coupled with energy dispersive spectrum. Analysis shows that the AgNPs uniformly distributed on the rGO nanosheets with the size of about 15–20 nm and HA formation initiated through Ca 2+ -adsorption upon complexation with -COO − groups of TGA on AgNPs. The results obtained indicated that the rGO/AgNPs/TGA/HA biocomposite may have immense potential application in bone tissue engineering fields for its outstanding and stable activities.

  9. ORF Alignment: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >1g8pA 7 306 385 684 6e-05 ... emb|CAD25272.1| DNA REPLICATION LICENSING... FACTOR MCM2 [Encephalitozoon cuniculi ... GB-M1] ref|NP_584768.1| DNA REPLICATION LICENSING FACTOR ...

  10. ORF Alignment: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >1wfiA 3 125 209 328 1e-34 ... ref|NP_705268.1| nuclear movement protein..., putative [Plasmodium falciparum 3D7] ... emb|CAD52505.1| nuclear movement protein, putative ...

  11. ORF Alignment: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >1a320 1 85 35 119 3e-17 ... gb|AAK39926.1| plastidal 30S ribosomal prot...ein S15 [Guillardia theta] pir||G90099 ... plastidal 30S ribosomal protein S15 [imported] - ... ... ... Guillardia theta nucleomorph ref|NP_113370.1| plastidal ... 30S ribosomal protein S15 [Guillardia t

  12. ORF Alignment: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >1e79I 1 47 1 47 1e-07 ... pdb|1E79|I Chain I, Bovine F1-Atpase Inhibite...d By Dccd ... (Dicyclohexylcarbodiimide) pdb|1H8E|I Chain I, ... (Adp.Alf4)2(Adp.So4) Bovine F1-Atpase

  13. Arabidopsis CDS blastp result: AK068433 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK068433 J013156D16 At1g20620.2 catalase 3 (SEN2) almost identical to catalase 3 SP...:Q42547, GI:3123188 from [Arabidopsis thaliana]; identical to catalase 3 (SEN2) mRNA, partial cds GI:3158369 1e-63 ...

  14. ORF Alignment: cds [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available cds gnl|CMER >1sg6B 30 343 72 371 7e-54 ... dbj|BAD07382.1| putative 2-epi-5-epi-valiolone synthase [Actinopla...nes sp. A40644] ... Length = 300 ... Query: 89 ... SRRFCVVDDSVWAIYGEKLKAYFDERNIASK

  15. Synthesis and Characterization of Mercaptoacetic Acid Capped Cadmium Sulphide Quantum Dots.

    Science.gov (United States)

    Wageh, S; Maize, Mai; Donia, A M; Al-Ghamdi, Ahmed A; Umar, Ahmad

    2015-12-01

    This paper reports the facile synthesis and detailed characterization of mercaptoacetic acid capped cadmium sulphide (CdS) quantum dots using various cadmium precursors. The mercaptoacetic acid capped CdS quantum dots were prepared by facile and simple wet chemical method and characterized by several techniques such as energy dispersive spectroscopy (EDS), X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, UV-vis. spectroscopy, photoluminescence spectroscopy, high-resolution transmission microscopy (HRTEM) and thremogravimetric analysis. The EDS studies revealed that the prepared quantum dots possess higher atomic percentage of sulfur compared to cadmium due to the coordination of thiolate to the quantum dots surfaces. The X-ray and absorption analyses exhibited that the size of quantum dots prepared by cadmium acetate is larger than the quantum dots prepared by cadmium chloride and cadmium nitrate. The increase in size can be attributed to the low stability constant of cadmium acetate in comparison with cadmium chloride and cadmium nitrate. The FTIR and thermogravimetric analysis showed that the nature of capping molecule on the surface of quantum dots are different depending on the cadmium precursors which affect the emission from CdS quantum dots. Photoemission spectroscopy revealed that the emission of quantum dots prepared by cadmium acetate has high intensity band edge emission along with low intensity trapping state emission. However the CdS quantum dots prepared by cadmium chloride and cadmium nitrate produced only trapping state emissions.

  16. Simultaneous determination of paracetamol and ascorbic acid using tetraoctylammonium bromide capped gold nanoparticles immobilized on 1,6-hexanedithiol modified Au electrode

    International Nuclear Information System (INIS)

    Nair, Santhosh S.; John, S. Abraham; Sagara, Takamasa

    2009-01-01

    Tetraoctylammonium bromide stabilized gold nanoparticles (TOAB-AuNPs) attached to 1,6-hexanedithiol (HDT) modified Au electrode was used for the simultaneous determination of paracetamol (PA) and ascorbic acid (AA) at physiological pH. The attachment of TOAB-AuNPs on HDT modified Au surface was confirmed by attenuated total reflectance (ATR)-FT-IR spectroscopy and atomic force microscope (AFM). The ATR-FT-IR spectrum of TOAB-AuNPs attached to the HDT monolayer showed a characteristic stretching modes corresponding to -CH 2 and -CH 3 of TOAB, confirming the immobilization of AuNPs with surface-protecting TOAB ions on the surface of the AuNPs after being attached to HDT modified Au electrode. AFM image showed that the immobilized AuNPs were spherical in shape and densely packed to a film of ca. 7 nm thickness. Interestingly, TOAB-AuNPs modified electrode shifted the oxidation potential of PA towards less positive potential by 70 mV and enhanced its oxidation current twice when compared to bare Au electrode. In addition, the AuNPs modified electrode separated the oxidation potentials of AA and PA by 210 mV, whereas bare Au electrode failed to resolve them. The amperometry current of PA was increased linearly from 1.50 x 10 -7 to 1.34 x 10 -5 M with a correlation coefficient of 0.9981 and the lowest detection limit was found to be 2.6 nM (S/N = 3). The present method was successfully used to determine the concentration of PA in human blood plasma and commercial drugs.

  17. Simultaneous determination of paracetamol and ascorbic acid using tetraoctylammonium bromide capped gold nanoparticles immobilized on 1,6-hexanedithiol modified Au electrode

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Santhosh S. [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Dindigul (India); John, S. Abraham [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Dindigul (India)], E-mail: abrajohn@yahoo.co.in; Sagara, Takamasa [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Dindigul (India)], E-mail: sagara@nagasaki-u.ac.jp

    2009-11-30

    Tetraoctylammonium bromide stabilized gold nanoparticles (TOAB-AuNPs) attached to 1,6-hexanedithiol (HDT) modified Au electrode was used for the simultaneous determination of paracetamol (PA) and ascorbic acid (AA) at physiological pH. The attachment of TOAB-AuNPs on HDT modified Au surface was confirmed by attenuated total reflectance (ATR)-FT-IR spectroscopy and atomic force microscope (AFM). The ATR-FT-IR spectrum of TOAB-AuNPs attached to the HDT monolayer showed a characteristic stretching modes corresponding to -CH{sub 2} and -CH{sub 3} of TOAB, confirming the immobilization of AuNPs with surface-protecting TOAB ions on the surface of the AuNPs after being attached to HDT modified Au electrode. AFM image showed that the immobilized AuNPs were spherical in shape and densely packed to a film of ca. 7 nm thickness. Interestingly, TOAB-AuNPs modified electrode shifted the oxidation potential of PA towards less positive potential by 70 mV and enhanced its oxidation current twice when compared to bare Au electrode. In addition, the AuNPs modified electrode separated the oxidation potentials of AA and PA by 210 mV, whereas bare Au electrode failed to resolve them. The amperometry current of PA was increased linearly from 1.50 x 10{sup -7} to 1.34 x 10{sup -5} M with a correlation coefficient of 0.9981 and the lowest detection limit was found to be 2.6 nM (S/N = 3). The present method was successfully used to determine the concentration of PA in human blood plasma and commercial drugs.

  18. Microtubule's conformational cap

    DEFF Research Database (Denmark)

    Flyvbjerg, H.

    1999-01-01

    The molecular mechanisms that allow elongation of the unstable microtubule lattice remain unclear. It is usually thought that the GDP-liganded tubulin lattice is capped by a small layer of GTP- or GDP-P(i)-liganded molecules, the so called "GTP-cap". Here, we point-out that the elastic properties...

  19. Structural and Spectroscopic Studies of Sm3+/CdS Nanocrystallites in Sol-Gel TiO2-ZrO2 Matrix

    Science.gov (United States)

    Karthika, S.; Prathibha, Vasudevan; Ann, Mary K. A.; Viji, Vidyadharan; Biju, P. R.; Unnikrishnan, N. V.

    2014-02-01

    A sol-gel method was used to prepare titania-zirconia matrices doped with Sm3+/CdS nanocrystallites. The structural properties of the matrices were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Fourier-transform infrared spectroscopy studies. The thermal stability of the material was determined by TGA/DTA analysis. The absorption spectrum shows the characteristic peaks of the Sm3+ ions and the absorption peak corresponding to the CdS nanocrystallites. The optical bandgap and size of the CdS nanoparticles were calculated from the absorption spectrum. From TEM, the interplanar distance ( d) was estimated to be 3.533 Å, which matches with the (1 0 0) plane of bulk CdS. The measurements yield a nanocrystallite size of around 7.8 nm. The optical absorption and emission spectra confirmed the formation of CdS nanoparticles along with samarium ions in the titania-zirconia matrices. The fluorescence intensity of the samarium ions was found to be greatly enhanced by codoping with CdS nanocrystallites.

  20. Synthesis and characterization of cds-p (nipam-co-maa) hybrid micro gels

    International Nuclear Information System (INIS)

    Khan, M.S.; Khan, G.T.; Khan, A.

    2014-01-01

    Copolymer containing both pH and thermo sensitive properties are very much interesting due to their broad nature to various stimuli. Further, the incorporation of inorganic nanoparticles into stimuli responsive copolymers enhances their utility in different applied nature properties. In the present work such an attempt is made to synthesize copolymer of N-isopropyl acrylamide (NIPAM) and Methacrylic acid (MAA) with CdS nanoparticles. The copolymer of N-isopropyl acrylamide (NIPAM) and Methacrylic acid (MAA) was prepared through emulsion polymerization technique with various compositions and characterized by Fourier transform infrared spectroscopy (FTIR). The microspheres thus prepared were employed as micro-reactors for the deposition of semiconductor cadmium sulfide (CdS) nanoparticles. The obtained composite was characterized using optical, structural and thermal techniques. The micro gels were found to be stable up to 200 degree C. The crystal structure and grain size of Cadmium sulfide-poly (isopropylacrylamide-co-methacrylic acid) (CdS-P(NIPAM-co-MAA)) hybrid micro gels was studied by using X - ray Diffraction. UV Visible spectroscopy and photoluminescence spectroscopy was engaged to get the optical properties of the samples. It was found that the synthesized nanoparticles have a blue shift (higher energy) at about 360 nm which may be due to the typical quantum confinement effects. (author)

  1. nanoparticles

    Science.gov (United States)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  2. Electrophoretic deposition of CdS coatings and their photocatalytic activities in the degradation of tetracycline antibiotic

    Energy Technology Data Exchange (ETDEWEB)

    Vázquez, A., E-mail: alejandro.lqi@gmail.com [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico); Hernández-Uresti, D.B., E-mail: ing.dianahdz@gmail.com [Universidad Autónoma de Nuevo León, CICFIM–Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico); Obregón, S. [Universidad Autónoma de Nuevo León, CICFIM–Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico)

    2016-11-15

    Highlights: • CdS photocatalyst was prepared by electrophoretic deposition. • The CdS coating was used in the photodegradation of antibiotics. • O{sub 2}{sup −} and ·OH radicals were responsible for the degradation of tetracycline. - Abstract: The photocatalytic activities of CdS coatings formed by electrophoretic deposition (EPD) were evaluated through the photodegradation of an antibiotic, tetracycline. First, CdS nanoparticles were synthesized under microwave irradiation of aqueous solutions containing the cadmium and sulfur precursors at stoichiometric amounts and by using trisodium citrate as stabilizer. Microwave irradiation was carried out in a conventional microwave oven at 2.45 GHz and 1650 W of nominal power, for 60 s. The CdS nanoparticles were characterized by UV–vis spectrophotometry, photoluminescence and X-ray diffraction. Electrophoretic deposition parameters were 300 mV, 600 mV and 900 mV of applied voltage between aluminum plates separated by 1 cm. The fractal dimensions of the surfaces were evaluated by atomic force microscopy and correlated to the morphological and topographic characteristics of the coatings. The photocatalytic activity of the CdS coatings was investigated by means the photodegradation of the tetracycline antibiotic under simulated sunlight irradiation. According to the results, the photoactivity of the coatings directly depends on the concentration of the precursors and the applied voltage during the deposition. The material obtained at 600 mV showed the best photocatalytic behavior, probably due to its physical properties, such as optimum load and suitable aggregate size.

  3. Kalopanacis Cortex extract-capped gold nanoparticles activate NRF2 signaling and ameliorate damage in human neuronal SH-SY5Y cells exposed to oxygen–glucose deprivation and reoxygenation

    Directory of Open Access Journals (Sweden)

    Park SY

    2017-06-01

    Full Text Available Sun Young Park,1 Seon Yeong Chae,1,2 Jin Oh Park,2 Kyu Jin Lee,2 Geuntae Park1,2 1Bio-IT Fusion Technology Research Institute, 2Department of Nanofusion Technology, Graduate School, Pusan National University, Busan, Republic of Korea Abstract: Recently, environment-friendly synthesis of gold nanoparticles (GNPs has been extensively explored by biologists and chemists. However, significant research is still required to determine whether “eco-friendly” GNPs are beneficial to human health and to elucidate the molecular mechanisms of their effects on human cells. We used human neuronal SH-SY5Y cells to show that treatment with Kalopanacis Cortex extract-capped GNPs (KC-GNs, prepared via an eco-friendly, fast, one-pot synthetic route, protected neuronal cells against oxygen–glucose deprivation/reoxygenation (OGD/R-induced damage. To prepare GNPs, Kalopanacis Cortex was used without any chemical reducing and stabilizing agents. Ultraviolet–visible spectroscopy showed maximum absorbance at 526 nm owing to KC-GN surface plasmon resonance. Hydrodynamic size (54.02±2.19 nm and zeta potential (-20.3±0.04 mV were determined by dynamic light scattering. The average diameter (41.07±3.05 nm was determined by high-resolution transmission electron microscopy. Energy-dispersive X-ray diffraction spectroscopy and X-ray diffraction confirmed the presence of assembled GNPs. Fourier transform infrared analysis suggested that functional groups such as O–H, C–C, and C–N participated in KC-GN formation. Cell viability assays indicated that KC-GNs restored the viability of OGD/R-treated SH-SY5Y cells. Flow cytometry demonstrated that KC-GNs inhibited the OGD/R-induced reactive oxygen species production and mitochondrial membrane potential disruption. KC-GNs also inhibited the apoptosis of OGD/R-exposed cells. Western blot analysis indicated that the OGD/R-induced cellular apoptosis and simultaneous increases in the expression of cleaved caspase-3, p

  4. Synthesis, characterization, and applications of microheterogeneous-templated CdS nanodispersions

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Indrajyoti [Jadavpur University, Centre for Surface Science, Department of Chemistry (India); Dinda, Gargi [Jadavpur University, Department of Food Technology and Biochemical Engineering (India); Ghosh, Soumen; Moulik, Satya P., E-mail: spmcss@yahoo.com [Jadavpur University, Centre for Surface Science, Department of Chemistry (India)

    2012-08-15

    CdS nanoparticles were prepared by reacting CdCl{sub 2} and Na{sub 2}S in different microemulsions and several micellar media comprising combinations of ionic liquid, ionic, nonionic, zwitterionic amphiphiles, isopropyl alcohol, and isopropylmyristate as templates. This simple chemical method was found to be effective in the preparation of CdS dispersions mostly in the range of 3-8 nm with moderate polydispersity. The dispersions were characterized by taking UV-Vis and fluorescence spectra as well as by DLS, EDX, SEM, and TEM methods. Globular, sharp-edged elongated flake-like, and wire type morphologies were witnessed by SEM. TEM results evidenced spherical nanoentities. The dispersions witnessed both fairly and weakly semiconducting varieties; insulator-type dispersions were also observed. They have shown characteristic fluorescence properties. The nanodispersions evidenced biocidal activities toward both gram-positive and gram-negative bacteria.

  5. Synthesis of Nanocrystalline CdS by SILAR and Their Characterization

    Directory of Open Access Journals (Sweden)

    Partha Protim Chandra

    2014-01-01

    Full Text Available A simple and cost effective chemical technique has been utilized to prepare cadmium sulphide (CdS nanoparticles at room temperature. The sample is characterized with XRD (X-ray diffractometer, SEM (scanning electron microscope, TEM (transmission electron microscope, FTIR (Fourier transform infrared, EDX (energy dispersive X-rays, and UV-VIS (ultraviolet visible spectrophotometer. The particle size estimated using X-ray line broadening method is ~21.5 nm. While particle size estimation, both instrumental and strain broadening was taken into account. The lattice strain was evaluated using Williamson-Hall equation. SEM illustrates formation of submicron size crystallites and TEM image gives a particle size of ~23.5 nm. The characteristic stretching vibration frequency of CdS was observed in the absorption band in FTIR spectrum. Optical absorption study exhibits a band gap energy value of about 2.44 eV.

  6. Fluorescence Quenching of Dendrimer-Encapsulated CdS Quantum Dots for the Detection of H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyojung; Kim, Hai Dong; Kim, Joohoon [Kyung Hee Un iversity, Seoul (Korea, Republic of)

    2016-02-15

    Hydrogen peroxide (H{sub 2}O{sub 2}) exists in natural environments as a byproduct of various enzymatic and photochemical reactions. Various approaches have been reported for the synthesis of cadmium sulfide (CdS) QDs using dendrimers, which can be categorized mainly into two general approaches. The first approach utilizes dendrimers as capping agents, resulting in the formation of agglomerates of spatially segregated QDs stabilized by multiple dendrimers. We have described the synthesis and characterization of the CdS QDs using G6-NH{sub 2} dendrimers. By controlling the molar ratios (n = Cd2+/G6-NH{sub 2}) between the Cd{sup 2+} ions and G6-NH{sub 2} dendrimers, we synthesized a set of CdS QDs with different structural and optical properties. Importantly, the synthesized CdS QDs exhibited H{sub 2}O{sub 2}-sensitive fluorescence, which can be utilized for the detection of H{sub 2}O{sub 2}. Especially, the CdS QDs with n = 64 displayed a Stern–Volmer relationship between the fluorescence of the CdS QDs and the concentration of H{sub 2}O{sub 2}, as well as the strongest fluorescence among the set of the synthesized CdS QDs. Since core-shell structures of QDs often result in enhanced stability and quantum efficiency of the QDs, we are currently working on core-shell structured QDs prepared using dendrimers to improve their stability and quantum yield compared to the CdS QDs reported in the present study.

  7. CENTRIFUGE END CAP

    Science.gov (United States)

    Beams, J.W.; Snoddy, L.B.

    1960-08-01

    An end cap for ultra-gas centrifuges is designed to impart or remove angular momentum to or from the gas and to bring the entering gas to the temperature of the gas inside the centrifuge. The end cap is provided with slots or fins for adjusting the temperature and the angular momentum of the entering gas to the temperature and momentum of the gas in the centrifuge and is constructed to introduce both the inner and the peripheral stream into the centrifuge.

  8. In situ synthesis of CdS decorated titanate nanosheets with highly efficient visible-light-induced photoactivity

    International Nuclear Information System (INIS)

    Liu, Zhi; Fang, Pengfei; Liu, Fuwei; Zhang, Yupeng; Liu, Xinzhao; Lu, Dingze; Li, Delong; Wang, Shaojie

    2014-01-01

    Appropriately dispersed CdS nanoparticles were intimately embedded into titanate nanosheets (TNS) through ion-exchange and in situ sulfurization process. The sheet-like intermediates of titanate during the transforming process into nanotubes were firstly used as substrate for the decoration of CdS nanoparticles, and the synthesis route was achieved by ion-exchange process between titanate precursor and Cd 2+ ions solution, and the following sulfuration process by using Na 2 S solutions. The catalytic activity of the photocatalyst was investigated by photodegradation of Rhodamine B under visible light irradiation. With an optimal Cd/Ti molar ratio of 15%, the CdS/TNS composite exhibits the highest photocatalytic performance, which is approximately 5.4 times greater than that of pure TNS. The mechanism of the separation behavior of the photogenerated charges was also discussed.

  9. CAPS Simulation Environment Development

    Science.gov (United States)

    Murphy, Douglas G.; Hoffman, James A.

    2005-01-01

    The final design for an effective Comet/Asteroid Protection System (CAPS) will likely come after a number of competing designs have been simulated and evaluated. Because of the large number of design parameters involved in a system capable of detecting an object, accurately determining its orbit, and diverting the impact threat, a comprehensive simulation environment will be an extremely valuable tool for the CAPS designers. A successful simulation/design tool will aid the user in identifying the critical parameters in the system and eventually allow for automatic optimization of the design once the relationships of the key parameters are understood. A CAPS configuration will consist of space-based detectors whose purpose is to scan the celestial sphere in search of objects likely to make a close approach to Earth and to determine with the greatest possible accuracy the orbits of those objects. Other components of a CAPS configuration may include systems for modifying the orbits of approaching objects, either for the purpose of preventing a collision or for positioning the object into an orbit where it can be studied or used as a mineral resource. The Synergistic Engineering Environment (SEE) is a space-systems design, evaluation, and visualization software tool being leveraged to simulate these aspects of the CAPS study. The long-term goal of the SEE is to provide capabilities to allow the user to build and compare various CAPS designs by running end-to-end simulations that encompass the scanning phase, the orbit determination phase, and the orbit modification phase of a given scenario. Herein, a brief description of the expected simulation phases is provided, the current status and available features of the SEE software system is reported, and examples are shown of how the system is used to build and evaluate a CAPS detection design. Conclusions and the roadmap for future development of the SEE are also presented.

  10. Biosynthesis of fluorescent CdS nanocrystals with semiconductor properties: Comparison of microbial and plant production systems.

    Science.gov (United States)

    Al-Shalabi, Zahwa; Doran, Pauline M

    2016-04-10

    This study investigated fission yeast (Schizosaccharomyces pombe) and hairy roots of tomato (Solanum lycopersicum) as in vitro production vehicles for biological synthesis of CdS quantum dots. Cd added during the mid-growth phase of the cultures was detoxified within the biomass into inorganic sulphide-containing complexes with the quantum confinement properties of semiconductor nanocrystals. Significant differences were found between the two host systems in terms of nanoparticle production kinetics, yield and quality. The much slower growth rate of hairy roots compared with yeast is a disadvantage for commercial scaled-up production. Nanoparticle extraction from the biomass was less effective for the roots: 19% of the Cd present in the hairy roots was recovered after extraction compared with 34% for the yeast. The overall yield of CdS quantum dots was also lower for the roots: relative to the amount of Cd taken up into the biomass, 8.5% was recovered in yeast gel filtration fractions exhibiting quantum dot properties whereas the result for hairy roots was only 0.99%. Yeast-produced CdS crystallites were somewhat smaller with diameters of approximately 2-6 nm compared with those of 4-10nm obtained from the roots. The average ratio of inorganic sulphide to Cd for the purified and size-fractionated particles was 0.44 for the yeast and 1.6 for the hairy roots. Despite the limitations associated with hairy roots in terms of culture kinetics and product yield, this system produced CdS nanoparticles with enhanced photostability and 3.7-13-fold higher fluorescence quantum efficiency compared with those generated by yeast. This work demonstrates that the choice of cellular host can have a significant effect on nanoparticle functional properties as well as on the bioprocessing aspects of biological quantum dot synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Interaction between serum albumins and sonochemically synthesized cadmium sulphide nanoparticles: a spectroscopic study

    International Nuclear Information System (INIS)

    Naveenraj, Selvaraj; Asiri, Abdullah M.; Anandan, Sambandam

    2013-01-01

    Cadmium Sulphide nanoparticles approximately 5–10 nm in size range were synthesized by sonochemical technique, which follows acoustic cavitation phenomenon and generates nanoparticles with a smaller size range and higher surface area. The in vitro binding interaction of these sonochemically synthesized CdS nanoparticles with serum albumins (SA) were investigated using UV–Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques since CdS nanoparticles has biological applications such as cellular labelling and deep-tissue imaging. UV–Vis absorption and fluorescence studies confirm that CdS nanoparticles bind with SA through ground state complex formation (static quenching mechanism). The results suggest that sonochemically synthesized CdS nanoparticles interact with HSA more than that of BSA and these nanoparticles can be easily transported and rapidly released to the targets by serum albumins. CD studies confirmed the conformational change of serum albumins on the interaction of CdS nanoparticles.Graphical AbstractThis paper investigates the in vitro binding interaction of Cadmium Sulphide (CdS) nanoparticles with serum albumins (HSA and BSA) using the UV-vis, steady-state fluorescence, time-resolved fluorescence, synchronous fluorescence and circular dichroism (CD) spectral techniques.

  12. Synthesis and Characterization of Cadmium Sulfide Nanoparticles by Chemical Precipitation Method.

    Science.gov (United States)

    Devi, R Aruna; Latha, M; Velumani, S; Oza, Goldie; Reyes-Figueroa, P; Rohini, M; Becerril-Juarez, I G; Lee, Jae-Hyeong; Yi, Junsin

    2015-11-01

    Cadmium sulfide (CdS) nanoparticles were synthesized by chemical precipitation method using cadmium chloride (CdCl2), sodium sulfide (Na2S) and water as a solvent by varying temperatures from 20-80 degrees C. The nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), High-resolution transmission electron microscopy (HR-TEM) and UV-Visible spectroscopy. XRD pattern revealed cubic crystal structure for all the synthesized CdS nanoparticles. Raman spectra showed first and second order longitudinal optical (LO) phonon vibrational modes of CdS. The size of CdS nanoparticles was found to be in the range of 15-80 nm by FE-SEM analysis, in all cases. The atomic percentage of cadmium and sulfur was confirmed to be 1:1 from EDS analysis. TEM micrograph depicts the spherical shape of the particles and the size is in the range of 15-85 nm while HR-TEM images of CdS nanoparticles exhibit well-resolved lattice fringes of the cubic structure of CdS. The optical properties of CdS were examined by UV-Visible spectroscopy which showed variation in absorption band from 460-480 nm. The band gap was calculated from the absorption edge and found to be in the range of 3.2-3.5 eV which is greater than the bulk CdS.

  13. Characterization of chemically synthesized CdS nanoparticles

    Indian Academy of Sciences (India)

    currently of great interest for their practical applications such as zero- ... ports are available in the literature on synthetic techniques as well as potential applications of nano-sized semiconductor particles [5–9]. Colloidal methods pro-.

  14. Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression through suppression of p300 stabilization and NFκB/c-Jun activation in breast cancer MDA-MB-231 cells.

    Science.gov (United States)

    Chen, Ying-Jung; Lee, Yuan-Chin; Huang, Chia-Hui; Chang, Long-Sen

    2016-11-01

    Triple-negative breast cancers (TNBCs) are highly invasive and have a higher rate of distant metastasis. Matrix metalloproteinase-9 (MMP-9) plays a crucial role in EGF/EGFR-mediated malignant progression and metastasis of TNBCs. Various studies have revealed that treatment with gallic acid down-regulates MMP-9 expression in cancer cells, and that conjugation of phytochemical compounds with gold nanoparticles (AuNPs) increases the anti-tumor activity of the phytochemical compounds. Thus, the effect of gallic acid-capped AuNPs (GA-AuNPs) on MMP-9 expression in EGF-treated TNBC MDA-MB-231 cells was analyzed in the present study. The so-called green synthesis of AuNPs by means of gallic acid was performed at pH10, and the resulting GA-AuNPs had spherical shape with an average diameter of approximately 50nm. GA-AuNPs notably suppressed migration and invasion of EGF-treated cells, and inhibited EGF-induced MMP-9 up-regulation. GA-AuNPs abrogated EGF-induced Akt/p65 and ERK/c-Jun phosphorylation, leading to down-regulation of MMP-9 mRNA and protein expression in EGF-treated cells. Meanwhile, EGF-induced p300 stabilization was found to be involved in MMP-9 expression, whereas GA-AuNPs inhibited the EGF-promoted stability of the p300 protein. Although GA-AuNPs and gallic acid suppressed EGF-induced MMP-9 up-regulation via the same signaling pathway, the effective concentration of gallic acid was approximately 100-fold higher than that of GA-AuNPs for inhibition of MMP-9 expression in EGF-treated cells to a similar extent. Collectively, our data indicate that, in comparison with gallic acid, GA-AuNPs have a superior ability to inhibit EGF/EGFR-mediated MMP-9 expression in TNBC MDA-MB-231 cells. Our findings also point to a way to improve the anti-tumor activity of gallic acid. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. C. pneumoniae CdsL regulates CdsN ATPase activity, and disruption with a peptide mimetic prevents bacterial invasion

    Directory of Open Access Journals (Sweden)

    Chris Blair Stone

    2011-02-01

    Full Text Available Chlamydiae are obligate intracellular pathogens that likely require type III secretion (T3S to invade cells and replicate intracellulary within a cytoplasmic vacuole called an inclusion body. C. pneumoniae possess a YscL ortholog, CdsL, that has been shown to interact with the T3S ATPase (CdsN. In this report we demonstrate that CdsL down-regulates CdsN enzymatic activity in a dose-dependent manner. Using PepScan epitope mapping we identified two separate binding domains to which CdsL binds viz. CdsN 221-229 and CdsN265-270. We confirmed the binding domains using a pull-down assay and showed that GST-CdsN221-270, which encompasses these peptides, co-purified with His-CdsL. Next, we used orthology modeling based on the crystal structure of a T3S ATPase ortholog from E. coli, EscN, to map the binding domains on the predicted three dimensional structure of CdsN. The CdsL binding domains mapped to the catalytic domain of the ATPase, one in the central channel of the ATPase hexamer and one on the outer face. Since peptide mimetics have been used to disrupt essential protein interactions of the chlamydial T3S system and inhibit T3S-mediated invasion of HeLa cells, we hypothesized that if CdsL – CdsN binding is essential for regulating T3S then a CdsN peptide mimetic could be used to potentially block T3S and Chlamydial invasion. Treatment of EBs with a CdsN peptide mimetic inhibited C. pneumoniae invasion into HeLa cells in a dose-dependent fashion. This report represents the first use of Pepscan technology to identify binding domains for specific T3S proteins viz. CdsL on the ATPase, CdsN, and demonstrates that peptide mimetics can be used as anti-virulence factors to block bacterial invasion.

  16. Influence of two different template removal methods on the micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres

    International Nuclear Information System (INIS)

    Wang, Han; Jin, Tingting; Zheng, Xing; Jiang, Bo; Zhu, Chaosheng; Yuan, Xiangdong; Zheng, Jingtang; Wu, Mingbo

    2016-01-01

    Hollow cadmium sulfide (CdS) nanospheres of about 260 nm average diameters and about 30 nm shell thickness can be easily synthesized via a sonochemical process, in which polystyrene (PS) nanoparticles were employed as templates. In order to remove the PS templates, both etching and calcination were applied in this paper. The influence of the two different template removal methods on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres was carefully performed a comparative study. Results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, FT-IR, thermogravimetric analysis, Brunauer–Emmett–Teller, diffused reflectance spectra, and decolorization experiments showed that the different template removal methods exhibited a significant influence on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres. The CdS hollow nanospheres as-prepared by etching had pure cubic sphalerite structure, higher –OH content, less defects and exhibited good photocatalytic activity for rhodamine-B, Methylene Blue and methyl orange under UV–vis light irradiation. However, CdS hollow nanospheres obtained by calcination with a hexagonal crystal structure, less –OH content, more defects have shown worse photocatalytic activity. This indicated that surface micromorphology and crystalline phase were mainly factors influencing photocatalytic activity of hollow CdS nanospheres.

  17. Influence of two different template removal methods on the micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres

    Science.gov (United States)

    Wang, Han; Jin, Tingting; Zheng, Xing; Jiang, Bo; Zhu, Chaosheng; Yuan, Xiangdong; Zheng, Jingtang; Wu, Mingbo

    2016-11-01

    Hollow cadmium sulfide (CdS) nanospheres of about 260 nm average diameters and about 30 nm shell thickness can be easily synthesized via a sonochemical process, in which polystyrene (PS) nanoparticles were employed as templates. In order to remove the PS templates, both etching and calcination were applied in this paper. The influence of the two different template removal methods on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres was carefully performed a comparative study. Results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, FT-IR, thermogravimetric analysis, Brunauer-Emmett-Teller, diffused reflectance spectra, and decolorization experiments showed that the different template removal methods exhibited a significant influence on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres. The CdS hollow nanospheres as-prepared by etching had pure cubic sphalerite structure, higher -OH content, less defects and exhibited good photocatalytic activity for rhodamine-B, Methylene Blue and methyl orange under UV-vis light irradiation. However, CdS hollow nanospheres obtained by calcination with a hexagonal crystal structure, less -OH content, more defects have shown worse photocatalytic activity. This indicated that surface micromorphology and crystalline phase were mainly factors influencing photocatalytic activity of hollow CdS nanospheres.

  18. Influence of two different template removal methods on the micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Han; Jin, Tingting [China University of Petroleum, State Key Laboratory of Heavy Oil Processing (China); Zheng, Xing, E-mail: znhk113@163.com [Beijing ZNHK Science and Technology Development Co., Ltd. (China); Jiang, Bo; Zhu, Chaosheng [China University of Petroleum, State Key Laboratory of Heavy Oil Processing (China); Yuan, Xiangdong [Baotou Light Industry and Vocational Technical College (China); Zheng, Jingtang, E-mail: jtzheng03@163.com; Wu, Mingbo [China University of Petroleum, State Key Laboratory of Heavy Oil Processing (China)

    2016-11-15

    Hollow cadmium sulfide (CdS) nanospheres of about 260 nm average diameters and about 30 nm shell thickness can be easily synthesized via a sonochemical process, in which polystyrene (PS) nanoparticles were employed as templates. In order to remove the PS templates, both etching and calcination were applied in this paper. The influence of the two different template removal methods on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres was carefully performed a comparative study. Results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, FT-IR, thermogravimetric analysis, Brunauer–Emmett–Teller, diffused reflectance spectra, and decolorization experiments showed that the different template removal methods exhibited a significant influence on the surface micromorphology, crystal structure, and photocatalytic activity of hollow CdS nanospheres. The CdS hollow nanospheres as-prepared by etching had pure cubic sphalerite structure, higher –OH content, less defects and exhibited good photocatalytic activity for rhodamine-B, Methylene Blue and methyl orange under UV–vis light irradiation. However, CdS hollow nanospheres obtained by calcination with a hexagonal crystal structure, less –OH content, more defects have shown worse photocatalytic activity. This indicated that surface micromorphology and crystalline phase were mainly factors influencing photocatalytic activity of hollow CdS nanospheres.

  19. Sequential electro-deposition of Bi{sub 2}S{sub 3}/CdS films as co-sensitizer photoanodes for liquid junction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Atanu; Hazra, Prasenjit; Hazra, Mukul; Datta, Jayati, E-mail: jayati_datta@rediffmail.com

    2016-11-01

    In this investigation multilayered conjugate films are formulated with Bi{sub 2}S{sub 3} and CdS nanoparticles (NPs) on FTO glass substrate. Thin layer Bi{sub 2}S{sub 3} was deposited and subsequently covered with various levels of CdS coating. Optical properties and XRD analysis of the films show existence of both the compound phases. The morphology of the films studied through electron microscopy reveals coverage of spherical CdS NPs on the network of Bi{sub 2}S{sub 3} NPs. The electrochemical impedance records and performances output characteristics of the n-type films show that the most efficient co-sensitizer matrix is produced with deep coating of CdS on thin layer of Bi{sub 2}S{sub 3}. - Highlights: • Multilayered Bi{sub 2}S{sub 3}/CdS conjugate films are formulated on FTO glass substrate. • Photo-degradation of Bi{sub 2}S{sub 3} is restricted by the coating of CdS layer. • High level of Cd coating on thin layer of Bi{sub 2}S{sub 3} have shown appreciable photocurrent output. • Photo-conversion efficiency of 0.93% is observed for the best conjugate film.

  20. Controllable architecture of CdS and CuS by single-source precursor-mediated approach and their photocatalytic activity

    International Nuclear Information System (INIS)

    Sahoo, Ashish K.; Srivastava, Suneel K.

    2013-01-01

    The present work deals with the preparation of hexagonal CdS and CuS by solvothermal decomposition of the morpholine-4-carbdithioate (MCDT) complexes of Cd and Cu in a water/THF mixture at 140–180 °C for 24 h and characterization. Scanning electron microscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy show that CdS exhibits a hierarchical star- and lotus flower-like morphology in the presence of disodium salt of ethylenediamine tetraaceticacid and sodium dodecyl benzene sulphonate as soft templates at 140 and 160 °C, respectively. However, Cu complex of MCDT forms CuS nanoparticles in the temperature range of 140–180 °C. On the contrary, CdS nanoparticles and CuS microparticles are formed in the absence of any template under the identical experimental conditions. Raman studies show the characteristic peak of CdS and CuS, irrespective of their size and morphology. Finally, CdS and CuS of varying morphology have successfully been used as catalysts in UV photocatalytic decomposition of methylene blue dye. These findings show that CdS lotus-like microflowers are more effective catalysts than hierarchical stars, though the latter is found to have better reusability.Graphical AbstractA simple soft template-assisted and single complex source precursor-mediated solvothermal synthesis of CdS and CuS with a diverse set of morphology has been reported. In addition, the morphology and application in photocatalysis are also discussed.

  1. Controllable architecture of CdS and CuS by single-source precursor-mediated approach and their photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Ashish K.; Srivastava, Suneel K., E-mail: sunil111954@yahoo.co.uk [Indian Institute of Technology Kharagpur, Department of Chemistry (India)

    2013-04-15

    The present work deals with the preparation of hexagonal CdS and CuS by solvothermal decomposition of the morpholine-4-carbdithioate (MCDT) complexes of Cd and Cu in a water/THF mixture at 140-180 Degree-Sign C for 24 h and characterization. Scanning electron microscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy show that CdS exhibits a hierarchical star- and lotus flower-like morphology in the presence of disodium salt of ethylenediamine tetraaceticacid and sodium dodecyl benzene sulphonate as soft templates at 140 and 160 Degree-Sign C, respectively. However, Cu complex of MCDT forms CuS nanoparticles in the temperature range of 140-180 Degree-Sign C. On the contrary, CdS nanoparticles and CuS microparticles are formed in the absence of any template under the identical experimental conditions. Raman studies show the characteristic peak of CdS and CuS, irrespective of their size and morphology. Finally, CdS and CuS of varying morphology have successfully been used as catalysts in UV photocatalytic decomposition of methylene blue dye. These findings show that CdS lotus-like microflowers are more effective catalysts than hierarchical stars, though the latter is found to have better reusability.Graphical AbstractA simple soft template-assisted and single complex source precursor-mediated solvothermal synthesis of CdS and CuS with a diverse set of morphology has been reported. In addition, the morphology and application in photocatalysis are also discussed.

  2. Thioglycolic acid-capped CdS quantum dots modified with Co2+ as ...

    Indian Academy of Sciences (India)

    54

    showed high selectivity toward the detection of dopamine over other ... several methods have been developed for the detection of DA including high performance liquid chromatography (HPLC) [11,12], electrochemistry [13,14], capillary ...

  3. Organic–Inorganic Nanostructure Architecture via Directly Capping Fullerenes onto Quantum Dots

    Directory of Open Access Journals (Sweden)

    Kim Jonggi

    2011-01-01

    Full Text Available Abstract A new form of fullerene-capped CdSe nanoparticles (PCBA-capped CdSe NPs, using carboxylate ligands with [60]fullerene capping groups that provides an effective synthetic methodology to attach fullerenes noncovalently to CdSe, is presented for usage in nanotechnology and photoelectric fields. Interestingly, either the internal charge transfer or the energy transfer in the hybrid material contributes to photoluminescence (PL quenching of the CdSe moieties.

  4. Organic-Inorganic Nanostructure Architecture via Directly Capping Fullerenes onto Quantum Dots.

    Science.gov (United States)

    Lee, Jae Kwan; Kim, Jonggi; Yang, Changduk

    2011-12-01

    A new form of fullerene-capped CdSe nanoparticles (PCBA-capped CdSe NPs), using carboxylate ligands with [60]fullerene capping groups that provides an effective synthetic methodology to attach fullerenes noncovalently to CdSe, is presented for usage in nanotechnology and photoelectric fields. Interestingly, either the internal charge transfer or the energy transfer in the hybrid material contributes to photoluminescence (PL) quenching of the CdSe moieties.

  5. Asymmetric Hybrid Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chumanov, George [Clemson Univ., SC (United States)

    2015-11-05

    Hybrid Nanoparticles (AHNs) are rationally-designed multifunctional nanostructures and novel building blocks for the next generation of advanced materials and devices. Nanoscale materials attract considerable interest because of their unusual properties and potential for practical applications. Most of the activity in this field is focused on the synthesis of homogeneous nanoparticles from metals, metal oxides, semiconductors, and polymers. It is well recognized that properties of nanoparticles can be further enhanced if they are made as hybrid structures. This program is concerned with the synthesis, characterization, and application of such hybrid structures termed AHNs. AHNs are composed of a homogeneous core and several caps of different materials deposited on its surface (Fig. 1). Combined properties of the core and the caps as well as new properties that arise from core-cap and cap-cap interactions render AHNs multifunctional. In addition, specific chemical reactivity of the caps enables directional self-assembly of AHNs into complex architectures that are not possible with only spherical nanoparticles.

  6. North Polar Cap

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour. In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime. The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap. Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen

  7. Regime-dependent determinants of Euro area sovereign CDS spreads

    NARCIS (Netherlands)

    Blommestein, H.J.; Eijffinger, Sylvester; Qian, Zongxin

    We study the determinants of sovereign CDS spreads of five Euro area countries (Greece, Ireland, Italy, Portugal, and Spain) after the collapse of Lehman Brothers. We find that global and/or European Monetary Union (EMU)-wide factors are the main drivers of changes in the sovereign CDS spreads in

  8. Direct Z-scheme TiO2/CdS hierarchical photocatalyst for enhanced photocatalytic H2-production activity

    Science.gov (United States)

    Meng, Aiyun; Zhu, Bicheng; Zhong, Bo; Zhang, Liuyang; Cheng, Bei

    2017-11-01

    Photocatalytic H2 evolution, which utilizes solar energy via water splitting, is a promising route to deal with concerns about energy and environment. Herein, a direct Z-scheme TiO2/CdS binary hierarchical photocatalyst was fabricated via a successive ionic layer adsorption and reaction (SILAR) technique, and photocatalytic H2 production was measured afterwards. The as-prepared TiO2/CdS hybrid photocatalyst exhibited noticeably promoted photocatalytic H2-production activity of 51.4 μmol h-1. The enhancement of photocatalytic activity was ascribed to the hierarchical structure, as well as the efficient charge separation and migration from TiO2 nanosheets to CdS nanoparticles (NPs) at their tight contact interfaces. Moreover, the direct Z-scheme photocatalytic reaction mechanism was demonstrated to elucidate the improved photocatalytic performance of TiO2/CdS composite photocatalyst. The photoluminescence (PL) analysis of hydroxyl radicals were conducted to provide clues for the direct Z-scheme mechanism. This work provides a facile route for the construction of redox mediator-free Z-scheme photocatalytic system for photocatalytic water splitting.

  9. Designing Smart Charter School Caps

    Science.gov (United States)

    Dillon, Erin

    2010-01-01

    In 2007, Andrew J. Rotherham proposed a new approach to the contentious issue of charter school caps, the statutory limits on charter school growth in place in several states. Rotherham's proposal, termed "smart charter school caps," called for quality sensitive caps that allow the expansion of high-performing charter schools while also…

  10. Synthesis of CdS Nanocrystals by Employing the By-Products of the Anaerobic Respiratory Process of Desulfovibrio alaskensis 6SR Bacteria

    Directory of Open Access Journals (Sweden)

    L. G. Rangel-Chávez

    2015-01-01

    Full Text Available A novel methodology for the direct synthesis of CdS nanoparticles, using a biological agent that avoids the extracellular processing, and the results of the characterization of CdS nanocrystals are presented. The by-products of the anaerobic respiratory process of Desulfovibrio alaskensis 6SR along with aqueous solutions of Cd salts were successfully employed to produce CdS nanocrystals with mixed cubic and hexagonal phases. Nanocrystal size has a narrow size distribution with little dependence on the Cd concentration. Both the presence of the crystallographic cubic phase and the crystalline order decrease as Cd concentration increases. The band gap values obtained from optical transmission measurements are lower than those of the bulk crystal. Raman spectroscopy characterization agrees with electron transmission microscopy images and X-ray diffraction results indicating that the method promotes the formation of high structural quality nanocrystals when low concentrations of the Cd salt are used.

  11. Technical training: CERN Document Server (CDS), Inspire and Library Services

    CERN Multimedia

    IT & GS Departments

    2012-01-01

    A new training course, “CERN Document Server (CDS), Inspire and Library Services”, is available since the beginning of the year. The training course is given by members of CERN’s CDS Team (IT-CIS group) and the Library Services (GIS SIS group) and is intended for all members of personnel of CERN. This course will present CDS and inspirehep.net and the content, scope and scientific information available in or with CDS, as much as the classification and organization of the documents. It is intended to give you the training needed to know how to use CDS most efficiently and in particular covers: the main characteristics and advanced features for the search of documents (scientific, multimedia, etc). the collaborative tools : baskets, alerts, comments, evaluation, etc. the submission of documents in CDS and examples of workflows. An important part of the training is composed of various exercises, designed to acquire practical ability to work with CDS in cases similar to re...

  12. Hydrogen-induced electrical and optical switching in Pd capped Pr ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. In this study, modification in the properties of hydrogen-induced switchable mirror based on Pr nanoparticle layers is reported. The reversible changes in hydrogen-induced electrical and optical properties of Pd capped Pr nanoparticle layers have been studied as a function of hydrogenation time and compared.

  13. Effect of CdS Growth Time on the Optical Properties of One-Pot Preparation of CdS-Ag2S Binary Compounds

    Science.gov (United States)

    Karimipour, M.; Izadian, L.; Molaei, M.

    2018-02-01

    CdS-Ag2S binary nanoparticles were synthesized using a facile one-pot microwave irradiation method. The effect of initial nucleation of CdS quantum dots (QDs) using 3 min, 5 min, and 7 min of microwave irradiation on the optical properties of the final compound was studied. The composition and crystal structure of the compounds were verified using energy dispersive x-ray spectroscopy and x-ray diffraction. They revealed that existence of Ag and Cd elements with an atomic ratio of 0.19 crystalizes in the form of monoclinic Ag2S and hexagonal CdS. Scanning electron microscope images showed a spherical morphology of the resultant compound, and transmission electron microscope images showed the formation of fine particles of CdS-Ag2S composites with an average size of 5-7 nm and 10-14 nm for CdS and Ag2S, respectively. Photoluminescence spectroscopy revealed that the initial growth time of CdS has a crucial effect on the emission of binary compounds such that for 3 min and 5 min of irradiation of CdS solution, the binary compound obtains strong red and considerable near-IR emission (850 nm), but for longer time, it rapidly quenches. The results indicate that the strong red emission can be tuned from 600 nm up to 700 nm with prolonging nucleation time of CdS. This study also emphasized that the origin of red emission strongly depends on the size and defects created in the CdS QDs.

  14. Synthesis and characterization of TiO{sub 2}/CdS core-shell nanorod arrays and their photoelectrochemical property

    Energy Technology Data Exchange (ETDEWEB)

    Cao Chunlan [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Department of Power Engineer, Chongqing Communication College, Chongqing 400035 (China); Hu Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Shen Weidong [Department of Power Engineer, Chongqing Communication College, Chongqing 400035 (China); Wang, Shuxia [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Tian Yongshu [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Department of Power Engineer, Chongqing Communication College, Chongqing 400035 (China); Wang Xue [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer TiO{sub 2}/CdS core-shell nanorod arrays were fabricated by spin-SILAR method. Black-Right-Pointing-Pointer The enhanced photocurrent was found in the TiO{sub 2}/CdS core-shell nanorod arrays. Black-Right-Pointing-Pointer The CdS coated on TiO{sub 2} increases the e-h separation and enlarges light absorption range. - Abstract: TiO{sub 2}/CdS core-shell nanorod arrays have been fabricated via a two-step method. Vertically aligned TiO{sub 2} nanorod arrays (NRs) were synthesized by a facile hydrothermal method, and followed by depositing CdS nanoparticles on TiO{sub 2} NRs by spin-coating successive ion layer adsorption and reaction (spin-SILAR) method. The surface morphology, structure, optical and photoelectrochemical behaviors of the core-shell NRs films are considered. The UV-vis absorption spectrum results suggested that the absorption peak of the TiO{sub 2}/CdS core-shell NRs shifts from the ultraviolet region to the visible region in comparison to that of the pure TiO{sub 2} NRs. The obviously enhanced photoelectrochemical (PEC) performances of the heterojunction NRs were found under illumination of the simulated sunlight in comparison with that of the TiO{sub 2} NRs. The enhanced PEC performance and formation mechanism of TiO{sub 2}/CdS core-shell NRs were discussed in detail.

  15. TiO2-CdS Nanocomposites: Effect of CdS Oxidation on the Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    A. Hamdi

    2016-01-01

    Full Text Available Nanocomposites TiO2-CdS with different relative contents of CdS (molar ratios Cd/Ti = 0.02, 0.03, 0.05, 0.1, 0.2, and 0.5 were studied. The structural, photophysical, and chemical properties were investigated using XRD, Raman spectroscopy, XPS, GSDR, and LIL. XRD and Raman results confirmed the presence of TiO2 and CdS with intensities dependent on the ratio Cd/Ti. The presence of CdSO4 was detected by XPS at the surface of all TiO2-CdS composites. The relative amount of sulphate was dependent on the CdS loading. Luminescence time-resolved spectra clearly proved the existence of an excitation transfer process from CdS to TiO2 through the luminescence emission from TiO2 after excitation of CdS at λexc=410 nm, where no direct excitation of TiO2 occurs. Photodegradation of a series of aromatic carboxylic acids—benzoic, salicylic, 4-bromobenzoic, 3-phenylpropionic, and veratric acids—showed a great enhancement in the photocatalytic efficiency of the TiO2-CdS composites, which is due, mainly, to the effect of the charge carriers’ increased lifetime. In addition, it was shown that the oxidation of CdS to CdSO4 did not result in the deactivation of the photocatalytic properties and even contributed to enhance the degradation efficiency.

  16. Non-covalent interactions of cadmium sulphide and gold nanoparticles with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Atay, Z. [Bogazici University, Department of Chemistry (Turkey); Biver, T., E-mail: tarita@dcci.unipi.i [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy); Corti, A. [Universita di Pisa, Dipartimento di Patologia Sperimentale BMIE (Italy); Eltugral, N. [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy); Lorenzini, E.; Masini, M.; Paolicchi, A. [Universita di Pisa, Dipartimento di Patologia Sperimentale BMIE (Italy); Pucci, A.; Ruggeri, G.; Secco, F.; Venturini, M. [Universita di Pisa, Dipartimento di Chimica e Chimica Industriale (Italy)

    2010-08-15

    Mercaptoethanol-capped CdS nanoparticles (CdS{sub np}) and monohydroxy-(1-mercaptoundec-11-yl)tetraethylene-glycol-capped Au nanoparticles (Au{sub np}) were synthesised, characterised and their interactions with DNA were investigated. Au{sub np} are stable in different aqueous solvents, whereas CdS{sub np} do precipitate in 0.1 M NaCl and form two different cluster types in 0.1 M NaNO{sub 3}. As regards the CdS{sub np}/DNA interaction, absorbance and fluorescence titrations, ethidium bromide displacement assays and gel electrophoresis experiments indicate that a non-covalent interaction between DNA and the CdS{sub np} external surface does take place. The binding constant was evaluated to be equal to (2.2 {+-} 0.5) x 10{sup 5} M{sup -1}. On the contrary, concerning Au{sub np}, no direct interaction with DNA could be observed. Possible interaction with serum albumin was also checked, but no effects could be observed for either CdS{sub np} or Au{sub np}. Finally, short-time exposure of cultured cells to nanoparticles revealed the ability of CdS{sub np} to enter the cells and allocate both in cytosol and nucleus, thus promoting cell proliferation at low concentration (p < 0.005), while longer-time exposure resulted in a significant inhibition of cell growth, accompanied by apoptotic cell death. Au{sub np} neither enter the cells, nor do affect cell proliferation. In conclusion, our data indicate that CdS{sub np} can strongly interact with living cells and nucleic acid while no effects or interactions were observed for Au{sub np}.

  17. Synthesis of hierarchically meso-macroporous TiO2/CdS heterojunction photocatalysts with excellent visible-light photocatalytic activity.

    Science.gov (United States)

    Zhao, Haixin; Cui, Shu; Yang, Lan; Li, Guodong; Li, Nan; Li, Xiaotian

    2018-02-15

    Photocatalysts with a hierarchically porous structure have attracted considerable attention owing to their wide pore size distribution and high surface area, which enhance the efficiency of transporting species to active sites. In this study, hierarchically meso-macroporous TiO 2 photocatalysts decorated with highly dispersed CdS nanoparticles were synthesized via hydrolysis, followed by a hydrothermal treatment. The textural mesopores and interconnected pore framework provided more accessible active sites and efficient mass transport for the photocatalytic process. The light collection efficiency was enhanced because of multiple scattering of incident light in the macropores. Moreover, the formation of a heterojunction between the Cd