Differential plasma protein binding to metal oxide nanoparticles

International Nuclear Information System (INIS)

Deng, Zhou J; Mortimer, Gysell; Minchin, Rodney F; Schiller, Tara; Musumeci, Anthony; Martin, Darren

2009-01-01

Nanoparticles rapidly interact with the proteins present in biological fluids, such as blood. The proteins that are adsorbed onto the surface potentially dictate the biokinetics of the nanomaterials and their fate in vivo. Using nanoparticles with different sizes and surface characteristics, studies have reported the effects of physicochemical properties on the composition of adsorbed plasma proteins. However, to date, few studies have been conducted focusing on the nanoparticles that are commonly exposed to the general public, such as the metal oxides. Using previously established ultracentrifugation approaches, two-dimensional gel electrophoresis and mass spectrometry, the current study investigated the binding of human plasma proteins to commercially available titanium dioxide, silicon dioxide and zinc oxide nanoparticles. We found that, despite these particles having similar surface charges in buffer, they bound different plasma proteins. For TiO 2 , the shape of the nanoparticles was also an important determinant of protein binding. Agglomeration in water was observed for all of the nanoparticles and both TiO 2 and ZnO further agglomerated in biological media. This led to an increase in the amount and number of different proteins bound to these nanoparticles. Proteins with important biological functions were identified, including immunoglobulins, lipoproteins, acute-phase proteins and proteins involved in complement pathways and coagulation. These results provide important insights into which human plasma proteins bind to particular metal oxide nanoparticles. Because protein absorption to nanoparticles may determine their interaction with cells and tissues in vivo, understanding how and why plasma proteins are adsorbed to these particles may be important for understanding their biological responses.

Cytotoxicity and oxidative stress induced by different metallic nanoparticles on human kidney cells

Directory of Open Access Journals (Sweden)

Ohayon-Courtès Céline

2011-03-01

Full Text Available Abstract Background Some manufactured nanoparticles are metal-based and have a wide variety of applications in electronic, engineering and medicine. Until now, many studies have described the potential toxicity of NPs on pulmonary target, while little attention has been paid to kidney which is considered to be a secondary target organ. The objective of this study, on human renal culture cells, was to assess the toxicity profile of metallic nanoparticles (TiO2, ZnO and CdS usable in industrial production. Comparative studies were conducted, to identify whether particle properties impact cytotoxicity by altering the intracellular oxidative status. Results Nanoparticles were first characterized by size, surface charge, dispersion and solubility. Cytotoxicity of NPs was then evaluated in IP15 (glomerular mesangial and HK-2 (epithelial proximal cell lines. ZnO and CdS NPs significantly increased the cell mortality, in a dose-dependent manner. Cytotoxic effects were correlated with the physicochemical properties of NPs tested and the cell type used. Analysis of reactive oxygen species and intracellular levels of reduced and oxidized glutathione revealed that particles induced stress according to their composition, size and solubility. Protein involved in oxidative stress such as NF-κb was activated with ZnO and CdS nanoparticles. Such effects were not observed with TiO2 nanoparticles. Conclusion On glomerular and tubular human renal cells, ZnO and CdS nanoparticles exerted cytotoxic effects that were correlated with metal composition, particle scale and metal solubility. ROS production and oxidative stress induction clearly indicated their nephrotoxic potential.

Electrochromic device containing metal oxide nanoparticles and ultraviolet blocking material

Science.gov (United States)

Garcia, Guillermo; Koo, Bonil; Gregoratto, Ivano; Basu, Sourav; Rosen, Evelyn; Holt, Jason; Thomsen, Scott

2017-10-17

An electrochromic device includes a nanostructured transition metal oxide bronze layer that includes one or more transition metal oxide and one or more dopant. The electrochromic device also includes nanoparticles containing one or more transparent conducting oxide (TCO), a solid state electrolyte, a counter electrode, and at least one protective layer to prevent degradation of the one or more nanostructured transition metal oxide bronze. The nanostructured transition metal oxide bronze selectively modulates transmittance of near-infrared (NIR) and visible radiation as a function of an applied voltage to the device.

Metal Oxide Nanoparticle Photoresists for EUV Patterning

KAUST Repository

Jiang, Jing

2014-01-01

© 2014SPST. Previous studies of methacrylate based nanoparticle have demonstrated the excellent pattern forming capability of these hybrid materials when used as photoresists under 13.5 nm EUV exposure. HfO2 and ZrO2 methacrylate resists have achieved high resolution (∼22 nm) at a very high EUV sensitivity (4.2 mJ/cm2). Further investigations into the patterning process suggests a ligand displacement mechanism, wherein, any combination of a metal oxide with the correct ligand could generate patterns in the presence of the suitable photoactive compound. The current investigation extends this study by developing new nanoparticle compositions with transdimethylacrylic acid and o-toluic acid ligands. This study describes their synthesis and patterning performance under 248 nm KrF laser (DUV) and also under 13.5 nm EUV exposures (dimethylacrylate nanoparticles) for the new resist compositions.

Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

Science.gov (United States)

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

2012-12-01

For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

KAUST Repository

Jin, Zhao; Xiao, Manda; Bao, Zhihong; Wang, Peng; Wang, Jianfang

2012-01-01

Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

KAUST Repository

Jin, Zhao

2012-04-26

Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO 2/0.1 mol Pd microspheres showed the highest turnover frequency in NaBH 4 reduction of 4-nitrophenol (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transition Metal Dopants Essential for Producing Ferromagnetism in Metal Oxide Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Johnson, Lydia; Thurber, Aaron P.; Anghel, Josh; Sabetian, Maryam; Engelhard, Mark H.; Tenne, D.; Hanna, Charles; Punnoose, Alex

2010-08-13

Recent claims that ferromagnetism can be produced in nanoparticles of metal oxides without the presence of transition metal dopants has been refuted in this work by investigating 62 high quality well-characterized nanoparticle samples of both undoped and Fe doped (0-10% Fe) ZnO. The undoped ZnO nanoparticles showed zero or negligible magnetization, without any dependence on the nanoparticle size. However, chemically synthesized Zn₁₋xFexO nanoparticles showed clear ferromagnetism, varying systematically with Fe concentration. Furthermore, the magnetic properties of Zn₁₋xFexO nanoparticles showed strong dependence on the reaction media used to prepare the samples. The zeta potentials of the Zn₁₋xFexO nanoparticles prepared using different reaction media were significantly different, indicating strong differences in the surface structure. Electron paramagnetic resonance studies clearly showed that the difference in the ferromagnetic properties of Zn₁₋xFexO nanoparticles with different surface structures originate from differences in the fraction of the doped Fe³⁺ ions that are coupled ferromagnetically.

Size characterization of metal oxide nanoparticles in commercial sunscreen products

Science.gov (United States)

Bairi, Venu Gopal; Lim, Jin-Hee; Fong, Andrew; Linder, Sean W.

2017-07-01

There is an increase in the usage of engineered metal oxide (TiO2 and ZnO) nanoparticles in commercial sunscreens due to their pleasing esthetics and greater sun protection efficiency. A number of studies have been done concerning the safety of nanoparticles in sunscreen products. In order to do the safety assessment, it is pertinent to develop novel analytical techniques to analyze these nanoparticles in commercial sunscreens. This study is focused on developing analytical techniques that can efficiently determine particle size of metal oxides present in the commercial sunscreens. To isolate the mineral UV filters from the organic matrices, specific procedures such as solvent extraction were identified. In addition, several solvents (hexane, chloroform, dichloromethane, and tetrahydrofuran) have been investigated. The solvent extraction using tetrahydrofuran worked well for all the samples investigated. The isolated nanoparticles were characterized by using several different techniques such as transmission electron microscopy, scanning electron microscopy, dynamic light scattering, differential centrifugal sedimentation, and x-ray diffraction. Elemental analysis mapping studies were performed to obtain individual chemical and morphological identities of the nanoparticles. Results from the electron microscopy techniques were compared against the bulk particle sizing techniques. All of the sunscreen products tested in this study were found to contain nanosized (≤100 nm) metal oxide particles with varied shapes and aspect ratios, and four among the 11 products were showed to have anatase TiO2.

Environmental dynamics of metal oxide nanoparticles in heterogeneous systems: A review

International Nuclear Information System (INIS)

Joo, Sung Hee; Zhao, Dongye

2017-01-01

Highlights: • Influence of contaminants on the mobility of metal oxide nanoparticles (MNPs). • Synergistic effects of MNPs in the presence of contaminants. • Effect of environmental factors on the transformed MNPs. • Research direction on the toxicity modeling assessment of heterogeneous systems. - Abstract: Metal oxide nanoparticles (MNPs) have been used for many purposes including water treatment, health, cosmetics, electronics, food packaging, and even food products. As their applications continue to expand, concerns have been mounting about the environmental fate and potential health risks of the nanoparticles in the environment. Based on the latest information, this review provides an overview of the factors that affect the fate, transformation and toxicity of MNPs. Emphasis is placed on the effects of various aquatic contaminants under various environmental conditions on the transformation of metal oxides and their transport kinetics – both in homogeneous and heterogeneous systems – and the effects of contaminants on the toxicity of MNPs. The presence of existing contaminants decreases bioavailability through hetero-aggregation, sorption, and/or complexation upon an interaction with MNPs. Contaminants also influence the fate and transport of MNPs and exhibit their synergistic toxic effects that contribute to the extent of the toxicity. This review will help regulators, engineers, and scientists in this field to understand the latest development on MNPs, their interactions with aquatic contaminants as well as the environmental dynamics of their fate and transformation. The knowledge gap and future research needs are also identified, and the challenges in assessing the environmental fate and transport of nanoparticles in heterogeneous systems are discussed.

Environmental dynamics of metal oxide nanoparticles in heterogeneous systems: A review

Energy Technology Data Exchange (ETDEWEB)

Joo, Sung Hee, E-mail: s.joo1@miami.edu [Department of Civil, Architectural, and Environmental Engineering, University of Miami, 1251 Memorial Dr. McArthur Engineering Building, Coral Gables, FL 33146-0630 (United States); Zhao, Dongye [Department of Civil and Environmental Engineering, 238 Harbert Engineering Center, Auburn University, Auburn, AL 36849 (United States)

2017-01-15

Highlights: • Influence of contaminants on the mobility of metal oxide nanoparticles (MNPs). • Synergistic effects of MNPs in the presence of contaminants. • Effect of environmental factors on the transformed MNPs. • Research direction on the toxicity modeling assessment of heterogeneous systems. - Abstract: Metal oxide nanoparticles (MNPs) have been used for many purposes including water treatment, health, cosmetics, electronics, food packaging, and even food products. As their applications continue to expand, concerns have been mounting about the environmental fate and potential health risks of the nanoparticles in the environment. Based on the latest information, this review provides an overview of the factors that affect the fate, transformation and toxicity of MNPs. Emphasis is placed on the effects of various aquatic contaminants under various environmental conditions on the transformation of metal oxides and their transport kinetics – both in homogeneous and heterogeneous systems – and the effects of contaminants on the toxicity of MNPs. The presence of existing contaminants decreases bioavailability through hetero-aggregation, sorption, and/or complexation upon an interaction with MNPs. Contaminants also influence the fate and transport of MNPs and exhibit their synergistic toxic effects that contribute to the extent of the toxicity. This review will help regulators, engineers, and scientists in this field to understand the latest development on MNPs, their interactions with aquatic contaminants as well as the environmental dynamics of their fate and transformation. The knowledge gap and future research needs are also identified, and the challenges in assessing the environmental fate and transport of nanoparticles in heterogeneous systems are discussed.

Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview

Directory of Open Access Journals (Sweden)

Kaja Kasemets

2008-08-01

Full Text Available Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles.

Uptake, accumulation, and biotransformation of metal oxide nanoparticles by a marine suspension-feeder

International Nuclear Information System (INIS)

Montes, Milka O.; Hanna, Shannon K.; Lenihan, Hunter S.; Keller, Arturo A.

2012-01-01

Highlights: ► Suspension-feeding by mussels can greatly alter mobility and fate of metal oxide nanoparticles. ► Bioprocessing of metal oxide nanoparticles by mussels removes large fraction from water column. ► Mussels repackage metal oxide nanoparticles in highly concentrated pseudofeces. ► Novel biological pathway between major compartments in marine systems. ► Very different outcome for ZnO and CeO 2 nanoparticles based on their solubility. - Abstract: A growing body of evidence indicates that some engineered nanoparticles (ENPs) are toxic to organisms that perform important ecosystem services in terrestrial and aquatic ecosystems. However, toxicity can be influenced by the biotransformation of contaminants, including ENPs, as it may alter the fate and transport of these substances. In turn, fate and transport can influence their bioavailability. To understand how biotransformation influences the fate and transport of ENPs in marine ecosystems, we exposed suspension-feeding mussels, Mytilus galloprovincialis, to two common nano-metal oxides, CeO 2 and ZnO, over a range of concentrations from 1 mg L −1 to 10 mg L −1 , in a laboratory experiment. Mussels exposed to 10 mg L −1 accumulated 62 μg g −1 of Ce and 880 μg g −1 of Zn on a dry tissue basis but rejected 21,000 μg g −1 for Ce and 63,000 μg g −1 for Zn in pseudofeces. Scanning electron microscope evidence indicates CeO 2 remained as ENPs but ZnO did not after being rejected by the mussels. Mussels filtered most of the CeO 2 from the aqueous media, while a significant fraction of Zn remained in solution. Differences in ENP solubility affect ENP uptake, excretion, and accumulation in mussels. Our study highlights the potential role of marine suspension feeders in biotransformation of ENPs.

A simple urea-based route to ternary metal oxynitride nanoparticles

International Nuclear Information System (INIS)

Gomathi, A.; Reshma, S.; Rao, C.N.R.

2009-01-01

Ternary metal oxynitrides are generally prepared by heating the corresponding metal oxides with ammonia for long durations at high temperatures. In order to find a simple route that avoids use of gaseous ammonia, we have employed urea as the nitriding agent. In this method, ternary metal oxynitrides are obtained by heating the corresponding metal carbonates and transition metal oxides with excess urea. By this route, ternary metal oxynitrides of the formulae MTaO 2 N (M=Ca, Sr or Ba), MNbO 2 N (M=Sr or Ba), LaTiO 2 N and SrMoO 3-x N x have been prepared successfully. The oxynitrides so obtained were generally in the form of nanoparticles, and were characterized by various physical techniques. - Graphical abstract: Nanoparticles of ternary metal oxynitrides can be synthesized by means of urea route. Given is the TEM image of the nanoparticles of CaTaO 2 N so obtained and the insets show the SAED pattern and HREM image of the nanoparticles

Systematic study of ligand structures of metal oxide EUV nanoparticle photoresists

KAUST Repository

Jiang, Jing

2015-03-19

Ligand stabilized metal oxide nanoparticle resists are promising candidates for EUV lithography due to their high sensitivity for high-resolution patterning and high etching resistance. As ligand exchange is responsible for the patterning mechanism, we systematically studied the influence of ligand structures of metal oxide EUV nanoparticles on their sensitivity and dissolution behavior. ZrO2 nanoparticles were protected with various aromatic ligands with electron withdrawing and electron donating groups. These nanoparticles have lower sensitivity compared to those with aliphatic ligands suggesting the structures of these ligands is more important than their pka on resist sensitivity. The influence of ligand structure was further studied by comparing the nanoparticles’ solubility for a single type ligand to mixtures of ligands. The mixture of nanoparticles showed improved pattern quality. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Is Neurotoxicity of Metallic Nanoparticles the Cascades of Oxidative Stress?

Science.gov (United States)

Song, Bin; Zhang, YanLi; Liu, Jia; Feng, XiaoLi; Zhou, Ting; Shao, LongQuan

2016-06-01

With the rapid development of nanotechnology, metallic (metal or metal oxide) nanoparticles (NPs) are widely used in many fields such as cosmetics, the food and building industries, and bio-medical instruments. Widespread applications of metallic NP-based products increase the health risk associated with human exposures. Studies revealed that the brain, a critical organ that consumes substantial amounts of oxygen, is a primary target of metallic NPs once they are absorbed into the body. Oxidative stress (OS), apoptosis, and the inflammatory response are believed to be the main mechanisms underlying the neurotoxicity of metallic NPs. Other studies have disclosed that antioxidant pretreatment or co-treatment can reverse the neurotoxicity of metallic NPs by decreasing the level of reactive oxygen species, up-regulating the activities of antioxidant enzymes, decreasing the proportion of apoptotic cells, and suppressing the inflammatory response. These findings suggest that the neurotoxicity of metallic NPs might involve a cascade of events following NP-induced OS. However, additional research is needed to determine whether NP-induced OS plays a central role in the neurotoxicity of metallic NPs, to develop a comprehensive understanding of the correlations among neurotoxic mechanisms and to improve the bio-safety of metallic NP-based products.

Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nano tubes and Their Applications

International Nuclear Information System (INIS)

Motshekga, S.C.; Pillai, S.K.; Ray, S.S.; Motshekga, S.C.; Ray, S.S.; Jalama, K.; Krause, Rui.W.M.

2012-01-01

The study of coating carbon nano tubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nano tubes in various applications, it is necessary to attach functional groups or other nano structures to their surface. The combination of the distinctive properties of carbon nano tubes and metal/oxides is expected to be applied in field emission displays, nano electronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nano tube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Recent Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nanotubes and Their Applications

Directory of Open Access Journals (Sweden)

Sarah C. Motshekga

2012-01-01

Full Text Available The study of coating carbon nanotubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nanotubes in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of carbon nanotubes and metal/oxides is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nanotube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

Chemoelectronic circuits based on metal nanoparticles

Science.gov (United States)

Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

2016-07-01

To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

Global DNA methylation and oxidative stress biomarkers in workers exposed to metal oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Liou, Saou-Hsing; Wu, Wei-Te; Liao, Hui-Yi [National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China); Chen, Chao-Yu; Tsai, Cheng-Yen; Jung, Wei-Ting [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China); Lee, Hui-Ling, E-mail: huilinglee3573@gmail.com [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China)

2017-06-05

Highlights: • Global methylation and oxidative DNA damage levels in nanomaterial handling workers were assessed. • 8-isoprostane in exhaled breath condensate of workers exposed to nanoparticles was higher. • 8-OHdG was negatively correlated with global methylation. • Exposure to metal oxide nanoparticles may lead to global methylation and DNA oxidative damage. - Abstract: This is the first study to assess global methylation, oxidative DNA damage, and lipid peroxidation in workers with occupational exposure to metal oxide nanomaterials (NMs). Urinary and white blood cell (WBC) 8-hydroxydeoxyguanosine (8-OHdG), and exhaled breath condensate (EBC) 8-isoprostane were measured as oxidative stress biomarkers. WBC global methylation was measured as an epigenetic alteration. Exposure to TiO{sub 2}, SiO{sub 2,} and indium tin oxide (ITO) resulted in significantly higher oxidative biomarkers such as urinary 8-OHdG and EBC 8-isoprostane. However, significantly higher WBC 8-OHdG and lower global methylation were only observed in ITO handling workers. Significant positive correlations were noted between WBC and urinary 8-OHdG (Spearman correlation r = 0.256, p = 0.003). Furthermore, a significant negative correlation was found between WBC 8-OHdG and global methylation (r = −0.272, p = 0.002). These results suggest that exposure to metal oxide NMs may lead to global methylation, DNA oxidative damage, and lipid peroxidation.

Depositing laser-generated nanoparticles on powders for additive manufacturing of oxide dispersed strengthened alloy parts via laser metal deposition

Science.gov (United States)

Streubel, René; Wilms, Markus B.; Doñate-Buendía, Carlos; Weisheit, Andreas; Barcikowski, Stephan; Henrich Schleifenbaum, Johannes; Gökce, Bilal

2018-04-01

We present a novel route for the adsorption of pulsed laser-dispersed nanoparticles onto metal powders in aqueous solution without using any binders or surfactants. By electrostatic interaction, we deposit Y2O3 nanoparticles onto iron-chromium based powders and obtain a high dispersion of nano-sized particles on the metallic powders. Within the additively manufactured component, we show that the particle spacing of the oxide inclusion can be adjusted by the initial mass fraction of the adsorbed Y2O3 particles on the micropowder. Thus, our procedure constitutes a robust route for additive manufacturing of oxide dispersion-strengthened alloys via oxide nanoparticles supported on steel micropowders.

Uptake, accumulation, and biotransformation of metal oxide nanoparticles by a marine suspension-feeder

Energy Technology Data Exchange (ETDEWEB)

Montes, Milka O. [University of California Center for Environmental Implications of Nanotechnology, Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106 (United States); University of Texas of the Permian Basin, 4901 E. University, Odessa, TX 79762 (United States); Hanna, Shannon K.; Lenihan, Hunter S. [University of California Center for Environmental Implications of Nanotechnology, Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106 (United States); Keller, Arturo A., E-mail: keller@bren.ucsb.edu [University of California Center for Environmental Implications of Nanotechnology, Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106 (United States)

2012-07-30

Highlights: Black-Right-Pointing-Pointer Suspension-feeding by mussels can greatly alter mobility and fate of metal oxide nanoparticles. Black-Right-Pointing-Pointer Bioprocessing of metal oxide nanoparticles by mussels removes large fraction from water column. Black-Right-Pointing-Pointer Mussels repackage metal oxide nanoparticles in highly concentrated pseudofeces. Black-Right-Pointing-Pointer Novel biological pathway between major compartments in marine systems. Black-Right-Pointing-Pointer Very different outcome for ZnO and CeO{sub 2} nanoparticles based on their solubility. - Abstract: A growing body of evidence indicates that some engineered nanoparticles (ENPs) are toxic to organisms that perform important ecosystem services in terrestrial and aquatic ecosystems. However, toxicity can be influenced by the biotransformation of contaminants, including ENPs, as it may alter the fate and transport of these substances. In turn, fate and transport can influence their bioavailability. To understand how biotransformation influences the fate and transport of ENPs in marine ecosystems, we exposed suspension-feeding mussels, Mytilus galloprovincialis, to two common nano-metal oxides, CeO{sub 2} and ZnO, over a range of concentrations from 1 mg L{sup -1} to 10 mg L{sup -1}, in a laboratory experiment. Mussels exposed to 10 mg L{sup -1} accumulated 62 {mu}g g{sup -1} of Ce and 880 {mu}g g{sup -1} of Zn on a dry tissue basis but rejected 21,000 {mu}g g{sup -1} for Ce and 63,000 {mu}g g{sup -1} for Zn in pseudofeces. Scanning electron microscope evidence indicates CeO{sub 2} remained as ENPs but ZnO did not after being rejected by the mussels. Mussels filtered most of the CeO{sub 2} from the aqueous media, while a significant fraction of Zn remained in solution. Differences in ENP solubility affect ENP uptake, excretion, and accumulation in mussels. Our study highlights the potential role of marine suspension feeders in biotransformation of ENPs.

Electrochemical determination of serotonin in urine samples based on metal oxide nanoparticles/MWCNT on modified glassy carbon electrode

Directory of Open Access Journals (Sweden)

Omolola E. Fayemi

2017-04-01

Full Text Available The electrochemical response of serotonin on the modified electrode based on multiwalled-carbon-nanotube (MWCNT doped respectively with nickel, zinc and iron oxide nanoparticles coating on glassy carbon electrode (GCE at physiological pH 7 was determined using cyclic voltammetry (CV and square wave voltammetry (SWV. The modified GCE/MWCNT-metal oxide electrodes exhibited excellent electrocatalytic activity towards the detection of serotonin at large peak current and lower oxidation potentials compared to other electrodes investigated. The dynamic range for the serotonin determination was between 5.98 × 10−3 μM to 62.8 μM with detection limits 118, 129 and 166 nM for GCE/MWCNT-NiO, GCE/MWCNT-ZnO and GCE/MWCNT-Fe3O4 sensors respectively. GCE-MWCNT-NiO was the best electrode in terms of serotonin current response, electrode stability, resistance to fouling and limit of detection towards the analyte. The developed sensors were found to be electrochemically stable, reusable, economically effective due to their extremely low operational cost, and have demonstrated good limit of detection, sensitivity and selectivity towards serotonin determination in urine samples. Keywords: Metal oxides nanoparticles, Multiwalled carbon nanotubes, Glassy carbon electrode, Serotonin, Cyclic voltammetry, Square wave voltammetry

In vitro antiplasmodial activity of PDDS-coated metal oxide nanoparticles against Plasmodium falciparum

Science.gov (United States)

Jacob Inbaneson, Samuel; Ravikumar, Sundaram

2013-06-01

Malaria is the most important parasitic disease, leading to annual death of about one million people and the Plasmodium falciparum develops resistant to well-established antimalarial drugs. The newest antiplasmodial drug from metal oxide nanoparticles helps in addressing this problem. Commercial nanoparticles such as Fe3O4, MgO, ZrO2, Al2O3 and CeO2 coated with PDDS and all the coated and non-coated nanoparticles were screened for antiplasmodial activity against P. falciparum. The Al2O3 nanoparticles (71.42 ± 0.49 μg ml-1) showed minimum level of IC50 value and followed by MgO (72.33 ± 0.37 μg ml-1) and Fe3O4 nanoparticles (77.23 ± 0.42 μg ml-1). The PDDS-Fe3O4 showed minimum level of IC50 value (48.66 ± 0.45 μg ml-1), followed by PDDS-MgO (60.28 ± 0.42 μg ml-1) and PDDS-CeO2 (67.06 ± 0.61 μg ml-1). The PDDS-coated metal oxide nanoparticles showed superior antiplasmodial activity than the non-PDDS-coated metal oxide nanoparticles. Statistical analysis reveals that, significant in vitro antiplasmodial activity ( P activity and it might be used for the development of antiplasmodial drugs.

Toxicity of Transition Metal Oxide Nanoparticles: Recent Insights from in vitro Studies

Directory of Open Access Journals (Sweden)

Robert S. Aronstam

2010-10-01

Full Text Available Nanotechnology has evolved to play a prominent role in our economy. Increased use of nanomaterials poses potential human health risk. It is therefore critical to understand the nature and origin of the toxicity imposed by nanomaterials (nanotoxicity. In this article we review the toxicity of the transition metal oxides in the 4th period that are widely used in industry and biotechnology. Nanoparticle toxicity is compellingly related to oxidative stress and alteration of calcium homeostasis, gene expression, pro-inflammatory responses, and cellular signaling events. The precise physicochemical properties that dictate the toxicity of nanoparticles have yet to be defined, but may include element-specific surface catalytic activity (e.g., metallic, semiconducting properties, nanoparticle uptake, or nanoparticle dissolution. These in vitro studies substantially advance our understanding in mechanisms of toxicity, which may lead to safer design of nanomaterials.

From basic physics to mechanisms of toxicity: the ``liquid drop'' approach applied to develop predictive classification models for toxicity of metal oxide nanoparticles

Science.gov (United States)

Sizochenko, Natalia; Rasulev, Bakhtiyor; Gajewicz, Agnieszka; Kuz'min, Victor; Puzyn, Tomasz; Leszczynski, Jerzy

2014-10-01

Many metal oxide nanoparticles are able to cause persistent stress to live organisms, including humans, when discharged to the environment. To understand the mechanism of metal oxide nanoparticles' toxicity and reduce the number of experiments, the development of predictive toxicity models is important. In this study, performed on a series of nanoparticles, the comparative quantitative-structure activity relationship (nano-QSAR) analyses of their toxicity towards E. coli and HaCaT cells were established. A new approach for representation of nanoparticles' structure is presented. For description of the supramolecular structure of nanoparticles the ``liquid drop'' model was applied. It is expected that a novel, proposed approach could be of general use for predictions related to nanomaterials. In addition, in our study fragmental simplex descriptors and several ligand-metal binding characteristics were calculated. The developed nano-QSAR models were validated and reliably predict the toxicity of all studied metal oxide nanoparticles. Based on the comparative analysis of contributed properties in both models the LDM-based descriptors were revealed to have an almost similar level of contribution to toxicity in both cases, while other parameters (van der Waals interactions, electronegativity and metal-ligand binding characteristics) have unequal contribution levels. In addition, the models developed here suggest different mechanisms of nanotoxicity for these two types of cells.Many metal oxide nanoparticles are able to cause persistent stress to live organisms, including humans, when discharged to the environment. To understand the mechanism of metal oxide nanoparticles' toxicity and reduce the number of experiments, the development of predictive toxicity models is important. In this study, performed on a series of nanoparticles, the comparative quantitative-structure activity relationship (nano-QSAR) analyses of their toxicity towards E. coli and HaCaT cells were

Biomedical application of hierarchically built structures based on metal oxides

Science.gov (United States)

Korovin, M. S.; Fomenko, A. N.

2017-12-01

Nowadays, the use of hierarchically built structures in biology and medicine arouses much interest. The aim of this work is to review and summarize the available literature data about hierarchically organized structures in biomedical application. Nanoparticles can serve as an example of such structures. Medicine holds a special place among various application methods of similar systems. Special attention is paid to inorganic nanoparticles based on different metal oxides and hydroxides, such as iron, zinc, copper, and aluminum. Our investigations show that low-dimensional nanostructures based on aluminum oxides and hydroxides have an inhibitory effect on tumor cells and possess an antimicrobial activity. At the same time, it is obvious that the large-scale use of nanoparticles by humans needs to thoroughly study their properties. Special attention should be paid to the study of nanoparticle interaction with living biological objects. The numerous data show that there is no clear understanding of interaction mechanisms between nanoparticles and various cell types.

Metal-based nanoparticle interactions with the nervous system: The challenge of brain entry and the risk of retention in the organism

Science.gov (United States)

This review of metal and metal-oxide based nanoparticles focuses on factors that influence their distribution into the nervous system, evidence that they enter brain parenchyma, and nervous system responses. Emphasis is placed on gold as a model metal-based nanoparticle and for r...

Microwave-assisted one-pot synthesis of metal/metal oxide nanoparticles on graphene and their electrochemical applications

International Nuclear Information System (INIS)

Wang Shuangyin; Jiang San Ping; Wang Xin

2011-01-01

Graphical abstract: Display Omitted Research highlights: → Microwave polyol method is efficient to deposit nanoparticles on graphene. → SnO 2 /graphene is more efficient than graphene for supercapacitor. → PtRu/graphene is more active than commercial PtRu/C for methanol oxidation. - Abstract: An effective synthesis strategy of hybrid metal (PtRu)/metal oxide (SnO 2 ) nanoparticles on graphene nanocomposites is developed using a microwave-assisted one-pot reaction process. The mixture of ethylene glycol (EG) and water is used as both solvent and reactant. In the reaction system for the synthesis of SnO 2 /graphene nanocomposite, EG not only reduces graphene oxide (GO) to graphene, but also results in the formation of SnO 2 facilitated by the presence of a small amount of water. On the other hand, in the reaction system for preparation of PtRu/graphene nanocomposites, EG acts as solvent and reducing agent for reduction of PtRu nanoparticles from their precursors and reduction of graphene from graphene oxide. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) characterizations confirm the feasibility of the microwave-assisted reaction system to simultaneously reduce graphene oxide and to form SnO 2 or PtRu nanoparticles. The as-synthesized SnO 2 /graphene hybrid composites show a much higher supercapacitance than the pure graphene, and the as-prepared PtRu/graphene show much better electrocatalytic activity for methanol oxidation compared to the commercial E-TEK PtRu/C electrocatalysts.

Free-Standing Metal Oxide Nanoparticle Superlattices Constructed with Engineered Protein Containers Show in Crystallo Catalytic Activity.

Science.gov (United States)

Lach, Marcel; Künzle, Matthias; Beck, Tobias

2017-12-11

The construction of defined nanostructured catalysts is challenging. In previous work, we established a strategy to assemble binary nanoparticle superlattices with oppositely charged protein containers as building blocks. Here, we show that these free-standing nanoparticle superlattices are catalytically active. The metal oxide nanoparticles inside the protein scaffold are accessible for a range of substrates and show oxidase-like and peroxidase-like activity. The stable superlattices can be reused for several reaction cycles. In contrast to bulk nanoparticle-based catalysts, which are prone to aggregation and difficult to characterize, nanoparticle superlattices based on engineered protein containers provide an innovative synthetic route to structurally defined heterogeneous catalysts with control over nanoparticle size and composition. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface interactions affect the toxicity of engineered metal oxide nanoparticles toward Paramecium.

Science.gov (United States)

Li, Kungang; Chen, Ying; Zhang, Wen; Pu, Zhichao; Jiang, Lin; Chen, Yongsheng

2012-08-20

To better understand the potential impacts of engineered metal oxide nanoparticles (NPs) in the ecosystem, we investigated the acute toxicity of seven different types of engineered metal oxide NPs against Paramecium multimicronucleatum, a ciliated protozoan, using the 48 h LC(50) (lethal concentration, 50%) test. Our results showed that the 48 h LC(50) values of these NPs to Paramecium ranged from 0.81 (Fe(2)O(3) NPs) to 9269 mg/L (Al(2)O(3) NPs); their toxicity to Paramecium increased as follows: Al(2)O(3) Paramecium; this implies that metal oxide NPs with strong association with the cell surface might induce more severe cytotoxicity in unicellular organisms.

Airway irritation, inflammation, and toxicity in mice following inhalation of metal oxide nanoparticles

DEFF Research Database (Denmark)

Larsen, Søren T; Jackson, Petra; Poulsen, Steen S

2016-01-01

Metal oxide nanoparticles are used in a broad range of industrial processes and workers may be exposed to aerosols of the particles both during production and handling. Despite the widespread use of these particles, relatively few studies have been performed to investigate the toxicological effects...... in the airways following inhalation. In the present study, the acute (24 h) and persistent (13 weeks) effects in the airways after a single exposure to metal oxide nanoparticles were studied using a murine inhalation model. Mice were exposed 60 min to aerosols of either ZnO, TiO2, Al2O3 or CeO2 and the deposited...

Comparison of properties of silver-metal oxide electrical contact materials

Directory of Open Access Journals (Sweden)

Ćosović V.

2012-01-01

Full Text Available Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

Iron Oxide Nanoparticle-Based Magnetic Ink Development for Fully Printed Tunable Radio-Frequency Devices

KAUST Repository

Vaseem, Mohammad

2018-01-30

The field of printed electronics is still in its infancy and most of the reported work is based on commercially available nanoparticle-based metallic inks. Although fully printed devices that employ dielectric/semiconductor inks have recently been reported, there is a dearth of functional inks that can demonstrate controllable devices. The lack of availability of functional inks is a barrier to the widespread use of fully printed devices. For radio-frequency electronics, magnetic materials have many uses in reconfigurable components but rely on expensive and rigid ferrite materials. A suitable magnetic ink can facilitate the realization of fully printed, magnetically controlled, tunable devices. This report presents the development of an iron oxide nanoparticle-based magnetic ink. First, a tunable inductor is fully printed using iron oxide nanoparticle-based magnetic ink. Furthermore, iron oxide nanoparticles are functionalized with oleic acid to make them compatible with a UV-curable SU8 solution. Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as-fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna is demonstrated using the magnetic and in-house silver-organo-complex inks. This is a step toward low-cost, fully printed, controllable electronic components.

Metal oxide nanoparticle mediated enhanced Raman scattering and its use in direct monitoring of interfacial chemical reactions.

Science.gov (United States)

Li, Li; Hutter, Tanya; Finnemore, Alexander S; Huang, Fu Min; Baumberg, Jeremy J; Elliott, Stephen R; Steiner, Ullrich; Mahajan, Sumeet

2012-08-08

Metal oxide nanoparticles (MONPs) have widespread usage across many disciplines, but monitoring molecular processes at their surfaces in situ has not been possible. Here we demonstrate that MONPs give highly enhanced (×10(4)) Raman scattering signals from molecules at the interface permitting direct monitoring of their reactions, when placed on top of flat metallic surfaces. Experiments with different metal oxide materials and molecules indicate that the enhancement is generic and operates at the single nanoparticle level. Simulations confirm that the amplification is principally electromagnetic and is a result of optical modulation of the underlying plasmonic metallic surface by MONPs, which act as scattering antennae and couple light into the confined region sandwiched by the underlying surface. Because of additional functionalities of metal oxides as magnetic, photoelectrochemical and catalytic materials, enhanced Raman scattering mediated by MONPs opens up significant opportunities in fundamental science, allowing direct tracking and understanding of application-specific transformations at such interfaces. We show a first example by monitoring the MONP-assisted photocatalytic decomposition reaction of an organic dye by individual nanoparticles.

Understanding Atom Probe Tomography of Oxide-Supported Metal Nanoparticles by Correlation with Atomic-Resolution Electron Microscopy and Field Evaporation Simulation.

Science.gov (United States)

Devaraj, Arun; Colby, Robert; Vurpillot, François; Thevuthasan, Suntharampillai

2014-04-17

Oxide-supported metal nanoparticles are widely used in heterogeneous catalysis. The increasingly detailed design of such catalysts necessitates three-dimensional characterization with high spatial resolution and elemental selectivity. Laser-assisted atom probe tomography (APT) is uniquely suited to the task but faces challenges with the evaporation of metal/insulator systems. Correlation of APT with aberration-corrected scanning transmission electron microscopy (STEM), for Au nanoparticles embedded in MgO, reveals preferential evaporation of the MgO and an inaccurate assessment of nanoparticle composition. Finite element field evaporation modeling is used to illustrate the evolution of the evaporation front. Nanoparticle composition is most accurately predicted when the MgO is treated as having a locally variable evaporation field, indicating the importance of considering laser-oxide interactions and the evaporation of various molecular oxide ions. These results demonstrate the viability of APT for analysis of oxide-supported metal nanoparticles, highlighting the need for developing a theoretical framework for the evaporation of heterogeneous materials.

Performance and properties of anodes reinforced with metal oxide nanoparticles for molten carbonate fuel cells

Science.gov (United States)

Accardo, Grazia; Frattini, Domenico; Yoon, Sung Pil; Ham, Hyung Chul; Nam, Suk Woo

2017-12-01

Development of electrode materials for molten carbonate fuel cells is a fundamental issue as a balance between mechanical and electrochemical properties is required due to the particular operating environments of these cells. As concern the anode, a viable strategy is to use nano-reinforced particles during electrodes' fabrication. Candidate nanomaterials comprise, but are not limited to, ZrO2, CeO2, TiO2, Ti, Mg, Al, etc. This work deals with the characterization and test of two different types of hard oxide nanoparticles as reinforce for NiAl-based anodes in molten carbonate fuel cells. Nano ceria and nano zirconia are compared each other and single cell test performances are presented. Compared to literature, the use of hard metal oxide nanoparticles allows good performance and promising perspectives with respect to the use a third alloying metal. However, nano zirconia performed slightly better than nano ceria as polarization and power curves are higher even if nano ceria has the highest mechanical properties. This means that the choice of nanoparticles to obtain improved anodes performance and properties is not trivial and a trade-off between relevant properties plays a key role.

Method for producing metallic nanoparticles

Science.gov (United States)

Phillips, Jonathan; Perry, William L.; Kroenke, William J.

2004-02-10

Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

Basic metal carbonate supported gold nanoparticles: enhanced performance in aerobic alcohol oxidation

NARCIS (Netherlands)

Yang, J.; Guan, Y.; Verhoeven, M.W.G.M.; Santen, van R.A.; Li, Can; Hensen, E.J.M.

2009-01-01

Gold nanoparticles supported by basic hydrozincite or bismuth carbonate are excellent catalysts for liquid-phase aerobic alcohol oxidation: the performance of a series of metal (Zn, Bi, Ce, La, Zr) carbonate supported gold catalysts depends strongly on the basicity of the support material.

Increased mobility of metal oxide nanoparticles due to photo and thermal induced disagglomeration.

Directory of Open Access Journals (Sweden)

Dongxu Zhou

Full Text Available Significant advances have been made on our understanding of the fate and transport of engineered nanomaterials. One unexplored aspect of nanoparticle aggregation is how environmental stimuli such as light exposure and temperature variations affect the mobility of engineered nanoparticles. In this study, TiO(2, ZnO, and CeO(2 were chosen as model materials for investigating the mobility of nanoparticles under three external stimuli: heat, light and sonication. Sunlight and high power sonication were able to partially disagglomerate metal oxide clusters, but primary particles bonded by solid state necks were left intact. A cycle of temperature increase from 25°C to 65°C and then decrease back was found to disagglomerate the compact clusters in the heating phase and reagglomerate them as more open fractal structures during the cooling phase. A fractal model summing the pair-wise DLVO interactions between primary particles within two fractal agglomerates predicts weak attractions on the order of a few kT. Our study shows that common environmental stimuli such as light exposure or temperature variation can disagglomerate nanoparticle clusters and enhance their mobility in open waters. This phenomenon warrants attention since it is likely that metal oxide nanoparticles will experience these natural stimuli during their transport in the environment.

A halogen-free synthesis of gold nanoparticles using gold(III) oxide

International Nuclear Information System (INIS)

Sashuk, Volodymyr; Rogaczewski, Konrad

2016-01-01

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.

CeO2/rGO/Pt sandwich nanostructure: rGO-enhanced electron transmission between metal oxide and metal nanoparticles for anodic methanol oxidation of direct methanol fuel cells.

Science.gov (United States)

Yu, Xue; Kuai, Long; Geng, Baoyou

2012-09-21

Pt-based nanocomposites have been of great research interest. In this paper, we design an efficient MO/rGO/Pt sandwich nanostructure as an anodic electrocatalyst for DMFCs with combination of the merits of rigid structure of metallic oxides (MOs) and excellent electronic conductivity of reduced oxidized graphene (rGO) as well as overcoming their shortcomings. In this case, the CeO(2)/rGO/Pt sandwich nanostructure is successfully fabricated through a facile hydrothermal approach in the presence of graphene oxide and CeO(2) nanoparticles. This structure has a unique building architecture where rGO wraps up the CeO(2) nanoparticles and Pt nanoparticles are homogeneously dispersed on the surface of rGO. This novel structure endows this material with great electrocatalytic performance in methanol oxidation: it reduces the overpotential of methanol oxidation significantly and its electrocatalytic activity and stability are much enhanced compared with Pt/rGO, CeO(2)/Pt and Pt/C catalysts. This work supplies a unique MO/rGO/Pt sandwich nanostructure as an efficient way to improve the electrocatalytic performance, which will surely shed some light on the exploration of some novel structures of electrocatalyst for DMFCs.

Precursor directed synthesis - ``molecular'' mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures

Science.gov (United States)

Seisenbaeva, Gulaim A.; Kessler, Vadim G.

2014-05-01

This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials. To Professor David Avnir on his 65th birthday.

Advanced cathode materials for polymer electrolyte fuel cells based on pt/ metal oxides: from model electrodes to catalyst systems.

Science.gov (United States)

Fabbri, Emiliana; Pătru, Alexandra; Rabis, Annett; Kötz, Rüdiger; Schmidt, Thomas J

2014-01-01

The development of stable catalyst systems for application at the cathode side of polymer electrolyte fuel cells (PEFCs) requires the substitution of the state-of-the-art carbon supports with materials showing high corrosion resistance in a strongly oxidizing environment. Metal oxides in their highest oxidation state can represent viable support materials for the next generation PEFC cathodes. In the present work a multilevel approach has been adopted to investigate the kinetics and the activity of Pt nanoparticles supported on SnO2-based metal oxides. Particularly, model electrodes made of SnO2 thin films supporting Pt nanoparticles, and porous catalyst systems made of Pt nanoparticles supported on Sb-doped SnO2 high surface area powders have been investigated. The present results indicate that SnO2-based supports do not modify the oxygen reduction reaction mechanism on the Pt nanoparticle surface, but rather lead to catalysts with enhanced specific activity compared to Pt/carbon systems. Different reasons for the enhancement in the specific activity are considered and discussed.

Genotoxicity of metal nanoparticles.

Science.gov (United States)

Xie, Hong; Mason, Michael M; Wise, John Pierce

2011-01-01

Nanotechnology is currently used in industry, medicine, and military applications, as well as in more than 300 commercial products. Yet, the same properties that make these particles exciting for technology also make them daunting public health concerns because their toxicity is unknown and relatively unexplored. Increased attention is being placed on the study of metal particle genotoxicity; however, a lot of unknowns remain about their effects and the mechanisms. In this article, we highlight some metal and metal oxide nanoparticles of interest and discuss the current in vivo and in vitro studies of genotoxic effects. Many metal nanoparticles were found to cause chromosomal aberrations, DNA strand breaks, oxidative DNA damage, and mutations. Inconsistencies are found in the literature, however, thus drawing conclusions is difficult due to a variety of factors. Therefore, the areas requiring further attention are highlighted and recommendations to improve our understanding of the genotoxic potential are addressed.

Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji-Won; Rondinone, Adam Justin; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

2017-09-19

The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component comprising at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

Science.gov (United States)

Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

2014-06-24

The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

In vitro screening of metal oxide nanoparticles for effects on neural function using cortical networks

Data.gov (United States)

U.S. Environmental Protection Agency — Data describe the effects of metal oxide nanoparticles on total spikes and active electrodes after exposure to various concentrations for 1, 24 and 48 hrs, or after...

A Novel Synthesis of Gold Nanoparticles Supported on Hybrid Polymer/Metal Oxide as Catalysts for p-Chloronitrobenzene Hydrogenation

Directory of Open Access Journals (Sweden)

Cristian H. Campos

2017-01-01

Full Text Available This contribution reports a novel preparation of gold nanoparticles on polymer/metal oxide hybrid materials (Au/P[VBTACl]-M metal: Al, Ti or Zr and their use as heterogeneous catalysts in liquid phase hydrogenation of p-chloronitrobenzene. The support was prepared by in situ radical polymerization/sol gel process of (4-vinyl-benzyltrimethylammonium chloride and 3-(trimethoxysilylpropyl methacrylate in conjunction with metal-alkoxides as metal oxide precursors. The supported catalyst was prepared by an ion exchange process using chloroauric acid (HAuCl4 as gold precursor. The support provided the appropriate environment to induce the spontaneous reduction and deposition of gold nanoparticles. The hybrid material was characterized. TEM and DRUV-vis results indicated that the gold forms spherical metallic nanoparticles and that their mean diameter increases in the sequence, Au/P[VBTACl]-Zr > Au/P[VBTACl]-Al > Au/P[VBTACl]-Ti. The reactivity of the Au catalysts toward the p-CNB hydrogenation reaction is attributed to the different particle size distributions of gold nanoparticles in the hybrid supports. The kinetic pseudo-first-order constant values for the catalysts in the hydrogenation reaction increases in the order, Au/P[VBTACl]-Al > Au/P[VBTACl]-Zr > Au/P[VBTACl]-Ti. The selectivity for all the catalytic systems was greater than 99% toward the chloroaniline target product. Finally the catalyst supported on the hybrid with Al as metal oxide could be reused at least four times without loss in activity or selectivity for the hydrogenation of p-CNB in ethanol as solvent.

Size Controlled Synthesis of Transition Metal Nanoparticles for Catalytic Applications

KAUST Repository

Esparza, Angel

2011-07-07

Catalysis offers cleaner and more efficient chemical reactions for environmental scientists. More than 90% of industrial processes are performed with a catalyst involved, however research it is still required to improve the catalyst materials. The purpose of this work is to contribute with the development of catalysts synthesis with two different approaches. First, the precise size control of non-noble metals nanoparticles. Second, a new one-pot synthesis method based on a microemulsion system was developed to synthesize size-controlled metal nanoparticles in oxide supports. The one-pot method represents a simple approach to synthesize both support and immobilized nanometer-sized non-noble metal nanoparticles in the same reaction system. Narrow size distribution nickel, cobalt, iron and cobalt-nickel nanoparticles were obtained. High metal dispersions are attainable regardless the metal or support used in the synthesis. Thus, the methodology is adaptable and robust. The sizecontrolled supported metal nanoparticles offer the opportunity to study size effects and metal-support interactions on different catalytic reactions with different sets of metals and supports.

Radiation-induced synthesis of gold, iron-oxide composite nanoparticles

International Nuclear Information System (INIS)

Seino, Satoshi; Yamamoto, Takao; Nakagawa, Takashi; Kinoshita, Takuya; Kojima, Takao; Taniguchi, Ryoichi; Okuda, Shuichi

2007-01-01

Composite nanoparticles consisting of magnetic iron oxide nanoparticles and gold nanoparticles were synthesized using gamma-rays or electron beam. Ionizing irradiation induces the generation of reducing species inside the aqueous solution, and gold ions are reduced to form metallic Au nanoparticles. The size of Au nanoparticles depended on the dose rate and the concentration of support iron oxide. The gold nanoparticles on iron oxide nanoparticles selectively adsorb biomolecules via Au-S bonding. By using magnetic property of the support iron oxide nanoparticles, the composite nanoparticles are expected as a new type of magnetic nanocarrier for biomedical applications. (author)

Reduced graphene oxide and inorganic nanoparticles composites – synthesis and characterization

Directory of Open Access Journals (Sweden)

Onyszko Magdalena

2015-12-01

Full Text Available Graphene – novel 2D material, which possesses variety of fascinating properties, can be considered as a convenient support material for the nanoparticles. In this work various methods of synthesis of reduced graphene oxide with metal or metal oxide nanoparticles will be presented. The hydrothermal approach for deposition of platinum, palladium and zirconium dioxide nanoparticles in ethylene glycol/water solution was applied. Here, platinum/reduced graphene oxide (Pt/RGO, palladium/reduced graphene oxide (Pd/RGO and zirconium dioxide/reduced graphene oxide (ZrO2/RGO nanocomposites were prepared. Additionally, manganese dioxide/reduced graphene oxide nanocomposite (MnO2/RGO was synthesized in an oleic-water interface. The obtained nanocomposites were investigated by transmission electron microscopy (TEM, X-ray diffraction analysis (XRD, Raman spectroscopy and thermogravimetric analysis (TGA. The results shows that GO can be successfully used as a template for direct synthesis of metal or metal oxide nanoparticles on its surface with a homogenous distribution.

A new rapid chemical route to prepare reduced graphene oxide using copper metal nanoparticles

International Nuclear Information System (INIS)

Wu Tao; Gao Jianping; Xu Xiaoyang; Qiu Haixia; Wang Wei; Gao Chunjuan

2013-01-01

Copper metal nanoparticles were used as a reducing agent to reduce graphene oxide (GO). The reaction was complete in about 10 min and did not involve the use of any toxic reagents or acids that are typically used in the reduction of GO by Zn and Fe powders. The high reduction activity of the Cu nanoparticles, compared to Cu powder, may be the result of the formation of Cu 2 O nanoparticles. The effect of the mass ratio of the metal to GO for this reduction was also investigated. The reduction of the GO was verified by ultraviolet–visible absorption spectroscopy, x-ray diffraction, thermogravimetric analysis, Raman spectroscopy, x-ray photoelectron spectroscopy and transmission electron microscopy. After reduction, Cu 2 O supported on reduced GO was formed and showed superior catalytic ability for the degradation of a model dye pollutant, methylene blue. (paper)

Effects of self-absorption on simultaneous estimation of temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames using a spectrometer

Science.gov (United States)

Liu, Guannan; Liu, Dong

2018-06-01

An improved inverse reconstruction model with consideration of self-absorption effect for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames was proposed based on the flame emission spectrometry. The effects of self-absorption on the temperature profile and concentration fields were investigated for various measurement errors, flame optical thicknesses and detecting lines numbers. The model neglecting the self-absorption caused serious reconstruction errors especially in the nanofluid fuel flames with large optical thicknesses, while the improved model was used to successfully recover the temperature distribution and concentration fields of soot and metal-oxide nanoparticles for the flames regardless of the optical thickness. Through increasing detecting lines number, the reconstruction accuracy can be greatly improved due to more flame emission information received by the spectrometer. With the adequate detecting lines number, the estimations for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in flames with large optical thicknesses were still satisfying even from the noisy radiation intensities with signal to noise ratio (SNR) as low as 46 dB. The results showed that the improved reconstruction model was effective and robust to concurrently retrieve the temperature distribution and volume fraction fields of soot and metal-oxide nanoparticles for the exact and noisy data in nanofluid fuel sooting flames with different optical thicknesses.

A general method to incorporate metal nanoparticles in zeolites and zeotypes

DEFF Research Database (Denmark)

2015-01-01

Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure.......Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure....

Chemical sensors based on molecularly modified metallic nanoparticles

International Nuclear Information System (INIS)

Haick, Hossam

2007-01-01

This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

Environmentally friendly preparation of metal nanoparticles

Science.gov (United States)

The book chapter summarizes the “state of the art” in the exploitation of various environmentally-friendly synthesis approaches, reaction precursors and conditions to manufacture metal and metal oxide nanoparticles for a vast variety of purposes.

Nanomaterials-based electrochemical sensors for nitric oxide

International Nuclear Information System (INIS)

Dang, Xueping; Hu, Hui; Wang, Shengfu; Hu, Shengshui

2015-01-01

Electrochemical sensing has been demonstrated to represent an efficient way to quantify nitric oxide (NO) in challenging physiological environments. A sensing interface based on nanomaterials opens up new opportunities and broader prospects for electrochemical NO sensors. This review (with 141 refs.) gives a general view of recent advances in the development of electrochemical sensors based on nanomaterials. It is subdivided into sections on (i) carbon derived nanomaterials (such as carbon nanotubes, graphenes, fullerenes), (ii) metal nanoparticles (including gold, platinum and other metallic nanoparticles); (iii) semiconductor metal oxide nanomaterials (including the oxides of titanium, aluminum, iron, and ruthenium); and finally (iv) nanocomposites (such as those formed from carbon nanomaterials with nanoparticles of gold, platinum, NiO or TiO 2 ). The various strategies are discussed, and the advances of using nanomaterials and the trends in NO sensor technology are outlooked in the final section. (author)

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

Directory of Open Access Journals (Sweden)

Azam A

2012-12-01

Full Text Available Ameer Azam,1,2 Arham S Ahmed,2 Mohammad Oves,3 Mohammad S Khan,3 Sami S Habib,1 Adnan Memic11Centre of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Centre of Excellence in Materials Science (Nanomaterials, 3Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaBackground: Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria.Methods and results: Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3 were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa and Gram-positive (Staphylococcus aureus and Bacillus subtilis bacteria.Conclusion: Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3

Interfacial bonding stabilizes rhodium and rhodium oxide nanoparticles on layered Nb oxide and Ta oxide supports.

Science.gov (United States)

Strayer, Megan E; Binz, Jason M; Tanase, Mihaela; Shahri, Seyed Mehdi Kamali; Sharma, Renu; Rioux, Robert M; Mallouk, Thomas E

2014-04-16

Metal nanoparticles are commonly supported on metal oxides, but their utility as catalysts is limited by coarsening at high temperatures. Rhodium oxide and rhodium metal nanoparticles on niobate and tantalate supports are anomalously stable. To understand this, the nanoparticle-support interaction was studied by isothermal titration calorimetry (ITC), environmental transmission electron microscopy (ETEM), and synchrotron X-ray absorption and scattering techniques. Nanosheets derived from the layered oxides KCa2Nb3O10, K4Nb6O17, and RbTaO3 were compared as supports to nanosheets of Na-TSM, a synthetic fluoromica (Na0.66Mg2.68(Si3.98Al0.02)O10.02F1.96), and α-Zr(HPO4)2·H2O. High surface area SiO2 and γ-Al2O3 supports were also used for comparison in the ITC experiments. A Born-Haber cycle analysis of ITC data revealed an exothermic interaction between Rh(OH)3 nanoparticles and the layered niobate and tantalate supports, with ΔH values in the range -32 kJ·mol(-1) Rh to -37 kJ·mol(-1) Rh. In contrast, the interaction enthalpy was positive with SiO2 and γ-Al2O3 supports. The strong interfacial bonding in the former case led to "reverse" ripening of micrometer-size Rh(OH)3, which dispersed as 0.5 to 2 nm particles on the niobate and tantalate supports. In contrast, particles grown on Na-TSM and α-Zr(HPO4)2·H2O nanosheets were larger and had a broad size distribution. ETEM, X-ray absorption spectroscopy, and pair distribution function analyses were used to study the growth of supported nanoparticles under oxidizing and reducing conditions, as well as the transformation from Rh(OH)3 to Rh nanoparticles. Interfacial covalent bonding, possibly strengthened by d-electron acid/base interactions, appear to stabilize Rh(OH)3, Rh2O3, and Rh nanoparticles on niobate and tantalate supports.

Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

Energy Technology Data Exchange (ETDEWEB)

Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

2006-10-15

Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

Gas Sensors Based on Tin Oxide Nanoparticles Synthesized from a Mini-Arc Plasma Source

Directory of Open Access Journals (Sweden)

Ganhua Lu

2006-01-01

Full Text Available Miniaturized gas sensors or electronic noses to rapidly detect and differentiate trace amount of chemical agents are extremely attractive. In this paper, we report on the fabrication and characterization of a functional tin oxide nanoparticle gas sensor. Tin oxide nanoparticles are first synthesized using a convenient and low-cost mini-arc plasma source. The nanoparticle size distribution is measured online using a scanning electrical mobility spectrometer (SEMS. The product nanoparticles are analyzed ex-situ by high resolution transmission electron microscopy (HRTEM for morphology and defects, energy dispersive X-ray (EDX spectroscopy for elemental composition, electron diffraction for crystal structure, and X-ray photoelectron spectroscopy (XPS for surface composition. Nonagglomerated rutile tin oxide (SnO2 nanoparticles as small as a few nm have been produced. Larger particles bear a core-shell structure with a metallic core and an oxide shell. The nanoparticles are then assembled onto an e-beam lithographically patterned interdigitated electrode using electrostatic force to fabricate the gas sensor. The nanoparticle sensor exhibits a fast response and a good sensitivity when exposed to 100 ppm ethanol vapor in air.

Silver Nanoparticles-graphene Oxide Nanocomposite for Antibacterial Purpose

International Nuclear Information System (INIS)

Chook, S.W.; Chia, C.H.; Sarani Zakaria; Mohd Khan Ayob; Chee, K.L.; Neoh, H.M.; Huang, N.M.

2011-01-01

Graphene oxide (GO) sheets, a single layer of carbon atoms which can be served as substrates for fabricating metallic nanoparticles-GO nano composites, have been used in this study The nanocomposite of silver nanoparticles and graphene oxide were produced via in-situ synthesis and with the aid of chitosan to investigate the formation of silver nanoparticles on the graphene oxide sheets. XRD and UV-Vis studies confirmed the formation of silver nanoparticles on GO sheets, while TEM and FESEM images presented the loading of silver nanoparticles on the GO sheets. The degree of loading and distribution of the silver nanoparticles on the graphene oxide were depended on the procedure during the formation of silver nanoparticles. The nano composites can be potentially used in food packaging and biomedical applications. (author)

A comparative investigation of metal-support interactions on the catalytic activity of Pt nanoparticles for ethanol oxidation in alkaline medium

Science.gov (United States)

Godoi, Denis R. M.; Villullas, Hebe M.; Zhu, Fu-Chun; Jiang, Yan-Xia; Sun, Shi-Gang; Guo, Junsong; Sun, Lili; Chen, Rongrong

2016-04-01

The effects of interactions of Pt nanoparticles with hybrid supports on reactivity towards ethanol oxidation in alkaline solution are investigated. Studies involve catalysts with identical Pt nanoparticles on six hybrid supports containing carbon powder and transition metal oxides (TiO2, ZrO2, SnO2, CeO2, MoO3 and WO3). In situ X-ray absorption spectroscopy (XAS) results evidence that metal-support interactions produce changes in the Pt 5d band vacancy, which appears to determine the catalytic activity. The highest and lowest activities are observed for Pt nanoparticles on hybrid supports containing TiO2 and CeO2, respectively. Further studies are presented for these two catalysts. In situ FTIR reflection spectroscopy measurements, taken using both multi-stepped FTIR spectroscopy (MS-FTIR) and single potential alteration FTIR spectroscopy (SPA-FTIR), evidence that the main product of ethanol oxidation is acetate, although signals attributed to carbonate and CO2 indicate some differences in CO2 production. Fuel cell performances of these catalysts, tested in a 4.5 cm2 single cell at different temperatures (40-90 °C) show good agreement with data obtained by electrochemical techniques. Results of this comprehensive study point out the possibility of compensating a reduction of noble metal load with an increase in activity promoted by interactions between metallic nanoparticles and a support.

Precursor directed synthesis--"molecular" mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures.

Science.gov (United States)

Seisenbaeva, Gulaim A; Kessler, Vadim G

2014-06-21

This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.

3D Plasmonic Ensembles of Graphene Oxide and Nobel Metal Nanoparticles with Ultrahigh SERS Activity and Sensitivity

OpenAIRE

Jing Lin; Xiansong Wang; Guangxia Shen; Daxiang Cui

2016-01-01

We describe a comparison study on 3D ensembles of graphene oxide (GO) and metal nanoparticles (silver nanoparticles (AgNPs), gold nanoparticles (GNPs), and gold nanorods (GNRs)) for surface-enhanced Raman scattering (SERS) application. For the first time, GNRs were successfully assembled on the surfaces of GO by means of electrostatic interactions without adding any surfactant. The SERS properties of GO/AgNPs, GO/GNPs, and GO/GNRs were compared using 2-mercaptopyridine (2-Mpy) as probing mole...

Exposure to titanium dioxide and other metallic oxide nanoparticles induces cytotoxicity on human neural cells and fibroblasts

Directory of Open Access Journals (Sweden)

James C K Lai

2008-12-01

Full Text Available James C K Lai1, Maria B Lai1, Sirisha Jandhyam1, Vikas V Dukhande1, Alok Bhushan1, Christopher K Daniels1, Solomon W Leung21Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, and Biomedical Research Institute; 2Department of Civil and Environmental Engineering, College of Engineering and Biomedical Research Institute, Idaho State University, Pocatello, ID, USAAbstract: The use of titanium dioxide (TiO2 in various industrial applications (eg, production of paper, plastics, cosmetics, and paints has been expanding thereby increasing the occupational and other environmental exposure of these nanoparticles to humans and other species. However, the health effects of exposure to TiO2 nanoparticles have not been systematically assessed even though recent studies suggest that such exposure induces inflammatory responses in lung tissue and cells. Because the effects of such nanoparticles on human neural cells are unknown, we have determined the putative cytotoxic effects of these nanoparticles on human astrocytes-like astrocytoma U87 cells and compared their effects on normal human fibroblasts. We found that TiO2 micro- and nanoparticles induced cell death on both human cell types in a concentration-related manner. We further noted that zinc oxide (ZnO nanoparticles were the most effective, TiO2 nanoparticles the second most effective, and magnesium oxide (MgO nanoparticles the least effective in inducing cell death in U87 cells. The cell death mechanisms underlying the effects of TiO2 micro- and nanoparticles on U87 cells include apoptosis, necrosis, and possibly apoptosis-like and necrosis-like cell death types. Thus, our findings may have toxicological and other pathophysiological implications on exposure of humans and other mammalian species to metallic oxide nanoparticles.Keywords: cytotoxicity of titanium dioxide micro- and nanoparticles, cytotoxicity of zinc oxide and magnesium oxide nanoparticles, human neural cells

The Composites of Graphene Oxide with Metal or Semimetal Nanoparticles and Their Effect on Pathogenic Microorganisms

Directory of Open Access Journals (Sweden)

Lukas Richtera

2015-05-01

Full Text Available The present experiment describes a synthesis process of composites based on graphene oxide, which was tested as a carrier for composites of metal- or metalloid-based nanoparticles (Cu, Zn, Mn, Ag, AgP, Se and subsequently examined as an antimicrobial agent for some bacterial strains (Staphylococcus aureus (S. aureus, methicillin-resistant Staphylococcus aureus (MRSA and Escherichia coli (E. coli. The composites were first applied at a concentration of 300 µM on all types of model organisms and their effect was observed by spectrophotometric analysis, which showed a decrease in absorbance values in comparison with the control, untreated strain. The most pronounced inhibition (87.4% of S. aureus growth was observed after the application of graphene oxide composite with selenium nanoparticles compared to control. Moreover, the application of the composite with silver and silver phosphate nanoparticles showed the decrease of 68.8% and 56.8%, respectively. For all the tested composites, the observed antimicrobial effect was found in the range of 26% to 87.4%. Interestingly, the effects of the composites with selenium nanoparticles significantly differed in Gram-positive (G+ and Gram-negative (G− bacteria. The effects of composites on bacterial cultures of S. aureus and MRSA, the representatives of G+ bacteria, increased with increasing concentrations. On the other hand, the effects of the same composites on G− bacteria E. coli was observed only in the highest applied concentration.

Grafting of diazonium salts on oxides surface: formation of aryl-O bonds on iron oxide nanoparticles

Science.gov (United States)

Brymora, Katarzyna; Fouineau, Jonathan; Eddarir, Asma; Chau, François; Yaacoub, Nader; Grenèche, Jean-Marc; Pinson, Jean; Ammar, Souad; Calvayrac, Florent

2015-11-01

Combining ab initio modeling and 57Fe Mössbauer spectrometry, we characterized the nature of the chemical linkage of aminoalkyl arenediazonium salt on the surface of iron oxide nanoparticles. We established that it is built through a metal-oxygen-carbon bonding and not a metal-carbon one, as usually suggested and commonly observed in previously studied metal- or carbon-based surfaces.

Introduction to metal-nanoparticle plasmonics

CERN Document Server

Pelton, Matthew

2013-01-01

Based on a popular article in Laser and Photonics Reviews, this book provides an explanation and overview of the techniques used to model, make, and measure metal nanoparticles, detailing results obtained and what they mean. It covers the properties of coupled metal nanoparticles, the nonlinear optical response of metal nanoparticles, and the phenomena that arise when light-emitting materials are coupled to metal nanoparticles. It also provides an overview of key potential applications and offers explanations of computational and experimental techniques giving readers a solid grounding

Cytotoxicity effects of metal oxide nanoparticles in human tumor cell lines

International Nuclear Information System (INIS)

Lozano, T; Rey, M; Gonzalez-Fernandez, Africa; Rojas, E; Moya, S; Fleddermann, J; Estrela-Lopis, I; Donath, E; Wang, B; Mao, Z; Gao, C

2011-01-01

Metallic and metal oxide nanoparticles (Nps) have a wide range of applications in various settings including household, cosmetics and chemical industries, as well as for coatings. Nevertheless, an in-depth study of the potential toxic effects of these Nps is still needed, in order to fulfill the mandatory requirement of ensuring the safety of workers, patients and the general public. In this study, Quick Cell colorimetric assays were used to evaluate the in vitro toxicity of different metal oxide Nps [Fe(II,III)O x , TiO x , ZnO and CeO 2 ] in several cell lines. The ZnO Nps were found to be highly toxic, with a lethal dose ≤100 μg/ml for all the cell lines studied. Western blot was also used to test the ability of the different Nps to activate the complement pathway. However, no activation of this cascade was observed when the Nps were added. In addition, the aggregation state and charge of the Nps in culture media was studied by dynamic light scattering (DLS) and measurement of zeta potential. Transmission Electron Microscopy was used to analyze Np uptake and localization at the cellular level.

Charge transport in metal oxide nanocrystal-based materials

Science.gov (United States)

Runnerstrom, Evan Lars

There is probably no class of materials more varied, more widely used, or more ubiquitous than metal oxides. Depending on their composition, metal oxides can exhibit almost any number of properties. Of particular interest are the ways in which charge is transported in metal oxides: devices such as displays, touch screens, and smart windows rely on the ability of certain metal oxides to conduct electricity while maintaining visible transparency. Smart windows, fuel cells, and other electrochemical devices additionally rely on efficient transport of ionic charge in and around metal oxides. Colloidal synthesis has enabled metal oxide nanocrystals to emerge as a relatively new but highly tunable class of materials. Certain metal oxide nanocrystals, particularly highly doped metal oxides, have been enjoying rapid development in the last decade. As in myriad other materials systems, structure dictates the properties of metal oxide nanocrystals, but a full understanding of how nanocrystal synthesis, the processing of nanocrystal-based materials, and the structure of nanocrystals relate to the resulting properties of nanocrystal-based materials is still nascent. Gaining a fundamental understanding of and control over these structure-property relationships is crucial to developing a holistic understanding of metal oxide nanocrystals. The unique ability to tune metal oxide nanocrystals by changing composition through the introduction of dopants or by changing size and shape affords a way to study the interplay between structure, processing, and properties. This overall goal of this work is to chemically synthesize colloidal metal oxide nanocrystals, process them into useful materials, characterize charge transport in materials based on colloidal metal oxide nanocrystals, and develop ways to manipulate charge transport. In particular, this dissertation characterizes how the charge transport properties of metal oxide nanocrystal-based materials depend on their processing and

Trends in the Catalytic CO Oxidation Activity of Nanoparticles

DEFF Research Database (Denmark)

Nørskov, Jens Kehlet; Falsig, Hanne; Larsen, Britt Hvolbæk

2008-01-01

Going for gold: Density functional calculations show how gold nanoparticles are more active catalysts for CO oxidation than other metal nanoparticles. The high catalytic activity of nanosized gold clusters at low temperature is found to be related to the ability of low-coordinate metal atoms...

Synthesis of MnFe2O4@Mn-Co oxide core-shell nanoparticles and their excellent performance for heavy metal removal.

Science.gov (United States)

Ma, Zichuan; Zhao, Dongyuan; Chang, Yongfang; Xing, Shengtao; Wu, Yinsu; Gao, Yuanzhe

2013-10-21

Magnetic nanomaterials that can be easily separated and recycled due to their magnetic properties have received considerable attention in the field of water treatment. However, these nanomaterials usually tend to aggregate and alter their properties. Herein, we report an economical and environmentally friendly method for the synthesis of magnetic nanoparticles with core-shell structure. MnFe2O4 nanoparticles have been successfully coated with amorphous Mn-Co oxide shells. The synthesized MnFe2O4@Mn-Co oxide nanoparticles have highly negatively charged surface in aqueous solution over a wide pH range, thus preventing their aggregation and enhancing their performance for heavy metal cation removal. The adsorption isotherms are well fitted to a Langmuir adsorption model, and the maximal adsorption capacities of Pb(II), Cu(II) and Cd(II) on MnFe2O4@Mn-Co oxide are 481.2, 386.2 and 345.5 mg g(-1), respectively. All the metal ions can be completely removed from the mixed metal ion solutions in a short time. Desorption studies confirm that the adsorbent can be effectively regenerated and reused.

Morphological changes of the red blood cells treated with metal oxide nanoparticles.

Science.gov (United States)

Kozelskaya, A I; Panin, A V; Khlusov, I A; Mokrushnikov, P V; Zaitsev, B N; Kuzmenko, D I; Vasyukov, G Yu

2016-12-01

The toxic effect of Al 2 O 3 , SiО 2 and ZrО 2 nanoparticles on red blood cells of Wistar rats was studied in vitro using the atomic force microscopy and the fluorescence analysis. Transformation of discocytes into echinocytes and spherocytes caused by the metal oxide nanoparticles was revealed. It was shown that only extremely high concentration of the nanoparticles (2mg/ml) allows correct estimating of their effect on the cell morphology. Besides, it was found out that the microviscosity changes of red blood cell membranes treated with nanoparticles began long before morphological modifications of the cells. On the contrary, the negatively charged ZrO 2 and SiO 2 nanoparticles did not affect ghost microviscosity up to concentrations of 1μg/ml and 0.1mg/ml, correspondingly. In its turn, the positively charged Al 2 O 3 nanoparticles induced structural changes in the lipid bilayer of the red blood cells already at a concentration of 0.05μg/ml. A decrease in microviscosity of the erythrocyte ghosts treated with Al 2 O 3 and SiO 2 nanoparticles was shown. It was detected that the interaction of ZrO 2 nanoparticles with the cells led to an increase in the membrane microviscosity and cracking of swollen erythrocytes. Copyright © 2016 Elsevier B.V. All rights reserved.

Immunological effects of iron oxide nanoparticles and iron-based complex drug formulations: Therapeutic benefits, toxicity, mechanistic insights, and translational considerations.

Science.gov (United States)

Shah, Ankit; Dobrovolskaia, Marina A

2018-04-01

Nanotechnology offers several advantages for drug delivery. However, there is the need for addressing potential safety concerns regarding the adverse health effects of these unique materials. Some such effects may occur due to undesirable interactions between nanoparticles and the immune system, and they may include hypersensitivity reactions, immunosuppression, and immunostimulation. While strategies, models, and approaches for studying the immunological safety of various engineered nanoparticles, including metal oxides, have been covered in the current literature, little attention has been given to the interactions between iron oxide-based nanomaterials and various components of the immune system. Here we provide a comprehensive review of studies investigating the effects of iron oxides and iron-based nanoparticles on various types of immune cells, highlight current gaps in the understanding of the structure-activity relationships of these materials, and propose a framework for capturing their immunotoxicity to streamline comparative studies between various types of iron-based formulations. Copyright © 2018 Elsevier Inc. All rights reserved.

A review of critical factors for assessing the dermal absorption of metal oxide nanoparticles from sunscreens applied to humans, and a research strategy to address current deficiencies.

Science.gov (United States)

Gulson, Brian; McCall, Maxine J; Bowman, Diana M; Pinheiro, Teresa

2015-11-01

Metal oxide nanoparticles in sunscreens provide broad-spectrum ultraviolet protection to skin. All studies to assess dermal penetration of nanoparticles have unanimously concluded that the overwhelming majority of nanoparticles remain on the outer surface of the skin. However, possibly due to many different experimental protocols in use, conclusions over the potential penetration to viable skin are mixed. Here, we review several factors that may influence experimental results for dermal penetration including the species studied (human, or animal model), size and coating of the metal oxide nanoparticles, composition of the sunscreen formulation, site of sunscreen application, dose and number of applications, duration of the study, types of biological samples analysed, methods for analysing samples, exposure to UV and skin flexing. Based on this information, we suggest an appropriate research agenda involving international collaboration that maximises the potential for dermal absorption of nanoparticles, and their detection, under normal conditions of sunscreen use by humans. If results from this research agenda indicate no absorption is observed, then concerns over adverse health effects from the dermal absorption of nanoparticles in sunscreens may be allayed.

Anticancer activity of Ficus religiosa engineered copper oxide nanoparticles

International Nuclear Information System (INIS)

Sankar, Renu; Maheswari, Ramasamy; Karthik, Selvaraju; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2014-01-01

The design, synthesis, characterization and application of biologically synthesized nanomaterials have become a vital branch of nanotechnology. There is a budding need to develop a method for environmentally benign metal nanoparticle synthesis, that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on an eco-friendly process for rapid synthesis of copper oxide nanoparticles using Ficus religiosa leaf extract as reducing and protecting agent. The synthesized copper oxide nanoparticles were confirmed by UV–vis spectrophotometer, absorbance peaks at 285 nm. The copper oxide nanoparticles were analyzed with field emission-scanning electron microscope (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS) and X-ray diffraction (XRD) spectrum. The FE-SEM and DLS analyses exposed that copper oxide nanoparticles are spherical in shape with an average particle size of 577 nm. FT-IR spectral analysis elucidates the occurrence of biomolecules required for the reduction of copper oxide ions. Zeta potential studies showed that the surface charge of the formed nanoparticles was highly negative. The XRD pattern revealed that synthesized nanoparticles are crystalline in nature. Further, biological activities of the synthesized nanoparticles were confirmed based on its stable anti-cancer effects. The apoptotic effect of copper oxide nanoparticles is mediated by the generation of reactive oxygen species (ROS) involving the disruption of mitochondrial membrane potential (Δψm) in A549 cells. The observed characteristics and results obtained in our in vitro assays suggest that the copper nanoparticles might be a potential anticancer agent. - Highlights: • Biogenic synthesis of copper oxide nanoparticles by leaf extract of Ficus religiosa • Characterized via UV–vis, FT-IR, DLS, FE-SEM with EDAX and XRD • Protein may act as an encapsulating, reducing and stabilizing

Anticancer activity of Ficus religiosa engineered copper oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sankar, Renu; Maheswari, Ramasamy; Karthik, Selvaraju [Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamilnadu (India); Shivashangari, Kanchi Subramanian, E-mail: shivashangari@gmail.com [Regional Forensic Science Laboratory, Tiruchirapalli, Tamilnadu (India); Ravikumar, Vilwanathan, E-mail: ravikumarbdu@gmail.com [Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamilnadu (India)

2014-11-01

The design, synthesis, characterization and application of biologically synthesized nanomaterials have become a vital branch of nanotechnology. There is a budding need to develop a method for environmentally benign metal nanoparticle synthesis, that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on an eco-friendly process for rapid synthesis of copper oxide nanoparticles using Ficus religiosa leaf extract as reducing and protecting agent. The synthesized copper oxide nanoparticles were confirmed by UV–vis spectrophotometer, absorbance peaks at 285 nm. The copper oxide nanoparticles were analyzed with field emission-scanning electron microscope (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS) and X-ray diffraction (XRD) spectrum. The FE-SEM and DLS analyses exposed that copper oxide nanoparticles are spherical in shape with an average particle size of 577 nm. FT-IR spectral analysis elucidates the occurrence of biomolecules required for the reduction of copper oxide ions. Zeta potential studies showed that the surface charge of the formed nanoparticles was highly negative. The XRD pattern revealed that synthesized nanoparticles are crystalline in nature. Further, biological activities of the synthesized nanoparticles were confirmed based on its stable anti-cancer effects. The apoptotic effect of copper oxide nanoparticles is mediated by the generation of reactive oxygen species (ROS) involving the disruption of mitochondrial membrane potential (Δψm) in A549 cells. The observed characteristics and results obtained in our in vitro assays suggest that the copper nanoparticles might be a potential anticancer agent. - Highlights: • Biogenic synthesis of copper oxide nanoparticles by leaf extract of Ficus religiosa • Characterized via UV–vis, FT-IR, DLS, FE-SEM with EDAX and XRD • Protein may act as an encapsulating, reducing and stabilizing

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

Science.gov (United States)

Li, L H; Deng, Z X; Xiao, J X; Yang, G W

2015-01-26

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

Nonvolatile memory characteristics in metal-oxide-semiconductors containing metal nanoparticles fabricated by using a unique laser irradiation method

International Nuclear Information System (INIS)

Yang, JungYup; Yoon, KapSoo; Kim, JuHyung; Choi, WonJun; Do, YoungHo; Kim, ChaeOk; Hong, JinPyo

2006-01-01

Metal-oxide-semiconductor (MOS) capacitors with metal nanoparticles (Co NP) were successfully fabricated by utilizing an external laser exposure technique for application of non-volatile memories. Images of high-resolution transmission electron microscopy reveal that the spherically shaped Co NP are clearly embedded in the gate oxide layer. Capacitance-voltage measurements exhibit typical charging and discharging effects with a large flat-band shift. The effects of the tunnel oxide thickness and the different tunnel materials are analyzed using capacitance-voltage and retention characteristics. In addition, the memory characteristics of the NP embedded in a high-permittivity material are investigated because the thickness of conventionally available SiO 2 gates is approaching the quantum tunneling limit as devices are scaled down. Finally, the suitability of NP memory devices for nonvolatile memory applications is also discussed. The present results suggest that our unique laser exposure technique holds promise for the NP formation as floating gate elements in nonvolatile NP memories and that the quality of the tunnel oxide is very important for enhancing the retention properties of nonvolatile memory.

Nanostructured Metal Oxides And Mixed Metal Oxides, Methods Of Making These Nanoparticles, And Methods Of Their Use

KAUST Repository

Polshettiwar, Vivek

2013-04-11

Embodiments of the present disclosure provide for nanoparticles, methods of making nanoparticles, methods of using the nanoparticles, and the like. Nanoparticles of the present disclosure can have a variety of morphologies, which may lead to their use in a variety of technologies and processes. Nanoparticles of the present may be used in sensors, optics, mechanics, circuits, and the like. In addition, nanoparticles of the present disclosure may be used in catalytic reactions, for CO oxidation, as super-capacitors, in hydrogen storage, and the like.

Nanostructured Metal Oxides And Mixed Metal Oxides, Methods Of Making These Nanoparticles, And Methods Of Their Use

KAUST Repository

Polshettiwar, Vivek; Fihri, Aziz

2013-01-01

Embodiments of the present disclosure provide for nanoparticles, methods of making nanoparticles, methods of using the nanoparticles, and the like. Nanoparticles of the present disclosure can have a variety of morphologies, which may lead to their use in a variety of technologies and processes. Nanoparticles of the present may be used in sensors, optics, mechanics, circuits, and the like. In addition, nanoparticles of the present disclosure may be used in catalytic reactions, for CO oxidation, as super-capacitors, in hydrogen storage, and the like.

Synthesis and optical properties of Au decorated colloidal tungsten oxide nanoparticles

International Nuclear Information System (INIS)

Tahmasebi, Nemat; Mahdavi, Seyed Mohammad

2015-01-01

Highlights: • Tungsten oxide nanoparticles were prepared by pulsed laser ablation (PLA). • A very fine metallic Au particles or coating are decorated on the surface of tungsten oxide nanoparticles. • UV–Vis spectroscopy shows an absorption peak at ∼530 nm which is due to SPR effect of gold. • After exposing to hydrogen gas, Au/WO_3 colloidal nanoparticles show excellent gasochromic coloring. - Abstract: In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl_4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au"3"+ ions were reduced to decorate gold metallic state (Au"0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV–Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms formation of gold state. Moreover, X-ray photoelectron spectroscopy reveals that Au ions’ reduction happens after adding HAuCl_4 solution into as-prepared colloidal tungsten oxide nanoparticles. Transmission electron microscope shows that an Au shell has been decorated onto colloidal WO_3 nanoparticles. Noble metal decorated tungsten oxide nanostructure could be an excellent candidate for photocatalysis, gas sensing and gasochromic applications. Finally, the gasochromic behavior of the synthesized samples was investigated by H_2 and O_2 gases bubbling into the produced colloidal Au/WO_3 nanoparticles. Synthesized colloidal nanoparticles show excellent coloration contrast (∼80%) through NIR spectra.

Effect of nanoparticle metal composition: mono- and bimetallic gold/copper dendrimer stabilized nanoparticles as solvent-free styrene oxidation catalysts

Science.gov (United States)

Blanckenberg, A.; Kotze, G.; Swarts, A. J.; Malgas-Enus, R.

2018-02-01

A range of mono- and bimetallic AumCun nanoparticles (NPs), with varying metal compositions, was prepared by using a third-generation diaminobutane poly(propylene imine) (G3 DAB-PPI) dendrimer, modified with alkyl chains, as a stabilizer. It was found that the length of the peripheral alkyl chain, ( M1 (C15), M2 (C11), and M3 (C5)), had a direct influence on the average nanoparticle size obtained, confirming the importance of the nanoparticle stabilizer during synthesis. The Au NPs showed the highest degree of agglomeration and polydispersity, whereas the Cu NPs were the smallest and most monodisperse of the NPs. The bimetallic NPs sizes were found to vary between those of the monometallic NPs, depending on the metal composition. Interestingly, the bimetallic NPs were found to be the most stable, showing very little variation in size over time, even up to 9 months. The DSNs were evaluated in the catalytic oxidation of styrene, using either H2O2 or TBHP as oxidant. Here, we show that the bimetallic DSNs are indeed the superior catalysts when compared to their monometallic analogues, under the same reaction conditions, since a good compromise between stability and activity can be achieved where the Au provides catalytic activity and the Cu serves as a stabilizer. These AumCun bimetallic DSNs present a less expensive and more stable catalyst with negligible loss of activity, opening the door to green catalysis.

Low pressure bottom-up synthesis of metal@oxide and oxide nanoparticles: control of structure and functional properties

Science.gov (United States)

D'Addato, Sergio; Chiara Spadaro, Maria

2018-03-01

Experimental activity on core@shell, metal@oxide, and oxide nanoparticles (NPs) grown with physical synthesis, and more specifically by low pressure gas aggregation sources (LPGAS) is reviewed, through a selection of examples encompassing some potential applications in nanotechnology. After an introduction to the applications of NPs, a brief description of the main characteristics of the growth process of clusters and NPs in LPGAS is given. Thereafter, some relevant case studies are reported: • Formation of native oxide shells around the metal cores in core@shell NPs. • Experimental efforts to obtain magnetic stabilization in magnetic core@shell NPs by controlling their structure and morphology. • Recent advancements in NP source design and new techniques of co-deposition, with relevant results in the realization of NPs with a greater variety of functionalities. • Recent results on reducible oxide NPs, with potentialities in nanocatalysis, energy storage, and other applications. Although this list is far from being exhaustive, the aim of the authors is to provide the reader a descriptive glimpse into the physics behind the growth and studies of low pressure gas-phase synthesized NPs, with their ever-growing potentialities for the rational design of new functional materials.

Colloidal metal oxide nanoparticle systems: the new promising way to prevent antibiotic resistance during treatment of local infectious processes

International Nuclear Information System (INIS)

Karasenkov, Y; Frolov, G; Gusev, A; Kuznetsov, D; Leont'ev, V; Pogorelsky, I; Latuta, N

2015-01-01

New bactericidal containing nanoparticles colloids for application in dentistry, maxillofacial surgery, urology, obstetrics, gynaecology, ENT, proctology have been developed. The various water colloidal nanodispersive systems of metals and oxides have been obtained by means of electric impulse – condensation (electroerosion) method. These systems are based pure elements and alloys of argentum (Ag), titanium dioxide (TiO 2 ), iron oxide (Fe 2 O 3 ), tantalum oxide (TaO), vanadium oxide (VO 2 ), cobalt oxide (CoO), tantalum dioxide TaO 2 , zinc oxide (ZnO), copper oxide (CuO) and mixed suspensions of titanium, aluminium and molybdenum oxides. The research has been made on culture of dentobacterial plaque and mixed culture issued from gingival spaces. The composition of culture was identified with S.aureus, S.epidermidis and nonfermentable kinds of E.coli. The observation period lasted more than nineteen days. All solutions showed highly prolonged bactericidal activity in dilutions from the whole solution 1-20 mg/L. The bactericidal activity of powder specimen of silica containing Ag and Fe 2 O 3 nanoparticles used as dental filling material and disintegrates of composite materials (produced by “StomaDent” CJSC) have been studied. Tested materials have long (up to 19 days and more) bactericidal activity. (paper)

Colloidal metal oxide nanoparticle systems: the new promising way to prevent antibiotic resistance during treatment of local infectious processes

Science.gov (United States)

Karasenkov, Y.; Frolov, G.; Pogorelsky, I.; Latuta, N.; Gusev, A.; Kuznetsov, D.; Leont'ev, V.

2015-11-01

New bactericidal containing nanoparticles colloids for application in dentistry, maxillofacial surgery, urology, obstetrics, gynaecology, ENT, proctology have been developed. The various water colloidal nanodispersive systems of metals and oxides have been obtained by means of electric impulse - condensation (electroerosion) method. These systems are based pure elements and alloys of argentum (Ag), titanium dioxide (TiO2), iron oxide (Fe2O3), tantalum oxide (TaO), vanadium oxide (VO2), cobalt oxide (CoO), tantalum dioxide TaO2, zinc oxide (ZnO), copper oxide (CuO) and mixed suspensions of titanium, aluminium and molybdenum oxides. The research has been made on culture of dentobacterial plaque and mixed culture issued from gingival spaces. The composition of culture was identified with S.aureus, S.epidermidis and nonfermentable kinds of E.coli. The observation period lasted more than nineteen days. All solutions showed highly prolonged bactericidal activity in dilutions from the whole solution 1-20 mg/L. The bactericidal activity of powder specimen of silica containing Ag and Fe2O3 nanoparticles used as dental filling material and disintegrates of composite materials (produced by “StomaDent” CJSC) have been studied. Tested materials have long (up to 19 days and more) bactericidal activity.

Synthesis of tungsten oxide, silver, and gold nanoparticles by radio frequency plasma in water

International Nuclear Information System (INIS)

Hattori, Yoshiaki; Nomura, Shinfuku; Mukasa, Shinobu; Toyota, Hiromichi; Inoue, Toru; Usui, Tomoya

2013-01-01

Highlights: •RF plasma in water was used for nanoparticle synthesis. •Nanoparticles were produced from erosion of metallic electrode. •Rectangular and spherical tungsten oxide nanoparticles were produced. •No oxidations of the silver and gold spherical nanoparticles were produced. -- Abstract: A process for synthesis of nanoparticles using plasma in water generated by a radio frequency of 27.12 MHz is proposed. Tungsten oxide, silver, and gold nanoparticles were produced at 20 kPa through erosion of a metallic electrode exposed to plasma. Characterization of the produced nanoparticles was carried out by XRD, absorption spectrum, and TEM. The nanoparticle sizes were compared with those produced by a similar technique using plasma in liquid

Linking interfacial chemistry of CO2 to surface structures of hydrated metal oxide nanoparticles: hematite.

Science.gov (United States)

Chernyshova, Irina V; Ponnurangam, Sathish; Somasundaran, Ponisseril

2013-05-14

A better understanding of interaction with dissolved CO2 is required to rationally design and model the (photo)catalytic and sorption processes on metal (hydr)oxide nanoparticles (NPs) in aqueous media. Using in situ FTIR spectroscopy, we address this problem for rhombohedral 38 nm hematite (α-Fe2O3) nanoparticles as a model. We not only resolve the structures of the adsorbed carbonate species, but also specify their adsorption sites and their location on the nanoparticle surface. The spectral relationships obtained present a basis for a new method of characterizing the microscopic structural and acid-base properties (related to individual adsorption sites) of hydrated metal (hydr)oxide NPs using atmospherically derived CO2 as a probe. Specifically, we distinguish two carbonate species suggesting two principally different adsorption mechanisms. One species, which is more weakly adsorbed, has an inner-sphere mononuclear monodentate structure which is formed by a conventional ligand-exchange mechanism. At natural levels of dissolved carbonate and pH from 3 to 11, this species is attached to the most acidic/reactive surface cations (surface states) associated with ferrihydrite-like surface defects. The second species, which is more strongly adsorbed, presents a mixed C and O coordination of bent CO2. This species uniquely recognizes the stoichiometric rhombohedral {104} facets in the NP texture. Like in gas phase, it is formed through the surface coordination of molecular CO2. We address how the adsorption sites hosting these two carbonate species are affected by the annealing and acid etching of the NPs. These results support the nanosize-induced phase transformation of hematite towards ferrihydrite under hydrous conditions, and additionally show that the process starts from the roughened areas of the facet intersections.

Metal nanoparticle film-based room temperature Coulomb transistor.

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-07-01

Single-electron transistors would represent an approach to developing less power-consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations.

Electrical memory features of ferromagnetic CoFeAlSi nano-particles embedded in metal-oxide-semiconductor matrix

International Nuclear Information System (INIS)

Lee, Ja Bin; Kim, Ki Woong; Lee, Jun Seok; An, Gwang Guk; Hong, Jin Pyo

2011-01-01

Half-metallic Heusler material Co 2 FeAl 0.5 Si 0.5 (CFAS) nano-particles (NPs) embedded in metal-oxide-semiconductor (MOS) structures with thin HfO 2 tunneling and MgO control oxides were investigated. The CFAS NPs were prepared by rapid thermal annealing. The formation of well-controlled CFAS NPs on thin HfO 2 tunneling oxide was confirmed by atomic force microscopy (AFM). Memory characteristics of CFAS NPs in MOS devices exhibited a large memory window of 4.65 V, as well as good retention and endurance times of 10 5 cycles and 10 9 s, respectively, demonstrating the potential of CFAS NPs as promising candidates for use in charge storage.

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India

Science.gov (United States)

2013-01-01

Background The biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable “green procedures”. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles. Result The preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM –EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria. Conclusion Based on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm. PMID:24298944

Highly stable noble-metal nanoparticles in tetraalkylphosphonium ionic liquids for in situ catalysis.

Science.gov (United States)

Banerjee, Abhinandan; Theron, Robin; Scott, Robert W J

2012-01-09

Gold and palladium nanoparticles were prepared by lithium borohydride reduction of the metal salt precursors in tetraalkylphosphonium halide ionic liquids in the absence of any organic solvents or external nanoparticle stabilizers. These colloidal suspensions remained stable and showed no nanoparticle agglomeration over many months. A combination of electrostatic interactions between the coordinatively unsaturated metal nanoparticle surface and the ionic-liquid anions, bolstered by steric protection offered by the bulky alkylated phosphonium cations, is likely to be the reason behind such stabilization. The halide anion strongly absorbs to the nanoparticle surface, leading to exceptional nanoparticle stability in halide ionic liquids; other tetraalkylphosphonium ionic liquids with non-coordinating anions, such as tosylate and hexafluorophosphate, show considerably lower affinities towards the stabilization of nanoparticles. Palladium nanoparticles stabilized in the tetraalkylphosphonium halide ionic liquid were stable, efficient, and recyclable catalysts for a variety of hydrogenation reactions at ambient pressures with sustained activity. Aerial oxidation of the metal nanoparticles occurred over time and was readily reversed by re-reduction of oxidized metal salts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal oxide nanostructures and their gas sensing properties: a review.

Science.gov (United States)

Sun, Yu-Feng; Liu, Shao-Bo; Meng, Fan-Li; Liu, Jin-Yun; Jin, Zhen; Kong, Ling-Tao; Liu, Jin-Huai

2012-01-01

Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given.

Metal nanoparticle film–based room temperature Coulomb transistor

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-01-01

Single-electron transistors would represent an approach to developing less power–consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations. PMID:28740864

Continuous Polyol Synthesis of Metal and Metal Oxide Nanoparticles Using a Segmented Flow Tubular Reactor (SFTR

Directory of Open Access Journals (Sweden)

Andrea Testino

2015-06-01

Full Text Available Over the last years a new type of tubular plug flow reactor, the segmented flow tubular reactor (SFTR, has proven its versatility and robustness through the water-based synthesis of precipitates as varied as CaCO3, BaTiO3, Mn(1−xNixC2O4·2H2O, YBa oxalates, copper oxalate, ZnS, ZnO, iron oxides, and TiO2 produced with a high powder quality (phase composition, particle size, and shape and high reproducibility. The SFTR has been developed to overcome the classical problems of powder production scale-up from batch processes, which are mainly linked with mass and heat transfer. Recently, the SFTR concept has been further developed and applied for the synthesis of metals, metal oxides, and salts in form of nano- or micro-particles in organic solvents. This has been done by increasing the working temperature and modifying the particle carrying solvent. In this paper we summarize the experimental results for four materials prepared according to the polyol synthesis route combined with the SFTR. CeO2, Ni, Ag, and Ca3(PO42 nanoparticles (NPs can be obtained with a production rate of about 1–10 g per h. The production was carried out for several hours with constant product quality. These findings further corroborate the reliability and versatility of the SFTR for high throughput powder production.

The base metal of the oxide-coated cathode

International Nuclear Information System (INIS)

Poret, F.; Roquais, J.M.

2005-01-01

The oxide-coated cathode has been the most widely used electron emitter in vacuum electronic devices. From one manufacturing company to another the emissive oxide is either a double-Ba, Sr-or a triple-Ba, Sr, Ca-oxide, having always the same respective compositions. Conversely, the base metal composition is very often proprietary because of its importance in the cathode emission performances. The present paper aims at explaining the operation of the base metal through a review. After a brief introduction, the notion of activator is detailed along with their diffusivities and their associated interfacial compounds. Then, the different cathode life models are described prior to few comments on the composition choice of a base metal. Finally, the specificities of the RCA/Thomson 'bimetal' base metal are presented with a discussion on the optimized composition choice illustrated by a long-term life-test of five different melts

Oxidation effect on templating of metal oxide nanoparticles within block copolymers

International Nuclear Information System (INIS)

Akcora, Pinar; Briber, Robert M.; Kofinas, Peter

2009-01-01

Amphiphilic norbornene-b-(norbornene dicarboxylic acid) diblock copolymers with different block ratios were prepared as templates for the incorporation of iron ions using an ion exchange protocol. The disordered arrangement of iron oxide particles within these copolymers was attributed to the oxidation of the iron ions and the strong interactions between iron oxide nanoparticles, particularly at high iron ion concentrations, which was found to affect the self-assembly of the block copolymer morphologies.

From iron coordination compounds to metal oxide nanoparticles.

Science.gov (United States)

Iacob, Mihail; Racles, Carmen; Tugui, Codrin; Stiubianu, George; Bele, Adrian; Sacarescu, Liviu; Timpu, Daniel; Cazacu, Maria

2016-01-01

Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe 2 III Fe II O(CH 3 COO) 6 (H 2 O) 3 ]·2H 2 O (FeAc1), μ 3 -oxo trinuclear iron(III) acetate, [Fe 3 O(CH 3 COO) 6 (H 2 O) 3 ]NO 3 ∙4H 2 O (FeAc2), iron furoate, [Fe 3 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeF), iron chromium furoate, FeCr 2 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeCrF), and an iron complex with an original macromolecular ligand (FePAZ) were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination) or using a nonconventional energy source (i.e., microwave or ultrasonic treatment) to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

From iron coordination compounds to metal oxide nanoparticles

Directory of Open Access Journals (Sweden)

Mihail Iacob

2016-12-01

Full Text Available Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe2IIIFeIIO(CH3COO6(H2O3]·2H2O (FeAc1, μ3-oxo trinuclear iron(III acetate, [Fe3O(CH3COO6(H2O3]NO3∙4H2O (FeAc2, iron furoate, [Fe3O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeF, iron chromium furoate, FeCr2O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeCrF, and an iron complex with an original macromolecular ligand (FePAZ were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination or using a nonconventional energy source (i.e., microwave or ultrasonic treatment to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

Radiation chemical route for preparation of metal nanoparticles

International Nuclear Information System (INIS)

Kapoor, S.; Mukherjee, T.

2006-01-01

Nanoparticles show properties that are neither seen in the bulk or at atomic level. The unusual properties are governed by quantum size effect. Due to this various methodologies have been endeavored to control the size of the particles. In the present work we show the use of two complimentary techniques (radiation and photo) to synthesize and control the size of the metal particles. In-situ synthesis of fine silver, thallium and cadmium particles has been carried out by gamma-irradiation and electron pulse irradiation at room temperature in the pre-organized gel of polyacrylamide or cyclodextrin cavity. The role of generation of nuclei in high concentrations in stabilization of metal nanoparticles in hydrophobic cavity is shown. Similarly the importance of entrapment of metal ions in the polymer matrix during its formation is highlighted. The work is further extended to exploit the microemulsion droplets for stabilization of Cd nanoparticles. Utility of pulse radiolysis in probing the mechanism of the formation of metal nanoparticles is also shown. Ultrafast laser pulses were employed to control the morphology of the pre-prepared Pt nanoparticles. The changes in reduction of shape and size are considered to occur through melting and vaporization of the nanoparticles. Pt nanoparticles were coated on the inner walls of the tubular pyrex reactor and tested for their catalytic activity for oxidation of CO. It was observed that Pt nanoparticles prepared in the presence of a stabilizer (gelatin) showed a higher tendency to adhere to the inner walls of the pyrex reactor as compared to that prepared in the presence of silica nanoparticles. The catalyst was found to be active at ≥150 degree C giving CO 2 . Chemically reduced Pt nanoparticles stabilized on silica nanoparticles gave ∼7% CO conversion per hr. However, radiolytically prepared Pt nanoaprticles stabilized by gelatin gave ∼10% conversion per hr. The data indicates that catalytic oxidation of CO takes place

Electrocatalytic Activity for CO, MeOH, and EtOH Oxidation on the Surface of Pt-Ru Nanoparticles Supported by Metal Oxide

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Kwang-Sik Sim

2011-01-01

Full Text Available This paper describes the electrocatalytic activity for CO, MeOH, and EtOH oxidation on the surface of Pt-Ru nanoparticles supported by metal oxide (Nb-TiO2-H prepared for use in a fuel cell. To prepare Nb-TiO2-supported Pt-Ru nanoparticles, first, the Nb-TiO2 supports were prepared by sol-gel reaction of titanium tetraisopropoxide with a small amount of the niobium ethoxide in polystyrene (PS colloids. Second, Pt-Ru nanoparticles were then deposited by chemical reduction of the Pt4+ and Ru3+ ions onto Nb-TiO2 supports (Pt-Ru@Nb-TiO2-CS. Nb element was used to reduce electrical resistance to facilitate electron transport during the electrochemical reactions on a fuel cell electrode. Finally, the Pt-Ru@Nb-TiO2-H catalysts were formed by the removal of core-polystyrene ball from Pt-Ru@TiO2-CS at 500∘C. The successfully prepared Pt-Ru electrocatalysts were confirmed via TEM, XPS, and ICP analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via CO, MeOH, and EtOH oxidation for use in a direct methanol fuel cell (DMFC. As a result, the Pt-Ru@Nb-TiO2-H electrodes showed high electrocatalytic activity for the electrooxidation of CO, MeOH, and EtOH.

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Science.gov (United States)

Liu, Lichen; Corma, Avelino

2018-05-23

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal-support interaction, and metal-reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results obtained from different systems and try to give a picture on how different types of metal species work in different reactions and give perspectives on the future directions toward better understanding of the catalytic behavior of different metal entities (single atoms, nanoclusters, and nanoparticles) in a unifying manner.

Dissolution of metal and metal oxide nanoparticles in aqueous media

International Nuclear Information System (INIS)

Odzak, Niksa; Kistler, David; Behra, Renata; Sigg, Laura

2014-01-01

The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin films), dialysis membrane (DM) and ultrafiltration (UF). Relatively small fractions of Ag nanoparticles dissolved, whereas ZnO dissolved nearly completely within few hours. Cu and CuO dissolved as a function of pH. Using DGT, less dissolved Ag was measured compared to UF and DM, likely due to differences in diffusion of organic complexes. Similar dissolved metal concentrations of ZnO, Cu and CuO nanoparticles were determined using DGT and UF, but lower using DM. The results indicate that there is a need to apply complementary techniques to precisely determine dissolution of nanoparticles in aqueous media. - Highlights: • Three different techniques used simultaneously to measure NPs dissolution. • ZnO-NPs are the most soluble, followed by CuO-NPs, carbon coated Cu-NPs and Ag-NPs. • Dissolution is an important process affecting the fate of nanoparticles. • Complementary techniques are needed to precisely determine dissolution of NPs. - Dissolution of several types of nanoparticles was examined in aqueous media using three complementary techniques

Metal oxide/polyaniline nanocomposites: Cluster size and ...

Indian Academy of Sciences (India)

Wintec

Metal oxide/polyaniline nanocomposites; structural properties; magnetic properties. 1. Introduction ... The powder obtained was ground in a motor and pestle, sonicated in ... Figure 1. XRD of (a) iron oxide nanoparticles and (b) iron oxide/PANI (1 : 0⋅4) composite. .... shape of the particles and the anisotropy energy, as also.

Application of Iron Oxide Nano materials for the Removal of Heavy Metals

International Nuclear Information System (INIS)

Dave, P.N.; Chopda, L.V.

2014-01-01

In the 21st century water polluted by heavy metal is one of the environment problems. Various methods for removal of the heavy metal ions from the water have extensively been studied. Application of iron oxide nana particles based nano materials for removal of heavy metals is well-known adsorbents for remediation of water. Due to its important physiochemical property, inexpensive method and easy regeneration in the presence of external magnetic field make them more attractive toward water purification. Surface modification strategy of iron oxide nanoparticles is also used for the remediation of water increases the efficiency of iron oxide for the removal of the heavy metal ions from the aqueous system.

Influence of Magnetite Nanoparticles on the Dielectric Properties of Metal Oxide/Polymer Nanocomposites Based on Polypropylene

Science.gov (United States)

Maharramov, A. A.; Ramazanov, M. A.; Di Palma, Luca; Shirinova, H. A.; Hajiyeva, F. V.

2018-01-01

Structure and dielectric properties of polymer nanocomposites based on isotactic polypropylene and iron oxide (Fe3O4) nanoparticles are studied. Distribution of magnetite nanoparticles in a polymer matrix was studied by scanning electron microscopy (SEM, Carl Zeiss). Dielectric properties of nanocomposites were examined by means of E7-21 impedance spectrometer in the frequency range of 102-106 Hz and temperature interval of 298-433 K. The frequency and temperature dependences of the dielectric permittivity ɛ, as well as the temperature dependence of log (ρ) were constructed. It is shown that introduction of the magnetite (Fe3O4) nanoparticles into a polypropylene matrix increases the dielectric permittivity of nanocomposites. An increase in the dielectric permittivity is explained by the increase in the polarization ability of nanocomposites. It is found that a decrease in the specific resistance with increasing temperature up to 318 K is associated with an increase in the ionic conductivity of nanocomposites. An increase in the resistance at temperatures higher than 358 K is due to the destruction of the crystalline phase of the polymer, as a result of which the distance between the Fe3O4 nanoparticles increases.

Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

2015-10-01

This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

Chromium Elimination from Water by use of Iron Oxide Nanoparticles Absorbents

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S Shokraei

2014-09-01

Results: results showed that best absorbent is soil absorbent and iron oxide nanoparticles, with maximum removal percent equal to 96.2%. Also best turnover was obtained from 8837 ppm of primary concentration of heavy metal. In other hand, in other experiments that used from iron oxide nanoparticles, adding of nanoparticles caused to increase in chrome absorption and conversion of Cr6+ to Cr3+. Conclusion: with use of the results of this study can be said that Combining of iron oxide nanoparticles with chrome removal filters can be convert Cr6+ to Cr3+, and process turnover will increased.

Nanofluid based on self-nanoencapsulated metal/metal alloys phase change materials with tuneable crystallisation temperature.

Science.gov (United States)

Navarrete, Nuria; Gimeno-Furio, Alexandra; Mondragon, Rosa; Hernandez, Leonor; Cabedo, Luis; Cordoncillo, Eloisa; Julia, J Enrique

2017-12-14

Nanofluids using nanoencapsulated Phase Change Materials (nePCM) allow increments in both the thermal conductivity and heat capacity of the base fluid. Incremented heat capacity is produced by the melting enthalpy of the nanoparticles core. In this work two important advances in this nanofluid type are proposed and experimentally tested. It is firstly shown that metal and metal alloy nanoparticles can be used as self-encapsulated nePCM using the metal oxide layer that forms naturally in most commercial synthesis processes as encapsulation. In line with this, Sn/SnOx nanoparticles morphology, size and thermal properties were studied by testing the suitability and performance of encapsulation at high temperatures and thermal cycling using a commercial thermal oil (Therminol 66) as the base fluid. Secondly, a mechanism to control the supercooling effect of this nePCM type based on non-eutectic alloys was developed.

Liquid metal/metal oxide frameworks with incorporated Ga2O3 for photocatalysis.

Science.gov (United States)

Zhang, Wei; Naidu, Boddu S; Ou, Jian Zhen; O'Mullane, Anthony P; Chrimes, Adam F; Carey, Benjamin J; Wang, Yichao; Tang, Shi-Yang; Sivan, Vijay; Mitchell, Arnan; Bhargava, Suresh K; Kalantar-Zadeh, Kourosh

2015-01-28

Solvothermally synthesized Ga2O3 nanoparticles are incorporated into liquid metal/metal oxide (LM/MO) frameworks in order to form enhanced photocatalytic systems. The LM/MO frameworks, both with and without incorporated Ga2O3 nanoparticles, show photocatalytic activity due to a plasmonic effect where performance is related to the loading of Ga2O3 nanoparticles. Optimum photocatalytic efficiency is obtained with 1 wt % incorporation of Ga2O3 nanoparticles. This can be attributed to the sub-bandgap states of LM/MO frameworks, contributing to pseudo-ohmic contacts which reduce the free carrier injection barrier to Ga2O3.

CHEMISTRY OF SO2 AND DESOX PROCESSES ON OXIDE NANOPARTICLES.

Energy Technology Data Exchange (ETDEWEB)

RODRIGUEZ, J.A.

2006-06-30

On bulk stoichiometric oxides, SO{sub 2} mainly reacts with the O centers to form SO{sub 3} or SO{sub 4} species that decompose at elevated temperatures. Adsorption on the metal cations occurs below 300 K and does not lead to cleavage of the S-O bonds. In bulk oxides, the occupied cation bands are too stable for effective bonding interactions with the LUMO of SO{sub 2}. The effects of quantum confinement on the electronic properties of oxide nanoparticles and the structural defects that usually accompany these systems in general favor the bonding and dissociation of SO{sub 2}. Thus, nanoparticles of MgO, CaO, SrO, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3} and CeO{sub 2} are all more efficient for sequestering SO{sub 2} than the corresponding bulk oxides. Structural imperfections in pure or metal-doped ceria nanoparticles accelerate the reduction of SO{sub 2} by CO by facilitating the formation and migration of O vacancies in the oxide surface.

Effect of metal oxide nanoparticles on Godavari river water treatment

Science.gov (United States)

Goud, Ravi Kumar; Ajay Kumar, V.; Reddy, T. Rakesh; Vinod, B.; Shravani, S.

2018-05-01

Nowadays there is a continuously increasing worldwide concern for the development of water treatment technologies. In the area of water purification, nanotechnology offers the possibility of an efficient removal of pollutants and germs. Nanomaterials reveal good results than other techniques used in water treatment because of its high surface area to volume ratio. In the present work, iron oxide and copper oxide nanoparticles were synthesized by simple heating method. The synthesized nanoparticles were used to purify Godavari river water. The effect of nanoparticles at 70°C temperature, 12 centimeter of sand bed height and pH of 8 shows good results as compared to simple sand bed filter. The attained values of BOD5, COD and Turbidity were in permissible limit of world health organization.

In vitro cardiotoxicity screening of silver and metal oxide nanoparticles using human induced pluripotent stem cell-derived cardiomyocytes

Science.gov (United States)

Exposure risk to silver and metal oxide nanoparticles (NPs) continues to increase due to their widespread use in products and applications. In vivo studies have shown Ag, TiO2 and CeO2 NPs translocate to the heart following various routes of exposure. Thus, it is critical to asse...

Sequential electrochemical oxidation and site-selective growth of nanoparticles onto AFM probes.

Science.gov (United States)

Wang, Haitao; Tian, Tian; Zhang, Yong; Pan, Zhiqiang; Wang, Yong; Xiao, Zhongdang

2008-08-19

In this work, we reported an approach for the site-selective growth of nanoparticle onto the tip apex of an atomic force microscopy (AFM) probe. The silicon AFM probe was first coated with a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) through a chemical vapor deposition (CVD) method. Subsequently, COOH groups were selectively generated at the tip apex of silicon AFM probes by applying an appropriate bias voltage between the tip and a flat gold electrode. The transformation of methyl to carboxylic groups at the tip apex of the AFM probe was investigated through measuring the capillary force before and after electrochemical oxidation. To prepare the nanoparticle terminated AFM probe, the oxidized AFM probe was then immersed in an aqueous solution containing positive metal ions, for example, Ag+, to bind positive metal ions to the oxidized area (COOH terminated area), followed by chemical reduction with aqueous NaBH 4 and further development (if desired) to give a metal nanoparticle-modified AFM probe. The formation of a metal nanoparticle at the tip apex of the AFM probe was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA).

Enhanced Radiofrequency Ablation With Magnetically Directed Metallic Nanoparticles.

Science.gov (United States)

Nguyen, Duy T; Tzou, Wendy S; Zheng, Lijun; Barham, Waseem; Schuller, Joseph L; Shillinglaw, Benjamin; Quaife, Robert A; Sauer, William H

2016-05-01

Remote heating of metal located near a radiofrequency ablation source has been previously demonstrated. Therefore, ablation of cardiac tissue treated with metallic nanoparticles may improve local radiofrequency heating and lead to larger ablation lesions. We sought to evaluate the effect of magnetic nanoparticles on tissue sensitivity to radiofrequency energy. Ablation was performed using an ablation catheter positioned with 10 g of force over prepared ex vivo specimens. Tissue temperatures were measured and lesion volumes were acquired. An in vivo porcine thigh model was used to study systemically delivered magnetically guided iron oxide (FeO) nanoparticles during radiofrequency application. Magnetic resonance imaging and histological staining of ablated tissue were subsequently performed as a part of ablation lesion analysis. Ablation of ex vivo myocardial tissue treated with metallic nanoparticles resulted in significantly larger lesions with greater impedance changes and evidence of increased thermal conductivity within the tissue. Magnet-guided localization of FeO nanoparticles within porcine thigh preps was demonstrated by magnetic resonance imaging and iron staining. Irrigated ablation in the regions with greater FeO, after FeO infusion and magnetic guidance, created larger lesions without a greater incidence of steam pops. Metal nanoparticle infiltration resulted in significantly larger ablation lesions with altered electric and thermal conductivity. In vivo magnetic guidance of FeO nanoparticles allowed for facilitated radiofrequency ablation without direct infiltration into the targeted tissue. Further research is needed to assess the clinical applicability of this ablation strategy using metallic nanoparticles for the treatment of cardiac arrhythmias. © 2016 American Heart Association, Inc.

Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated "metallic" oxides.

Science.gov (United States)

Apgar, Brent A; Lee, Sungki; Schroeder, Lauren E; Martin, Lane W

2013-11-20

n-n Schottky, n-n ohmic, and p-n Schottky heterojunctions based on TiO2 /correlated "metallic" oxide couples exhibit strong solar-light absorption driven by the unique electronic structure of the "metallic" oxides. Photovoltaic and photocatalytic responses are driven by hot electron injection from the "metallic" oxide into the TiO2 , enabling new modalities of operation for energy systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Green Synthesis and Evaluation of Silver Nanoparticles and Zinc Oxide Nanoparticles

Science.gov (United States)

Gebear-Eigzabher, Bellsabel

Nanoparticle (NP) research has received exceptional attention as the field of study that contributes to transforming the world of materials science. When implementing NPs in consumer and industrial products, their unique properties improve technologies to the extent of significant game-changing breakthroughs. Conversely, the increased production of NPs, their use, their disposal or inadvertent release in the environment drove the need for processes and policies that ensures consumer and environmental safety. Mitigation of any harmful effects that NPs could potentially have combines methods of safe preparation, safe handling and safe disposal as well as containment of any inadvertent release. Our focus is in safe preparation of nanomaterials and we report green and energy efficient synthesis methods for metal NPs and metal oxide NPs of two popular materials: silver (Ag) and zinc oxide (ZnO). The thesis explained: 1) The impact of NPs in nowadays' world; 2) Synthesis methods that were designed to include environmentally-friendly staring materials and energy-saving fabrication processes, with emphasis on maintaining NPs final size and morphology when compared with existing methods; and 3) Nanoparticles characterization and data collection which allowed us to determine and/or validate their properties. Nanoparticles were studied using transmission electron microscope (TEM), X-Ray powder diffraction (XRD), low-voltage (5 keV) transmission electron microscopy (LV EM 5), Fourier-Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible (UV-Vis) spectroscopy. We developed an aqueous-based preparation of zinc oxide nanoparticles (ZnO NPs) using microwave-assisted chemistry to render a well-controlled particle size distribution within each set of reaction conditions in the range of 15 nm to 75 nm. We developed a scalable silver nanoparticles synthesis by chemical reduction methods. The NPs could be used in consumer products. The measurement tools for consumer products

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells.

Science.gov (United States)

Trost, S; Becker, T; Zilberberg, K; Behrendt, A; Polywka, A; Heiderhoff, R; Görrn, P; Riedl, T

2015-01-16

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

Metal-nanoparticle single-electron transistors fabricated using electromigration

DEFF Research Database (Denmark)

Bolotin, K I; Kuemmeth, Ferdinand; Pasupathy, A N

2004-01-01

We have fabricated single-electron transistors from individual metal nanoparticles using a geometry that provides improved coupling between the particle and the gate electrode. This is accomplished by incorporating a nanoparticle into a gap created between two electrodes using electromigration, all...... on top of an oxidized aluminum gate. We achieve sufficient gate coupling to access more than ten charge states of individual gold nanoparticles (5–15 nm in diameter). The devices are sufficiently stable to permit spectroscopic studies of the electron-in-a-box level spectra within the nanoparticle as its...

Antimicrobial Polymers with Metal Nanoparticles

Science.gov (United States)

Palza, Humberto

2015-01-01

Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

Is there lattice contraction in multicomponent metal oxides? Case study for GdVO4:Eu3+ nanoparticles

Science.gov (United States)

Yang, Liusai; Li, Liping; Zhao, Minglei; Fu, Chaochao; Li, Guangshe

2013-08-01

Metal oxide nanomaterials have been found to have great potential for diverse applications due to their unique relationships between structure and properties. Lattice expansion as particle size reduces was previously considered to be general for metal oxide nanomaterials. It is now a great challenge to see if lattice contraction could be induced by the size effect for metal oxide nanomaterials. ABO4 metal oxides (e.g., CaWO4, GdVO4, and CdWO4) are some of the most important functional materials with many applications, while such oxides at the nanoscale are never reported to show a lattice contraction. This work presents a first report on the variation from lattice expansion to lattice contraction by tuning the microstructures of GdVO4:Eu3+ nanocrystals. A hydrothermal method was adopted to synthesize GdVO4:Eu3+ nanocrystals, and then these nanoparticles were calcined at 600 ° C in air. It is found that particle size reduction led to a lattice contraction for the calcined samples, which is in contrast to the lattice expansion observed for the hydrothermally synthesized counterparts or many other metal oxide nanomaterials. In addition, the lattice symmetry of the calcined samples remained almost a constant. The results indicate that the negative surface stress was eliminated by calcination treatment, leading to a homogeneous compression process in the lattice structure of the calcined GdVO4:Eu3+ nanocrystals. Furthermore, Eu3+ was taken as a structural probe and a luminescence center to study the local environments pertinent to these structural changes and to optimize the photoluminescence performance.

Airborne Nanoparticle Release and Toxicological Risk from Metal-Oxide-Coated Textiles: Toward a Multiscale Safe-by-Design Approach.

Science.gov (United States)

Mantecca, Paride; Kasemets, Kaja; Deokar, Archana; Perelshtein, Ilana; Gedanken, Aharon; Bahk, Yeon Kyoung; Kianfar, Baharh; Wang, Jing

2017-08-15

Nano metal oxides have been proposed as alternatives to silver (Ag) nanoparticles (NPs) for antibacterial coatings. Here, cotton and polyester-cotton fabrics were sonochemically coated with zinc oxide (ZnO) and copper oxide (CuO) NPs. By varying the reaction solvent (water or ethanol), NPs with different sizes and shapes were synthesized. The cytotoxic and pro-inflammatory effects of studied NPs were investigated in vitro in human alveolar epithelial A549 and macrophage-like THP1 cells. To understand the potential respiratory impact of the NPs, the coated textiles were subjected to the abrasion tests, and the released airborne particles were measured. A very small amount of the studied metal oxides NPs was released from abrasion of the textiles coated by the ethanol-based sonochemical process. The release from the water-based coating was comparably higher. Lung and immune cells viability decreased after 24 h of exposure only at the highest studied NPs concentration (100 μg/mL). Different from the ZnO NPs, both formulations of CuO NPs induced IL-8 release in the lung epithelial cells already at subtoxic concentrations (1-10 μg/mL) but not in immune cells. All of the studied NPs did not induce IL-6 release by the lung and immune cells. Calculations revealed that the exposures of the NPs to human lung due to the abrasion of the textiles were lower or comparable to the minimum doses in the cell viability tests (0.1 μg/mL), at which acute cytotoxicity was not observed. The results alleviate the concerns regarding the potential risk of these metal oxide NPs in their applications for the textile coating and provide insight for the safe-by-design approach.

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring.

Science.gov (United States)

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Di Leandro, Luana; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-28

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the "double-faced" Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml(-1). Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and "green" routes to 3D reduced GO-metal composite materials.

Formation of uranium based nanoparticles via gamma-irradiation

Energy Technology Data Exchange (ETDEWEB)

Nenoff, Tina M., E-mail: tmnenof@sandia.gov [Nanoscale Sciences Department, Sandia National Laboratories, P.O. Box 5800, MS-1415, Albuquerque, NM 87185 (United States); Ferriera, Summer R. [Nanoscale Sciences Department, Sandia National Laboratories, P.O. Box 5800, MS-1415, Albuquerque, NM 87185 (United States); Huang, Jianyu [Center for Integrated Nanotechnology, Sandia National Laboratories, P.O. Box 5800, MS-1315, Albuquerque, NM 87185 (United States); Hanson, Donald J. [Department of Hot Cells and Gamma Facilities, Sandia National Laboratories, P.O. Box 5800, MS-1143, Albuquerque, NM 87185 (United States)

2013-11-15

Graphical abstract: TEM image of d-U nanoparticles formed in aqueous solution by gamma irradiation. Display Omitted -- Highlights: •d-U nanoparticles were grown in solution by gamma irradiation. •The reaction solution does not exceed 25 °C (room temperature). •Only after multiday exposure to air is there evidence of oxidation of the d-U nanoparticles. •Evidence of d-U alloy nanoparticle formation confirmed by TEM/energy-dispersive X-ray (EDS) analysis. -- Abstract: The ability to fabricate nuclear fuels at low temperatures allows for the production of complex Uranium metal and alloys with minimum volatility of alloy components in the process. Gamma irradiation is a valuable method for the synthesis of a wide range of metal-based nanoparticles. We report on the synthesis via room temperature radiolysis and characterization of uranium (depleted, d-U) metal and uranium–lathanide (d-ULn, Ln = lanthanide surrogates) alloy nanoparticles from aqueous acidic salt solutions. The lanthanide surrogates chosen include La and Eu due to their similarity in ionic size and charge in solution. Detailed characterization results including UV–vis, TEM/HR-TEM, and single particle EDX (elemental analyses) are presented for the room temperature formed nanoparticle products.

Formation of uranium based nanoparticles via gamma-irradiation

International Nuclear Information System (INIS)

Nenoff, Tina M.; Ferriera, Summer R.; Huang, Jianyu; Hanson, Donald J.

2013-01-01

Graphical abstract: TEM image of d-U nanoparticles formed in aqueous solution by gamma irradiation. Display Omitted -- Highlights: •d-U nanoparticles were grown in solution by gamma irradiation. •The reaction solution does not exceed 25 °C (room temperature). •Only after multiday exposure to air is there evidence of oxidation of the d-U nanoparticles. •Evidence of d-U alloy nanoparticle formation confirmed by TEM/energy-dispersive X-ray (EDS) analysis. -- Abstract: The ability to fabricate nuclear fuels at low temperatures allows for the production of complex Uranium metal and alloys with minimum volatility of alloy components in the process. Gamma irradiation is a valuable method for the synthesis of a wide range of metal-based nanoparticles. We report on the synthesis via room temperature radiolysis and characterization of uranium (depleted, d-U) metal and uranium–lathanide (d-ULn, Ln = lanthanide surrogates) alloy nanoparticles from aqueous acidic salt solutions. The lanthanide surrogates chosen include La and Eu due to their similarity in ionic size and charge in solution. Detailed characterization results including UV–vis, TEM/HR-TEM, and single particle EDX (elemental analyses) are presented for the room temperature formed nanoparticle products

in vivo EFFECTS OF RARE-EARTH BASED NANOPARTICLES ON OXIDATIVE BALANCE IN RATS

Directory of Open Access Journals (Sweden)

V. K. Klochkov

2016-12-01

Full Text Available The purpose of the research was to find the influence of rare-earth based nanoparticles (CeO2, GdVO2: Eu3+ on the oxidative balance in rats. We analyzed biochemical markers of oxidative stress (lipid peroxidation level, nitric oxide metabolites, sulfhydryl groups content and enzyme activities (superoxide dismutase, catalase in tissues of rats. It has been found that administration of both types of the nanoparticles increased nitric oxide metabolites and products of lipid peroxidation in liver and spleen within 5 days. At injections of GdVO2: Eu3+ lipid peroxidation products, nitric oxide metabolites in serum at 5, 10 and 15 days of the experiment was also increased whereas the level of sulfhydryl groups decreased compared to the intact state and the control. In contrast, under the influence of nanoparticle CeO2 level diene conjugates were not significantly changed and the level of nitric oxide metabolites within 15 day even decreased. During this period, under the influence of both types of nanoparticles the activity of superoxide dismutase was increased, catalase activity was not changed. Oxidative stress coefficient showed the less pronounced CeO2 prooxidant effect (2.04 in comparison to GdVO2: Eu3+ (6.89. However, after-effect of both types of nanoparticles showed complete restoration of oxidative balance values.

Effects of Metallic Nanoparticles on Interfacial Intermetallic Compounds in Tin-Based Solders for Microelectronic Packaging

Science.gov (United States)

Haseeb, A. S. M. A.; Arafat, M. M.; Tay, S. L.; Leong, Y. M.

2017-10-01

Tin (Sn)-based solders have established themselves as the main alternative to the traditional lead (Pb)-based solders in many applications. However, the reliability of the Sn-based solders continues to be a concern. In order to make Sn-based solders microstructurally more stable and hence more reliable, researchers are showing great interest in investigating the effects of the incorporation of different nanoparticles into them. This paper gives an overview of the influence of metallic nanoparticles on the characteristics of interfacial intermetallic compounds (IMCs) in Sn-based solder joints on copper substrates during reflow and thermal aging. Nanocomposite solders were prepared by mechanically blending nanoparticles of nickel (Ni), cobalt (Co), zinc (Zn), molybdenum (Mo), manganese (Mn) and titanium (Ti) with Sn-3.8Ag-0.7Cu and Sn-3.5Ag solder pastes. The composite solders were then reflowed and their wetting characteristics and interfacial microstructural evolution were investigated. Through the paste mixing route, Ni, Co, Zn and Mo nanoparticles alter the morphology and thickness of the IMCs in beneficial ways for the performance of solder joints. The thickness of Cu3Sn IMC is decreased with the addition of Ni, Co and Zn nanoparticles. The thickness of total IMC layer is decreased with the addition of Zn and Mo nanoparticles in the solder. The metallic nanoparticles can be divided into two groups. Ni, Co, and Zn nanoparticles undergo reactive dissolution during solder reflow, causing in situ alloying and therefore offering an alternative route of alloy additions to solders. Mo nanoparticles remain intact during reflow and impart their influence as discrete particles. Mechanisms of interactions between different types of metallic nanoparticles and solder are discussed.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Photocatalytic composites based on titania nanoparticles and carbon nanomaterials

International Nuclear Information System (INIS)

Nguyen, Bich Ha; Nguyen, Van Hieu; Vu, Dinh Lam

2015-01-01

In this article we present a review on recent experimental works toward the formation of visible light responsive composite photocatalysts on the basis of titania nanoparticles and carbon nanomaterials of different types. The research results achieved in last years has shown that the nanocomposite photocatalysts comprising titania nanoparticles and graphene or graphene oxide sheets, and also nanoparticles of noble metals and metallic oxides, exhibited the evident priority compared to the others. Therefore our review emphasizes the research on these promising visible light responsive nanophotocatalysts. (review)

Scalable fractionation of iron oxide nanoparticles using a CO2 gas-expanded liquid system

International Nuclear Information System (INIS)

Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B.

2015-01-01

Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO 2 gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

Evaluation of Colloidal Stability and Ecotoxicity of Metal-based Nanoparticles in the Aquatic and Terrestrial Systems

Science.gov (United States)

Pokhrel, Lok Raj

Intrinsic to the many nano-enabled products are atomic-size multifunctional engineered nanomaterials, which upon release contaminate the environments, raising considerable health and safety concerns. This Ph.D. dissertation is designed to investigate (i) whether metals or oxide nanoparticles are more toxic than ions, and if MetPLATE(TM) bioassay is applicable as a rapid nanotoxicity screening tool; (ii) how variable water chemistry (dissolved organic carbon (DOC), pH, and hardness) and organic compounds (cysteine, humic acid, and trolox) modulate colloidal stability, ion release, and aquatic toxicity of silver nanoparticles (AgNP); and (iii) the developmental responses of crop plants exposed to Ag- or ZnO- (zinc oxide) nanoparticles. Results suggest that the MetPLATE can be considered a high-throughput screening tool for rapid nanotoxicity evaluation. Detectable changes in the colloidal diameter, surface charge, and plasmonic resonance revealed modulating effects of variable water chemistry and organic ligands on the particle stability, dissolution, and toxicity of AgNPs against Escherichia coli or Daphnia magna. Silver dissolution increased as a function of DOC concentrations but decreased with increasing hardness, pH, cysteine, or trolox levels. Notably, the dissociated Ag+ was inadequate to explain AgNP toxicity, and that the combined effect of AgNPs and dissolved Ag+ under each ligand treatment was lower than of AgNO 3. Significant attenuation by trolox signifies an oxidative stress-mediated AgNP toxicity; its inability to attenuate AgNO3 toxicity, however, negates oxidative stress as Ag+ toxicity mechanism, and that cysteine could effectively quench free Ag+ to alleviate AgNO 3 toxicity in D. magna. Surprisingly, DOC-AgNPs complex that apparently formed at higher DOC levels might have led daphnids filter-feed on aggregates, potentially elevating internal dose, and thus higher mortality. Maize root anatomy showed differential alterations upon exposure to Ag

Grafting of diazonium salts on oxides surface: formation of aryl-O bonds on iron oxide nanoparticles

International Nuclear Information System (INIS)

Brymora, Katarzyna; Fouineau, Jonathan; Eddarir, Asma; Chau, François; Yaacoub, Nader; Grenèche, Jean-Marc; Pinson, Jean; Ammar, Souad; Calvayrac, Florent

2015-01-01

Combining ab initio modeling and 57 Fe Mössbauer spectrometry, we characterized the nature of the chemical linkage of aminoalkyl arenediazonium salt on the surface of iron oxide nanoparticles. We established that it is built through a metal–oxygen–carbon bonding and not a metal–carbon one, as usually suggested and commonly observed in previously studied metal- or carbon-based surfaces

Grafting of diazonium salts on oxides surface: formation of aryl-O bonds on iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Brymora, Katarzyna [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France); Fouineau, Jonathan; Eddarir, Asma; Chau, François [Université Paris Diderot, Sorbonne Paris Cité, ITODYS CNRS UMR 7086 (France); Yaacoub, Nader; Grenèche, Jean-Marc [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France); Pinson, Jean; Ammar, Souad [Université Paris Diderot, Sorbonne Paris Cité, ITODYS CNRS UMR 7086 (France); Calvayrac, Florent, E-mail: florent.calvayrac@univ-lemans.fr [LUNAM Université du Maine, IMMM UMR CNRS 6283 (France)

2015-11-15

Combining ab initio modeling and {sup 57}Fe Mössbauer spectrometry, we characterized the nature of the chemical linkage of aminoalkyl arenediazonium salt on the surface of iron oxide nanoparticles. We established that it is built through a metal–oxygen–carbon bonding and not a metal–carbon one, as usually suggested and commonly observed in previously studied metal- or carbon-based surfaces.

Effect of metal oxide nanoparticles on microbial community structure and function in two different soil types.

Directory of Open Access Journals (Sweden)

Sammy Frenk

Full Text Available Increased availability of nanoparticle-based products will, inevitably, expose the environment to these materials. Engineered nanoparticles (ENPs may thus find their way into the soil environment via wastewater, dumpsters and other anthropogenic sources; metallic oxide nanoparticles comprise one group of ENPs that could potentially be hazardous for the environment. Because the soil bacterial community is a major service provider for the ecosystem and humankind, it is critical to study the effects of ENP exposure on soil bacteria. These effects were evaluated by measuring bacterial community activity, composition and size following exposure to copper oxide (CuO and magnetite (Fe3O4 nanosized (<50 nm particles. Two different soil types were examined: a sandy loam (Bet-Dagan and a sandy clay loam (Yatir, under two ENP concentrations (1%, 0.1%. Results indicate that the bacterial community in Bet-Dagan soil was more susceptible to change due to exposure to these ENPs, relative to Yatir soil. More specifically, CuO had a strong effect on bacterial hydrolytic activity, oxidative potential, community composition and size in Bet-Dagan soil. Few effects were noted in the Yatir soil, although 1% CuO exposure did cause a significant decreased oxidative potential and changes to community composition. Fe3O4 changed the hydrolytic activity and bacterial community composition in Bet-Dagan soil but did not affect the Yatir soil bacterial community. Furthermore, in Bet-Dagan soil, abundance of bacteria annotated to OTUs from the Bacilli class decreased after addition of 0.1% CuO but increased with 1% CuO, while in Yatir soil their abundance was reduced with 1% CuO. Other important soil bacterial groups, including Rhizobiales and Sphingobacteriaceae, were negatively affected by CuO addition to soil. These results indicate that both ENPs are potentially harmful to soil environments. Furthermore, it is suggested that the clay fraction and organic matter in

Capacitance characteristics of metal-oxide-semiconductor capacitors with a single layer of embedded nickel nanoparticles for the application of nonvolatile memory

International Nuclear Information System (INIS)

Wei, Li; Ling, Xu; Wei-Ming, Zhao; Hong-Lin, Ding; Zhong-Yuan, Ma; Jun, Xu; Kun-Ji, Chen

2010-01-01

This paper reports that metal-oxide-semiconductor (MOS) capacitors with a single layer of Ni nanoparticles were successfully fabricated by using electron-beam evaporation and rapid thermal annealing for application to nonvolatile memory. Experimental scanning electron microscopy images showed that Ni nanoparticles of about 5 nm in diameter were clearly embedded in the SiO 2 layer on p-type Si (100). Capacitance–voltage measurements of the MOS capacitor show large flat-band voltage shifts of 1.8 V, which indicate the presence of charge storage in the nickel nanoparticles. In addition, the charge-retention characteristics of MOS capacitors with Ni nanoparticles were investigated by using capacitance–time measurements. The results showed that there was a decay of the capacitance embedded with Ni nanoparticles for an electron charge after 10 4 s. But only a slight decay of the capacitance originating from hole charging was observed. The present results indicate that this technique is promising for the efficient formation or insertion of metal nanoparticles inside MOS structures. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

In vitro effects of metal oxide nanoparticles on barley oxalate oxidase

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Nidhi [M. D. University, Department of Biochemistry (India); Hooda, Vinita [M. D. University, Department of Botany (India); Pundir, C. S., E-mail: pundircs@rediffmail.com [M. D. University, Department of Biochemistry (India)

2013-03-15

Barley oxalate oxidase (OxO), a manganese-containing protein, is largely employed for determination of oxalate in various biologic materials. The present report describes in vitro effects of nanoparticles (NPs) of three metal oxides, i.e., zinc oxide (ZnO), copper oxide (CuO), and manganese oxide (MnO{sub 2}), on the activity and stability of OxO purified from barley roots. The transmission electron microscopy and X-ray diffraction studies of these NPs revealed their very fine crystalline structure with the dimeter in the range 30-70, 50-60, and 20-60 nm for ZnO NPs, CuO NPs, and MnO{sub 2} NPs, respectively. The addition of suspension of these three NPs into assay mixture of enzyme individually, led to the adsorption of OxO over their surface, as confirmed by Fourier transform infrared spectra and UV-Vis spectroscopic studies. Compared to free enzyme, MnO{sub 2} NPs-bound enzyme showed improved activity (35 % stimulation at 2.5 mg/ml concentration), while ZnO NPs- and CuO NPs-bound enzyme had no substantial improvement. The kinetic properties of individually NPs-bound enzyme were studied and compared with those of free enzyme. The MnO{sub 2} NPs-bound enzyme also showed marked improvement in its storage and thermal stability compared to free enzyme.

In vitro effects of metal oxide nanoparticles on barley oxalate oxidase

Science.gov (United States)

Chauhan, Nidhi; Hooda, Vinita; Pundir, C. S.

2013-03-01

Barley oxalate oxidase (OxO), a manganese-containing protein, is largely employed for determination of oxalate in various biologic materials. The present report describes in vitro effects of nanoparticles (NPs) of three metal oxides, i.e., zinc oxide (ZnO), copper oxide (CuO), and manganese oxide (MnO2), on the activity and stability of OxO purified from barley roots. The transmission electron microscopy and X-ray diffraction studies of these NPs revealed their very fine crystalline structure with the dimeter in the range 30-70, 50-60, and 20-60 nm for ZnO NPs, CuO NPs, and MnO2 NPs, respectively. The addition of suspension of these three NPs into assay mixture of enzyme individually, led to the adsorption of OxO over their surface, as confirmed by Fourier transform infrared spectra and UV-Vis spectroscopic studies. Compared to free enzyme, MnO2 NPs-bound enzyme showed improved activity (35 % stimulation at 2.5 mg/ml concentration), while ZnO NPs- and CuO NPs-bound enzyme had no substantial improvement. The kinetic properties of individually NPs-bound enzyme were studied and compared with those of free enzyme. The MnO2 NPs-bound enzyme also showed marked improvement in its storage and thermal stability compared to free enzyme.

Efficient One-Pot Synthesis of Colloidal Zirconium Oxide Nanoparticles for High-Refractive-Index Nanocomposites.

Science.gov (United States)

Liu, Chao; Hajagos, Tibor Jacob; Chen, Dustin; Chen, Yi; Kishpaugh, David; Pei, Qibing

2016-02-01

Zirconium oxide nanoparticles are promising candidates for optical engineering, photocatalysis, and high-κ dielectrics. However, reported synthetic methods for the colloidal zirconium oxide nanoparticles use unstable alkoxide precursors and have various other drawbacks, limiting their wide application. Here, we report a facile one-pot method for the synthesis of colloidally stable zirconium oxide nanoparticles. Using a simple solution of zirconium trifluoroacetate in oleylamine, highly stable zirconium oxide nanoparticles have been synthesized with high yield, following a proposed amidization-assisted sol-gel mechanism. The nanoparticles can be readily dispersed in nonpolar solvents, forming a long-term stable transparent solution, which can be further used to fabricate high-refractive-index nanocomposites in both monolith and thin-film forms. In addition, the same method has also been extended to the synthesis of titanium oxide nanoparticles, demonstrating its general applicability to all group IVB metal oxide nanoparticles.

Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

Science.gov (United States)

Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

2016-04-05

Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoparticles of complex metal oxides synthesized using the ...

Indian Academy of Sciences (India)

ASHOK K GANGULI∗, TOKEER AHMAD, PADAM R ARYA and PIKA JHA ... nanoparticles of several dielectric oxides like BaTiO3, Ba2TiO4, SrTiO3, PbTiO3 .... reasonable stability till 150◦C. All the lead-doped phases (sintered at 900◦C) show.

Ball lightning from atmospheric discharges via metal nanosphere oxidation: from soils, wood or metals.

Science.gov (United States)

Abrahamson, John

2002-01-15

The slow (diffusion-limited) oxidation of metal nanoparticles has previously been proposed as the mechanism for ball lightning energy release, and argued to be the result of a normal lightning strike on soil. Here this basic model of networked nanoparticles is detailed further, and extended to lightning strikes on metal structures, and also to the action of other storm-related discharges or man-made discharges. The basic model predicted the important properties of "average" observed ball lightning, and the extension in this paper also covers high-energy examples of ball lightning. Laboratory checks of the theory are described, and predictions given of what conditions are necessary for observing ball lightning in the laboratory. Key requirements of the model are a sheltered region near the strike foot and starting materials which can generate a metal vapour under intensive heating, including soil, wood or a metal structure. The evolution of hydrocarbons (often plastics) along with metal vapour can ensure the local survival of the metal vapour even in an oxidizing atmosphere. Subsequent condensation of this vapour to metallic nanoparticles in networks provides the coherence of a ball structure, which also releases light over an extended time. Also discussed is the passage of ball lightning through a sheet of building material, including glass, and its occasional charring of flesh on close contact.

Electrochemical investigation of gold nanoparticles incorporated zinc based metal-organic framework for selective recognition of nitrite and nitrobenzene

International Nuclear Information System (INIS)

Yadav, Dharmendra Kumar; Ganesan, Vellaichamy; Sonkar, Piyush Kumar; Gupta, Rupali; Rastogi, Pankaj Kumar

2016-01-01

Highlights: • Gold nanoparticles incorporated zinc based metal-organic framework is synthesized. • It electro-catalyzes nitrite oxidation and nitrobenzene reduction. • Nitrite and nitrobenzene is determined with high sensitivity. • Hydrodynamic voltammetry studies of nitrite oxidation and nitrobenzene reduction are reported. - Abstract: An electrochemical sensing platform which comprises gold nanoparticles (Au NPs) incorporated zinc based metal-organic framework (MOF-5) is developed for the sensitive determination of nitrite and nitrobenzene. MOF-5 and Au NPs incorporated MOF-5 (Au-MOF-5) are synthesized and characterized by UV-vis absorption, powder X-ray diffraction, FT-IR, scanning electron microscopy with energy dispersive X-ray analysis and elemental mapping, transmission electron microscopy and atomic force microscopy. Oxidation of nitrite is effectively electrocatalyzed at Au-MOF-5 with significant increase in oxidation current (41 and 38% in comparison with bare glassy carbon (GC) and MOF-5 coated GC (GC/MOF-5) electrodes, respectively) and with considerable decrease in the oxidation potential (0. 17 and 0.25 V in comparison with bare GC and GC/MOF-5 electrodes, respectively). The electrocatalytic reduction of nitrobenzene at GC/Au-MOF-5 is confirmed by an appreciable increase in the reduction current (79 and 36% in comparison with bare GC and GC/MOF-5 electrodes, respectively) and a small shift in the reduction potential (20 mV in comparison with GC/MOF-5). The detection limit is calculated as 1.0 μM with a sensitivity of 0.23 μAμM"−"1 cm"−"2 for nitrite and 15.3 μM with a sensitivity of 0.43 μAμM"−"1cm"−"2 for nitrobenzene determinations. The Au-MOF-5 based electrochemical sensing platform shows high stability and selectivity even in the presence of several interferences (including phenols, inorganic ions and biologically important molecules) with a broad calibration range. Certain kinetic parameters of nitrite oxidation and

High performance supercapacitors using metal oxide anchored graphene nanosheet electrodes

KAUST Repository

Baby, Rakhi Raghavan

2011-01-01

Metal oxide nanoparticles were chemically anchored onto graphene nanosheets (GNs) and the resultant composites - SnO2/GNs, MnO2/GNs and RuO2/GNs (58% of GNs loading) - coated over conductive carbon fabric substrates were successfully used as supercapacitor electrodes. The results showed that the incorporation of metal oxide nanoparticles improved the capacitive performance of GNs due to a combination of the effect of spacers and redox reactions. The specific capacitance values (with respect to the composite mass) obtained for SnO2/GNs (195 F g-1) and RuO 2/GNs (365 F g-1) composites at a scan rate of 20 mV s-1 in the present study are the best ones reported to date for a two electrode configuration. The resultant supercapacitors also exhibited high values for maximum energy (27.6, 33.1 and 50.6 W h kg-1) and power densities (15.9, 20.4 and 31.2 kW kg-1) for SnO2/GNs, MnO2/GNs and RuO2/GNs respectively. These findings demonstrate the importance and great potential of metal oxide/GNs based composite coated carbon fabric in the development of high-performance energy-storage systems. © 2011 The Royal Society of Chemistry.

Comparative metal oxide nanoparticle toxicity using embryonic zebrafish

Directory of Open Access Journals (Sweden)

Leah C. Wehmas

2015-01-01

Full Text Available Engineered metal oxide nanoparticles (MO NPs are finding increasing utility in the medical field as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO, titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to associate NP characteristics such as size and charge with toxicity. However, data from our agglomerated MO NPs suggests that the elemental composition and dissolution potential are major drivers of toxicity. Only ZnO caused significant adverse effects of all MO particles tested, and only when prepared in pure water (point estimate median lethal concentration = 3.5–9.1 mg/L. This toxicity was life stage dependent. The 24 h toxicity increased greatly (∼22.7 fold when zebrafish exposures started at the larval life stage compared to the 24 h toxicity following embryonic exposure. Investigation into whether dissolution could account for ZnO toxicity revealed high levels of zinc ion (40–89% of total sample were generated. Exposure to zinc ion equivalents revealed dissolved Zn2+ may be a major contributor to ZnO toxicity.

Thin films of metal-organic compounds and metal nanoparticle

Indian Academy of Sciences (India)

Thin films of metal-organic compounds and metal nanoparticle-embedded polymers for nonlinear optical applications. S Philip Anthony Shatabdi Porel D ... Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored. A family of zinc complexes which ...

Scalable fractionation of iron oxide nanoparticles using a CO{sub 2} gas-expanded liquid system

Energy Technology Data Exchange (ETDEWEB)

Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B., E-mail: croberts@eng.auburn.edu [Auburn University, Department of Chemical Engineering (United States)

2015-10-15

Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO{sub 2} gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

Flexible supercapacitor electrodes based on real metal-like cellulose papers.

Science.gov (United States)

Ko, Yongmin; Kwon, Minseong; Bae, Wan Ki; Lee, Byeongyong; Lee, Seung Woo; Cho, Jinhan

2017-09-14

The effective implantation of conductive and charge storage materials into flexible frames has been strongly demanded for the development of flexible supercapacitors. Here, we introduce metallic cellulose paper-based supercapacitor electrodes with excellent energy storage performance by minimizing the contact resistance between neighboring metal and/or metal oxide nanoparticles using an assembly approach, called ligand-mediated layer-by-layer assembly. This approach can convert the insulating paper to the highly porous metallic paper with large surface areas that can function as current collectors and nanoparticle reservoirs for supercapacitor electrodes. Moreover, we demonstrate that the alternating structure design of the metal and pseudocapacitive nanoparticles on the metallic papers can remarkably increase the areal capacitance and rate capability with a notable decrease in the internal resistance. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1 mW cm -2 and 267.3 μWh cm -2 , respectively, substantially outperforming the performance of conventional paper or textile-type supercapacitors.With ligand-mediated layer-by-layer assembly between metal nanoparticles and small organic molecules, the authors prepare metallic paper electrodes for supercapacitors with high power and energy densities. This approach could be extended to various electrodes for portable/wearable electronics.

Facile radiolytic synthesis of ruthenium nanoparticles on graphene oxide and carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Rojas, J.V., E-mail: jvrojas@vcu.edu [Mechanical and Nuclear Engineering Department, Virginia Commonwealth University, 401 West Main Street, Richmond, Virginia, 23284 (United States); Toro-Gonzalez, M.; Molina-Higgins, M.C. [Mechanical and Nuclear Engineering Department, Virginia Commonwealth University, 401 West Main Street, Richmond, Virginia, 23284 (United States); Castano, C.E., E-mail: cecastanolond@vcu.edu [Nanomaterials Core Characterization Facility, Chemical and Life Science Engineering Department, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia, 23284 (United States)

2016-03-15

Graphical abstract: - Highlights: • Facile radiolytic synthesis of Ru nanoparticles on graphene oxide and carbon nanotubes. • Homogeneously distributed Rh nanoparticles on supports are ∼2.5 nm in size. • Simultaneous reduction of graphene oxide and Ru ions occurs during the synthesis. • Ru-O bonds evidenced the interaction of the nanoparticles with the support. - Abstract: Ruthenium nanoparticles on pristine (MWCNT) and functionalized carbon nanotubes (f-MWCNT), and graphene oxide have been prepared through a facile, single step radiolytic method at room temperature, and ambient pressure. This synthesis process relies on the interaction of high energy gamma rays from a {sup 60}Co source with the water in the aqueous solutions containing the Ru precursor, leading to the generation of highly reducing species that further reduce the Ru metal ions to zero valence state. Transmission electron microscopy and X-Ray diffraction revealed that the nanoparticles were homogeneously distributed on the surface of the supports with an average size of ∼2.5 nm. X-ray Photoelectron spectroscopy analysis showed that the interaction of the Ru nanoparticles with the supports occurred through oxygenated functionalities, creating metal-oxygen bonds. This method demonstrates to be a simple and clean approach to produce well dispersed nanoparticles on the aforementioned supports without the need of any hazardous chemical.

Facile radiolytic synthesis of ruthenium nanoparticles on graphene oxide and carbon nanotubes

International Nuclear Information System (INIS)

Rojas, J.V.; Toro-Gonzalez, M.; Molina-Higgins, M.C.; Castano, C.E.

2016-01-01

Graphical abstract: - Highlights: • Facile radiolytic synthesis of Ru nanoparticles on graphene oxide and carbon nanotubes. • Homogeneously distributed Rh nanoparticles on supports are ∼2.5 nm in size. • Simultaneous reduction of graphene oxide and Ru ions occurs during the synthesis. • Ru-O bonds evidenced the interaction of the nanoparticles with the support. - Abstract: Ruthenium nanoparticles on pristine (MWCNT) and functionalized carbon nanotubes (f-MWCNT), and graphene oxide have been prepared through a facile, single step radiolytic method at room temperature, and ambient pressure. This synthesis process relies on the interaction of high energy gamma rays from a "6"0Co source with the water in the aqueous solutions containing the Ru precursor, leading to the generation of highly reducing species that further reduce the Ru metal ions to zero valence state. Transmission electron microscopy and X-Ray diffraction revealed that the nanoparticles were homogeneously distributed on the surface of the supports with an average size of ∼2.5 nm. X-ray Photoelectron spectroscopy analysis showed that the interaction of the Ru nanoparticles with the supports occurred through oxygenated functionalities, creating metal-oxygen bonds. This method demonstrates to be a simple and clean approach to produce well dispersed nanoparticles on the aforementioned supports without the need of any hazardous chemical.

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

International Nuclear Information System (INIS)

Raja, Mohan; Shanmugharaj, A.M.; Ryu, Sung Hun; Subha, J.

2011-01-01

Highlights: → Polyurethane based on pristine and metal (Ag and Cu) nanoparticle decorated CNTs nanocomposites are prepared through melt blending process. → The electrical, mechanical, dynamic mechanical, thermal conductivity and electro active shape memory properties of the PU nanocomposites were investigated. → The influence of metal nanoparticle decorated CNTs showed significant improvement in their all properties to compare to pristine CNTs. → Electro active shape memory studies of the PU/M-CNTs nanocomposites reveal extraordinary recoverability of its shape at lower applied dc voltages. - Abstract: Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.

Metal oxide nanoparticle transport in porous media – an analysis about (un)certainties in environmental research

International Nuclear Information System (INIS)

Heidmann, I

2013-01-01

Research about the fate and behavior of engineered nanoparticles in the environment is despite its wide applications still in the early stages. The fast-growing area of nanoparticle research and the high level of uncertainty create a big challenge for describing clearly the recent state of the current scientific knowledge. Therefore, in this study the certain knowledge, the known uncertainties and the identified knowledge gaps concerning mobility of engineered metal oxide nanoparticles in porous media are analyzed. The mobility of nanoparticles is mainly investigated in model laboratory studies under well-defined conditions, which are often not realistic for natural systems. In these model systems, nanoparticles often retain in the pore system due to aggregation and sedimentation. However, under environmental conditions, the presence of natural organic matter may cause stabilization or disaggregation of nanoparticles and favors therefore higher mobility of nanoparticles. Additionally, potential higher mobility of particles using preferential flow paths is not considered. Knowledge of the long-term behavior of nanoparticles concerning disaggregation, dissolution or remobilization in soils under environmental conditions is scarce. Scientific uncertainty itself is rarely mentioned in the research papers. Seldom known methodically uncertainties in nanoparticle characterization are referred to. The uncertainty about the transferability of the results to environmental conditions is discussed more often. Due to the sparse studies concerning natural material or natural pore systems, certain conclusions concerning the mobility of nanoparticles in the soil environment are not possible to drawn.

Aluminum Oxide Nanoparticles for Highly Efficient Asphaltene Separation from Crude Oil Using Ceramic Membrane Technology

Directory of Open Access Journals (Sweden)

Rezakazemi Mashallah

2017-11-01

Full Text Available The effects of aluminum oxide nanoparticles on the removal of asphaltenes from an Iranian crude oil (Soroush using a ceramic membrane with pore size of 0.2 µm were investigated. In order to achieve superior asphaltene separation by ultrafiltration, it is essential to make some changes for destabilizing asphaltene in crude oil. The asphaltene destabilization was done using crude oil contact with an acid containing dissolved metal ions. Metal oxide nanoparticles adsorbed asphaltene molecules and increased their molecular size. The nanoparticle of aluminum oxide was applied to alter precipitation and peptization properties of asphaltenes. Dynamic Light Scattering (DLS was used to measurement of the asphaltene molecular size dissolved in toluene. Raman spectroscopy and the Tuinstra equation were used to determine the aromatic sheet diameter (La via the integrated intensities of the G and D1 modes. This revealed that the asphaltene particles react with nano aluminum oxide and the average molecular size of asphaltene was raised from 512.754 to 2949.557 nm and La from 5.482 to 13.787. The obtained results showed that using nano aluminum oxides, asphaltene separation increased from 60–85 wt% to 90–97 wt% based on the asphaltene content of crude oil.

Assessment of Carbon- and Metal-Based Nanoparticle DNA Damage with Microfluidic Electrophoretic Separation Technology.

Science.gov (United States)

Schrand, Amanda M; Powell, Thomas; Robertson, Tiffany; Hussain, Saber M

2015-02-01

In this study, we examined the feasibility of extracting DNA from whole cell lysates exposed to nanoparticles using two different methodologies for evaluation of fragmentation with microfluidic electrophoretic separation. Human lung macrophages were exposed to five different carbon- and metal-based nanoparticles at two different time points (2 h, 24 h) and two different doses (5 µg/ml, 100 µg/ml). The primary difference in the banding patterns after 2 h of nanoparticle exposure is more DNA fragmentation at the higher NP concentration when examining cells exposed to nanoparticles of the same composition. However, higher doses of carbon and silver nanoparticles at both short and long dosing periods can contribute to erroneous or incomplete data with this technique. Also comparing DNA isolation methodologies, we recommend the centrifugation extraction technique, which provides more consistent banding patterns in the control samples compared to the spooling technique. Here we demonstrate that multi-walled carbon nanotubes, 15 nm silver nanoparticles and the positive control cadmium oxide cause similar DNA fragmentation at the short time point of 2 h with the centrifugation extraction technique. Therefore, the results of these studies contribute to elucidating the relationship between nanoparticle physicochemical properties and DNA fragmentation results while providing the pros and cons of altering the DNA isolation methodology. Overall, this technique provides a high throughput way to analyze subcellular alterations in DNA profiles of cells exposed to nanomaterials to aid in understanding the consequences of exposure and mechanistic effects. Future studies in microfluidic electrophoretic separation technologies should be investigated to determine the utility of protein or other assays applicable to cellular systems exposed to nanoparticles.

Multifunctional metal ferrite nanoparticles for MR imaging applications

International Nuclear Information System (INIS)

Joshi, Hrushikesh M.

2013-01-01

Magnetic Resonance Imaging (MRI) is a very powerful non-invasive tool for in vivo imaging and clinical diagnosis. With rapid advancement in nanoscience and nanotechnology, there is rapid growth in nanoparticles-based contrast agents. Progress in synthetic protocols enable synthesis of multifunctional nanoparticles which facilitated efforts toward the development of multimodal contrast agents. In this review, recent developments in metal ferrite-based MR contrast agents have been described. Specifically, effect of size, shape, composition, assembly and surface modification of metal ferrite nanoparticles on their T 2 contrast have been discussed. The review further outlines the effect of leaching on MRI contrast and other various factors which affect the multimodal ability of the (T 1 –T 2 and T 2 -thermal activation) metal ferrite nanoparticles.

Hollow carbon sphere/metal oxide nanocomposites anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Wenelska, K.; Ottmann, A.; Schneider, P.; Thauer, E.; Klingeler, R.; Mijowska, E.

2016-01-01

HCS (Hollow carbon spheres) covered with metal oxide nanoparticles (SnO_2 and MnO_2, respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer–Emmett–Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO_2 is 370 mA hg"−"1 after 45 cycles (266 mA hg"−"1 in HCS/MnO_2) which clearly exceeds the value of 188 mA hg"−"1 in pristine HCS. Remarkably, the data imply excellent long term cycling stability after 100 cycles in both cases. The results hence show that mesoporous HCS/metal oxide nanocomposites enable exploiting the potential of metal oxide anode materials in Lithium-ion batteries by providing a HCS host structure which is both conductive and stable enough to accommodate big volume change effects. - Highlights: • Strategy to synthesize hollow carbon spheres decorated by metal oxides nanoparticles. • High-performance of HCS/MOx storage as mesoporous hybrid material. • The results hence demonstrate high electrochemical activity of the HCS/MOx.

Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

Directory of Open Access Journals (Sweden)

Xiao-Chen Yang

2014-01-01

Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

Metal-based nanoparticle interactions with the nervous system: the challenge of brain entry and the risk of retention in the organism.

Science.gov (United States)

Yokel, Robert; Grulke, Eric; MacPhail, Robert

2013-01-01

This review of metal-based nanoparticles focuses on factors influencing their distribution into the nervous system, evidence they enter brain parenchyma, and nervous system responses. Gold is emphasized as a model metal-based nanoparticle and for risk assessment in the companion review. The anatomy and physiology of the nervous system, basics of colloid chemistry, and environmental factors that influence what cells see are reviewed to provide background on the biological, physical-chemical, and internal milieu factors that influence nervous system nanoparticle uptake. The results of literature searches reveal little nanoparticle research included the nervous system, which about equally involved in vitro and in vivo methods, and very few human studies. The routes of uptake into the nervous system and mechanisms of nanoparticle uptake by cells are presented with examples. Brain nanoparticle uptake inversely correlates with size. The influence of shape has not been reported. Surface charge has not been clearly shown to affect flux across the blood-brain barrier. There is very little evidence for metal-based nanoparticle distribution into brain parenchyma. Metal-based nanoparticle disruption of the blood-brain barrier and adverse brain changes have been shown, and are more pronounced for spheres than rods. Study concentrations need to be put in exposure contexts. Work with dorsal root ganglion cells and brain cells in vitro show the potential for metal-based nanoparticles to produce toxicity. Interpretation of these results must consider the ability of nanoparticles to distribute across the barriers protecting the nervous system. Effects of the persistence of poorly soluble metal-based nanoparticles are of particular concern. Copyright © 2013 Wiley Periodicals, Inc.

Mono and bimetallic nanoparticles of gold, silver and palladium-catalyzed NADH oxidation-coupled reduction of Eosin-Y

Science.gov (United States)

Santhanalakshmi, J.; Venkatesan, P.

2011-02-01

Mono metallic (Au, Ag, Pd) and bimetallic (Au-Ag, Ag-Pd, Au-Pd) with 1:1 mol stoichiometry, nanoparticles are synthesized using one-pot, temperature controlled chemical method using cetyltrimethylammonium bromide (CTAB) as the capping agent. The particle sizes (Au = 5.6, Ag = 5.0, Pd = 6.0, Au-Ag = 9.2, Ag-Pd = 9.6, Au-Pd = 9.4 nm) are characterized by UV-Vis, HRTEM, and XRD measurements, respectively. CTAB bindings onto mono and bimetallic nanoparticles are analyzed by FTIR spectra. The catalytic activities of mono and bimetallic nanoparticles are tested on the reaction between NADH oxidation and Eosin-Y reduction. The effects of base, pH, ionic strength, nature of mono and bimetallic catalysts are studied and the reaction conditions are optimized. Bimetallic nanoparticles exhibited better catalysis than the mono metallic nanoparticles, which may be due to the electronic effects of the core to shell metal atoms.

Molecular dynamics simulations of zinc oxide solubility: From bulk down to nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Escorihuela, Laura; Fernández, Alberto; Rallo, Robert; Martorell, Benjamí

2018-02-01

The solubility of metal oxides is one of the key descriptors for the evaluation of their potential toxic effects, both in the bulk form and in nanoparticulated aggregates. Current work presents a new methodology for the in silico assessment of the solubility of metal oxides, which is demonstrated using a well-studied system, ZnO. The calculation of the solubility is based on statistical thermodynamics tools combined with Density Functional Tight Binding theory for the evaluation of the free energy exchange during the dissolution process. Models of small ZnO clusters are used for describing the final dissolved material, since the complete ionic dissolution of ZnO is hindered by the formation of O2- anions in solution, which are highly unstable. Results show very good agreement between the computed solubility values and experimental data for ZnO bulk, up to 0.5 mg·L-1 and equivalents of 50 g·L-1 for the free Zn2+ cation in solution. However, the reference model for solid nanoparticles formed by free space nanoparticles can only give a limited quantitative solubility evaluation for ZnO nanoparticles.

Synthesis of oxide-free aluminum nanoparticles for application to conductive film

Science.gov (United States)

Jong Lee, Yung; Lee, Changsoo; Lee, Hyuck Mo

2018-02-01

Aluminum nanoparticles are considered promising as alternatives to conventional ink materials, replacing silver and copper nanoparticles, due to their extremely low cost and low melting temperature. However, a serious obstacle to realizing their use as conductive ink materials is the oxidation of aluminum. In this research, we synthesized the oxide-free aluminum nanoparticles using catalytic decomposition and an oleic acid coating method, and these materials were applied to conductive ink for the first time. The injection time of oleic acid determines the size of the aluminum nanoparticles by forming a self-assembled monolayer on the nanoparticles instead of allowing the formation of an oxide phase. Fabricated nanoparticles were analyzed by transmission electron microscopy and x-ray photoelectron spectroscopy to verify their structural and chemical composition. In addition, conductive inks made of these nanoparticles exhibit electrical properties when they are sintered at over 300 °C in a reducing atmosphere. This result shows that aluminum nanoparticles can be used as an alternative conductive material in printed electronics and can solve the cost issues associated with noble metals.

Co-immobilization of gold nanoparticles with glucose oxidase to improve bioelectrocatalytic glucose oxidation

Science.gov (United States)

Aquino Neto, Sidney; Milton, Ross D.; Crepaldi, Laís B.; Hickey, David P.; de Andrade, Adalgisa R.; Minteer, Shelley D.

2015-07-01

Recently, there has been much effort in developing metal nanoparticle catalysts for fuel oxidation, as well as the development of enzymatic bioelectrocatalysts for fuel oxidation. However, there has been little study of the synergy of hybrid electrocatalytic systems. We report the preparation of hybrid bioanodes based on Au nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) co-immobilized with glucose oxidase (GOx). Mediated electron transfer was achieved by two strategies: ferrocene entrapped within polypyrrole and a ferrocene-modified linear poly(ethylenimine) (Fc-LPEI) redox polymer. Electrochemical characterization of the Au nanoparticles supported on MWCNTs indicate that this catalyst exhibits an electrocatalytic response for glucose even in acidic conditions. Using the redox polymer Fc-LPEI as the mediator, voltammetric and amperometric data demonstrated that these bioanodes can efficiently achieve mediated electron transfer and also indicated higher catalytic currents with the hybrid bioelectrode. From the amperometry, the maximum current density (Jmax) achieved with the hybrid bioelectrode was 615 ± 39 μA cm-2, whereas the bioanode employing GOx only achieved a Jmax of 409 ± 26 μA cm-2. Biofuel cell tests are consistent with the electrochemical characterization, thus confirming that the addition of the metallic species into the bioanode structure can improve fuel oxidation and consequently, improve the power generated by the system.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb; Tahir, Muhammad Nawaz; Adil, Syed F; Khan, Hadayat Ullah; Siddiqui, Rafiq H; Al-Warthan, Abdulrahman Abdullah; Tremel, Wolfgang

2015-01-01

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

GRAPHENE BASED METAL AND METAL OXIDE NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND THEIR APPLICATIONS

KAUST Repository

Khan, Mujeeb

2015-06-11

Graphene, an atomically thin two-dimensional carbonaceous material, has attracted tremendous attention in the scientific community, due to its exceptional electronic, electrical, and mechanical properties. Indeed, with the recent explosion of methods for a large-scale synthesis of graphene, the number of publications related to graphene and other graphene based materials have increased exponentially. Particularly the easy preparation of graphene like materials, such as, highly reduced graphene oxide (HRG) via reduction of graphite oxide (GO), offers a wide range of possibilities for the preparation of graphene based inorganic nanocomposites by the incorporation of various functional nanomaterials for a variety of applications. In this review, we discuss the current development of graphene based metal and metal oxide nanocomposites, with a detailed account of their synthesis and properties. Specifically, much attention has been given to their wide range of applications in various fields, including, electronics, electrochemical and electrical fields. Overall, by the inclusion of various references, this review covers in detail aspects of the graphene-based inorganic nanocomposites.

Oxide-nitride-oxide dielectric stacks with Si nanoparticles obtained by low-energy ion beam synthesis

International Nuclear Information System (INIS)

Ioannou-Sougleridis, V; Dimitrakis, P; Vamvakas, V Em; Normand, P; Bonafos, C; Schamm, S; Mouti, A; Assayag, G Ben; Paillard, V

2007-01-01

Formation of a thin band of silicon nanoparticles within silicon nitride films by low-energy (1 keV) silicon ion implantation and subsequent thermal annealing is demonstrated. Electrical characterization of metal-insulator-semiconductor capacitors reveals that oxide/Si-nanoparticles-nitride/oxide dielectric stacks exhibit enhanced charge transfer characteristics between the substrate and the silicon nitride layer compared to dielectric stacks using unimplanted silicon nitride. Attractive results are obtained in terms of write/erase memory characteristics and data retention, indicating the large potential of the low-energy ion-beam-synthesis technique in SONOS memory technology

Size-dependent cytotoxicity of yttrium oxide nanoparticles on primary osteoblasts in vitro

Energy Technology Data Exchange (ETDEWEB)

Zhou, Guoqiang, E-mail: zhougq1982@163.com; Li, Yunfei; Ma, Yanyan; Liu, Zhu; Cao, Lili; Wang, Da; Liu, Sudan; Xu, Wenshi; Wang, Wenying [Hebei University, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science (China)

2016-05-15

Yttrium oxide nanoparticles are an excellent host material for the rare earth metals and have high luminescence efficiency providing a potential application in photodynamic therapy and biological imaging. In this study, the effects of yttrium oxide nanoparticles with four different sizes were investigated using primary osteoblasts in vitro. The results demonstrated that the cytotoxicity generated by yttrium oxide nanoparticles depended on the particle size, and smaller particles possessed higher toxicological effects. For the purpose to elucidate the relationship between reactive oxygen species generation and cell damage, cytomembrane integrity, intracellular reactive oxygen species level, mitochondrial membrane potential, cell apoptosis rate, and activity of caspase-3 in cells were then measured. Increased reactive oxygen species level was also observed in a size-dependent way. Thus, our data demonstrated that exposure to yttrium oxide nanoparticles resulted in a size-dependent cytotoxicity in cultured primary osteoblasts, and reactive oxygen species generation should be one possible damage pathway for the toxicological effects produced by yttrium oxide particles. The results may provide useful information for more rational applications of yttrium oxide nanoparticles in the future.

Block-copolymer assisted synthesis of arrays of metal nanoparticles and their catalytic activities for the growth of SWNTs

International Nuclear Information System (INIS)

Bhaviripudi, Sreekar; Reina, Alfonso; Qi, Jifa; Kong, Jing; Belcher, Angela M

2006-01-01

Block copolymer micellar templates were used for the controlled synthesis of large arrays of mono-metallic (Fe, Co, Ni, Mo) and bi-metallic (Fe-Mo) nanoparticles with average diameters ranging from 1 to 4 nm and the distance between the nanoparticles ranging from 40 to 45 nm. XPS data reveal the presence of mono-metallic nanoparticles in their oxidized states. These uniform arrays of nanoparticles serve as an excellent tool to investigate the catalytic effect of different metal/metal oxide nanoparticles for the growth of carbon nanotubes, and in this work, they were used to investigate the growth of single-walled carbon nanotubes with the chemical vapour deposition (CVD) process, using both ethanol and hydrocarbon (methane + ethylene) gases as carbon sources. The periodicity and the arrangement of nanoparticles were unaffected even at high growth temperatures, indicating that nanoparticle agglomeration on the Si substrate does not take place during growth. AFM and SEM results reveal uniform growth of nanotubes with diameters smaller than the initial size of the catalyst nanoparticles. The Fe, Co and Ni nanoparticles all serve as effective catalysts for nanotube growth with both types of carbon feed stock, and Co and Ni give rise to a relatively higher yield than Fe. The catalytic activity of Fe and bi-metallic Fe-Mo nanoparticles of similar size and identical densities using ethanol CVD are also compared

Increasing the solar cell power output by coating with transition metal-oxide nanorods

International Nuclear Information System (INIS)

Kuznetsov, I.A.; Greenfield, M.J.; Mehta, Y.U.; Merchan-Merchan, W.; Salkar, G.; Saveliev, A.V.

2011-01-01

Highlights: → Nanoparticles enhance solar cell efficiency. → Solar cell power increase by nanorod coating. → Metal-oxide nanorods are prepared in flames. → Molybdenum oxide nanorods effectively scatter light on solar cell surface. → Scattering efficiency depends on coating density. -- Abstract: Photovoltaic cells produce electric current through interactions among photons from an ambient light source and electrons in the semiconductor layer of the cell. However, much of the light incident on the panel is reflected or absorbed without inducing the photovoltaic effect. Transition metal-oxide nanoparticles, an inexpensive product of a process called flame synthesis, can cause scattering of light. Scattering can redirect photon flux, increasing the fraction of light absorbed in the thin active layer of silicon solar cells. This research aims to demonstrate that the application of transition metal-oxide nanorods to the surface of silicon solar panels can enhance the power output of the panels. Several solar panels were coated with a nanoparticle-methanol suspension, and the power outputs of the panels before and after the treatment were compared. The results demonstrate an increase in power output of up to 5% after the treatment. The presence of metal-oxide nanorods on the surface of the coated solar cells is confirmed by electron microscopy.

Biomolecule-coated metal nanoparticles on titanium.

Science.gov (United States)

Christensen, Stephen L; Chatt, Amares; Zhang, Peng

2012-02-07

Immobilizations of nanoparticles and biomolecules on biocompatible substrates such as titanium are two promising approaches to bringing new functionalities to Ti-based biomaterials. Herein, we used a variety of X-ray spectroscopic techniques to study and better understand metal-thiolate interactions in biofunctionalized metal nanoparticle systems supported on Ti substrates. Using a facile one-step procedure, a series of Au nanoparticle samples with varied biomolecule coatings ((2-mercatopropionyl)glycine (MPG) and bovine serum albumin (BSA)) and biomolecule concentrations are prepared. Ag and Pd systems are also studied to observe change with varying metal composition. The structure and properties of these biomolecule-coated nanoparticles are investigated with scanning electron microscopy (SEM) and element-specific X-ray techniques, including extended X-ray absorption fine structure (Au L(3)-edge), X-ray absorption near-edge structure (Au L(3), Ag L(3), Pd L(3), and S K-edge), and X-ray photoelectron spectroscopy (Au 4f, Ag 3d, Pd 3d, and S 2p core level). It was found that, by comparison of SEM and X-ray spectroscopy results, the coating of metal nanoparticles with varying model biomolecule systems can have a significant effect on both surface coverage and organization. This work offers a facile chemical method for bio- and nanofunctionalization of Ti substrates as well as provides a physical picture of the structure and bonding of biocoated metal nanoparticles, which may lead to useful applications in orthopedics and biomedicine.

Oxidation behaviour of Zr-based bulk metallic glasses

International Nuclear Information System (INIS)

Wang, Bin

2011-01-01

The Zr-based bulk metallic glasses, developed since the late 1980's, have very interesting mechanical properties, which can be considered for many applications including working under oxidizing atmosphere conditions at high temperatures. It is therefore interesting to study their oxidation resistance and to characterize the oxide scale formed on alloys surface. The fundamental objective of this thesis is to enhance the understanding of the role of various thermodynamic and chemistry parameters on the oxidation behaviour of the Zr-based bulk metallic glasses at high temperature under dry air, to determine the residual stresses in the oxide layer, in comparison with their crystalline alloys with the same chemical composition after an annealing treatment. The oxidation kinetics of these glasses and the crystalline structure of oxide scale ZrO 2 depend on the temperature and the oxidation duration: for short periods of oxidation or at a temperature below Tg, the kinetics follows a parabolic law, whereas, if the sample is oxidized at T ≥ Tg, the kinetics can be divided into two parts. The crystalline counterparts are oxidized by a parabolic rule whatever the temperature; for long oxidation duration at a temperature close to Tg, the kinetics becomes more complex because of the crystallisation of the glasses during the oxidation tests. Also the crystalline structure of the oxide layers depends on the oxidation temperature: the oxide layer consists only in tetragonal Zirconia at T ≤ Tg, while monoclinic Zirconia was formed at higher temperature. The mechanism of the formation of the oxide scale is due to both the interior diffusion of Oxygen ions and the external diffusion of Zirconium ions. However the diffusion of Zirconium ions slows gradually during the crystallisation process of the glass matrix. When the crystallisation is completed, the formation of Zirconia is controlled by only the internal diffusion of oxygen ions. The corresponding residual stresses

Semiconductor-metal transition of Se in Ru-Se Catalyst Nanoparticles

Science.gov (United States)

Babu, P. K.; Lewera, Adam; Oldfield, Eric; Wieckowski, Andrzej

2009-03-01

Ru-Se composite nanoparticles are promising catalysts for the oxygen reduction reaction (ORR) in fuel cells. Though the role of Se in enhancing the chemical stability of Ru nanoparticles is well established, the microscopic nature of Ru-Se interaction was not clearly understood. We carried out a combined investigation of ^77Se NMR and XPS on Ru-Se nanoparticles and our results indicate that Se, a semiconductor in elemental form, becomes metallic when interacting with Ru. ^77Se spin-lattice relaxation rates are found to be proportional to T, the well-known Korringa behavior characteristic of metals. The NMR results are supported by the XPS binding energy shifts which suggest that a possible Ru->Se charge transfer could be responsible for the semiconductor->metal transition of Se which also makes Ru less susceptible to oxidation during ORR.

Microbial exopolysaccharide-mediated synthesis and stabilization of metal nanoparticles.

Science.gov (United States)

Sathiyanarayanan, Ganesan; Dineshkumar, Krishnamoorthy; Yang, Yung-Hun

2017-11-01

Exopolysaccharides (EPSs) are structurally and functionally valuable biopolymer secreted by different prokaryotic and eukaryotic microorganisms in response to biotic/abiotic stresses and to survive in extreme environments. Microbial EPSs are fascinating in various industrial sectors due to their excellent material properties and less toxic, highly biodegradable, and biocompatible nature. Recently, microbial EPSs have been used as a potential template for the rapid synthesis of metallic nanoparticles and EPS-mediated metal reduction processes are emerging as simple, harmless, and environmentally benign green chemistry approaches. EPS-mediated synthesis of metal nanoparticles is a distinctive metabolism-independent bio-reduction process due to the formation of interfaces between metal cations and the polyanionic functional groups (i.e. hydroxyl, carboxyl and amino groups) of the EPS. In addition, the range of physicochemical features which facilitates the EPS as an efficient stabilizing or capping agents to protect the primary structure of the metal nanoparticles with an encapsulation film in order to separate the nanoparticle core from the mixture of composites. The EPS-capping also enables the further modification of metal nanoparticles with expected material properties for multifarious applications. The present review discusses the microbial EPS-mediated green synthesis/stabilization of metal nanoparticles, possible mechanisms involved in EPS-mediated metal reduction, and application prospects of EPS-based metal nanoparticles.

The development of latent fingerprints by zinc oxide and tin oxide nanoparticles prepared by precipitation technique

Science.gov (United States)

Luthra, Deepali; Kumar, Sacheen

2018-05-01

Fingerprints are the very important evidence at the crime scene which must be developed clearly with shortest duration of time to solve the case. Metal oxide nanoparticles could be the mean to develop the latent fingerprints. Zinc oxide and Tin Oxide Nanoparticles were prepared by using chemical precipitation technique which were dried and characterized by X-ray diffraction, UV-Visible spectroscopy and FTIR. The size of zinc oxide crystallite was found to be 14.75 nm with minimum reflectance at 360 nm whereas tin oxide have the size of 90 nm and reflectance at minimum level 321 nm. By using these powdered samples on glass, plastic and glossy cardboard, latent fingerprints were developed. Zinc oxide was found to be better candidate than tin oxide for the fingerprint development on all the three types of substrates.

Cryochemistry of Metal Nanoparticles

International Nuclear Information System (INIS)

Sergeev, Gleb B.

2003-01-01

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia

Cryochemistry of Metal Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sergeev, Gleb B. [Moscow State University, Laboratory of Low Temperature Chemistry, Chemistry Department (Russian Federation)], E-mail: gbs@kinet.chem.msu.ru

2003-12-15

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.

Cryochemistry of Metal Nanoparticles

Science.gov (United States)

Sergeev, Gleb B.

2003-12-01

The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.

Mono and bimetallic nanoparticles of gold, silver and palladium-catalyzed NADH oxidation-coupled reduction of Eosin-Y

International Nuclear Information System (INIS)

Santhanalakshmi, J.; Venkatesan, P.

2011-01-01

Mono metallic (Au, Ag, Pd) and bimetallic (Au–Ag, Ag–Pd, Au–Pd) with 1:1 mol stoichiometry, nanoparticles are synthesized using one-pot, temperature controlled chemical method using cetyltrimethylammonium bromide (CTAB) as the capping agent. The particle sizes (Au = 5.6, Ag = 5.0, Pd = 6.0, Au–Ag = 9.2, Ag–Pd = 9.6, Au–Pd = 9.4 nm) are characterized by UV–Vis, HRTEM, and XRD measurements, respectively. CTAB bindings onto mono and bimetallic nanoparticles are analyzed by FTIR spectra. The catalytic activities of mono and bimetallic nanoparticles are tested on the reaction between NADH oxidation and Eosin-Y reduction. The effects of base, pH, ionic strength, nature of mono and bimetallic catalysts are studied and the reaction conditions are optimized. Bimetallic nanoparticles exhibited better catalysis than the mono metallic nanoparticles, which may be due to the electronic effects of the core to shell metal atoms.Graphical Abstract

Au Nanoparticle Sub-Monolayers Sandwiched between Sol-Gel Oxide Thin Films

Science.gov (United States)

Della Gaspera, Enrico; Menin, Enrico; Sada, Cinzia

2018-01-01

Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO2, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers. The desired organization of Au nanoparticles and the morphological structure of the prepared multi-layered structures has been confirmed by Rutherford backscattering spectrometry (RBS), Secondary Ion Mass Spectrometry (SIMS), and Scanning Electron Microscopy (SEM) analyses that show a high quality sandwich structure. The multi-layered structures have been also tested as optical gas sensors. PMID:29538338

Hydrogen storage evaluation based on investigations of the catalytic properties of metal/metal oxides in electrospun carbon fibers

Energy Technology Data Exchange (ETDEWEB)

Im, Ji Sun; Lee, Young-Seak [Department of Fine Chemical Engineering and Chemistry, Chungnam National University, Daejeon 305-764 (Korea); Park, Soo-Jin [Department of Chemistry, Inha University, Incheon 402-751 (Korea); Kim, Taejin [Core Technology Research Center for Fuel Cell, Jeollabuk-do 561-844 (Korea)

2009-05-15

In order to investigate the catalytic capacity of metals and metal oxides based on electrospun carbon fibers for improving hydrogen storage, electrospinning and heat treatments were carried out to obtain metal/metal oxide-embedded carbon fibers. Although the fibers were treated with the same activation procedure, they had different pore structures, due to the nature of the metal oxide. When comparing the catalytic capacity of metal and metal oxide, metal exhibits better performance as a catalyst for the improvement of hydrogen storage, when considering the hydrogen storage system. When a metal oxide with an m.p. lower than the temperature of heat treatment was used, the metal oxide was changed to metal during the heat treatment, developing a micropore structure. The activation process produced a high specific surface area of up to 2900 m{sup 2}/g and a pore volume of up to 2.5 cc/g. The amount of hydrogen adsorption reached approximately 3 wt% at 100 bar and room temperature. (author)

Effect of Metal Oxides on Plant Germination: Phytotoxicity of Nanoparticles, Bulk Materials, and Metal Ions

Czech Academy of Sciences Publication Activity Database

Landa, Přemysl; Cyrusová, Tereza; Jeřábková, J.; Drábek, O.; Vaněk, Tomáš; Podlipná, Radka

2016-01-01

Roč. 227, č. 12 (2016), č. článku 448. ISSN 0049-6979 R&D Projects: GA MŠk(CZ) LD14100; GA MŠk LD14125 Institutional support: RVO:61389030 Keywords : zno nanoparticles * pseudokirchneriella-subcapitata * particle solubility * oxidative stress * root-growth * toxicity * aluminum * cuo * ph * cytotoxicity * Nanoparticles * Phytotoxicity * Accumulation * Germination * Sinapis alba Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.702, year: 2016

Microwave-Assisted Conversion of Levulinic Acid to γ-Valerolactone Using Low-Loaded Supported Iron Oxide Nanoparticles on Porous Silicates

Directory of Open Access Journals (Sweden)

Alfonso Yepez

2015-09-01

Full Text Available The microwave-assisted conversion of levulinic acid (LA has been studied using low-loaded supported Fe-based catalysts on porous silicates. A very simple, productive, and highly reproducible continuous flow method has been used for the homogeneous deposition of metal oxide nanoparticles on the silicate supports. Formic acid was used as a hydrogen donating agent for the hydrogenation of LA to effectively replace high pressure H2 mostly reported for LA conversion. Moderate LA conversion was achieved in the case of non-noble metal-based iron oxide catalysts, with a significant potential for further improvements to compete with noble metal-based catalysts.

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

Directory of Open Access Journals (Sweden)

Adlim Adlim

2010-06-01

Full Text Available Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

PREPARATIONS AND APPLICATION OF METAL NANOPARTICLES

OpenAIRE

Adlim, Adlim

2010-01-01

Terminology of metal nanoparticles, the uniqueness properties in terms of the surface atom, the quantum dot, and the magnetism are described. The further elaboration was on the synthesis of nanoparticles. Applications of metal nanoparticles in electronic, ceramic medical and catalysis were overviewed. The bibliography includes 81 references with 99% are journal articles.   Keywords: metal nanoparticles

First-Row-Transition Ion Metals(II-EDTA Functionalized Magnetic Nanoparticles as Catalysts for Solvent-Free Microwave-Induced Oxidation of Alcohols

Directory of Open Access Journals (Sweden)

Nuno M. R. Martins

2017-11-01

Full Text Available A series of first-row transition-metals combined with ethylenediamine tetraacetic acid (EDTA, as metal-based N,O-chelating ligands, at the surface of ferrite magnetic nanoparticles (MNPs was prepared by a co-precipitation method. Those EDTA functionalized MNPs with general formula Fe3O4@EDTA-M2+ [M = Mn2+ (1, Fe2+ (2, Co2+ (3, Ni2+ (4, Cu2+ (5 or Zn2+ (6] were characterized by FTIR (Fourier Transform Infrared spectroscopy, powder XRD (X-ray Diffraction, SEM (Scanning Electron Microscope, EDS (Energy Dispersive Spectrometer, VSM (Vibrating Sample Magnetometer and TGA (Thermal Gravity Analysis. The application of the magnetic NPs towards the microwave-assisted oxidation of several alcohol substrates in a solvent-free medium was evaluated. The influence of reaction parameters such as temperature, time, type of oxidant, and presence of organic radicals was investigated. This study demonstrates that these MNPs can act as efficient catalysts for the conversion of alcohols to the corresponding ketones or aldehydes with high selectivity and yields up to 99% after 2 h of reaction at 110 °C using t-BuOOH as oxidant. Moreover, they have the advantage of being magnetically recoverable catalysts that can be easily recycled in following runs.

Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis.

Science.gov (United States)

Gawande, Manoj B; Goswami, Anandarup; Felpin, François-Xavier; Asefa, Tewodros; Huang, Xiaoxi; Silva, Rafael; Zou, Xiaoxin; Zboril, Radek; Varma, Rajender S

2016-03-23

The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications in catalysis. The synthesis part discusses numerous preparative protocols for Cu and Cu-based nanoparticles, whereas the application sections describe their utility as catalysts, including electrocatalysis, photocatalysis, and gas-phase catalysis. We believe this critical appraisal will provide necessary background information to further advance the applications of Cu-based nanostructured materials in catalysis.

3D Plasmonic Ensembles of Graphene Oxide and Nobel Metal Nanoparticles with Ultrahigh SERS Activity and Sensitivity

Directory of Open Access Journals (Sweden)

Jing Lin

2016-01-01

Full Text Available We describe a comparison study on 3D ensembles of graphene oxide (GO and metal nanoparticles (silver nanoparticles (AgNPs, gold nanoparticles (GNPs, and gold nanorods (GNRs for surface-enhanced Raman scattering (SERS application. For the first time, GNRs were successfully assembled on the surfaces of GO by means of electrostatic interactions without adding any surfactant. The SERS properties of GO/AgNPs, GO/GNPs, and GO/GNRs were compared using 2-mercaptopyridine (2-Mpy as probing molecule. We found that GO/AgNPs and GO/GNPs substrates are not suitable for detecting 2-Mpy due to the very strong π-π stacking interaction between the 2-Mpy molecules and sp2 carbon structure of GO. Conversely, the GO/GNRs substrates show ultrahigh SERS activity and sensitivity of 2-Mpy with the detection limit as low as ~10-15 M, which is ~2-3 orders of magnitude higher than that of the corresponding GNRs.

Electronically conductive perovskite-based oxide nanoparticles and films for optical sensing applications

Science.gov (United States)

Ohodnicki, Jr., Paul R; Schultz, Andrew M

2015-04-28

The disclosure relates to a method of detecting a change in a chemical composition by contacting a electronically conducting perovskite-based metal oxide material with a monitored stream, illuminating the electronically conducting perovskite-based metal oxide with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The electronically conducting perovskite-based metal oxide has a perovskite-based crystal structure and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The electronically conducting perovskite-based metal oxide has an empirical formula A.sub.xB.sub.yO.sub.3-.delta., where A is at least a first element at the A-site, B is at least a second element at the B-site, and where 0.8perovskite-based oxides include but are not limited to La.sub.1-xSr.sub.xCoO.sub.3, La.sub.1-xSr.sub.xMnO.sub.3, LaCrO.sub.3, LaNiO.sub.3, La.sub.1-xSr.sub.xMn.sub.1-yCr.sub.yO.sub.3, SrFeO.sub.3, SrVO.sub.3, La-doped SrTiO.sub.3, Nb-doped SrTiO.sub.3, and SrTiO.sub.3-.delta..

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review

Science.gov (United States)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2012-12-01

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review.

Science.gov (United States)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2013-01-07

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

Facile and large-scale preparation of sandwich-structured graphene-metal oxide composites as anode materials for Li-ion batteries

International Nuclear Information System (INIS)

Fang, Hongmei; Zhao, Li; Yue, Wenbo; Wang, Yuan; Jiang, Yang; Zhang, Yuan

2015-01-01

Graphene-based metal oxides are desirable as potential anode materials for lithium-ion batteries (LIBs) owing to their superior electrochemical properties. In this work, sandwich-structured graphene-metal oxide (ZnO, NiO) composites are facilely synthesized on a large scale through self-assembly of graphene oxide nanosheets and metal ammine complexes, and then thermal decomposition of the self-assembled products. ZnO or NiO nanoparticles with diameters of 5∼10 nm are immobilized between the layers of graphene nanosheets, which may provide the space for accommodating the volume change of metal oxides during cycles, and highly improve the electronic conductivity of the composites. Accordingly, these sandwich-structured composites exhibit enhanced electrochemical performances compared to metal oxide particles or stacked graphene nanosheets. This facile synthesis method is very suitable for the large-scale production of three-dimensional graphene-based composites as high-performance anodes for LIBs.

Bi-metallic nanoparticles as cathode electrocatalysts

Science.gov (United States)

Lu, Jun; Amine, Khalil; Wang, Xiaoping; Luo, Xiangyi; Myers, Deborah J.

2018-03-27

A lithium-air battery cathode catalyst includes core-shell nanoparticles on a carbon support, wherein: a core of the core-shell nanoparticles is platinum metal; and a shell of the core-shell nanoparticles is copper metal; wherein: the core-shell nanoparticles have a weight ratio of the copper metal to the platinum metal from about 4% to about 6% copper to from about 2% to about 12% platinum, with a remaining percentage being the carbon support.

Fabrication of Metallic Hollow Nanoparticles

Science.gov (United States)

Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2016-01-01

Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

Synthesis of PtNi Alloy Nanoparticles on Graphene-Based Polymer Nanohybrids for Electrocatalytic Oxidation of Methanol

Directory of Open Access Journals (Sweden)

Tung-Yuan Yung

2016-12-01

Full Text Available We have successfully produced bimetallic PtNi alloy nanoparticles on poly(diallyldimethylammonium chloride (PDDA-modified graphene nanosheets (PtNi/PDDA-G by the “one-pot” hydrothermal method. The size of PtNi alloy nanoparticles is approximately 2–5 nm. The PDDA-modified graphene nanosheets (PDDA-G provides an anchored site for metal precursors; hence, the PtNi nanoparticles could be easily bond on the PDDA-G substrate. PtNi alloy nanoparticles (2–5 nm display a homogenous alloy phase embedded on the PDDA-G substrate, evaluated by Raman, X-ray diffractometer (XRD, thermal gravity analysis (TGA, electron surface chemical analysis (ESCA, and electron energy loss spectroscopy (EELS. The Pt/Ni ratio of PtNi alloy nanoparticles is ~1.7, examined by the energy dispersive spectroscopy (EDS spectra of transmitting electron microscopy (EDS/TEM spectra and mapping technique. The methanol electro-oxidation of PtNi/PDDA-G was evaluated by cyclic voltammetry (CV in 0.5 M of H2SO4 and 0.5 M of CH3OH. Compared to Pt on carbon nanoparticles (Pt/C and Pt on Graphene (Pt/G, the PtNi/PDDA-G exhibits the optimal electrochemical surface area (ECSA, methanol oxidation reaction (MOR activity, and durability by chrono amperometry (CA test, which can be a candidate for MOR in the electro-catalysis of direct methanol fuel cells (DMFC.

Base-oxidant promoted metal-free N-demethylation of arylamines

Indian Academy of Sciences (India)

A metal-free oxidative N-demethylation of arylamines with triethylamine as a base and tert-butyl hydroperoxide (TBHP) as oxidant is reported in this paper. The reaction is general, practical, inexpensive, non-toxic, and the method followed is environmentally benign, with moderate to good yields.

Metal Nanoparticles and Carbon-Based Nanostructures as Advanced Materials for Cathode Application in Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Pietro Calandra

2010-01-01

Full Text Available We review the most advanced methods for the fabrication of cathodes for dye-sensitized solar cells employing nanostructured materials. The attention is focused on metal nanoparticles and nanostructured carbon, among which nanotubes and graphene, whose good catalytic properties make them ideal for the development of counter electrode substrates, transparent conducting oxide, and advanced catalyst materials.

Electrocatalytic properties of monometallic and bimetallic nanoparticles-incorporated polypyrrole films for electro-oxidation of methanol

Energy Technology Data Exchange (ETDEWEB)

Selvaraj, V.; Alagar, M. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India); Hamerton, I. [Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2006-10-06

Oxidative electrochemical polymerization of pyrrole at indium-doped tin oxide (ITO) is accomplished from a neat monomer solution with a supporting electrolyte (0.3M n-tetrabutyl ammonium tetrafluoroborate) by multiple-scan cyclic voltammetry. Polypyrrole (Ppy) films containing nanometer-sized platinum and Pt/Pd bimetallic particles are electro-synthesized on ITO glass plates by voltammetric cycling between -0.1 and +1V (versus Ag/AgCl/3M NaCl). The electrocatalytic oxidation of methanol on the nanoparticle-modified polypyrrole films is studied by means of electrochemical techniques. The modified electrode exhibits significant eletrocatalytic activity for methanol oxidation. The enhanced electrocatalytic activities may be due to the uniform dispersion of nanoparticles in the polypyrrole film and a synergistic effect of the highly-dispersed metal particles so that the polypyrrole film reduces electrode poisoning by adsorbed CO species. The monometallic (Pt) and bimetallic (Pt/Pd) nanoparticles are uniformly dispersed in polypyrrole matrixes, as confirmed by scanning electron microscopic and atomic force microscopic analysis. Energy dispersive X-ray analysis is used to characterize the composition of metal present in the nanoparticle-modified electrodes. (author)

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes

Energy Technology Data Exchange (ETDEWEB)

Jiang, Hao [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ma, Jan [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Li, Chunzhong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2012-08-08

Supercapacitors have attracted huge attention in recent years as they have the potential to satisfy the demand of both huge energy and power density in many advanced technologies. However, poor conductivity and cycling stability remains to be the major challenge for its widespread application. Various strategies have been developed for meeting the ever-increasing energy and power demands in supercapacitors. This Research News article aims to review recent progress in the development of mesoporous carbon incorporated metal oxide nanomaterials, especially metal oxide nanoparticles confined in ordered mesoporous carbon and 1D metal oxides coated with a layer of mesoporous carbon for high-performance supercapacitor applications. In addition, a recent trend in supercapacitor development - hierarchical porous graphitic carbons (HPGC) combining macroporous cores, mesoporous walls, and micropores as an excellent support for metal oxides - is also discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Some inferences from in vivo experiments with metal and metal oxide nanoparticles: the pulmonary phagocytosis response, subchronic systemic toxicity and genotoxicity, regulatory proposals, searching for bioprotectors (a self-overview

Directory of Open Access Journals (Sweden)

Katsnelson BA

2015-04-01

Full Text Available Boris A Katsnelson,1 Larisa I Privalova,1 Marina P Sutunkova,1 Vladimir B Gurvich,1 Nadezhda V Loginova,1 Ilzira A Minigalieva,1 Ekaterina P Kireyeva,1 Vladimir Y Shur,2 Ekaterina V Shishkina,2 Ya B Beikin,3 Oleg H Makeyev,4 Irene E Valamina4 1The Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Ekaterinburg, Russia; 2The Institute of Natural Sciences, The Ural Federal University, Ekaterinburg, Russia; 3The City Clinical Diagnostics Centre, Ekaterinburg, Russia; 4The Ural State Medical University, Ekaterinburg, Russia Abstract: The purpose of this paper is to overview and summarize previously published results of our experiments on white rats exposed to either a single intratracheal instillation or repeated intraperitoneal injections of silver, gold, iron oxide, copper oxide, nickel oxide, and manganese oxide nanoparticles (NPs in stable water suspensions without any chemical additives. Based on these results and some corroborating data of other researchers we maintain that these NPs are much more noxious on both cellular and systemic levels as compared with their 1 µm or even submicron counterparts. However, within the nanometer range the dependence of systemic toxicity on particle size is intricate and non-unique due to complex and often contra-directional relationships between the intrinsic biological aggressiveness of the specific NPs, on the one hand, and complex mechanisms that control their biokinetics, on the other. Our data testify to the high activity of the pulmonary phagocytosis of NPs deposited in airways. This fact suggests that safe levels of exposure to airborne NPs are possible in principle. However, there are no reliable foundations for establishing different permissible exposure levels for particles of different size within the nanometric range. For workroom air, such permissible exposure levels of metallic NP can be proposed at this stage, even if tentatively, based on a sufficiently

Nanoparticle-based drug delivery systems: promising approaches against infections

International Nuclear Information System (INIS)

Ranghar, Shweta; Sirohi, Parul; Verma, Pritam; Agarwal, Vishnu

2014-01-01

Despite the fact that many new drugs and technologies have been developed to combat the infectious diseases, these have continued to be global health challenges. The use of conventional antimicrobial agents against these infections is always associated with problems such as the development of multiple drug resistance and adverse side effects. In addition, the inefficient traditional drug delivery system results in inadequate therapeutic index, low bioavailability of drugs and many other limitations. In this regard, antimicrobial nanoparticles and nanosized drug delivery carriers have emerged as potent effective agents against the infections. Nanoparticles have unique properties owing to their ultra small and controllable size such as high surface area, enhanced reactivity, and functionalizable structure. This review focused on different classes of antimicrobial nanoparticles, including metal, metal oxide and others along with their mechanism of action and their potential use against the infections. The review also focused on the development of nanoparticle systems for antimicrobial drug delivery and use of these systems for delivery of various antimicrobial agents, giving an overview about modern nanoparticle based therapeutic strategies against the infections. (author)

Nanoparticle-based drug delivery systems: promising approaches against infections

Energy Technology Data Exchange (ETDEWEB)

Ranghar, Shweta; Sirohi, Parul [Department of Applied Mechanics, Motilal Nehru National Institute of Technology, Allahabad (India); Verma, Pritam; Agarwal, Vishnu [Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad (India)

2014-03-15

Despite the fact that many new drugs and technologies have been developed to combat the infectious diseases, these have continued to be global health challenges. The use of conventional antimicrobial agents against these infections is always associated with problems such as the development of multiple drug resistance and adverse side effects. In addition, the inefficient traditional drug delivery system results in inadequate therapeutic index, low bioavailability of drugs and many other limitations. In this regard, antimicrobial nanoparticles and nanosized drug delivery carriers have emerged as potent effective agents against the infections. Nanoparticles have unique properties owing to their ultra small and controllable size such as high surface area, enhanced reactivity, and functionalizable structure. This review focused on different classes of antimicrobial nanoparticles, including metal, metal oxide and others along with their mechanism of action and their potential use against the infections. The review also focused on the development of nanoparticle systems for antimicrobial drug delivery and use of these systems for delivery of various antimicrobial agents, giving an overview about modern nanoparticle based therapeutic strategies against the infections. (author)

The Biomechanisms of Metal and Metal-Oxide Nanoparticles’ Interactions with Cells

Directory of Open Access Journals (Sweden)

Sondra S. Teske

2015-01-01

Full Text Available Humans are increasingly exposed to nanoparticles (NPs in medicine and in industrial settings, where significant concentrations of NPs are common. However, NP interactions with and effects on biomolecules and organisms have only recently been addressed. Within we review the literature regarding proposed modes of action for metal and metal-oxide NPs, two of the most prevalent types manufactured. Iron-oxide NPs, for instance, are used as tracers for magnetic resonance imaging of oncological tumors and as vehicles for therapeutic drug delivery. Factors and theories that determine the physicochemical and biokinetic behaviors of NPs are discussed, along with the observed toxicological effects of NPs on cells. Key thermodynamic and kinetic models that explain the sources of energy transfer from NPs to biological targets are summarized, in addition to quantitative structural activity relationship (QSAR modeling efforts. Future challenges for nanotoxicological research are discussed. We conclude that NP studies based on cell culture are often inconsistent and underestimate the toxicity of NPs. Thus, the effect of NPs needs to be examined in whole animal systems.

Synthesis and characterization of zinc oxide nanoparticles by laser ablation of zinc in liquid

International Nuclear Information System (INIS)

Thareja, R.K.; Shukla, Shobha

2007-01-01

We report formation of colloidal suspension of zinc oxide nanoparticles by pulsed laser ablation of a zinc metal target at room temperature in different liquid environment. We have used photoluminescence, atomic force microscopy and X-ray diffraction to characterize the nanoparticles. The sample ablated in deionized water showed the photoluminescence peak at 384 nm (3.23 eV), whereas peaks at 370 nm (3.35 eV) were observed for sample prepared in isopropanol. The use of water and isopropanol as a solvent yielded spherical nanoparticles of 14-20 nm while in acetone we found two types of particles, one spherical nanoparticles with sizes around 100 nm and another platelet-like structure of 1 μm in diameter and 40 nm in width. The absorption peak of samples prepared in deionized water and isopropanol are seen to be substantially blue shifted relative to that of the bulk zinc oxide due to the strong confinement effect. The technique offers an alternative for preparing the nanoparticles of active metal

Nanotoxicity: the toxicity research progress of metal and metal-containing nanoparticles.

Science.gov (United States)

Ding, Lingling; Liu, Zhidong; Aggrey, Mike Okweesi; Li, Chunhua; Chen, Jing; Tong, Ling

2015-01-01

Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine, cosmetics and industry. Despite some unique advantages of nanoformulations, there exist potentially worrying toxic effects, particularly those related to metal and metal-containing nanoparticles (NPs). Although various researches have been conducted to assess the metallic and metal-containing nanoparticles toxic effects, only little is known about the toxicity expressive types and evaluation, reasons and mechanisms, influencing factors and research methods of metal and metal-containing nanotoxicity. Therefore, it is of importance to acquire a better understanding of metal and metal-containing nanoparticles toxicity for medical application. This review presents a summary on the metal and metal-containing nanoparticles toxicity research progress consulting relevant literature.

Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

Science.gov (United States)

Patki, Gauri Dilip

mole of Si. We compare our silicon nanoparticles (˜10nm diameter) with commercial silicon nanopowder (rate upon decreasing the particle size to 10 nm was even greater than would be expected based upon the increase in surface area. While specific surface area increased by a factor of 6 in going from rate increased by a factor of 150. However, in all cases, silicon requires a base (e.g. NaOH, KOH, hydrazine) to catalyze its reaction with water. Metal hydrides are also promising hydrogen storage materials. The optimum metal hydride would possess high hydrogen storage density at moderate temperature and pressure, release hydrogen safely and controllably, and be stable in air. Alkali metal hydrides have high hydrogen storage density, but exhibit high uncontrollable reactivity with water. In an attempt to control this explosive nature while maintaining high storage capacity, we mixed our silicon nanoparticles with the hydrides. This has dual benefits: (1) the hydride- water reaction produces the alkali hydroxide needed for base-catalyzed silicon oxidation, and (2) dilution with 10nm coating by, the silicon may temper the reactivity of the hydride, making the process more controllable. Initially, we analyzed hydrolysis of pure alkali metal hydrides and alkaline earth metal hydrides. Lithium hydride has particularly high hydrogen gravimetric density, along with faster reaction kinetics than sodium hydride or magnesium hydride. On analysis of hydrogen production we found higher hydrogen yield from the silicon nanoparticle—metal hydride mixture than from pure hydride hydrolysis. The silicon-hydride mixtures using our 10nm silicon nanoparticles produced high hydrogen yield, exceeding the theoretical yield. Some evidence of slowing of the hydride reaction rate upon addition of silicon nanoparticles was observed.

Synthesis of metal-fluoride nanoparticles supported on thermally reduced graphite oxide

Directory of Open Access Journals (Sweden)

Alexa Schmitz

2017-11-01

Full Text Available Metal-fluoride nanoparticles, (MFx-NPs with M = Fe, Co, Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO were obtained by microwave-assisted thermal decomposition of transition-metal amidinates, (M{MeC[N(iPr]2}n or [M(AMDn] with M = Fe(II, Co(II, Pr(III, and tris(2,2,6,6-tetramethyl-3,5-heptanedionatoeuropium, Eu(dpm3, in the presence of TRGO in the ionic liquid (IL 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]. The crystalline phases of the metal fluorides synthesized in [BMIm][BF4] were identified by powder X-ray diffraction (PXRD to be MF2 for M = Fe, Co and MF3 for M = Eu, Pr. The diameters and size distributions of MFx@TRGO were from (6 ± 2 to (102 ± 41 nm. Energy-dispersive X-ray spectroscopy (EDX and X-ray photoelectron spectroscopy (XPS were used for further characterization of the MFx-NPs. Electrochemical investigations of the FeF2-NPs@TRGO as cathode material for lithium-ion batteries were evaluated by galvanostatic charge/discharge profiles. The results indicate that the FeF2-NPs@TRGO as cathode material can present a specific capacity of 500 mAh/g at a current density of 50 mA/g, including a significant interfacial charge storage contribution. The obtained nanomaterials show a good rate capacity as well (220 mAh/g and 130 mAh/g at a current density of 200 and 500 mA/g, respectively.

Infrared photodetectors based on reduced graphene oxide nanoparticles and graphene oxide

Science.gov (United States)

Ahmad, H.; Tajdidzadeh, M.; Thambiratnam, K.; Yasin, M.

2018-06-01

Two photodiode (PD) designs incorporating graphene oxide (GO) and reduced graphene oxide (rGO) are proposed and fabricated. Both PDs have 50 mm thick silver electrodes deposited on the active area, and another electrode consisting of either GO or rGO nanoparticles (NPs). The GO and rGO NPs are deposited onto the p-type silicon substrate by the drop casting method. Both fabricated PDs show good sensitivity and quick responses under 974 nm laser illumination at 150 mW. The photoresponsivity values and external quantum efficiency of both photodetectors are measured to be approximately 800 µAw‑1 and 0.12% for the GO based PD and 1.6 m Aw‑1 and 0.20% for the rGO based PD. Both PDs also have response and recovery times of 114 µs and 276 µs as well as 11 µs and 678 µs for the GO and rGO based PDs respectively. The proposed PDs would have significant applications in many optoelectronic devices as well as nanoelectronics.

Chemical nature of catalysts of oxide nanoparticles in environment

Indian Academy of Sciences (India)

Carbon nanostructures (CNS) are often grown using oxide nanoparticles as catalyst in chemical vapour deposition and these oxides are not expected to survive as such during growth. In the present study, the catalysts of cobalt- and nickel oxide-based nanoparticles of sizes varying over a range have been reduced at 575 ...

Surface modification by metal ion implantation forming metallic nanoparticles in an insulating matrix

International Nuclear Information System (INIS)

Salvadori, M.C.; Teixeira, F.S.; Sgubin, L.G.; Cattani, M.; Brown, I.G.

2014-01-01

Highlights: • Metal nanoparticles can be produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. • The nanoparticles nucleate near the maximum of the implantation depth profile, that can be estimated by computer simulation using the TRIDYN. • Nanocomposites, obtained by this way, can be produced in different insulator materials. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. • The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted, reaching the percolation threshold. • Excellent agreement was found between the experimental results and the predictions of the theory. - Abstract: There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We have investigated nanocomposites produced by metal ion implantation into insulating substrates, where the implanted metal self-assembles into nanoparticles. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), which can be estimated by computer simulation using the TRIDYN code. TRIDYN is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study show that the nanoparticles form a bidimentional array buried a few nanometers below the substrate surface. We have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples show that metallic nanoparticles form in

One - Step synthesis of nitrogen doped reduced graphene oxide with NiCo nanoparticles for ethanol oxidation in alkaline media.

Science.gov (United States)

Kakaei, Karim; Marzang, Kamaran

2016-01-15

Development of anode catalysts and catalyst supporting carbonaceous material containing non-precious metal have attracted tremendous attention in the field of direct ethanol fuel cells (DEFCs). Herein, we report the synthesis and electrochemical properties of nitrogen-doped reduced graphene oxide (NRGO) supported Co, Ni and NiCo nanocomposites. The metal NRGO nanocomposites, in which metal nanoparticles are embedded in the highly porous nitrogen-doped graphene matrix, have been synthesized by simply and one-pot method at a mild temperature using GO, urea choline chloride and urea as reducing and doping agent. The fabricated NiCo/NRGO exhibit remarkable electrocatalytic activity (with Tafel slope of 159.1mVdec(-1)) and high stability for the ethanol oxidation reaction (EOR). The superior performance of the alloy based NRGO is attributed to high surface area, well uniform distribution of high-density nitrogen, metal active sites and synergistic effect. Copyright © 2015 Elsevier Inc. All rights reserved.

Nickel Oxide (NiO nanoparticles prepared by solid-state thermal decomposition of Nickel (II schiff base precursor

Directory of Open Access Journals (Sweden)

Aliakbar Dehno Khalaji

2015-06-01

Full Text Available In this paper, plate-like NiO nanoparticles were prepared by one-pot solid-state thermal decomposition of nickel (II Schiff base complex as new precursor. First, the nickel (II Schiff base precursor was prepared by solid-state grinding using nickel (II nitrate hexahydrate, Ni(NO32∙6H2O, and the Schiff base ligand N,N′-bis-(salicylidene benzene-1,4-diamine for 30 min without using any solvent, catalyst, template or surfactant. It was characterized by Fourier Transform Infrared spectroscopy (FT-IR and elemental analysis (CHN. The resultant solid was subsequently annealed in the electrical furnace at 450 °C for 3 h in air atmosphere. Nanoparticles of NiO were produced and characterized by X-ray powder diffraction (XRD at 2θ degree 0-140°, FT-IR spectroscopy, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD and FT-IR results showed that the product is pure and has good crystallinity with cubic structure because no characteristic peaks of impurity were observed, while the SEM and TEM results showed that the obtained product is tiny, aggregated with plate-like shape, narrow size distribution with an average size between 10-40 nm. Results show that the solid state thermal decomposition method is simple, environmentally friendly, safe and suitable for preparation of NiO nanoparticles. This method can also be used to synthesize nanoparticles of other metal oxides.

Hierarchical oxide-based composite nanostructures for energy, environmental, and sensing applications

Science.gov (United States)

Gao, Pu-Xian; Shimpi, Paresh; Cai, Wenjie; Gao, Haiyong; Jian, Dunliang; Wrobel, Gregory

2011-02-01

Self-assembled composite nanostructures integrate various basic nano-elements such as nanoparticles, nanofilms and nanowires toward realizing multifunctional characteristics, which promises an important route with potentially high reward for the fast evolving nanoscience and nanotechnology. A broad array of hierarchical metal oxide based nanostructures have been designed and fabricated in our research group, involving semiconductor metal oxides, ternary functional oxides such as perovskites and spinels and quaternary dielectric hydroxyl metal oxides with diverse applications in efficient energy harvesting/saving/utilization, environmental protection/control, chemical sensing and thus impacting major grand challenges in the area of materials and nanotechnology. Two of our latest research activities have been highlighted specifically in semiconductor oxide alloy nanowires and metal oxide/perovskite composite nanowires, which could impact the application sectors in ultraviolet/blue lighting, visible solar absorption, vehicle and industry emission control, chemical sensing and control for vehicle combustors and power plants.

Dynamic Behavior of CuZn Nanoparticles under Oxidizing and Reducing Conditions

DEFF Research Database (Denmark)

Holse, Christian; Elkjær, Christian Fink; Nierhoff, Anders Ulrik Fregerslev

2015-01-01

migrate to the Cu surface forming a Cu–Zn surface alloy. The oxidation and reduction dynamics of the CuZn nanoparticles is of great importance to industrial methanol synthesis for which the direct interaction of Cu and ZnO nanocrystals synergistically boosts the catalytic activity. Thus, the present......The oxidation and reduction of CuZn nanoparticles was studied using X-ray photoelectron spectroscopy (XPS) and in situ transmission electron microscopy (TEM). CuZn nanoparticles with a narrow size distribution were produced with a gas-aggregation cluster source in conjunction with mass......-filtration. A direct comparison between the spatially averaged XPS information and the local TEM observations was thus made possible. Upon oxidation in O2, the as-deposited metal clusters transform into a polycrystalline cluster consisting of separate CuO and ZnO nanocrystals. Specifically, the CuO is observed...

In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

Science.gov (United States)

Divya, Kizhmuri P; Miroshnikov, Mikhail; Dutta, Debjit; Vemula, Praveen Kumar; Ajayan, Pulickel M; John, George

2016-09-20

The allure of integrating the tunable properties of soft nanomaterials with the unique optical and electronic properties of metal nanoparticles has led to the development of organic-inorganic hybrid nanomaterials. A promising method for the synthesis of such organic-inorganic hybrid nanomaterials is afforded by the in situ generation of metal nanoparticles within a host organic template. Due to their tunable surface morphology and porosity, soft organic materials such as gels, liquid crystals, and polymers that are derived from various synthetic or natural compounds can act as templates for the synthesis of metal nanoparticles of different shapes and sizes. This method provides stabilization to the metal nanoparticles by the organic soft material and advantageously precludes the use of external reducing or capping agents in many instances. In this Account, we exemplify the green chemistry approach for synthesizing these materials, both in the choice of gelators as soft material frameworks and in the reduction mechanisms that generate the metal nanoparticles. Established herein is the core design principle centered on conceiving multifaceted amphiphilic soft materials that possess the ability to self-assemble and reduce metal ions into nanoparticles. Furthermore, these soft materials stabilize the in situ generated metal nanoparticles and retain their self-assembly ability to generate metal nanoparticle embedded homogeneous organic-inorganic hybrid materials. We discuss a remarkable example of vegetable-based drying oils as host templates for metal ions, resulting in the synthesis of novel hybrid nanomaterials. The synthesis of metal nanoparticles via polymers and self-assembled materials fabricated via cardanol (a bioorganic monomer derived from cashew nut shell liquid) are also explored in this Account. The organic-inorganic hybrid structures were characterized by several techniques such as UV-visible spectroscopy, scanning electron microscopy (SEM), and

Biosynthesis of Metal Nanoparticles: Novel Efficient Heterogeneous Nanocatalysts

Science.gov (United States)

Palomo, Jose M.; Filice, Marco

2016-01-01

This review compiles the most recent advances described in literature on the preparation of noble metal nanoparticles induced by biological entities. The use of different free or substituted carbohydrates, peptides, proteins, microorganisms or plants have been successfully applied as a new green concept in the development of innovative strategies to prepare these nanoparticles as different nanostructures with different forms and sizes. As a second part of this review, the application of their synthetic ability as new heterogonous catalysts has been described in C–C bond-forming reactions (as Suzuki, Heck, cycloaddition or multicomponent), oxidations and dynamic kinetic resolutions. PMID:28335213

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

International Nuclear Information System (INIS)

Quinby, T.C.

1980-01-01

A method for preparing particulate metal or metal oxide of controlled partile size comprises contacting an an aqueous solution containing dissolved metal values with excess urea at a temperature sufficient to cause urea to react with water to provide a molten urea solution containing the metal values; heating the molten urea solution to cause the metal values to precipitate, forming a mixture containing precipitated metal values; heating the mixture containing precipitated metal values to evaporate volatile material leaving a dry powder containing said metal values. The dry powder can be calcined to provide particulate metal oxide or reduced to provide particulate metal. Oxide mixtures are provided when the aqueous solution contains values of more than one metal. Homogeneousmetal-metal oxide mistures for preparing cermets can be prepared by selectively reducing at least one of the metal oxides. (auth)

Method of producing homogeneous mixed metal oxides and metal--metal oxide mixtures

International Nuclear Information System (INIS)

Quinby, T.C.

1978-01-01

Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution to leave a molten urea solution containing the metal values. The molten urea solution is heated to above about 180 0 C, whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles

Metal oxide nanoparticles as antimicrobial agents: a promise for the future.

Science.gov (United States)

Raghunath, Azhwar; Perumal, Ekambaram

2017-02-01

Microbial infectious diseases are a global threat to human health. Excess and improper use of antibiotics has created antimicrobial-resistant microbes that can defy clinical treatment. The hunt for safe and alternate antimicrobial agents is on in order to overcome such resistant micro-organisms, and the birth of nanotechnology offers promise to combat infectious organisms. Over the past two decades, metal oxide nanoparticles (MeO-NPs) have become an attractive alternative source to combat microbes that are highly resistant to various classes of antibiotics. Their vast array of physicochemical properties enables MeO-NPs to act as antimicrobial agents through various mechanisms. Apart from exhibiting antimicrobial properties, MeO-NPs also serve as carriers of drugs, thus barely providing a chance for micro-organisms to develop resistance. These immense multiple properties exhibited by MeO-NPs will have an impact on the treatment of deadly infectious diseases. This review discusses the mechanisms of action of MeO-NPs against micro-organisms, safety concerns, challenges and future perspectives. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

A general mechanism for intracellular toxicity of metal-containing nanoparticles

Science.gov (United States)

Sabella, Stefania; Carney, Randy P.; Brunetti, Virgilio; Malvindi, Maria Ada; Al-Juffali, Noura; Vecchio, Giuseppe; Janes, Sam M.; Bakr, Osman M.; Cingolani, Roberto; Stellacci, Francesco; Pompa, Pier Paolo

2014-05-01

The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment - where particles are abundantly internalized - is responsible for the cascading events associated with nanoparticles-induced intracellular toxicity. We call this mechanism a ``lysosome-enhanced Trojan horse effect'' since, in the case of nanoparticles, the protective cellular machinery designed to degrade foreign objects is actually responsible for their toxicity. To test our hypothesis, we compare the toxicity of similar gold particles whose main difference is in the internalization pathways. We show that particles known to pass directly through cell membranes become more toxic when modified so as to be mostly internalized by endocytosis. Furthermore, using experiments with chelating and lysosomotropic agents, we found that the toxicity mechanism for different metal containing NPs (such as metallic, metal oxide, and semiconductor NPs) is mainly associated with the release of the corresponding toxic ions. Finally, we show that particles unable to release toxic ions (such as stably coated NPs, or diamond and silica NPs) are not harmful to intracellular environments.The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment - where

Recent trends in the microwave-assisted synthesis of metal oxide nanoparticles supported on carbon nanotubes and their applications

CSIR Research Space (South Africa)

Motshekga, SC

2012-01-01

Full Text Available of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size...

CuO and ZnO nanoparticles: phytotoxicity, metal speciation, and induction of oxidative stress in sand-grown wheat

Science.gov (United States)

Dimkpa, Christian O.; McLean, Joan E.; Latta, Drew E.; Manangón, Eliana; Britt, David W.; Johnson, William P.; Boyanov, Maxim I.; Anderson, Anne J.

2012-09-01

Metal oxide nanoparticles (NPs) are reported to impact plant growth in hydroponic systems. This study describes the impact of commercial CuO (release did not account for the changes in plant growth. Bioaccumulation of Cu, mainly as CuO and Cu(I)-sulfur complexes, and Zn as Zn-phosphate was detected in the shoots of NP-challenged plants. Total Cu and Zn levels in shoot were similar whether NP or bulk materials were used. Oxidative stress in the NP-treated plants was evidenced by increased lipid peroxidation and oxidized glutathione in roots and decreased chlorophyll content in shoots; higher peroxidase and catalase activities were present in roots. These findings correlate with the NPs causing increased production of reactive oxygen species. The accumulation of Cu and Zn from NPs into edible plants has relevance to the food chain.

Cerium oxide and platinum nanoparticles protect cells from oxidant-mediated apoptosis

International Nuclear Information System (INIS)

Clark, Andrea; Zhu Aiping; Sun Kai; Petty, Howard R.

2011-01-01

Catalytic nanoparticles represent a potential clinical approach to replace or correct aberrant enzymatic activities in patients. Several diseases, including many blinding eye diseases, are promoted by excessive oxidant stress due to reactive oxygen species (ROS). Cerium oxide and platinum nanoparticles represent two potentially therapeutic nanoparticles that de-toxify ROS. In the present study, we directly compare these two classes of catalytic nanoparticles. Cerium oxide and platinum nanoparticles were found to be 16 ± 2.4 and 1.9 ± 0.2 nm in diameter, respectively. Using surface plasmon-enhanced microscopy, we find that these nanoparticles associate with cells. Furthermore, cerium oxide and platinum nanoparticles demonstrated superoxide dismutase catalytic activity, but did not promote hemolytic or cytolytic pathways in living cells. Importantly, both cerium oxide and platinum nanoparticles reduce oxidant-mediated apoptosis in target cells as judged by the activation of caspase 3. The ability to diminish apoptosis may contribute to maintaining healthy tissues.

Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

KAUST Repository

Pan, Yue

2010-03-16

Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures. © 2010 American Chemical Society.

Halide based MBE of crystalline metals and oxides

Energy Technology Data Exchange (ETDEWEB)

Greenlee, Jordan D.; Calley, W. Laws; Henderson, Walter; Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, Georgia (United States)

2012-02-15

A halide based growth chemistry has been demonstrated which can deliver a range of transition metals using low to moderate effusion cell temperatures (30-700 C) even for high melting point metals. Previously, growth with transition metal species required difficult to control electron beam or impurity inducing metal organic sources. Both crystalline oxide and metal films exhibiting excellent crystal quality are grown using this halide-based growth chemistry. Films are grown using a plasma assisted Molecular Beam Epitaxy (MBE) system with metal-chloride precursors. Crystalline niobium, cobalt, iron, and nickel were grown using this chemistry but the technology can be generalized to almost any metal for which a chloride precursor is available. Additionally, the oxides LiNbO{sub 3} and LiNbO{sub 2} were grown with films exhibiting X-ray diffraction (XRD) rocking curve full-widths at half maximum of 150 and 190 arcseconds respectively. LiNbO{sub 2} films demonstrate a memristive response due to the rapid movement of lithium in the layered crystal structure. The rapid movement of lithium ions in LiNbO{sub 2} memristors is characterized using impedance spectroscopy measurements. The impedance spectroscopy measurements suggest an ionic current of.1 mA for a small drive voltage of 5 mV AC or equivalently an ionic current density of {proportional_to}87 A/cm{sup 2}. This high ionic current density coupled with low charge transfer resistance of {proportional_to}16.5 {omega} and a high relaxation frequency (6.6 MHz) makes this single crystal material appealing for battery applications in addition to memristors. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles: Strategies and applications.

Science.gov (United States)

Zhang, Zhiyang; Wang, Han; Chen, Zhaopeng; Wang, Xiaoyan; Choo, Jaebum; Chen, Lingxin

2018-08-30

Plasmonic colorimetric sensors have emerged as a powerful tool in chemical and biological sensing applications due to the localized surface plasmon resonance (LSPR) extinction in the visible range. Among the plasmonic sensors, the most famous sensing mode is the "aggregation" plasmonic colorimetric sensor which is based on plasmon coupling due to nanoparticle aggregation. Herein, this review focuses on the newly-developing plasmonic colorimetric sensing mode - the etching or the growth of metal nanoparticles induces plasmon changes, namely, "non-aggregation" plasmonic colorimetric sensor. This type of sensors has attracted increasing interest because of their exciting properties of high sensitivity, multi-color changes, and applicability to make a test strip. Of particular interest, the test strip by immobilization of nanoparticles on the substrate can avoid the influence of nanoparticle auto-aggregation and increase the simplicity in storage and use. Although there are many excellent reviews available that describe the advance of plasmonic sensors, limited attention has been paid to the plasmonic colorimetric sensors based on etching or growth of metal nanoparticles. This review highlights recent progress on strategies and application of "non-aggregation" plasmonic colorimetric sensors. We also provide some personal insights into current challenges associated with "non-aggregation" plasmonic colorimetric sensors and propose future research directions. Copyright © 2018 Elsevier B.V. All rights reserved.

Towards the Development of Global Nano-Quantitative Structure–Property Relationship Models: Zeta Potentials of Metal Oxide Nanoparticles

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Andrey A. Toropov

2018-04-01

Full Text Available Zeta potential indirectly reflects a charge of the surface of nanoparticles in solutions and could be used to represent the stability of the colloidal solution. As processes of synthesis, testing and evaluation of new nanomaterials are expensive and time-consuming, so it would be helpful to estimate an approximate range of properties for untested nanomaterials using computational modeling. We collected the largest dataset of zeta potential measurements of bare metal oxide nanoparticles in water (87 data points. The dataset was used to develop quantitative structure–property relationship (QSPR models. Essential features of nanoparticles were represented using a modified simplified molecular input line entry system (SMILES. SMILES strings reflected the size-dependent behavior of zeta potentials, as the considered quasi-SMILES modification included information about both chemical composition and the size of the nanoparticles. Three mathematical models were generated using the Monte Carlo method, and their statistical quality was evaluated (R2 for the training set varied from 0.71 to 0.87; for the validation set, from 0.67 to 0.82; root mean square errors for both training and validation sets ranged from 11.3 to 17.2 mV. The developed models were analyzed and linked to aggregation effects in aqueous solutions.

Titania and Zinc Oxide Nanoparticles: Coating with Polydopamine and Encapsulation within Lecithin Liposomes—Water Treatment Analysis by Gel Filtration Chromatography with Fluorescence Detection

Directory of Open Access Journals (Sweden)

Xuhao Zhao

2018-02-01

Full Text Available The interplay of metal oxide nanoparticles, environmental pollution, and health risks is key to all industrial and drinking water treatment processes. In this work we present a study using gel filtration chromatography for the analytical investigation of metal oxide nanoparticles in water, their coating with polydopamine, and their encapsulation within lecithin liposomes. Polydopamine prevents TiO2 and ZnO nanoparticles from aggregation during chromatographic separation. Lecithin forms liposomes that encapsulate the nanoparticles and carry them through the gel filtration column, producing an increase of peak area for quantitative analysis without any change in retention time to affect qualitative identification. To the best of our knowledge, this is the first report that demonstrates the potential application of lecithin liposomes for cleaning up metal oxide nanoparticles in water treatment. Encapsulation of graphene quantum dots by liposomes would allow for monitoring of nanoparticle-loaded liposomes to ensure their complete removal by membrane ultrafiltration from treated water.

TiO2 structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

Science.gov (United States)

Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

2017-05-01

Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

Bio-sensing applications of cerium oxide nanoparticles: Advantages and disadvantages.

Science.gov (United States)

Charbgoo, Fahimeh; Ramezani, Mohammad; Darroudi, Majid

2017-10-15

Cerium oxide nanoparticles (CNPs) contain several properties such as catalytic activity, fluorescent quencher and electrochemical, high surface area, and oxygen transfer ability, which have attracted considerable attention in developing high-sensitive biosensors. CNPs can be used as a whole sensor or a part of recognition or transducer element. However, reports have shown that applying these nanoparticles in sensor design could remarkably enhance detection sensitivity. CNP's outstanding properties in biosensors which go from high catalytic activity and surface area to oxygen transfer and fluorescent quenching capabilities are also highlighted. Herein, we discuss the advantages and disadvantages of CNPs-based biosensors that function through various detection modes including colorimetric, electrochemistry, and chemoluminescent regarding the detection of small organic chemicals, metal ions and biomarkers. Copyright © 2017 Elsevier B.V. All rights reserved.

UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

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Kuang-Hung Tseng

2014-06-01

Full Text Available The purpose of this study was to investigate the difference between tungsten inert gas (TIG welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

Synthesis and heating effect of iron/iron oxide composite and iron oxide nanoparticles.

Science.gov (United States)

Zeng, Q; Baker, I; Loudis, J A; Liao, Y F; Hoopes, P J

2007-02-09

Fe/Fe oxide nanoparticles, in which the core consists of metallic Fe and the shell is composed of Fe oxides, were obtained by reduction of an aqueous solution of FeCl 3 within a NaBH 4 solution, or, using a water-in-oil micro-emulsion with CTAB as the surfactant. The reduction was performed either in an inert atmosphere or in air, and passivation with air was performed to produce the Fe/Fe 3 O 4 core/shell composite. Phase identification and particle size were determined by X-ray diffraction and TEM. Thermal analysis was performed using a differential scanning calorimeter. The quasistatic magnetic properties were measured using a VSM, and the specific absorption rates (SARs) of both Fe oxide and Fe/Fe 3 O 4 composite nanoparticles either dispersed in methanol or in an epoxy resin were measured by Luxtron fiber temperature sensors in an alternating magnetic field of 150 Oe at 250 kHz. It was found that the preparation conditions, including the concentrations of solutions, the mixing procedure and the heat treatment, influence the particle size, the crystal structure and consequently the magnetic properties of the particles. Compared with Fe oxides, the saturation magnetization ( M S ) of Fe/Fe 3 O 4 particles (100-190 emu/g) can be twice as high, and the coercivity ( H C ) can be tunable from several Oe to several hundred Oe. Hence, the SAR of Fe/Fe 3 O 4 composite nanoparticles can be much higher than that of Fe oxides, with a maximum SAR of 345 W/g. The heating behavior is related to the magnetic behavior of the nanoparticles.

METAL OXIDE NANOPARTICLES

Energy Technology Data Exchange (ETDEWEB)

FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

2007-10-01

This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

Fabrication of transparent ceramics using nanoparticles

Science.gov (United States)

Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

2012-09-18

A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

Science.gov (United States)

Gogurla, Narendar; Sinha, Arun K.; Naskar, Deboki; Kundu, Subhas C.; Ray, Samit K.

2016-03-01

Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

Carbon composites with metal nanoparticles for Alcohol fuel cells

Science.gov (United States)

Ventrapragada, Lakshman; Siddhardha, R. S.; Podilla, Ramakrishna; Muthukumar, V. S.; Creager, Stephen; Rao, A. M.; Ramamurthy, Sai Sathish

2015-03-01

Graphene due to its high surface area and superior conductivity has attracted wide attention from both industrial and scientific communities. We chose graphene as a substrate for metal nanoparticle deposition for fuel cell applications. There are many chemical routes for fabrication of metal-graphene composites, but they have an inherent disadvantage of low performance due to the usage of surfactants, that adsorb on their surface. Here we present a design for one pot synthesis of gold nanoparticles and simultaneous deposition on graphene with laser ablation of gold strip and functionalized graphene. In this process there are two natural advantages, the nanoparticles are synthesized without any surfactants, therefore they are pristine and subsequent impregnation on graphene is linker free. These materials are well characterized with electron microscopy to find their morphology and spectroscopic techniques like Raman, UV-Vis. for functionality. This gold nanoparticle decorated graphene composite has been tested for its electrocatalytic oxidation of alcohols for alkaline fuel cell applications. An electrode made of this composite showed good stability for more than 200 cycles of operation and reported a low onset potential of 100 mV more negative, an important factor for direct ethanol fuel cells.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-11-03

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

KAUST Repository

Nanda, Himansu Sekhar

2016-01-01

The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

Directory of Open Access Journals (Sweden)

Himansu Sekhar Nanda

2016-11-01

Full Text Available The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium-doped cerium oxide nanoparticles (SmCNPs as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy-ethoxy]-ethoxy}-hexyl triethoxysilane (MEEETES were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

Effects of tungsten and titanium oxide nanoparticles on the diazotrophic growth and metals acquisition by Azotobacter vinelandii under molybdenum limiting condition.

Science.gov (United States)

Allard, Patrick; Darnajoux, Romain; Phalyvong, Karine; Bellenger, Jean-Philippe

2013-02-19

The acquisition of essential metals, such as the metal cofactors (molybdenum (Mo) and iron (Fe)) of the nitrogenase, the enzyme responsible for the reduction of dinitrogen (N(2)) to ammonium, is critical to N(2) fixing bacteria in soil. The release of metal nanoparticles (MNPs) to the environment could be detrimental to N(2) fixing bacteria by introducing a new source of toxic metals and by interfering with the acquisition of essential metals such as Mo. Since Mo has been reported to limit nonsymbiotic N(2) fixation in many ecosystems from tropical to cold temperate, this question is particularly acute in the context of Mo limitation. Using a combination of microbiology and analytical chemistry techniques, we have evaluated the effect of titanium (Ti) and tungsten (W) oxide nanoparticles on the diazotrophic growth and metals acquisition in pure culture of the ubiquitous N(2) fixing bacterium Azotobacter vinelandii under Mo replete and Mo limiting conditions. We report that under our conditions (≤10 mg·L(-1)) TiO(2) NPs have no effects on the diazotrophic growth of A. vinelandii while WO(3) NPs are highly detrimental to the growth especially under Mo limiting conditions. Our results show that the toxicity of WO(3) NPs to A. vinelandii is due to an interference with the catechol-metalophores assisted uptake of Mo.

Titanium oxide nanoparticles as additives in engine oil

Directory of Open Access Journals (Sweden)

Meena Laad

2018-04-01

Full Text Available This research study investigates the tribological behaviour of titanium oxide (TiO2 nanoparticles as additives in mineral based multi-grade engine oil. All tests were performed under variable load and varying concentrations of nanoparticles in lubricating oil. The friction and wear experiments were performed using pin-on-disc tribotester. This study shows that mixing of TiO2 nanoparticles in engine oil significantly reduces the friction and wear rate and hence improves the lubricating properties of engine oil. The dispersion analysis of TiO2 nanoparticles in lubricating oil using UV spectrometer confirms that TiO2 nanoparticles possess good stability and solubility in the lubricant and improve the lubricating properties of the engine oil. Keywords: Titanium oxide, Nanoparticles, UV spectrometer, Tribotester, Engine oil

Synthesis metal nanoparticle

Science.gov (United States)

Bunge, Scott D.; Boyle, Timothy J.

2005-08-16

A method for providing an anhydrous route for the synthesis of amine capped coinage-metal (copper, silver, and gold) nanoparticles (NPs) using the coinage-metal mesityl (mesityl=C.sub.6 H.sub.2 (CH.sub.3).sub.3 -2,4,6) derivatives. In this method, a solution of (Cu(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5, (Ag(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.4, or (Au(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5 is dissolved in a coordinating solvent, such as a primary, secondary, or tertiary amine; primary, secondary, or tertiary phosphine, or alkyl thiol, to produce a mesityl precursor solution. This solution is subsequently injected into an organic solvent that is heated to a temperature greater than approximately 100.degree. C. After washing with an organic solvent, such as an alcohol (including methanol, ethanol, propanol, and higher molecular-weight alcohols), oxide free coinage NP are prepared that could be extracted with a solvent, such as an aromatic solvent (including, for example, toluene, benzene, and pyridine) or an alkane (including, for example, pentane, hexane, and heptane). Characterization by UV-Vis spectroscopy and transmission electron microscopy showed that the NPs were approximately 9.2.+-.2.3 nm in size for Cu.degree., (no surface oxide present), approximately 8.5.+-.1.1 nm Ag.degree. spheres, and approximately 8-80 nm for Au.degree..

Air-stable superparamagnetic metal nanoparticles entrapped in graphene oxide matrix

Czech Academy of Sciences Publication Activity Database

Tuček, J.; Sofer, Z.; Bouša, D.; Pumera, M.; Holá, K.; Malá, Aneta; Poláková, K.; Havrdová, M.; Čépe, K.; Tomanec, O.; Zbořil, R.

2016-01-01

Roč. 7, SEP 16 (2016), 12879:1-11, č. článku 12879. ISSN 2041-1723 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : magnetic nanoparticles * biomedical applications * iron(iii) oxide * functionalization * mri * delivery * design Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 12.124, year: 2016 http://www.nature.com/articles/ncomms12879

Shuttling single metal atom into and out of a metal nanoparticle.

Science.gov (United States)

Wang, Shuxin; Abroshan, Hadi; Liu, Chong; Luo, Tian-Yi; Zhu, Manzhou; Kim, Hyung J; Rosi, Nathaniel L; Jin, Rongchao

2017-10-10

It has long been a challenge to dope metal nanoparticles with a specific number of heterometal atoms at specific positions. This becomes even more challenging if the heterometal belongs to the same group as the host metal because of the high tendency of forming a distribution of alloy nanoparticles with different numbers of dopants due to the similarities of metals in outmost electron configuration. Herein we report a new strategy for shuttling a single Ag or Cu atom into a centrally hollow, rod-shaped Au 24 nanoparticle, forming AgAu 24 and CuAu 24 nanoparticles in a highly controllable manner. Through a combined approach of experiment and theory, we explain the shuttling pathways of single dopants into and out of the nanoparticles. This study shows that the single dopant is shuttled into the hollow Au 24 nanoparticle either through the apex or side entry, while shuttling a metal atom out of the Au 25 to form the Au 24 nanoparticle occurs mainly through the side entry.Doping a metal nanocluster with heteroatoms dramatically changes its properties, but it remains difficult to dope with single-atom control. Here, the authors devise a strategy to dope single atoms of Ag or Cu into hollow Au nanoclusters, creating precise alloy nanoparticles atom-by-atom.

Novel lanthanide-labeled metal oxide nanoparticles improve the measurement of in vivo clearance and translocation

Directory of Open Access Journals (Sweden)

Abid Aamir D

2013-01-01

Full Text Available Abstract The deposition, clearance and translocation of europium-doped gadolinium oxide nanoparticles in a mouse lung were investigated experimentally. Nanoparticles were synthesized by spray flame pyrolysis. The particle size, crystallinity and surface properties were characterized. Following instillation, the concentrations of particles in organs were determined with inductively coupled plasma mass spectrometry. The protein corona coating the nanoparticles was found to be similar to the coating on more environmentally relevant nanoparticles such as iron oxide. Measurements of the solubility of the nanoparticles in surrogates of biological fluids indicated very little propensity for dissolution, and the elemental ratio of particle constituents did not change, adding further support to the contention that intact nanoparticles were measured. The particles were intratracheally instilled into the mouse lung. After 24 hours, the target organs were harvested, acid digested and the nanoparticle mass in each organ was measured by inductively coupled plasma mass spectrometry (ICP-MS. The nanoparticles were detected in all the studied organs at low ppb levels; 59% of the particles remained in the lung. A significant amount of particles was also detected in the feces, suggesting fast clearance mechanisms. The nanoparticle system used in this work is highly suitable for quantitatively determining deposition, transport and clearance of nanoparticles from the lung, providing a quantified measure of delivered dose.

Synthesis of self-detached nanoporous titanium-based metal oxide

International Nuclear Information System (INIS)

Hu, F.; Wen, Y.; Chan, K.C.; Yue, T.M.; Zhou, Y.Z.; Zhu, S.L.; Yang, X.J.

2015-01-01

In this study, self-detached nanoporous titanium-based metal oxide was synthesized for the first time by ultrafast anodization in a fluoride-free electrolyte containing 10% HNO 3 . The nanoporous oxide has through-holes with diameters ranging from 10 to 60 nm. The as-formed oxides are amorphous, and were transformed to crystalline structures by annealing. The performance of a dye sensitized solar cell using nanoporpous Ti–10Zr oxide (TZ10) was further studied. It was found that the TZ10 film could increase both the short-circuit current and the open-circuit photovoltage of the solar cell. The overall efficiency of the solar cell was 6.99%, an increase of 20.7% as compared to that using a pure TiO 2 (P25) film. - Graphical abstract: The nanoporous Ti–xZr(x=10, 30) oxide layers are fabricated by anodizing in a dilute nitric acid solvent. The power conversion efficiency of the DSSC by a covering of a Ti–10Zr thin film is increased by 20.7%, with an η of 7.69% , a short circuit current of 12.4 mA/cm 2 , a open circuit voltage of 0.833 V, and a fill factor of 0.679. - Highlights: • Self-detached nanoporous titanium-based metal (TiZr) oxide was synthesized. • The TiZr oxides have through-hole nanopores with diameters ranging from 10 to 60 nm. • The nanoporous Ti–10Zr oxide can improve the power conversion efficiency of a DSSC

Synthesis of self-detached nanoporous titanium-based metal oxide

Energy Technology Data Exchange (ETDEWEB)

Hu, F. [Advanced Manufacturing Technology Research Center, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University (Hong Kong); Jiangxi Key Laboratory of Advanced Ceramic Materials, School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jiangxi 343001 (China); Wen, Y. [Jiangxi Key Laboratory of Advanced Ceramic Materials, School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jiangxi 343001 (China); Chan, K.C., E-mail: mfkcchan@inet.polyu.edu.hk [Advanced Manufacturing Technology Research Center, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University (Hong Kong); Yue, T.M. [Advanced Manufacturing Technology Research Center, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University (Hong Kong); Zhou, Y.Z. [Jiangxi Key Laboratory of Advanced Ceramic Materials, School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jiangxi 343001 (China); Zhu, S.L.; Yang, X.J. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2015-09-15

In this study, self-detached nanoporous titanium-based metal oxide was synthesized for the first time by ultrafast anodization in a fluoride-free electrolyte containing 10% HNO{sub 3}. The nanoporous oxide has through-holes with diameters ranging from 10 to 60 nm. The as-formed oxides are amorphous, and were transformed to crystalline structures by annealing. The performance of a dye sensitized solar cell using nanoporpous Ti–10Zr oxide (TZ10) was further studied. It was found that the TZ10 film could increase both the short-circuit current and the open-circuit photovoltage of the solar cell. The overall efficiency of the solar cell was 6.99%, an increase of 20.7% as compared to that using a pure TiO{sub 2} (P25) film. - Graphical abstract: The nanoporous Ti–xZr(x=10, 30) oxide layers are fabricated by anodizing in a dilute nitric acid solvent. The power conversion efficiency of the DSSC by a covering of a Ti–10Zr thin film is increased by 20.7%, with an η of 7.69% , a short circuit current of 12.4 mA/cm{sup 2}, a open circuit voltage of 0.833 V, and a fill factor of 0.679. - Highlights: • Self-detached nanoporous titanium-based metal (TiZr) oxide was synthesized. • The TiZr oxides have through-hole nanopores with diameters ranging from 10 to 60 nm. • The nanoporous Ti–10Zr oxide can improve the power conversion efficiency of a DSSC.

Generation and oxidation of aerosol deposited PdAg nanoparticles

Science.gov (United States)

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

2013-10-01

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

Synthesis of Metal Nanoparticles by Bacteria

Directory of Open Access Journals (Sweden)

Fikriye Alev Akçay

2018-04-01

Full Text Available Metal particles reduced to nano size by nanotechnological methods are confronted in many different fields such as biomedical and physicochemical, pharmaceutical, electric-electronic, automotive and food industries. Nanoparticles can be produced using chemical, physical and biological methods, of which chemical processes are in common use. However, physical and chemical methods are not environmentally friendly and economical because they require the use of high temperature, high pressure and toxic chemicals. For this reason, interest in the production of metal nanoparticles by biological methods, also called green technology, an environmentally friendly and sustainable approach, has increased in recent years. With some plant extracts and intracellular and extracellular secretions of microorganisms, some reduction reactions take place and metal nanoparticles are produced. Bacteria have been actively involved in nanotechnology in recent years due to their diversity in nature, their ease of isolation, and ease of nanoparticle synthesis. In this article, production and application of metal nanoparticles by using bacterial methods have been reviewed.

Revisiting the electrochemical oxidation of ammonia on carbon-supported metal nanoparticle catalysts

International Nuclear Information System (INIS)

Li, Zhe-Fei; Wang, Yuxuan; Botte, Gerardine G.

2017-01-01

Highlights: • A procedure to pretreat electrocatalysts to study the ammonia oxidation is provided. • N ads and O/OH ads were identified as the major deactivation species that prevent ammonia oxidatoin. • The electrocatalytic activity, thermodynamics, and possible deactivation mechanisms for ammonia oxidation were elucidated. • The onset potential for ammonia oxidation is related to the hydrogen binding energy of the catalyst. • Ammonia electro-oxidation involves a complex decoupled electron and proton transfer process. - Abstract: The ammonia electro-oxidation reaction (AOR) has been studied due to its promising applications in ammonia electrolysis, wastewater remediation, direct ammonia fuel cells, and sensors. However, it is difficult to compare and analyze the reported electrocatalytic activity of AOR reliably, likely due to the variation in catalyst synthesis, electrode composition, electrode morphology, and testing protocol. In this paper, the electro-oxidation of ammonia on different carbon-supported precious metal nanoparticle catalysts was revisited. The effect of experimental conditions, electrochemical test parameters, electrocatalytic activity, thermodynamics, and possible deactivation mechanism of the catalysts were investigated. Pt/C catalyst possesses the highest electrocatalytic activity, while Ir/C and Rh/C show lower overpotential. The onset potential of the AOR is related to the hydrogen binding energy of the catalyst. N ads is one major cause of deactivation accompanied with the formation of surface O/OH ads at high potentials. The coulombic efficiency of N ads formation on Pt is about 1% initially and gradually decreases with reaction time. Increase in ammonia concentration leads to increase in current density, while increase in hydroxyl ions concentration can enhance the current density and reduce the overpotential simultaneously. The slopes of AOR onset potential and hydrogen adsorption/desorption potential of Pt/C as a function of p

Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

Science.gov (United States)

Wang, Ye; Zi, Xiao-Yuan; Su, Juan; Zhang, Hong-Xia; Zhang, Xin-Rong; Zhu, Hai-Ying; Li, Jian-Xiu; Yin, Meng; Yang, Feng; Hu, Yi-Ping

2012-01-01

In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs) can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS) and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy. PMID:22679374

Metal Nanoparticles Covered with a Metal-Organic Framework: From One-Pot Synthetic Methods to Synergistic Energy Storage and Conversion Functions.

Science.gov (United States)

Kobayashi, Hirokazu; Mitsuka, Yuko; Kitagawa, Hiroshi

2016-08-01

Hybrid materials composed of metal nanoparticles and metal-organic frameworks (MOFs) have attracted much attention in many applications, such as enhanced gas storage and catalytic, magnetic, and optical properties, because of the synergetic effects between the metal nanoparticles and MOFs. In this Forum Article, we describe our recent progress on novel synthetic methods to produce metal nanoparticles covered with a MOF (metal@MOF). We first present Pd@copper(II) 1,3,5-benzenetricarboxylate (HKUST-1) as a novel hydrogen-storage material. The HKUST-1 coating on Pd nanocrystals results in a remarkably enhanced hydrogen-storage capacity and speed in the Pd nanocrystals, originating from charge transfer from Pd nanocrystals to HKUST-1. Another material, Pd-Au@Zn(MeIM)2 (ZIF-8, where HMeIM = 2-methylimidazole), exhibits much different catalytic activity for alcohol oxidation compared with Pd-Au nanoparticles, indicating a design guideline for the development of composite catalysts with high selectivity. A composite material composed of Cu nanoparticles and Cr3F(H2O)2O{C6H3(CO2)3}2 (MIL-100-Cr) demonstrates higher catalytic activity for CO2 reduction into methanol than Cu/γ-Al2O3. We also present novel one-pot synthetic methods to produce composite materials including Pd/ZIF-8 and Ni@Ni2(dhtp) (MOF-74, where H4dhtp = 2,5-dihydroxyterephthalic acid).

Metal Oxide Nanoparticle Photoresists for EUV Patterning

KAUST Repository

Jiang, Jing; Chakrabarty, Souvik; Yu, Mufei; Ober, Christopher K.

2014-01-01

© 2014SPST. Previous studies of methacrylate based nanoparticle have demonstrated the excellent pattern forming capability of these hybrid materials when used as photoresists under 13.5 nm EUV exposure. HfO2 and ZrO2 methacrylate resists have

A dewetting route to grow heterostructured nanoparticles based on thin film heterojunctions.

Science.gov (United States)

Li, Junjie; Yin, Deqiang; Li, Qiang; Chen, Chunlin; Huang, Sumei; Wang, Zhongchang

2015-12-21

Heterostructured nanoparticles have received considerable attention for their various applications due to their unique and tunable functionalities with respect to their individual bulk constituents. However, the current wet chemical synthesis of multicomponent heterostructured nanoparticles is rather complicated. Here, we report a simple and quick method to fabricate Co-Au dumbbell arrays by dewetting Co/Au heterojunctions on a Si substrate and demonstrate that the Co-Au dumbbells vary in size from 2 to 28 nm. We further show by chemical mapping that Co bells are covered by a pseudomorphic Au wetting layer of ∼4 Å, preventing the bells from oxidation. By controlling the thickness of metal heterojunctions and the annealing time, the morphology of the Co-Au nanoparticle is found to be transformed from the dumbbell to the core shell. This facile route is demonstrated to be useful for fabricating other metal-metal and metal-oxide heterostructures and hence holds technological promise for functional applications.

Heavy metal removal from water/wastewater by nanosized metal oxides: A review

International Nuclear Information System (INIS)

Hua, Ming; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

2012-01-01

Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs’ preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance.

Sustainable green catalysis by supported metal nanoparticles.

Science.gov (United States)

Fukuoka, Atsushi; Dhepe, Paresh L

2009-01-01

The recent progress of sustainable green catalysis by supported metal nanoparticles is described. The template synthesis of metal nanoparticles in ordered porous materials is studied for the rational design of heterogeneous catalysts capable of high activity and selectivity. The application of these materials in green catalytic processes results in a unique activity and selectivity arising from the concerted effect of metal nanoparticles and supports. The high catalytic performances of Pt nanoparticles in mesoporous silica is reported. Supported metal catalysts have also been applied to biomass conversion by heterogeneous catalysis. Additionally, the degradation of cellulose by supported metal catalysts, in which bifunctional catalysis of acid and metal plays the key role for the hydrolysis and reduction of cellulose, is also reported. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

Energy Technology Data Exchange (ETDEWEB)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun [Dongguk University, Seoul (Korea, Republic of)

2016-05-15

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications.

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

International Nuclear Information System (INIS)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun

2016-01-01

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications

Homogeneous dispersion of gadolinium oxide nanoparticles into a non-aqueous-based polymer by two surface treatments

Energy Technology Data Exchange (ETDEWEB)

Samuel, Jorice, E-mail: jorice.samuel@gmail.com [AREVA T and D UK Ltd, AREVA T and D Research and Technology Centre (United Kingdom); Raccurt, Olivier [NanoChemistry and Nanosafety Laboratory (DRT/LITEN/DTNM/LCSN), CEA Grenoble, Department of NanoMaterials (France); Mancini, Cedric; Dujardin, Christophe; Amans, David; Ledoux, Gilles [Universite de Lyon, Laboratoire de Physico Chimie des Materiaux Luminescents (LPCML) (France); Poncelet, Olivier [NanoChemistry and Nanosafety Laboratory (DRT/LITEN/DTNM/LCSN), CEA Grenoble, Department of NanoMaterials (France); Tillement, Olivier [Universite de Lyon, Laboratoire de Physico Chimie des Materiaux Luminescents (LPCML) (France)

2011-06-15

Gadolinium oxide nanoparticles are more and more used. They can notably provide interesting fluorescence properties. Herein they are incorporated into a non-aqueous-based polymer, the poly(methyl methacrylate). Their dispersion within the polymer matrix is the key to improve the composite properties. As-received gadolinium oxide nanopowders cannot be homogeneously dispersed in such a polymer matrix. Two surface treatments are, therefore, detailed and compared to achieve a good stability of the nanoparticles in a non-aqueous solvent such as the 2-butanone. Then, once the liquid suspensions have been stabilized, they are used to prepare nanocomposites with homogeneous particles dispersion. The two approaches proposed are an hybrid approach based on the growth of a silica shell around the gadolinium oxide nanoparticles, and followed by a suitable silane functionalization; and a non-hybrid approach based on the use of surfactants. The surface treatments and formulations involved in both methods are detailed, adjusted and compared. Thanks to optical methods and in particular to the use of a 'home made' confocal microscope, the dispersion homogeneity within the polymer can be assessed. Both methods provide promising and conclusive results.

Oxidation behaviour of metallic glass foams

Energy Technology Data Exchange (ETDEWEB)

Barnard, B.R. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States)], E-mail: bbarnard@utk.edu; Liaw, P.K. [Department of Materials Science and Engineering, 434 Dougherty Hall, University of Tennessee, Knoxville, TN 37996-2200 (United States); Demetriou, M.D.; Johnson, W.L. [Department of Materials Science, Keck Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)

2008-08-15

In this study, the effects of porosity on the oxidation behaviour of bulk-metallic glasses were investigated. Porous Pd- and Fe-based bulk-metallic glass (BMG) foams and Metglas ribbons were studied. Oxidizing experiments were conducted at 70 deg. C, and around 80 deg. C below glass-transition temperatures, (T{sub g}s). Scanning-electron microscopy/energy-dispersive spectroscopy (SEM/EDS) studies revealed little evidence of oxidation at 70 deg. C. Specimens exhibited greater oxidation at T{sub g} - 80 deg. C. Oxides were copper-based for Pd-based foams, Fe-, Cr-, and Mo-based for Fe-based foams, and Co-based with borosilicates likely for the Metglas. Pd-based foams demonstrated the best oxidation resistance, followed by Metglas ribbons, followed by Fe-based foams.

Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection

Directory of Open Access Journals (Sweden)

Kwangjae Lee

2017-02-01

Full Text Available A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD technique is used to make the highly porous structure such as nanocolumns (NCs of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides (PVC decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C, the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C. The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.

Biosensors based on inorganic nanoparticles with biomimetic properties: Biomedical applications and in vivo cytotoxicity measurements

Science.gov (United States)

Ispas, Cristina R.

. This work introduces a new generic approach of improving the sensitivity of oxidase-based enzymatic assays and indicates that ceria and its mixture with other metal oxide nanoparticles could be used to minimize the problems associated with variations of the oxygen. These materials have great potential in bioanalytical and biotechnological applications and offer great opportunities for development of implantable sensing devices for in vivo and in vitro monitoring of analytes of clinical relevance. Additionally, this thesis evaluates the toxicity of different metal and metal oxide nanoparticles by using zebrafish embryos as a toxicological target. Because of their similarities with other vertebrates, rapid development and low cost, zebrafish embryos are ideal animal models for probing toxicological effects of engineered nanomaterials. Among the nanomaterials tested, nickel nanoparticles were characterized by high toxicity and induced delayed development and morphological malformations, while metal oxides nanoparticles (i.e. ceria nanoparticles) had no toxic effects.

CuO and ZnO nanoparticles: phytotoxicity, metal speciation, and induction of oxidative stress in sand-grown wheat

Energy Technology Data Exchange (ETDEWEB)

Dimkpa, Christian O., E-mail: cdimkpa@usu.edu [Utah State University, Department of Biological Engineering (United States); McLean, Joan E. [Utah State University, Utah Water Research Laboratory (United States); Latta, Drew E. [Argonne National Laboratory, Biosciences Division (United States); Manangon, Eliana [University of Utah, Department of Geology and Geophysics (United States); Britt, David W. [Utah State University, Department of Biological Engineering (United States); Johnson, William P. [University of Utah, Department of Geology and Geophysics (United States); Boyanov, Maxim I. [Argonne National Laboratory, Biosciences Division (United States); Anderson, Anne J. [Utah State University, Department of Biological Engineering (United States)

2012-09-15

Metal oxide nanoparticles (NPs) are reported to impact plant growth in hydroponic systems. This study describes the impact of commercial CuO (<50 nm) and ZnO (<100 nm) NPs on wheat (Triticum aestivum) grown in a solid matrix, sand. The NPs contained both metallic and non-metallic impurities to different extents. Dynamic light scattering and atomic force microscopy (AFM) assessments confirmed aggregation of the NPs to submicron sizes. AFM showed transformation of ZnO NPs from initial rhomboid shapes in water to elongated rods in the aqueous phase of the sand matrix. Solubilization of metals occurred in the sand at similar rates from CuO or ZnO NPs as their bulk equivalents. Amendment of the sand with 500 mg Cu and Zn/kg sand from the NPs significantly (p = 0.05) reduced root growth, but only CuO NPs impaired shoot growth; growth reductions were less with the bulk amendments. Dissolved Cu from CuO NPs contributed to their phytotoxicity but Zn release did not account for the changes in plant growth. Bioaccumulation of Cu, mainly as CuO and Cu(I)-sulfur complexes, and Zn as Zn-phosphate was detected in the shoots of NP-challenged plants. Total Cu and Zn levels in shoot were similar whether NP or bulk materials were used. Oxidative stress in the NP-treated plants was evidenced by increased lipid peroxidation and oxidized glutathione in roots and decreased chlorophyll content in shoots; higher peroxidase and catalase activities were present in roots. These findings correlate with the NPs causing increased production of reactive oxygen species. The accumulation of Cu and Zn from NPs into edible plants has relevance to the food chain.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

Energy Technology Data Exchange (ETDEWEB)

Chu, Wenya [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Zhou, Qun, E-mail: zhq@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Li, Shuangshuang [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China); Zhao, Wei; Li, Na [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); Zheng, Junwei, E-mail: jwzheng@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, and Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, Soochow University, Suzhou 215123 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China)

2015-10-30

Highlights: • Gold nanoparticles assembled on electrodes are incorporated into polyaniline film. • Composite film electrodes exhibit synergistic effect on electrocatalytic oxidation. • Ascorbic acid and dopamine can be detected simultaneously on composite electrodes. - Abstract: Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

International Nuclear Information System (INIS)

Chu, Wenya; Zhou, Qun; Li, Shuangshuang; Zhao, Wei; Li, Na; Zheng, Junwei

2015-01-01

Highlights: • Gold nanoparticles assembled on electrodes are incorporated into polyaniline film. • Composite film electrodes exhibit synergistic effect on electrocatalytic oxidation. • Ascorbic acid and dopamine can be detected simultaneously on composite electrodes. - Abstract: Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Nitride stabilized core/shell nanoparticles

Science.gov (United States)

Kuttiyiel, Kurian Abraham; Sasaki, Kotaro; Adzic, Radoslav R.

2018-01-30

Nitride stabilized metal nanoparticles and methods for their manufacture are disclosed. In one embodiment the metal nanoparticles have a continuous and nonporous noble metal shell with a nitride-stabilized non-noble metal core. The nitride-stabilized core provides a stabilizing effect under high oxidizing conditions suppressing the noble metal dissolution during potential cycling. The nitride stabilized nanoparticles may be fabricated by a process in which a core is coated with a shell layer that encapsulates the entire core. Introduction of nitrogen into the core by annealing produces metal nitride(s) that are less susceptible to dissolution during potential cycling under high oxidizing conditions.

Highly Conductive, Transparent Flexible Films Based on Metal Nanoparticle-Carbon Nanotube Composites

Directory of Open Access Journals (Sweden)

Wen-Yin Ko

2013-01-01

Full Text Available Metallic nanoparticles decorated on MWCNTs based transparent conducting thin films (TCFs show a cheap and efficient option for the applications in touch screens and the replacement of the ITO film because of their interesting properties of electrical conductivity, mechanical property, chemical inertness, and other unique properties, which may not be accessible by their individual components. However, a great challenge that always remains is to develop effective ways to prepare junctions between metallic nanoparticles and MWCNTs for the improvement of high-energy barriers, high contact resistances, and weak interactions which could lead to the formation of poor conducting pathways and result in the CNT-based devices with low mechanical flexibility. Herein, we not only discuss recent progress in the preparation of MNP-CNT flexible TCFs but also describe our research studies in the relevant areas. Our result demonstrated that the MNP-CNT flexible TCFs we prepared could achieve a highly electrical conductivity with the sheet resistance of ~100 ohm/sq with ~80% transmittance at 550 nm even after being bent 500 times. This electrical conductivity is much superior to the performances of other MWCNT-based transparent flexible films, making it favorable for next-generation flexible touch screens and optoelectronic devices.

Microemulsion Synthesis of Nanoparticles

Directory of Open Access Journals (Sweden)

Gotić, M.

2013-11-01

Full Text Available Nanoparticles and nanomaterials have wide applications in electronics, physics, material design, being also utilized as sensors, catalysts, and more and more in biomedicine. Microemulsions are an exceptionally suitable medium for the synthesis of nanoparticles due to their thermodynamical stability, great solubility of both polar and nonpolar components, as well as their ability to control the size, dispersity and shape of the particles. This review presents microemulsion techniques for the synthesis of inorganic nanoparticles. It takes place in water-in-oil microemulsions by mixing one microemulsion with a cationic precursor, and the other with a precipitating or reducing agent, or by direct addition of reducing agents or gas (O2, NH3 ili CO2 into microemul sion (Fig. 1. Metal nanoparticles are used as catalysts, sensors, ferrofluids etc. They are produced by reducing the metal cation with a suitable reducing agent. In a similar way, one can prepare nanoparticles of alloys from the metal salts, provided that the metals are mutually soluble. The microemulsion technique is also suitable for depositing nanoparticles onto various surfaces. Highly active catalysts made from nanoparticles of Pt, Pd, Rh and other noble metals may be obtained in this way. Metal oxides and hydroxides may be prepared by hydrolysis or precipitation in the water core of microemulsion. Precipitation can be initiated by adding the base or precipitating agent into the microemulsion with water solution of metal ions. Similarly, nanoparticles may be prepared of sulphides, halogenides, cyanides, carbonates, sulphates and other insoluble metal salts. To prevent oxidation of nanoparticles, especially Fe, the particles are coated with inert metals, oxides, various polymers etc. Coating may provide additional functionality; e.g. coating with gold allows subsequent functionalization with organic compounds containing sulphur, due to the strong Au–S bond. Polymer coatings decrease

A Review on Metal Nanoparticles Nucleation and Growth on/in Graphene

OpenAIRE

Francesco Ruffino; Filippo Giannazzo

2017-01-01

In this review, the fundamental aspects (with particular focus to the microscopic thermodynamics and kinetics mechanisms) concerning the fabrication of graphene-metal nanoparticles composites are discussed. In particular, the attention is devoted to those fabrication methods involving vapor-phase depositions of metals on/in graphene-based materials. Graphene-metal nanoparticles composites are, nowadays, widely investigated both from a basic scientific and from several technological point of v...

Gas Sensors Based on Locally Heated Multiwall Carbon Nanotubes Decorated with Metal Nanoparticles

Directory of Open Access Journals (Sweden)

R. Savu

2015-01-01

Full Text Available We report the design and fabrication of microreactors and sensors based on metal nanoparticle-decorated carbon nanotubes. Titanium adhesion layers and gold films were sputtered onto Si/SiO2 substrates for obtaining the electrical contacts. The gold layers were electrochemically thickened until 1 μm and the electrodes were patterned using photolithography and wet chemical etching. Before the dielectrophoretic deposition of the nanotubes, a gap 1 μm wide and 5 μm deep was milled in the middle of the metallic line by focused ion beam, allowing the fabrication of sensors based on suspended nanotubes bridging the electrodes. Subsequently, the sputtering technique was used for decorating the nanotubes with metallic nanoparticles. In order to test the as-obtained sensors, microreactors (100 μL volume were machined from a single Kovar piece, being equipped with electrical connections and 1/4′′ Swagelok-compatible gas inlet and outlets for controlling the atmosphere in the testing chamber. The sensors, electrically connected to the contact pins by wire-bonding, were tested in the 10−5 to 10−2 W working power interval using oxygen as target gas. The small chamber volume allowed the measurement of fast characteristic times (response/recovery, with the sensors showing good sensitivity.

The effect of magnetite nanoparticles synthesis conditions on their ability to separate heavy metal ions

Directory of Open Access Journals (Sweden)

Bobik Magdalena

2017-06-01

Full Text Available Magnetite nanoparticles have become a promising material for scientific research. Among numerous technologies of their synthesis, co-precipitation seems to be the most convenient, less time-consuming and cheap method which produces fine and pure iron oxide particles applicable to environmental issues. The aim of the work was to investigate how the co-precipitation synthesis parameters, such as temperature and base volume, influence the magnetite nanoparticles ability to separate heavy metal ions. The synthesis were conducted at nine combinations of different ammonia volumes - 8 cm3, 10 cm3, 15 cm3 and temperatures - 30°C, 60°C, 90°C for each ammonia volume. Iron oxides synthesized at each combination were examined as an adsorbent of seven heavy metals: Cr(VI, Pb(II, Cr(III, Cu(II, Zn(II, Ni(II and Cd(II. The representative sample of magnetite was characterized using XRD, SEM and BET methods. It was observed that more effective sorbent for majority of ions was produced at 30°C using 10 cm3 of ammonia. The characterization of the sample produced at these reaction conditions indicate that pure magnetite with an average crystallite size of 23.2 nm was obtained (XRD, the nanosized crystallites in the sample were agglomerated (SEM and the specific surface area of the aggregates was estimated to be 55.64 m2·g-1 (BET. The general conclusion of the work is the evidence that magnetite nanoparticles have the ability to adsorb heavy metal ions from the aqueous solutions. The effectiveness of the process depends on many factors such as kind of heavy metal ion or the synthesis parameters of the sorbent.

The effect of water on the stability of iron oxide and iron carbide nanoparticles in hydrogen and syngas followed by in situ X-ray absorption spectroscopy

NARCIS (Netherlands)

Thuene, P.C.; Moodley - Gengan, P.; Scheijen, F.J.E.; Fredriksson, H.O.A.; Lancee, R.J.; Kropf, J.; Miller, J.T.; Niemantsverdriet, J.W.

2012-01-01

The effect of water on iron-based nanoparticles under hydrogen and syngas was investigated by in situ X-ray absorption spectroscopy. The iron oxide (¿-Fe2O3) nanoparticles, dispersed as a monolayer on flat silica surfaces, were readily converted into metallic iron in dry hydrogen at 350 °C and into

UV stabilization of wood by nano metal oxides dispersed in propylene glycol.

Science.gov (United States)

Nair, Sreeja; Nagarajappa, Giridhar B; Pandey, Krishna K

2018-06-01

Nanoparticles of some of the metal oxides are known to have high UV protective efficiency. The UV filtering efficiency of nanoparticles invariably depends on their size and stability in the dispersion. In the present work, a stable dispersion of nanoparticles of three metal oxides, zinc oxide (ZnO), cerium oxide (CeO 2 ) and titanium dioxide (TiO 2 ), was prepared in propylene glycol (PG) using ultrasonication. The method is easy and useful as no additional surfactant or dispersant is needed. The particle size and its distribution was confirmed by Scanning Electron Microscopy and Dynamic Light Scattering. The stability of dispersion was assessed by UV-visible absorption spectroscopy. The UV stability of wood surfaces of Wrightia tinctoria coated with nanodispersions of ZnO, CeO 2 and TiO 2 was evaluated under laboratory conditions in an accelerated weathering tester. Changes in the colour and FTIR spectra of exposed specimens were measured periodically. Rapid colour darkening (yellowing) was observed in uncoated and PG coated specimens. In contrast, nanodispersion coated specimens prevented photo-yellowing considerably with significant reduction in colour changes examined by CIE L*, a*, b* and ΔE*. Increase in concentration of nanoparticles in the dispersion imparted higher resistance to UV induced degradation. However, increased concentration of nanoparticles reduced the transparency of the coating. FTIR analysis indicated rapid degradation of lignin in uncoated and PG coated specimens due to UV exposure. Coating of wood surfaces with nanodispersions restricted lignin degradation. The study also demonstrates the potential of propylene glycol as a dispersant for developing stable and efficient UV protective nanodispersions for wood coating. Copyright © 2018 Elsevier B.V. All rights reserved.

A general mechanism for intracellular toxicity of metal-containing nanoparticles

KAUST Repository

Sabella, Stefania

2014-04-09

The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment-where particles are abundantly internalized-is responsible for the cascading events associated with nanoparticles-induced intracellular toxicity. We call this mechanism a "lysosome-enhanced Trojan horse effect" since, in the case of nanoparticles, the protective cellular machinery designed to degrade foreign objects is actually responsible for their toxicity. To test our hypothesis, we compare the toxicity of similar gold particles whose main difference is in the internalization pathways. We show that particles known to pass directly through cell membranes become more toxic when modified so as to be mostly internalized by endocytosis. Furthermore, using experiments with chelating and lysosomotropic agents, we found that the toxicity mechanism for different metal containing NPs (such as metallic, metal oxide, and semiconductor NPs) is mainly associated with the release of the corresponding toxic ions. Finally, we show that particles unable to release toxic ions (such as stably coated NPs, or diamond and silica NPs) are not harmful to intracellular environments. The Royal Society of Chemistry 2014.

A general mechanism for intracellular toxicity of metal-containing nanoparticles

KAUST Repository

Sabella, Stefania; Carney, Randy P.; Brunetti, Virgilio; Malvindi, Maria Ada; Al-Juffali, Noura; Vecchio, Giuseppe; Janes, Sam M.; Bakr, Osman; Cingolani, Roberto; Stellacci, Francesco; Pompa, Pier Paolo

2014-01-01

The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment-where particles are abundantly internalized-is responsible for the cascading events associated with nanoparticles-induced intracellular toxicity. We call this mechanism a "lysosome-enhanced Trojan horse effect" since, in the case of nanoparticles, the protective cellular machinery designed to degrade foreign objects is actually responsible for their toxicity. To test our hypothesis, we compare the toxicity of similar gold particles whose main difference is in the internalization pathways. We show that particles known to pass directly through cell membranes become more toxic when modified so as to be mostly internalized by endocytosis. Furthermore, using experiments with chelating and lysosomotropic agents, we found that the toxicity mechanism for different metal containing NPs (such as metallic, metal oxide, and semiconductor NPs) is mainly associated with the release of the corresponding toxic ions. Finally, we show that particles unable to release toxic ions (such as stably coated NPs, or diamond and silica NPs) are not harmful to intracellular environments. The Royal Society of Chemistry 2014.

Bipolar resistive switching in graphene oxide based metal insulator metal structure for non-volatile memory applications

Science.gov (United States)

Singh, Rakesh; Kumar, Ravi; Kumar, Anil; Kashyap, Rajesh; Kumar, Mukesh; Kumar, Dinesh

2018-05-01

Graphene oxide based devices have attracted much attention recently because of their possible application in next generation electronic devices. In this study, bipolar resistive switching characteristics of graphene oxide based metal insulator metal structure were investigated for nonvolatile memories. The graphene oxide was prepared by the conventional Hummer's method and deposited on ITO coated glass by spin-coating technique. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament inside the graphene oxide. The conduction mechanism for low and high resistance states are dominated by two mechanism the ohmic conduction and space charge limited current (SCLC) mechanism, respectively. Atomic Force Microscopy, X-ray diffraction, Cyclic-Voltammetry were conducted to observe the morphology, structure and behavior of the material. The fabricated device with Al/GO/ITO structure exhibited reliable bipolar resistive switching with set & reset voltage of -2.3 V and 3V respectively.

Optimal descriptor as a translator of eclectic data into prediction of cytotoxicity for metal oxide nanoparticles under different conditions.

Science.gov (United States)

Toropova, Alla P; Toropov, Andrey A; Rallo, Robert; Leszczynska, Danuta; Leszczynski, Jerzy

2015-02-01

The Monte Carlo technique has been used to build up quantitative structure-activity relationships (QSARs) for prediction of dark cytotoxicity and photo-induced cytotoxicity of metal oxide nanoparticles to bacteria Escherichia coli (minus logarithm of lethal concentration for 50% bacteria pLC50, LC50 in mol/L). The representation of nanoparticles include (i) in the case of the dark cytotoxicity a simplified molecular input-line entry system (SMILES), and (ii) in the case of photo-induced cytotoxicity a SMILES plus symbol '^'. The predictability of the approach is checked up with six random distributions of available data into the visible training and calibration sets, and invisible validation set. The statistical characteristics of these models are correlation coefficient 0.90-0.94 (training set) and 0.73-0.98 (validation set). Copyright © 2014 Elsevier Inc. All rights reserved.

Trophic transfer of metal-based nanoparticles in aquatic environments

DEFF Research Database (Denmark)

Tangaa, Stine Rosendal; Selck, Henriette; Winther-Nielsen, Margrethe

2016-01-01

Metal-containing engineered nanoparticles (Me-ENPs) are used in a wide range of products including inks, plastics, personal care products, clothing and electronic devices. The release of Me-ENPs has been demonstrated from some products, and thus, particles are likely to enter the aquatic environm......Metal-containing engineered nanoparticles (Me-ENPs) are used in a wide range of products including inks, plastics, personal care products, clothing and electronic devices. The release of Me-ENPs has been demonstrated from some products, and thus, particles are likely to enter the aquatic...... environment where they have been shown to be taken up by a variety of species. Therefore, there is a possibility that Me-ENPs will enter and pass through aquatic food webs, but research on this topic is limited. In this tutorial review, we discuss the factors contributing to trophic transfer of Me......-ENPs, and where this information is scarce, we utilize the existing literature on aqueous metal trophic transfer as a potential starting point for greater mechanistic insight and for setting directions for future studies. We identify four key factors affecting trophic transfer of Me-ENPs: (1) environmental...

Assessment of the Phytotoxicity of Metal Oxide Nanoparticles on Two Crop Plants, Maize (Zea mays L.) and Rice (Oryza sativa L.).

Science.gov (United States)

Yang, Zhongzhou; Chen, Jing; Dou, Runzhi; Gao, Xiang; Mao, Chuanbin; Wang, Li

2015-11-30

In this study, the phytotoxicity of seven metal oxide nanoparticles(NPs)-titanium dioxide (nTiO₂), silicon dioxide (nSiO₂), cerium dioxide (nCeO₂), magnetite (nFe₃O₄), aluminum oxide (nAl₂O₃), zinc oxide (nZnO) and copper oxide (nCuO)-was assessed on two agriculturally significant crop plants (maize and rice). The results showed that seed germination was not affected by any of the seven metal oxide NPs. However, at the concentration of 2000 mg·L(-1), the root elongation was significantly inhibited by nCuO (95.73% for maize and 97.28% for rice), nZnO (50.45% for maize and 66.75% for rice). On the contrary, minor phytotoxicity of nAl₂O₃ was only observed in maize, and no obvious toxic effects were found in the other four metal oxide NPs. By further study we found that the phytotoxic effects of nZnO, nAl₂O₃ and nCuO (25 to 2000 mg·L(-)¹) were concentration dependent, and were not caused by the corresponding Cu(2+), Zn(2+) and Al(3+) ions (0.11 mg·L(-)¹, 1.27 mg·L(-)¹ and 0.74 mg·L(-)¹, respectively). Furthermore, ZnO NPs (<50 nm) showed greater toxicity than ZnO microparticles(MPs)(<5 μm) to root elongation of both maize and rice. Overall, this study provided valuable information for the application of engineered NPs in agriculture and the assessment of the potential environmental risks.

Molecular and physiological responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis

Science.gov (United States)

- Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that e...

Spinel-based coatings for metal supported solid oxide fuel cells

DEFF Research Database (Denmark)

Stefan, Elena; Neagu, Dragos; Blennow Tullmar, Peter

2017-01-01

Metal supports and metal supported half cells developed at DTU are used for the study of a solution infiltration approach to form protective coatings on porous metal scaffolds. The metal particles in the anode layer, and sometimes even in the support may undergo oxidation in realistic operating...... conditions leading to severe cell degradation. Here, a controlled oxidation of the porous metal substrate and infiltration of Mn and/or Ce nitrate solutions are applied for in situ formation of protective coatings. Our approach consists of scavenging the FeCr oxides formed during the controlled oxidation...... into a continuous and well adhered coating. The effectiveness of coatings is the result of composition and structure, but also of the microstructure and surface characteristics of the metal scaffolds....

In vitro assessment of the antimicrobial activity of silver and zinc oxide nanoparticles against fish pathogens.

Science.gov (United States)

Shaalan, Mohamed Ibrahim; El-Mahdy, Magdy Mohamed; Theiner, Sarah; El-Matbouli, Mansour; Saleh, Mona

2017-07-21

Antibiotic resistance is a global issue that threatens public health. The excessive use of antibiotics contributes to this problem as the genes of antibiotic resistance can be transferred between the bacteria in humans, animals and aquatic organisms. Metallic nanoparticles could serve as future substitutes for some conventional antibiotics because of their antimicrobial activity. The aim of this study was to evaluate the antimicrobial effects of silver and zinc oxide nanoparticles against major fish pathogens and assess their safety in vitro. Silver nanoparticles were synthesized by chemical reduction and characterized with UV-Vis spectroscopy, transmission electron microscopy and zeta sizer. The concentrations of silver and zinc oxide nanoparticles were measured using inductively coupled plasma-mass spectrometry. Subsequently, silver and zinc oxide nanoparticles were tested for their antimicrobial activity against Aeromonas hydrophila, Aeromonas salmonicida subsp. salmonicida, Edwardsiella ictaluri, Edwardsiella tarda, Francisella noatunensis subsp. orientalis, Yersinia ruckeri and Aphanomyces invadans and the minimum inhibitory concentrations were determined. MTT assay was performed on eel kidney cell line (EK-1) to determine the cell viability after incubation with nanoparticles. The interaction between silver nanoparticles and A. salmonicida was investigated by transmission electron microscopy. The tested nanoparticles exhibited marked antimicrobial activity. Silver nanoparticles inhibited the growth of both A. salmonicida and A. invadans at a concentration of 17 µg/mL. Zinc oxide nanoparticles inhibited the growth of A. salmonicida, Y. ruckeri and A. invadans at concentrations of 15.75, 31.5 and 3.15 µg/mL respectively. Silver nanoparticles showed higher cell viability when compared to zinc oxide nanoparticles in the MTT assay. Transmission electron microscopy showed the attachment of silver nanoparticles to the bacterial membrane and disruption of its

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

Science.gov (United States)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-01

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

Science.gov (United States)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-18

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Biocompatible nanocarriers that respond to oxidative environments via interactions between chitosan and multiple metal ions

Directory of Open Access Journals (Sweden)

Zhang S

2016-06-01

Full Text Available Shichang Zhang, Liye Xia, Chenchen Ding, Lu Wen, Weihua Wan, Gang Chen Department of Pharmaceutics, Guangdong Pharmaceutical University, Guangzhou, People’s Republic of China Abstract: Hydrogen peroxide (H2O2 functions as an early damage signal contributing to the oxidative stress response and can act as a trigger in smart oxidation-responsive drug delivery systems that are currently in development. Current H2O2-triggered oxidation-responsive polymeric systems are usually derived from chemical synthesis and rarely include natural polymers. Herein, we report two series of nanoparticle (NP complexes prepared with the biopolymer chitosan (CS and four different metal ions (Cu2+, Ca2+, Zn2+, and Fe3+, defined as CSNPs-metal complexes (Series 1 and CS-metal complexes NPs (Series 2, which responded to oxidation by dissolving upon H2O2 exposure. Experiments examining Nile red release and H2O2-triggered degradation confirmed that both series of complexes showed better sensitivity to oxidation than the CSNPs alone. Furthermore, preliminary cytotoxicity and histological observations indicated that the two series exhibited little or no cytotoxicity and generated a mild inflammatory response. Our work provides a novel and promising strategy for developing NPs for use as intelligent oxidation-responsive systems. Keywords: oxidation-responsive system, chitosan, nanoparticles, hydrogen peroxide, metal complexes

Redox switching and oxygen evolution at oxidized metal and metal oxide electrodes: iron in base.

Science.gov (United States)

Lyons, Michael E G; Doyle, Richard L; Brandon, Michael P

2011-12-28

Outstanding issues regarding the film formation, redox switching characteristics and the oxygen evolution reaction (OER) electrocatalytic behaviour of multicycled iron oxyhydroxide films in aqueous alkaline solution have been revisited. The oxide is grown using a repetitive potential multicycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasised. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mV dec(-1) and ca. 120 mV dec(-1) are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity changes from ca. 3/2 to ca. 1 as the potential is increased. These observations are rationalised in terms of a kinetic scheme involving Temkin adsorption and the rate determining formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the potential dependence of the surface coverage of adsorbed intermediates.

Metal oxide nanorod arrays on monolithic substrates

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

2018-01-02

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

Unified computational model of transport in metal-insulating oxide-metal systems

Science.gov (United States)

Tierney, B. D.; Hjalmarson, H. P.; Jacobs-Gedrim, R. B.; Agarwal, Sapan; James, C. D.; Marinella, M. J.

2018-04-01

A unified physics-based model of electron transport in metal-insulator-metal (MIM) systems is presented. In this model, transport through metal-oxide interfaces occurs by electron tunneling between the metal electrodes and oxide defect states. Transport in the oxide bulk is dominated by hopping, modeled as a series of tunneling events that alter the electron occupancy of defect states. Electron transport in the oxide conduction band is treated by the drift-diffusion formalism and defect chemistry reactions link all the various transport mechanisms. It is shown that the current-limiting effect of the interface band offsets is a function of the defect vacancy concentration. These results provide insight into the underlying physical mechanisms of leakage currents in oxide-based capacitors and steady-state electron transport in resistive random access memory (ReRAM) MIM devices. Finally, an explanation of ReRAM bipolar switching behavior based on these results is proposed.

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

International Nuclear Information System (INIS)

Xi Dong; Luo Xiaoping; Lu Qianghua; Yao Kailun; Liu Zuli; Ning Qin

2008-01-01

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method

Vacancy-Mediated Magnetism in Pure Copper Oxide Nanoparticles

Science.gov (United States)

2010-01-01

Room temperature ferromagnetism (RTF) is observed in pure copper oxide (CuO) nanoparticles which were prepared by precipitation method with the post-annealing in air without any ferromagnetic dopant. X-ray photoelectron spectroscopy (XPS) result indicates that the mixture valence states of Cu1+ and Cu2+ ions exist at the surface of the particles. Vacuum annealing enhances the ferromagnetism (FM) of CuO nanoparticles, while oxygen atmosphere annealing reduces it. The origin of FM is suggested to the oxygen vacancies at the surface/or interface of the particles. Such a ferromagnet without the presence of any transition metal could be a very good option for a class of spintronics. PMID:20671775

Metallic Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

A. Hernando

2005-01-01

Full Text Available In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm, covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

Thin-film transistors with a channel composed of semiconducting metal oxide nanoparticles deposited from the gas phase

International Nuclear Information System (INIS)

Busch, C.; Schierning, G.; Theissmann, R.; Nedic, A.; Kruis, F. E.; Schmechel, R.

2012-01-01

The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25 nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO x , and indium oxide, In 2 O 3 . The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10 −6 cm 2V−1s−1 , the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected.

Oxidation and sensing of ascorbic acid and dopamine on self-assembled gold nanoparticles incorporated within polyaniline film

Science.gov (United States)

Chu, Wenya; Zhou, Qun; Li, Shuangshuang; Zhao, Wei; Li, Na; Zheng, Junwei

2015-10-01

Electrochemical biosensors based on conducting polymers incorporated with metallic nanoparticles can greatly enhance sensitivity and selectivity. Herein, we report a facile fabrication approach for polyaniline (PAN) incorporated with a gold nanoparticle (AuNP) composite electrode by electrodeposition of PAN on a self-assembled AuNP layer on the surface of an indium tin oxide electrode. The resulting AuNP/PAN composite electrode exhibits a remarkable synergistic effect on the electrocatalytic oxidation of ascorbic acid (AA) and dopamine (DA). It is demonstrated that the oxidation reaction of AA mainly occurs at AuNPs inside the PAN film as the ascorbate anions are doped into the polymer during the oxidation of the PAN film. Conversely, the oxidation of positively charged DA may only take place at the PAN/solution interface. The different mechanisms of the electrode reactions result in the oxidation of AA and DA occurring at different potentials. As a result, the AuNP/PAN composite electrode can be employed to simultaneously detect AA and DA with a good linear range, high sensitivity, and low detection limit.

Mesoporous Transition Metal Oxides for Supercapacitors.

Science.gov (United States)

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-10-14

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Synthesis, Characterization and Catalytic Performance in the Selective Oxidation of Alcohols by Metallophthalocyanines Supported on Zinc Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Amin Ebadi

2017-01-01

Full Text Available Unsubstituted phthalocyanines of Co, Fe and Mn supported on zinc oxide nanoparticles were prepared and were well characterized with X-ray diffraction and scanning electron microscopy. The oxidation of alcohols with tert-butylhydroperoxide, in the presence of metallophthalocyanines supported on zinc oxide nanoparticles was investigated. These MPc/ZnO nanocomposites were effective catalysts for the oxidation of alcohols such as cyclohexanol (83.4% conversion; 100% selectivity, benzyl alcohol (70.5% conversion; 100% selectivity and hexanol (62.3% conversion; 100% selectivity. The influences of reaction time, various metals and type of substrates and oxidants on the oxidation of alcohols were also studied, and optimized conditions were investigated. Under these reaction conditions, the activity of the catalysts decreases in the following order:  CoPc/nano-ZnO > FePc/nano-ZnO > MnPc/nano-ZnO. It shows that TBHP is more efficient oxidant due to weaker O-O bond with respect to H2O2 and the following order has been observed for the percentage of conversions of alcohols: 2º > benzylic > 1º.

Biomedical applications of green synthesized Nobel metal nanoparticles.

Science.gov (United States)

Khan, Zia Ul Haq; Khan, Amjad; Chen, Yongmei; Shah, Noor S; Muhammad, Nawshad; Khan, Arif Ullah; Tahir, Kamran; Khan, Faheem Ullah; Murtaza, Behzad; Hassan, Sadaf Ul; Qaisrani, Saeed Ahmad; Wan, Pingyu

2017-08-01

Synthesis of Nobel metal nanoparticles, play a key role in the field of medicine. Plants contain a substantial number of organic constituents, like phenolic compounds and various types of glycosides that help in synthesis of metal nanoparticles. Synthesis of metal nanoparticles by green method is one of the best and environment friendly methods. The major significance of the green synthesis is lack of toxic by-products produced during metal nanoparticle synthesis. The nanoparticles, synthesized by green method show various significant biological activities. Most of the research articles report the synthesized nanoparticles to be active against gram positive and gram negative bacteria. Some of these bacteria include Escherichia coli, Bacillus subtilis, Klebsiella pneumonia and Pseudomonas fluorescens. The synthesized nanoparticles also show significant antifungal activity against Trichophyton simii, Trichophyton mentagrophytes and Trichophyton rubrum as well as different types of cancer cells such as breast cancer cell line. They also exhibit significant antioxidant activity. The activities of these Nobel metal nano-particles mainly depend on the size and shape. The particles of small size with large surface area show good activity in the field of medicine. The synthesized nanoparticles are also active against leishmanial diseases. This research article explores in detail the green synthesis of the nanoparticles and their uses thereof. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents

Czech Academy of Sciences Publication Activity Database

Štengl, Václav; Henych, Jiří; Janos, P.; Skoumal, M.

2016-01-01

Roč. 236, č. 2016 (2016), s. 239-258 ISSN 0179-5953 R&D Projects: GA ČR(CZ) GAP106/12/1116 Institutional support: RVO:61388980 Keywords : chemical warfare agent * metal nanoparticle * unique surface- chemistry * mesoporous manganese oxide Subject RIV: CA - Inorganic Chemistry Impact factor: 3.930, year: 2016

Chemical Sensors Based on Metal Oxide Nanostructures

Science.gov (United States)

Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

2006-01-01

This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

Laser assisted embedding of nanoparticles into metallic materials

International Nuclear Information System (INIS)

Lin Dong; Suslov, Sergey; Ye Chang; Liao Yiliang; Liu, C. Richard; Cheng, Gary J.

2012-01-01

This paper reports a methodology of half-embedding nanoparticles into metallic materials. Transparent and opaque nanoparticles are chosen to demonstrate the process of laser assisted nanoparticle embedding. Dip coating method is used to coat transparent or opaque nanoparticle on the surface of metallic material. Nanoparticles are embedded into substrate by laser irradiation. In this study, the mechanism and process of nanoparticle embedding are investigated. It is found both transparent and opaque nanoparticles embedding are with high densities and good uniformities.

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

Science.gov (United States)

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

2018-08-01

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

Tuning the reactivity of Ru nanoparticles by defect engineering of the reduced graphene oxide support

KAUST Repository

Liu, Xin

2014-01-01

We systematically investigated the electronic structure of Ru nanoparticles supported on various local structures on reduced graphene oxide (rGO) by first-principles-based calculations. We showed that Ru nanoparticles prefer to nucleate at these localized defect structures on rGO, which act as strong trapping sites for Ru nanoparticles and inhibit their aggregation. The binding of Ru nanoparticles to rGO, which is dependent on these local defect structures and correlates with the interfacial charge transfer, determines the electronic structure of the composites. Further study reveals that the performance of these composites against oxygen adsorption changes proportionally with the shift of the d-band center of the nanoparticles. The correlation between the defect structures on rGO and the reactivity of the composites suggests that controlled modification of the graphenic support by defect engineering would be an efficient way to fabricate new transition metal/rGO composites with high stability and desired reactivity. This journal is © the Partner Organisations 2014.

Controlled synthesis of size-tunable nickel and nickel oxide nanoparticles using water-in-oil microemulsions

International Nuclear Information System (INIS)

Kumar, Ajeet; Saxena, Amit; Shankar, Ravi; Mozumdar, Subho; De, Arnab

2013-01-01

Industrial demands have generated a growing need to synthesize pure metal and metal–oxide nanoparticles of a desired size. We report a novel and convenient method for the synthesis of spherical, size tunable, well dispersed, stable nickel and nickel oxide nanoparticles by reduction of nickel nitrate at room temperature in a TX-100/n-hexanol/cyclohexane/water system by a reverse microemulsion route. We determined that reduction with alkaline sodium borohydrate in nitrogen atmosphere leads to the formation of nickel nanoparticles, while the use of hydrazine hydrate in aerobic conditions leads to the formation of nickel oxide nanoparticles. The influence of several reaction parameters on the size of nickel and nickel oxide nanoparticles were evaluated in detail. It was found that the size can be easily controlled either by changing the molar ratio of water to surfactant or by simply altering the concentration of the reducing agent. The morphology and structure of the nanoparticles were characterized by quasi-elastic light scattering (QELS), transmission electron microscopy (TEM), x-ray diffraction (XRD), electron diffraction analysis (EDA) and energy dispersive x-ray (EDX) spectroscopy. The results show that synthesized nanoparticles are of high purity and have an average size distribution of 5–100 nm. The nanoparticles prepared by our simple methodology have been successfully used for catalyzing various chemical reactions. (paper)

Colloidal stability of superparamagnetic iron oxide nanoparticles in the central nervous system: a review.

Science.gov (United States)

Champagne, Pierre-Olivier; Westwick, Harrison; Bouthillier, Alain; Sawan, Mohamad

2018-06-01

Superparamagnetic iron oxide nanoparticles (SPIONs) consist of nanosized metallic-based particles with unique magnetic properties. Their potential in both diagnostic and therapeutic applications in the CNS is at the source of an expanding body of the literature in recent years. Colloidal stability of nanoparticles represents their ability to resist aggregation and is a central aspect for the use of SPION in biological environment such as the CNS. This review gives a comprehensive update of the recent developments and knowledge on the determinants of colloidal stability of SPIONs in the CNS. Factors leading to aggregate formation and the repercussions of colloidal instability of SPION are reviewed in detail pertaining to their use in the CNS.

A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

KAUST Repository

Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A

2015-01-01

Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

KAUST Repository

Choudhury, Snehashis

2015-12-04

Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

Ultra-low Pt decorated PdFe Alloy Nanoparticles for Formic Acid Electro-oxidation

International Nuclear Information System (INIS)

Zhou, Yawei; Du, Chunyu; Han, Guokang; Gao, Yunzhi; Yin, Geping

2016-01-01

Highlights: • A cost-efficient way is used to prepare transition-noble metal alloy nanoparticles. • The Pd 50 Fe 50 /C catalyst shows excellent activity for formic acid oxidation (FAO). • Much activity enhancement of FAO is acquired by ultra-low Pt decorated Pd 50 Fe 50 . • A synergistic mechanism between Pt clusters and PdFe is proposed during the FAO. - Abstract: Palladium (Pd), has demonstrated promising electro-catalytic activity for formic acid oxidation, but suffers from extremely low abundance. Recently alloying with a transition metal has been considered as an effective approach to reducing the loading of Pd and enhancing the activity of Pd-based catalysts simultaneously. Herein, carbon supported PdFe nanoparticles (NPs) are synthesized at room temperature by using sodium borohydride as reducing agent and potassium ferrocyanide as Fe precursor. The Pd 50 Fe 50 alloy sample annealed at 900 °C for 1 h shows the best catalytic activity among Pd x Fe 1-x (x = 0.2, 0.4, 0.5, 0.6, and 0.8) towards formic acid oxidation. To further improve both catalytic activity and stability, the ultra-low Pt (0.09 wt %) decorated Pd 50 Fe 50 NPs (PtPd/PdFe) are prepared via the galvanic replacement reaction. Compared with Pd 50 Fe 50 /C, the PtPd/PdFe/C Exhibits 1.52 times higher catalytic activity and lower onset potential (−0.12 V). The significant enhancements of formic acid oxidation can be attributed to the accelerated dehydrogenation reaction of formic acid by Pt atomic clusters. Moreover, the PtPd/PdFe/C also demonstrates better tolerance to poisons during formic acid oxidation.

Disruptive chemical doping in a ferritin-based iron oxide nanoparticle to decrease r2 and enhance detection with T1-weighted MRI.

Science.gov (United States)

Clavijo Jordan, M Veronica; Beeman, Scott C; Baldelomar, Edwin J; Bennett, Kevin M

2014-01-01

Inorganic doping was used to create flexible, paramagnetic nanoparticle contrast agents for in vivo molecular magnetic resonance imaging (MRI) with low transverse relaxivity (r2). Most nanoparticle contrast agents formed from superparamagnetic metal oxides are developed with high r2. While sensitive, they can have limited in vivo detection due to a number of constraints with T2 or T2*-weighted imaging. T1-weighted imaging is often preferred for molecular MRI, but most T1-shortening agents are small chelates with low metal payload or are nanoparticles that also shorten T2 and limit the range of concentrations detectable with T1-weighting. Here we used tungsten and iron deposition to form doped iron oxide crystals inside the apoferritin cavity to form a WFe nanoparticle with a disordered crystal and un-coupled atomic magnetic moments. The atomic magnetic moments were thus localized, resulting in a principally paramagnetic nanoparticle. The WFe nanoparticles had no coercivity or saturation magnetization at 5 K and sweeping up to ± 20,000 Oe, while native ferritin had a coercivity of 3000 Oe and saturation at ± 20,000 Oe. This tungsten-iron crystal paramagnetism resulted in an increased WFe particle longitudinal relaxivity (r1) of 4870 mm(-1) s(-1) and a reduced transverse relaxivity (r2) of 9076 mm(-1) s(-1) compared with native ferritin. The accumulation of the particles was detected with T1-weighted MRI in concentrations from 20 to 400 nm in vivo, both injected in the rat brain and targeted to the rat kidney glomerulus. The WFe apoferritin nanoparticles were not cytotoxic up to 700 nm particle concentrations, making them potentially important for targeted molecular MRI. Copyright © 2014 John Wiley & Sons, Ltd.

Electrocatalysis of chemically synthesized noble metal nanoparticles on carbon electrodes

DEFF Research Database (Denmark)

Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

Noble metal nanoparticles (NPs), such as platinum (Pt) and palladium (Pd) NPs are promising catalysts for dioxygen reduction and oxidation of molecules such as formic acid and ethanol in fuel cells. Carbon nanomaterials are ideal supporting materials for electrochemical catalysts due to their good...... by electrochemical SPM. This study offers promise for development of new high-efficiency catalyst types with low-cost for fuel cell technology...

Cerium and yttrium oxide nanoparticles are neuroprotective

International Nuclear Information System (INIS)

Schubert, David; Dargusch, Richard; Raitano, Joan; Chan, S.-W.

2006-01-01

The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems

Near-field effects and energy transfer in hybrid metal-oxide nanostructures.

Science.gov (United States)

Herr, Ulrich; Kuerbanjiang, Balati; Benel, Cahit; Papageorgiou, Giorgos; Goncalves, Manuel; Boneberg, Johannes; Leiderer, Paul; Ziemann, Paul; Marek, Peter; Hahn, Horst

2013-01-01

One of the big challenges of the 21st century is the utilization of nanotechnology for energy technology. Nanoscale structures may provide novel functionality, which has been demonstrated most convincingly by successful applications such as dye-sensitized solar cells introduced by M. Grätzel. Applications in energy technology are based on the transfer and conversion of energy. Following the example of photosynthesis, this requires a combination of light harvesting, transfer of energy to a reaction center, and conversion to other forms of energy by charge separation and transfer. This may be achieved by utilizing hybrid nanostructures, which combine metallic and nonmetallic components. Metallic nanostructures can interact strongly with light. Plasmonic excitations of such structures can cause local enhancement of the electrical field, which has been utilized in spectroscopy for many years. On the other hand, the excited states in metallic structures decay over very short lifetimes. Longer lifetimes of excited states occur in nonmetallic nanostructures, which makes them attractive for further energy transfer before recombination or relaxation sets in. Therefore, the combination of metallic nanostructures with nonmetallic materials is of great interest. We report investigations of hybrid nanostructured model systems that consist of a combination of metallic nanoantennas (fabricated by nanosphere lithography, NSL) and oxide nanoparticles. The oxide particles were doped with rare-earth (RE) ions, which show a large shift between absorption and emission wavelengths, allowing us to investigate the energy-transfer processes in detail. The main focus is on TiO2 nanoparticles doped with Eu(3+), since the material is interesting for applications such as the generation of hydrogen by photocatalytic splitting of water molecules. We use high-resolution techniques such as confocal fluorescence microscopy for the investigation of energy-transfer processes. The experiments are

Development of metal oxide gas sensors for very low concentration (ppb) of BTEX vapors

Science.gov (United States)

Favard, A.; Aguir, K.; Contaret, T.; Caris, L.; Bendahan, M.

2017-12-01

The control and analysis of air quality have become a major preoccupation of the last twenty years. In 2008, the European Union has introduced a Directive (2008/50/EC) to impose measurement obligations and thresholds to not exceed for some pollutants, including BTEX gases, in view of their adverse effects on the health. In this paper, we show the ability to detect very low concentrations of BTEX using a gas microsensor based on metal oxide thin-film. A test bench able to generate very low vapors concentrations has been achieved and fully automated. Thin metal oxides layers have been realized by reactive magnetron sputtering. The sensitive layers are functionalized with gold nanoparticles by thermal evaporation technique. Our sensors have been tested on a wide range of concentrations of BTEX (5 - 500 ppb) and have been able to detect concentrations of a few ppb for operating temperatures below 593 K. These results are very promising for detection of very low BTEX concentration for indoor as well as outdoor application. We showed that the addition of gold nanoparticles on the sensitive layers decreases the sensors operating temperature and increases the response to BTEX gas. The best results are obtained with a sensitive layer based on ZnO.

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

Science.gov (United States)

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

2017-12-01

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

Electrochemical energy storage devices using electrodes incorporating carbon nanocoils and metal oxides nanoparticles

KAUST Repository

Baby, Rakhi Raghavan

2011-07-28

Carbon nanocoil (CNC) based electrodes are shown to be promising candidates for electrochemical energy storage applications, provided the CNCs are properly functionalized. In the present study, nanocrystalline metal oxide (RuO 2, MnO2, and SnO2) dispersed CNCs were investigated as electrodes for supercapacitor applications using different electrochemical methods. In the two electrode configuration, the samples exhibited high specific capacitance with values reaching up to 311, 212, and 134 F/g for RuO2/CNCs, MnO2/CNCs, and SnO2/CNCs, respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be superior to those reported for metal oxide dispersed multiwalled carbon nanotubes in two electrode configuration. In addition, the fabricated supercapacitors retained excellent cycle life with ∼88% of the initial specific capacitance retained after 2000 cycles. © 2011 American Chemical Society.

Iron Oxide Doped Alumina-Zirconia Nanoparticle Synthesis by Liquid Flame Spray from Metal Organic Precursors

OpenAIRE

Juha-Pekka Nikkanen; Helmi Keskinen; Mikko Aromaa; Mikael Järn; Tomi Kanerva; Erkki Levänen; Jyrki M. Mäkelä; Tapio Mäntylä

2008-01-01

The liquid flame spray (LFS) method was used to make iron oxide doped alumina-zirconia nanoparticles. Nanoparticles were generated using a turbulent, high-temperature (Tmax⁡∼3000 K) H2-O2 flame. The precursors were aluminium-isopropoxide, zirconium-n-propoxide, and ferrocene in xylene solution. The solution was atomized into micron-sized droplets by high velocity H2 flow and introduced into the flame where nanoparticles were formed. The particle morphology, size, phase, and chemical compositi...

A novel electrochemical sensor based on metal-organic framework for electro-catalytic oxidation of L-cysteine.

Science.gov (United States)

Hosseini, Hadi; Ahmar, Hamid; Dehghani, Ali; Bagheri, Akbar; Tadjarodi, Azadeh; Fakhari, Ali Reza

2013-04-15

A novel electrochemical sensor based on Au-SH-SiO₂ nanoparticles supported on metal-organic framework (Au-SH-SiO₂@Cu-MOF) has been developed for electrocatalytic oxidation and determination of L-cysteine. The Au-SH-SiO₂@Cu-MOF was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and cyclic voltammetry. The electrochemical behavior of L-cysteine at the Au-SH-SiO₂@Cu-MOF was investigated by cyclic voltammetry. The Au-SH-SiO₂@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1 M phosphate buffer solution (pH 5.0). The oxidation overpotentials of L-cysteine decreased significantly and their oxidation peak currents increased dramatically at Au-SH-SiO₂@Cu-MOF. The potential utility of the sensor was demonstrated by applying it to the analytical determination of L-cysteine concentration. The results showed that the electrocatalytic current increased linearly with the L-cysteine concentration in the range of 0.02-300 μM and the detection limit was 0.008 μM. Finally, the sensor was applied to determine L-cysteine in water and biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Controlled Deposition of Tin Oxide and Silver Nanoparticles Using Microcontact Printing

Directory of Open Access Journals (Sweden)

Joo C. Chan

2015-02-01

Full Text Available This report describes extensive studies of deposition processes involving tin oxide (SnOx nanoparticles on smooth glass surfaces. We demonstrate the use of smooth films of these nanoparticles as a platform for spatially-selective electroless deposition of silver by soft lithographic stamping. The edge and height roughness of the depositing metallic films are 100 nm and 20 nm, respectively, controlled by the intrinsic size of the nanoparticles. Mixtures of alcohols as capping agents provide further control over the size and shape of nanoparticles clusters. The distribution of cluster heights obtained by atomic force microscopy (AFM is modeled through a modified heterogeneous nucleation theory as well as Oswald ripening. The thermodynamic modeling of the wetting properties of nanoparticles aggregates provides insight into their mechanism of formation and how their properties might be further exploited in wide-ranging applications.

Transformation and bioavailability of metal oxide nanoparticles in aquatic and terrestrial environments. A review.

Science.gov (United States)

Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

2017-11-01

Metal oxide nanoparticles (MeO-NPs) are among the most consumed NPs and also have wide applications in various areas which increased their release into the environmental system. Aquatic (water and sediments) and terrestrial compartments are predicted to be the destination of the released MeO-NPs. In these compartments, the particles are subjected to various dynamic processes such as physical, chemical and biological processes, and undergo transformations which drive them away from their pristine state. These transformation pathways can have strong implications for the fate, transport, persistence, bioavailability and toxic-effects of the NPs. In this critical review, we provide the state-of-the-knowledge on the transformation processes and bioavailability of MeO-NPs in the environment, which is the topic of interest to researchers. We also recommend future research directions in the area which will support future risk assessments by enhancing our knowledge of the transformation and bioavailability of MeO-NPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Zinc oxide nanoparticles induce migration and adhesion of monocytes to endothelial cells and accelerate foam cell formation

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Yuka; Tada-Oikawa, Saeko [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan); Ichihara, Gaku [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya (Japan); Yabata, Masayuki; Izuoka, Kiyora [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan); Suzuki, Masako; Sakai, Kiyoshi [Nagoya City Public Health Research Institute, Nagoya (Japan); Ichihara, Sahoko, E-mail: saho@gene.mie-u.ac.jp [Graduate School of Regional Innovation Studies, Mie University, Tsu (Japan)

2014-07-01

Metal oxide nanoparticles are widely used in industry, cosmetics, and biomedicine. However, the effects of exposure to these nanoparticles on the cardiovascular system remain unknown. The present study investigated the effects of nanosized TiO{sub 2} and ZnO particles on the migration and adhesion of monocytes, which are essential processes in atherosclerogenesis, using an in vitro set-up of human umbilical vein endothelial cells (HUVECs) and human monocytic leukemia cells (THP-1). We also examined the effects of exposure to nanosized metal oxide particles on macrophage cholesterol uptake and foam cell formation. The 16-hour exposure to ZnO particles increased the level of monocyte chemotactic protein-1 (MCP-1) and induced the migration of THP-1 monocyte mediated by increased MCP-1. Exposure to ZnO particles also induced adhesion of THP-1 cells to HUVECs. Moreover, exposure to ZnO particles, but not TiO{sub 2} particles, upregulated the expression of membrane scavenger receptors of modified LDL and increased cholesterol uptake in THP-1 monocytes/macrophages. In the present study, we found that exposure to ZnO particles increased macrophage cholesterol uptake, which was mediated by an upregulation of membrane scavenger receptors of modified LDL. These results suggest that nanosized ZnO particles could potentially enhance atherosclerogenesis and accelerate foam cell formation. - Highlights: • Effects of metal oxide nanoparticles on foam cell formation were investigated. • Exposure to ZnO nanoparticles induced migration and adhesion of monocytes. • Exposure to ZnO nanoparticles increased macrophage cholesterol uptake. • Expression of membrane scavenger receptors of modified LDL was also increased. • These effects were not observed after exposure to TiO{sub 2} nanoparticles.

Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Hasan, E-mail: h.bagheri@bmsu.ac.ir [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Hajian, Ali [Laboratory for Sensors, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges Köhler Allee 103, 79110 Freiburg (Germany); Rezaei, Mosayeb; Shirzadmehr, Ali [Young Researchers and Elite Club, Hamedan Branch, Islamic Azad University, Hamedan (Iran, Islamic Republic of)

2017-02-15

Highlights: • An electrochemical sensor based on Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide modified glassy carbon electrode was developed. • Simultaneous electrochemical determination of nitrate and nitrite by fabricated sensor was performed. • Modification improved the sensitivity and detection limit of the method. • It is a useful method for determining of nitrate and nitrite in various real samples. - Abstract: In the present research, we aimed to fabricate a novel electrochemical sensor based on Cu metal nanoparticles on the multiwall carbon nanotubes-reduced graphene oxide nanosheets (Cu/MWCNT/RGO) for individual and simultaneous determination of nitrite and nitrate ions. The morphology of the prepared nanocomposite on the surface of glassy carbon electrode (GCE) was characterized using various methods including scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. Under optimal experimental conditions, the modified GCE showed excellent catalytic activity toward the electro-reduction of nitrite and nitrate ions (pH = 3.0) with a significant increase in cathodic peak currents in comparison with the unmodified GCE. By square wave voltammetry (SWV) the fabricated sensor demonstrated wide dynamic concentration ranges from 0.1 to 75 μM with detection limits (3S{sub b}/m) of 30 nM and 20 nM method for nitrite and nitrate ions, respectively. Furthermore, the applicability of the proposed modified electrode was demonstrated by measuring the concentration of nitrite and nitrate ions in the tap and mineral waters, sausages, salami, and cheese samples.

Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

International Nuclear Information System (INIS)