Science.gov

Sample records for individual metal nanoparticles

  1. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  2. Metallic magnetic nanoparticles.

    PubMed

    Hernando, A; Crespo, P; García, M A

    2005-12-22

    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.

  3. Introduction to metallic nanoparticles.

    PubMed

    Mody, Vicky V; Siwale, Rodney; Singh, Ajay; Mody, Hardik R

    2010-10-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe(3)O(4)), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe(3)O(4)), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  4. Introduction to metallic nanoparticles

    PubMed Central

    Mody, Vicky V.; Siwale, Rodney; Singh, Ajay; Mody, Hardik R.

    2010-01-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe3O4), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe3O4), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  5. Method for producing metallic nanoparticles

    DOEpatents

    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.

  6. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

    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.

  7. Metal Nanoparticle Aerogel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  8. Synthesis metal nanoparticle

    DOEpatents

    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..

  9. Chemiresistive sensing with chemically modified metal and alloy nanoparticles.

    PubMed

    Ibañez, Francisco J; Zamborini, Francis P

    2012-01-23

    This review describes the use of chemically modified pure and alloyed metal nanoparticles for chemiresistive sensing applications. Chemically modified metal nanoparticles consist of a pure or alloyed metallic core with some type of chemical coating. Researchers have studied the electronic properties of 1D, 2D, and 3D assemblies of chemically modified metal nanoparticles, and even single individual nanoparticles. The interaction with the analyte alters the conductivity of the sensitive material, providing a signal to measure the analyte concentration. This review focuses on chemiresistive sensing of a wide variety of gas- and liquid-phase analytes with metal nanoparticles coated with organothiols, ions, polymers, surfactants, and biomolecules. Different strategies used to incorporate chemically modified nanoparticles into chemiresistive sensing devices are reviewed, focusing on the different types of metal and alloy compositions, coatings, methods of assembly, and analytes (vapors, gases, liquids, biological materials), along with other important factors.

  10. Antimicrobial Polymers with Metal Nanoparticles

    PubMed Central

    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

  11. Optical Properties of Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vallée, F.

    The bright and changing colours obtained by dispersing metallic compounds in a glass matrix have been known empirically for centuries. Indeed, glasses have been coloured in the bulk by inclusion of metallic powders since ancient times to make jewellery and ornaments (see Chap. 25). Then in the Middle Ages, they were used for stained glass windows and later on for coloured glass artefacts, e.g., ruby red glass objects. However, the role played by nanoparticles in this colouring effect, i.e., the effects of nanoparticles on optical properties, were only first studied scientifically in the nineteenth century, by Michael Faraday [1].

  12. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    DOEpatents

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  13. Electron dynamics in metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bigot, J.-Y.; Halté, V.; Merle, J.-C.; Daunois, A.

    2000-01-01

    We studied the dynamics of electrons in copper and silver nanoparticles embedded in a transparent matrix, using the technique of pump-probe femtosecond spectroscopy. Comparative measurements are made in thin films of the same metals. In the case of the nanoparticles, the electron dynamics is strongly influenced by the surface at the boundary of the metal and the surrounding dielectric matrix. A detailed study of the pump-probe signals near the plasmon resonance of the nanoparticles reveals the importance of electron-electron scattering during several hundreds of femtoseconds. The influence of these scattering processes on the real and imaginary parts of the metal dielectric function is compared in the nanoparticles and thin films. In addition, the non-thermal component of the electrons and the heat transfer to the surrounding dielectric are measured. The results are analyzed with a model of effective medium, where the metal dielectric function is described in the random phase approximation, including the surface effects in a phenomenological way.

  14. Multiscale study of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Byeongchan

    Extremely small structures with reduced dimensionality have emerged as a scientific motif for their interesting properties. In particular, metal nanoparticles have been identified as a fundamental material in many catalytic activities; as a consequence, a better understanding of structure-function relationship of nanoparticles has become crucial. The functional analysis of nanoparticles, reactivity for example, requires an accurate method at the electronic structure level, whereas the structural analysis to find energetically stable local minima is beyond the scope of quantum mechanical methods as the computational cost becomes prohibitingly high. The challenge is that the inherent length scale and accuracy associated with any single method hardly covers the broad scale range spanned by both structural and functional analyses. In order to address this, and effectively explore the energetics and reactivity of metal nanoparticles, a hierarchical multiscale modeling is developed, where methodologies of different length scales, i.e. first principles density functional theory, atomistic calculations, and continuum modeling, are utilized in a sequential fashion. This work has focused on identifying the essential information that bridges two different methods so that a successive use of different methods is seamless. The bond characteristics of low coordination systems have been obtained with first principles calculations, and incorporated into the atomistic simulation. This also rectifies the deficiency of conventional interatomic potentials fitted to bulk properties, and improves the accuracy of atomistic calculations for nanoparticles. For the systematic shape selection of nanoparticles, we have improved the Wulff-type construction using a semi-continuum approach, in which atomistic surface energetics and crystallinity of materials are added on to the continuum framework. The developed multiscale modeling scheme is applied to the rational design of platinum

  15. Metal nanoparticle inks

    DOEpatents

    Lewis, Jennifer A.; Ahn, Bok Yeop; Duoss, Eric B.

    2011-04-12

    Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

  16. Environmentally friendly preparation of metal nanoparticles

    EPA Science Inventory

    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.

  17. Method for producing metal oxide nanoparticles

    DOEpatents

    Phillips, Jonathan; Mendoza, Daniel; Chen, Chun-Ku

    2008-04-15

    Method for producing metal oxide nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating 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 into metal vapor. The metal vapor is directed away from the hot zone and into the cooler plasma afterglow where it oxidizes, cools and condenses to form solid metal oxide nanoparticles.

  18. Metal-metal bonding using silver/copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Kobayashi, Y.; Maeda, T.; Yasuda, Y.; Morita, T.

    2016-08-01

    A method for producing nanoparticles composed of silver and copper and a metal-metal bonding technique using the silver/copper nanoparticles are proposed. The method consists of three steps. First, copper oxide nanoparticles are produced by mixing Cu(NO3)2 aqueous solution and NaOH aqueous solution. Second, copper metal nanoparticles are fabricated by reducing the copper oxide nanoparticles with hydrazine in the presence of poly(vinylpyrrolidone) (PVP). Third, silver/copper nanoparticles are synthesized by reducing Ag+ ions with hydrazine in the presence of the copper metal nanoparticles. Initial concentrations in the final silver/copper particle colloid, composed of 0.0075 M Cu2+, 0.0025 M Ag+, 1.0 g/L PVP, and 0.6 M hydrazine, produced silver/copper nanoparticles with an average size of 49 nm and a crystal size of 16.8 nm. Discs of copper metal were successfully bonded by the silver/copper nanoparticles under annealing at 400 °C and pressurizing at 1.2 MPa for 5 min in not only hydrogen gas but also nitrogen gas. The shear force required to separate the bonded discs was 22.3 MPa for the hydrogen gas annealing and 14.9 MPa for the nitrogen gas annealing (namely, 66.8 % of that for hydrogen gas annealing).

  19. Enhanced potentiometry by metallic nanoparticles.

    PubMed

    Noyhouzer, T; Valdinger, I; Mandler, D

    2013-09-01

    Measuring the oxidation-reduction potential (Eh) requires an interface that is not selective toward specific species but exchanges electrons with all redox couples in the solution. Sluggish electron transfer (ET) kinetics with the species will not reflect the "true" Eh of the solution. Here, we present a novel approach by which adsorbed metal nanoparticles (NPs) are used for enhancing ET exchange rates between redox species and electrode surface and therefore affect significantly the measurement of the open circuit potential (OCP) and cyclic voltammetry (CV). The OCP and CV of various organic and inorganic species such as l-dopa, dopac, iron(II), and iodide are measured by bare stainless steel and by stainless steel modified by either Pt or Au NPs. We study the effect of the surface coverage of the stainless steel surface by NPs on the electrochemical response. Moreover, the stainless steel electrode was modified simultaneously by Au and Pt nanoparticles. This improved concurrently the stainless steel response (CV and potentiometry) toward two different species; l-dopa, which shows fast electron transfer on Pt, and catechol, which exhibits fast electron transfer on Au. We believe that this approach could be a first step toward developing a superior electrode for measuring the "true" Eh of complex aquatic systems.

  20. Assembly of metals and nanoparticles into novel nanocomposite superstructures

    PubMed Central

    Xu, Jiaquan; Chen, Lianyi; Choi, Hongseok; Konish, Hiromi; Li, Xiaochun

    2013-01-01

    Controlled assembly of nanoscale objects into superstructures is of tremendous interests. Many approaches have been developed to fabricate organic-nanoparticle superstructures. However, effective fabrication of inorganic-nanoparticle superstructures (such as nanoparticles linked by metals) remains a difficult challenge. Here we show a novel, general method to assemble metals and nanoparticles rationally into nanocomposite superstructures. Novel metal-nanoparticle superstructures are achieved by self-assembly of liquid metals and nanoparticles in immiscible liquids driven by reduction of free energy. Superstructures with various architectures, such as metal-core/nanoparticle-shell, nanocomposite-core/nanoparticle-shell, network of metal-linked core/shell nanostructures, and network of metal-linked nanoparticles, were successfully fabricated by simply tuning the volume ratio between nanoparticles and liquid metals. Our approach provides a simple, general way for fabrication of numerous metal-nanoparticle superstructures and enables a rational design of these novel superstructures with desired architectures for exciting applications.

  1. Chemoelectronic circuits based on metal nanoparticles.

    PubMed

    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. PMID:26974958

  2. Chemoelectronic circuits based on metal nanoparticles

    NASA Astrophysics Data System (ADS)

    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.

  3. Metal nanoparticles functionalized with metal-ligand covalent bonds

    NASA Astrophysics Data System (ADS)

    Kang, Xiongwu

    Metal-organic contact has been recognized to play important roles in regulation of optical and electronic properties of nanoparticles. In this thesis, significant efforts have been devoted into synthesis of ruthenium nanoparticles with various metal-ligand interfacial linkages and investigation of their electronic and optical properties. Ruthenium nanoparticles were prepared by the self-assembly of functional group onto bare Ru colloid surface. As to Ru-alkyne nanoparticles, the formation of a Ru-vinylidene (Ru=C=CH--R) interfacial bonding linkage was confirmed by the specific reactivity of the nanoparticles with imine derivatives and olefin at the metal-ligand interface, as manifested in NMR, photoluminescence, and electrochemical measurements. Interestingly, it was found the electronic coupling coefficient (beta)for strongly depend upon such metal-ligand interfacial bonding. Next, such metal-ligand interfacial bonding was extended to ruthenium-nitrene pi bonds on ruthenium colloids, which were investigated by XPS. The nanoparticles exhibited a 1:1 atomic ratio of nitrogen to sulfur, consistent with that of sulfonyl nitrene fragments. In addition, the nanoparticle-bound nitrene moieties behaved analogously to azo derivatives, as manifested in UV-vis and fluorescence measurements. Further testimony of the formation of Ru=N interfacial linkages was highlighted in the unique reactivity of the nanoparticles with alkenes by imido transfer. Extensive conjugation between metal-ligand interfacial bond results in remarkable intraparticle charge delocalization on Ru-alkynide nanoparticles, which was manipulated by simple chemical reduction or oxidation. Charging of extra electrons into the nanoparticle cores led to an electron-rich metal core and hence red-shift of the triple bond stretching mode, lower binding energy of sp hybridized C 1s and dimmed fluorescence of nanoparticles. Instead, chemical oxidation resulted in the opposite impacts on these properties. By taking

  4. Antimicrobial activity of the metals and metal oxide nanoparticles.

    PubMed

    Dizaj, Solmaz Maleki; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad Hossein; Adibkia, Khosro

    2014-11-01

    The ever increasing resistance of pathogens towards antibiotics has caused serious health problems in the recent years. It has been shown that by combining modern technologies such as nanotechnology and material science with intrinsic antimicrobial activity of the metals, novel applications for these substances could be identified. According to the reports, metal and metal oxide nanoparticles represent a group of materials which were investigated in respect to their antimicrobial effects. In the present review, we focused on the recent research works concerning antimicrobial activity of metal and metal oxide nanoparticles together with their mechanism of action. Reviewed literature indicated that the particle size was the essential parameter which determined the antimicrobial effectiveness of the metal nanoparticles. Combination therapy with the metal nanoparticles might be one of the possible strategies to overcome the current bacterial resistance to the antibacterial agents. However, further studies should be performed to minimize the toxicity of metal and metal oxide nanoparticles to apply as proper alternatives for antibiotics and disinfectants especially in biomedical applications. PMID:25280707

  5. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    functions, such as magnetism and light absorption, to the catalytic properties. In particular, metal-semiconductor hybrid nanostructures could behave as effective visible photocatalysts for hydrogen evolution and CO oxidation reactions. Resulting from the large surface area and high local concentration of the reactants, a double-shell hollow structure showed reaction activities higher than those of filled nanoparticles. The introduction of plasmonic Au probes into the Pt-CdS double-shell hollow particles facilitated the monitoring of photocatalytic hydrogen generation that occurred on an individual particle surface by single particle measurements. Further development of catalysis research using well-defined metal hybrid nanocatalysts with various in situ spectroscopic tools provides a means of maximizing catalytic performances until they are comparable to or better than those of homogeneous catalysts, and this would have possibly useful implications for industrial applications.

  6. Spectral dependence of fluorescence near plasmon resonant metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Yeechi

    The optical properties of fluorophores are significantly modified when placed within the near field (0--100 nm) of plasmon resonant metal nanostructures, due to the competition between increased decay rates and "hotspots" of concentrated electric fields. The decay rates and effective electric field intensities are highly dependent on the relative position of dye and metal and the overlap between plasmon resonance and dye absorption and emission. Understanding these dependencies can greatly improve the performance of biosensing and nanophotonic devices. In this dissertation, the fluorescence intensity of organic dyes and CdSe quantum dots near single metal nanoparticles is studied as a function of the local surface plasmon resonance (LSPR) of the nanoparticle. Single metal nanoparticles have narrow, well-defined, intense local surface plasmon resonances that are tunable across the visible spectrum by changes in size and shape. First, we show that organic dyes can be self-assembled on single silver nanoprisms into known configurations by the hybridization of thiolated DNA oligomers. We correlate the fluorescence intensity of the dyes to the LSPR of the individual nanoprism to which they are attached. For each of three different organic dyes, we observe a strong correlation between the fluorescence intensity of the dye and the degree of spectral overlap with the plasmon resonance of the nanoparticle. On average, we observe the brightest fluorescence from dyes attached to metal nanoparticles that have a LSPR scattering peak 40--120 meV higher in energy than the emission peak of the fluorophore. Second, the plasmon-enhanced fluorescence from CdSe/CdS/CdZnS/ZnS core/shell quantum dots is studied near a variety of silver and gold nanoparticles. With single-particle scattering spectroscopy, the localized surface plasmon resonance spectra of single metal nanoparticles is correlated with the photoluminescence excitation (PLE) spectra of the nearby quantum dots. The PLE

  7. Solution synthesis of metal silicide nanoparticles.

    PubMed

    McEnaney, Joshua M; Schaak, Raymond E

    2015-02-01

    Transition-metal silicides are part of an important family of intermetallic compounds, but the high-temperature reactions that are generally required to synthesize them preclude the formation of colloidal nanoparticles. Here, we show that palladium, copper, and nickel nanoparticles react with monophenylsilane in trioctylamine and squalane at 375 °C to form colloidal Pd(2)Si, Cu(3)Si, and Ni(2)Si nanoparticles, respectively. These metal silicide nanoparticles were screened as electrocatalysts for the hydrogen evolution reaction, and Pd(2)Si and Ni(2)Si were identified as active catalysts that require overpotentials of -192 and -243 mV, respectively, to produce cathodic current densities of -10 mA cm(-2).

  8. Noble Metal Nanoparticles for Biosensing Applications

    PubMed Central

    Doria, Gonçalo; Conde, João; Veigas, Bruno; Giestas, Leticia; Almeida, Carina; Assunção, Maria; Rosa, João; Baptista, Pedro V.

    2012-01-01

    In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios) that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory. PMID:22438731

  9. Spectral variation of fluorescence lifetime near single metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-02-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine.

  10. Alloy metal nanoparticles for multicolor cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Baptista, Pedro V.; Doria, Gonçalo; Conde, João

    2011-03-01

    Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus results in a more accurate indicator of degree of cancerous activity than either locus alone. Metal nanoparticles have been thoroughly used as labels for in vitro identification and quantification of target sequences. We have synthesized nanoparticles with assorted noble metal compositions in an alloy format and functionalized them with thiol-modified ssDNA (nanoprobes). These nanoprobes were then used for the simultaneous specific identification of several mRNA targets involved in cancer development - one pot multicolor detection of cancer expression. The different metal composition in the alloy yield different "colors" that can be used as tags for identification of a given target. Following a non-cross-linking hybridization procedure previously developed in our group for gold nanoprobes, these multicolor nanoprobes were used for the molecular recognition of several different targets including differently spliced variants of relevant genes (e.g. gene products involved in chronic myeloid leukemia BCR, ABL, BCR-ABL fusion product). Based on the spectral signature of mixtures, before and after induced aggregation of metal nanoparticles, the correct identification could be made. Further application to differentially quantify expression of each locus in relation to another will be presented. The differences in nanoparticle stability and labeling efficiency for each metal combination composing the colloids, as well as detection capability for each nanoprobe will be discussed. Additional studies will be conducted towards allele specific expression studies.

  11. Synthesis of Graphite Encapsulated Metal Nanoparticles and Metal Catalyzed Nanotubes

    NASA Technical Reports Server (NTRS)

    vanderWal, R. L.; Dravid, V. P.

    1999-01-01

    This work focuses on the growth and inception of graphite encapsulated metal nanoparticles and metal catalyzed nanotubes using combustion chemistry. Deciphering the inception and growth mechanism(s) for these unique nanostructures is essential for purposeful synthesis. Detailed knowledge of these mechanism(s) may yield insights into alternative synthesis pathways or provide data on unfavorable conditions. Production of these materials is highly desirable given many promising technological applications.

  12. Characterization, sorption, and exhaustion of metal oxide nanoparticles as metal adsorbents

    NASA Astrophysics Data System (ADS)

    Engates, Karen Elizabeth

    Safe drinking water is paramount to human survival. Current treatments do not adequately remove all metals from solution, are expensive, and use many resources. Metal oxide nanoparticles are ideal sorbents for metals due to their smaller size and increased surface area in comparison to bulk media. With increasing demand for fresh drinking water and recent environmental catastrophes to show how fragile water supplies are, new approaches to water conservation incorporating new technologies like metal oxide nanoparticles should be considered as an alternative method for metal contaminant adsorbents from typical treatment methods. This research evaluated the potential of manufactured iron, anatase, and aluminum nanoparticles (Al2O3, TiO2, Fe2O3) to remove metal contaminants (Pb, Cd, Cu, Ni, Zn) in lab-controlled and natural waters in comparison to their bulk counterparts by focusing on pH, contaminant and adsorbent concentrations, particle size, and exhaustive capabilities. Microscopy techniques (SEM, BET, EDX) were used to characterize the adsorbents. Adsorption experiments were performed using 0.01, 0.1, or 0.5 g/L nanoparticles in pH 8 solution. When results were normalized by mass, nanoparticles adsorbed more than bulk particles but when surface area normalized the opposite was observed. Adsorption was pH-dependent and increased with time and solid concentration. Aluminum oxide was found to be the least acceptable adsorbent for the metals tested, while titanium dioxide anatase (TiO2) and hematite (alpha-Fe2O3) showed great ability to remove individual and multiple metals from pH 8 and natural waters. Intraparticle diffusion was likely part of the complex kinetic process for all metals using Fe2O3 but not TiO 2 nanoparticles within the first hour of adsorption. Adsorption kinetics for all metals tested were described by a modified first order rate equation used to consider the diminishing equilibrium metal concentrations with increasing metal oxides, showing faster

  13. Dynamic depolarization in plasmonic metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Apell, S. Peter; Zorić, Igor; Langhammer, Christoph

    2016-08-01

    At very low photon energies most metals have a very large and negative dielectric function. For the response of a metal nanoparticle to an external field in this limit, this means that the particular choice of metal does not matter and the localized surface plasmon energy mainly depends on the shape and size of the particle. Here, we present a theoretical framework to describe this situation and unearth the interplay between the depolarization factor of the problem at hand and the dielectric function of the particle. Available experimental results compare favorably with our theoretical framework.

  14. Odyssey in Polyphasic Catalysis by Metal Nanoparticles.

    PubMed

    Denicourt-Nowicki, Audrey; Roucoux, Alain

    2016-08-01

    Nanometer-sized metal particles constitute an unavoidable family of catalysts, combining the advantages of molecular complexes in regards to their catalytic performances and the ones of heterogeneous systems in terms of easy recycling. As part of this research, our group aims at designing well-defined metal nanoparticles based-catalysts, in non-conventional media (ionic liquids or water), for various catalytic applications (hydrogenation, dehalogenation, carbon-carbon coupling, asymmetric catalysis) in mild reaction conditions. In the drive towards a more eco-responsible chemistry, the main focuses rely on the search of highly active and selective nanocatalysts, in association with an efficient recycling mainly under pure biphasic liquid-liquid conditions. In this Personal Account, we proposed our almost fifteen-years odyssey in the world of metal nanoparticles for a sustainable catalysis.

  15. Odyssey in Polyphasic Catalysis by Metal Nanoparticles.

    PubMed

    Denicourt-Nowicki, Audrey; Roucoux, Alain

    2016-08-01

    Nanometer-sized metal particles constitute an unavoidable family of catalysts, combining the advantages of molecular complexes in regards to their catalytic performances and the ones of heterogeneous systems in terms of easy recycling. As part of this research, our group aims at designing well-defined metal nanoparticles based-catalysts, in non-conventional media (ionic liquids or water), for various catalytic applications (hydrogenation, dehalogenation, carbon-carbon coupling, asymmetric catalysis) in mild reaction conditions. In the drive towards a more eco-responsible chemistry, the main focuses rely on the search of highly active and selective nanocatalysts, in association with an efficient recycling mainly under pure biphasic liquid-liquid conditions. In this Personal Account, we proposed our almost fifteen-years odyssey in the world of metal nanoparticles for a sustainable catalysis. PMID:27427501

  16. Metal nanoparticles in DBS card materials modification

    NASA Astrophysics Data System (ADS)

    Metelkin, A.; Frolov, G.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

    2015-11-01

    In the recent years the method of collecting and storing Dried Blood Spots (DBS) on special cellulose membrane (paper) has gained wide popularity. But possible damage of biosamples caused by microorganisms in case of their incomplete drying is a disadvantage of the method. It can be overcome by treating sample-collection membranes with colloidal solutions of metal nanoparticles, having antibacterial effect. The team studied antibacterial properties of nonwoven material samples with various coatings (alcohol sols of copper, aluminium, iron, titanium, silver and vanadium nanoparticles). Colloidal solutions of nanoparticles were obtained by means of electroerosion method with further low-temperature plasma condensation. Antibacterial activity of fiberglass and cellulose membrane samples with nanoparticle coatings was studied using B. cereus and plaque bacteria cultures. It was revealed that nanostructured coatings can suppress bacterial activity; in addition they can diffuse from the membrane surface into medium which leads to widening the areas of inhibiting testing cultures’ growth. Thus, membrane materials treatment with alcohol-sols of metal nanoparticles can be seen as promising for conferring antibacterial properties to DBS carriers.

  17. Ferromagnetism exhibited by nanoparticles of noble metals.

    PubMed

    Maitra, Urmimala; Das, Barun; Kumar, Nitesh; Sundaresan, Athinarayanan; Rao, C N R

    2011-08-22

    Gold nanoparticles with average diameters in the range 2.5-15 nm, prepared at the organic/aqueous interface by using tetrakis(hydroxymethyl)phosphonium chloride (THPC) as reducing agent, exhibit ferromagnetism whereby the saturation magnetization M(S) increases with decreasing diameter and varies linearly with the fraction of surface atoms. The value of M(S) is higher when the particles are present as a film instead of as a sol. Capping with strongly interacting ligands such as alkane thiols results in a higher M(S) value, which varies with the strength of the metal-sulfur bond. Ferromagnetism is also found in Pt and Ag nanoparticles prepared as sols, and the M(S) values vary as Pt>Au>Ag. A careful study of the temperature variation of the magnetization of Au nanoparticles, along with certain other observations, suggests that small bare nanoparticles of noble metals could indeed possess ferromagnetism, albeit weak, which is accentuated in the presence of capping agents, specially alkane thiols which form strong metal-sulfur bonds.

  18. SERS of Individual Nanoparticles on a Mirror: Size Does Matter, but so Does Shape

    PubMed Central

    2016-01-01

    Coupling noble metal nanoparticles by a 1 nm gap to an underlying gold mirror confines light to extremely small volumes, useful for sensing on the nanoscale. Individually measuring 10 000 of such gold nanoparticles of increasing size dramatically shows the different scaling of their optical scattering (far-field) and surface-enhanced Raman emission (SERS, near-field). Linear red-shifts of the coupled plasmon modes are seen with increasing size, matching theory. The total SERS from the few hundred molecules under each nanoparticle dramatically increases with increasing size. This scaling shows that maximum SERS emission is always produced from the largest nanoparticles, irrespective of tuning to any plasmonic resonances. Changes of particle facet with nanoparticle size result in vastly weaker scaling of the near-field SERS, without much modifying the far-field, and allows simple approaches for optimizing practical sensing. PMID:27223478

  19. Silicon nanocrystal-noble metal hybrid nanoparticles.

    PubMed

    Sugimoto, H; Fujii, M; Imakita, K

    2016-06-01

    We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion. PMID:27121127

  20. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    NASA Technical Reports Server (NTRS)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Poudel, Bed (Inventor); Kumar, Shankar (Inventor); Wang, Wenzhong (Inventor); Dresselhaus, Mildred (Inventor)

    2009-01-01

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  1. Metal-doped semiconductor nanoparticles and methods of synthesis thereof

    DOEpatents

    Ren, Zhifeng; Chen, Gang; Poudel, Bed; Kumar, Shankar; Wang, Wenzhong; Dresselhaus, Mildred

    2009-09-08

    The present invention generally relates to binary or higher order semiconductor nanoparticles doped with a metallic element, and thermoelectric compositions incorporating such nanoparticles. In one aspect, the present invention provides a thermoelectric composition comprising a plurality of nanoparticles each of which includes an alloy matrix formed of a Group IV element and Group VI element and a metallic dopant distributed within the matrix.

  2. Biosurfactant Mediated Biosynthesis of Selected Metallic Nanoparticles

    PubMed Central

    Płaza, Grażyna A.; Chojniak, Joanna; Banat, Ibrahim M.

    2014-01-01

    Developing a reliable experimental protocol for the synthesis of nanomaterials is one of the challenging topics in current nanotechnology particularly in the context of the recent drive to promote green technologies in their synthesis. The increasing need to develop clean, nontoxic and environmentally safe production processes for nanoparticles to reduce environmental impact, minimize waste and increase energy efficiency has become essential in this field. Consequently, recent studies on the use of microorganisms in the synthesis of selected nanoparticles are gaining increased interest as they represent an exciting area of research with considerable development potential. Microorganisms are known to be capable of synthesizing inorganic molecules that are deposited either intra- or extracellularly. This review presents a brief overview of current research on the use of biosurfactants in the biosynthesis of selected metallic nanoparticles and their potential importance. PMID:25110864

  3. Noble Metal Nanoparticles Applications in Cancer

    PubMed Central

    Conde, João; Doria, Gonçalo; Baptista, Pedro

    2012-01-01

    Nanotechnology has prompted new and improved materials for biomedical applications with particular emphasis in therapy and diagnostics. Special interest has been directed at providing enhanced molecular therapeutics for cancer, where conventional approaches do not effectively differentiate between cancerous and normal cells; that is, they lack specificity. This normally causes systemic toxicity and severe and adverse side effects with concomitant loss of quality of life. Because of their small size, nanoparticles can readily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. This way, a variety of nanoparticles with the possibility of diversified modification with biomolecules have been investigated for biomedical applications including their use in highly sensitive imaging assays, thermal ablation, and radiotherapy enhancement as well as drug and gene delivery and silencing. Here, we review the available noble metal nanoparticles for cancer therapy, with particular focus on those already being translated into clinical settings. PMID:22007307

  4. Anderson localization in metallic nanoparticle arrays.

    PubMed

    Mai, Zhijie; Lin, Fang; Pang, Wei; Xu, Haitao; Tan, Suiyan; Fu, Shenhe; Li, Yongyao

    2016-06-13

    Anderson localization has been observed in various types of waves, such as matter waves, optical waves and acoustic waves. Here we reveal that the effect of Anderson localization can be also induced in metallic nonlinear nanoparticle arrays excited by a random electrically driving field. We find that the dipole-induced nonlinearity results in ballistic expansion of dipole intensity during evolution; while the randomness of the external driving field can suppress such an expansion. Increasing the strength of randomness above the threshold value, a localized pattern of dipole intensity can be generated in the metallic nanoparticle arrays. By means of statistics, the mean intensity distribution of the dipoles reveals the formation of Anderson localization. We further show that the generated Anderson localization is highly confined, with its size down to the scale of incident wavelength. The reported results might facilitate the manipulations of electromagnetic fields in the scale of wavelength. PMID:27410338

  5. Microbial-mediated method for metal oxide nanoparticle formation

    DOEpatents

    Rondinone, Adam J.; Moon, Ji Won; Love, Lonnie J.; Yeary, Lucas W.; Phelps, Tommy J.

    2015-09-08

    The invention is directed to a method for producing metal oxide nanoparticles, the method comprising: (i) subjecting a combination of reaction components to conditions conducive to microbial-mediated formation of metal oxide nanoparticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium suitable for sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible metal oxide component containing one or more reducible metal species, and one or more electron donors that provide donatable electrons to said metal-reducing microbes during consumption of the electron donor by said metal-reducing microbes; and (ii) isolating said metal oxide nanoparticles, which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide nanoparticle compositions produced by the inventive method.

  6. Screening Methods for Metal-Containing Nanoparticles in Water

    EPA Science Inventory

    Screening-level analysis of water for metal-containing nanoparticles is achieved with single particle-inductively coupled plasma mass spectrometry (SP-ICPMS). This method measures both the concentration of nanoparticles containing an analyte metal and the mass of the metal in eac...

  7. The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

    ERIC Educational Resources Information Center

    Moore, Lewis Ryan

    2006-01-01

    The purpose of this research was to determine how metal oxide used in a thermite reaction can impact the production of nanoparticles. The results showed the presence of nanoparticles (less than 1 micron in diameter) of at least one type produced by each metal oxide. The typical particles were metallic spheres, which ranged from 300 nanometers in…

  8. Radio-frequency capacitance spectroscopy of metallic nanoparticles.

    PubMed

    Frake, James C; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G; Buitelaar, Mark R

    2015-06-04

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory.

  9. Radio-frequency capacitance spectroscopy of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Frake, James C.; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G.; Buitelaar, Mark R.

    2015-06-01

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7 nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory.

  10. Silicon nanocrystal-noble metal hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Sugimoto, H.; Fujii, M.; Imakita, K.

    2016-05-01

    We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion.We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion. Electronic supplementary information (ESI) available: Additional TEM images and extinction spectra of Si-metal hybrid NPs are shown in Fig. S1

  11. “Green” Nanotechnologies: Synthesis of Metal Nanoparticles Using Plants

    PubMed Central

    Makarov, V. V.; Love, A. J.; Sinitsyna, O. V.; Makarova, S. S.; Yaminsky, I. V.; Taliansky, M. E.; Kalinina, N. O.

    2014-01-01

    While metal nanoparticles are being increasingly used in many sectors of the economy, there is growing interest in the biological and environmental safety of their production. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. The present review is devoted to the possibility of metal nanoparticle synthesis using plant extracts. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. This review provides a detailed analysis of the various factors affecting the morphology, size, and yield of metal nanoparticles. The main focus is on the role of the natural plant biomolecules involved in the bioreduction of metal salts during the nanoparticle synthesis. Examples of effective use of exogenous biomatrices (peptides, proteins, and viral particles) to obtain nanoparticles in plant extracts are discussed. PMID:24772325

  12. Metal oxide nanoparticles with low toxicity.

    PubMed

    Ng, Alan Man Ching; Guo, Mu Yao; Leung, Yu Hang; Chan, Charis M N; Wong, Stella W Y; Yung, Mana M N; Ma, Angel P Y; Djurišić, Aleksandra B; Leung, Frederick C C; Leung, Kenneth M Y; Chan, Wai Kin; Lee, Hung Kay

    2015-10-01

    A number of different nanomaterials produced and incorporated into various products are rising. However, their environmental hazards are frequently unknown. Here we consider three different metal oxide compounds (SnO2, In2O3, and Al2O3), which have not been extensively studied and are expected to have low toxicity. This study aimed to comprehensively characterize the physicochemical properties of these nanomaterials and investigate their toxicity on bacteria (Escherichia coli) under UV illumination and in the dark, as well as on a marine diatom (Skeletonema costatum) under ambient illumination/dark (16-8h) cycles. The material properties responsible for their low toxicity have been identified based on comprehensive experimental characterizations and comparison to a metal oxide exhibiting significant toxicity under illumination (anatase TiO2). The metal oxide materials investigated exhibited significant difference in surface properties and interaction with the living organisms. In order for a material to exhibit significant toxicity, it needs to be able to both form a stable suspension in the culture medium and to interact with the cell walls of the test organism. Our results indicated that the observed low toxicities of the three nanomaterials could be attributed to the limited interaction between the nanoparticles and cell walls of the test organisms. This could occur either due to the lack of significant attachment between nanoparticles and cell walls, or due to their tendency to aggregate in solution. PMID:26143160

  13. Photoactivable caps for reactive metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Patel, Ashish

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

  14. Spectral variation of fluorescence lifetime near single metal nanoparticles

    PubMed Central

    Li, Jia; Krasavin, Alexey V.; Webster, Linden; Segovia, Paulina; Zayats, Anatoly V.; Richards, David

    2016-01-01

    We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine. PMID:26876780

  15. Symmetry breaking in individual plasmonic nanoparticles

    PubMed Central

    Wang, Hui; Wu, Yanpeng; Lassiter, Britt; Nehl, Colleen L.; Hafner, Jason H.; Nordlander, Peter; Halas, Naomi J.

    2006-01-01

    The plasmon resonances of a concentric metallic nanoshell arise from the hybridization of primitive plasmon modes of the same angular momentum on its inner and outer surfaces. For a nanoshell with an offset core, the reduction in symmetry relaxes these selection rules, allowing for an admixture of dipolar components in all plasmon modes of the particle. This metallodielectric nanostructure with reduced symmetry exhibits a core offset-dependent multipeaked spectrum, seen in single-particle spectroscopic measurements, and exhibits significantly larger local-field enhancements on its external surface than the equivalent concentric spherical nanostructure. PMID:16829573

  16. Ferroplasmons: Intense Localized Surface Plasmons in Metal-Ferromagnetic Nanoparticles

    SciTech Connect

    Sachan, Ritesh; Malasi, Abhinav; Ge, Jingxuan; Yadavali, Sagar P; Gangopadhyay, Anup; Krishna, Dr. Hare; Garcia, Hernando; Duscher, Gerd J M; Kalyanaraman, Ramki

    2014-01-01

    Interaction of photons with matter at length scales far below their wavelengths has given rise to many novel phenomena, including localized surface plasmon resonance (LSPR). However, LSPR with narrow bandwidth (BW) is observed only in a select few noble metals, and ferromagnets are not among them. Here, we report the discovery of LSPR in ferromagnetic Co and CoFe alloy (8% Fe) in contact with Ag in the form of bimetallic nanoparticles prepared by pulsed laser dewetting. These plasmons in metal-erromagnetic nanostructures, or ferroplasmons (FP) for short, are in the visible spectrum with comparable intensity and BW to those of the LSPRs from the Ag regions. This finding was enabled by electron energy-loss mapping across individual nanoparticles in a monochromated scanning transmission electron microscope. The appearance of the FP is likely due to plasmonic interaction between the contacting Ag and Co nanoparticles. Since there is no previous evidence for materials that simultaneously show ferromagnetism and such intense LSPRs, this discovery may lead to the design of improved plasmonic materials and applications. It also demonstrates that materials with interesting plasmonic properties can be synthesized using bimetallic nanostructures in contact with each other.

  17. Are Some Neurons Hypersensitive to Metallic Nanoparticles?

    PubMed Central

    Scott, Bobby R.

    2010-01-01

    Engineered metallic nanomaterial particles (MENAP) represent a significant breakthrough in developing new products for use by consumers and industry. Skin application (e.g., via creams and sprays containing nanoparticles) may provide a key route of potential intake of MENAP and can lead to retrograde transport from nerve endings in the skin to the somatosensory neurons in dorsal root ganglia (DRG). This paper uses a novel theoretical model (stochastic threshold microdose [STM] model) to characterize survival of DRG neurons exposed in cell culture replicates to copper nanoparticles, based on published data. Cell death via autophagy is assumed here to occur as a result of the uptake (called hits) of the nanoparticles by mitochondria. Theoretical results are presented for the existence of a hypersensitive fraction (about 20%) of neurons that are killed in significant numbers when on average > 1 hit to the at-risk mitochondria occurs. Further, most hypersensitive neurons appear to be killed by a cumulative exposure of about 2,000 micromolar-hours and the remaining resistant cells may have dysfunctional mitochondria. Based on these theoretical findings, it is predicted that repeated exposure (e.g., over years) of the skin of humans to MENAP could lead to significant nervous system damage and related morbidity. PMID:22423227

  18. Cell Surface-based Sensing with Metallic Nanoparticles

    PubMed Central

    Jiang, Ziwen; Rotello, Vincent M.

    2015-01-01

    Metallic nanoparticles provide versatile scaffolds for biosensing applications. In this review, we focus on the use of metallic nanoparticles for cell surface sensings. Examples of the use of both specific recognition and array-based “chemical nose” approaches to cell surface sensing will be discussed. PMID:25853985

  19. Ultrafast spectroscopic studies of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Min

    An important aim of nanoparticle research is to understand how the properties of materials depend on their size and shape. In this thesis, time-resolved spectroscopy has been used to measure the physical properties of nanometer sized objects, such as the characteristic time scale for heat dissipation and their elastic moduli. In our experiments, metal nanoparticles are excited with a sub-picosecond laser pulse, which causes a rapid increase in the lattice temperature. In the first project, the rate of heat dissipation from Au nanoparticles to their surroundings was examined for different size gold nanospheres in aqueous solution. Laser induced lattice heating can also impulsively excite the phonon modes of the particle that correlate with the expansion co-ordinates. For spherical Au particles the symmetric breathing mode is excited. Experimental results for ˜50 nm diameter Au particles were compared to a model calculation where the expansion coordinate is treated as a damped harmonic oscillator. This gives information about the excitation mechanism. In the second project, the extensional and breathing modes of cylindrical gold nanorods were studied by time-resolved spectroscopy. These experiments yield values for the elastic constants for the rods. Both the extensional mode and the breathing mode results show that gold nanorods produced by wet chemical techniques have a smaller elastic moduli than bulk gold. HR-TEM and SAED studies show that the rods have a 5-fold twinned structure with growth along the [110] crystal direction. However, neither the growth direction nor the twinning provide a simple explanation for the reduced elastic moduli measured in the experiments. In a final project, polydisperse silver nanoparticle samples were investigated. A signal due to coherently excited vibrational motion was observed. The analysis shows that the observed signal arises from the triangular-shaped particles, rather than the rods or spheres that are present in the sample

  20. Strategic role of selected noble metal nanoparticles in medicine.

    PubMed

    Rai, Mahendra; Ingle, Avinash P; Birla, Sonal; Yadav, Alka; Santos, Carolina Alves Dos

    2016-09-01

    Noble metals and their compounds have been used as therapeutic agents from the ancient time in medicine for the treatment of various infections. Recently, much progress has been made in the field of nanobiotechnology towards the development of different kinds of nanomaterials with a wide range of applications. Among the metal nanoparticles, noble metal nanoparticles have demonstrated potential biomedical applications. Due to the small size, nanoparticles can easily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. Noble metal nanoparticles inspired the researchers due to their remarkable role in detection and treatment of dreadful diseases. In this review, we have attempted to focus on the biomedical applications of noble metal nanoparticles particularly, silver, gold, and platinum in diagnosis and treatment of dreaded diseases such as cancer, human immunodeficiency virus (HIV), tuberculosis (TB), and Parkinson disease. In addition, the role of silver nanoparticles (AgNPs) such as novel antimicrobials, gold nanoparticles (AuNPs) such as efficient drug carrier, uses of platinum nanoparticles (PtNPs) in bone allograft, dentistry, etc. have been critically reviewed. Moreover, the toxicity due to the use of metal nanoparticles and some unsolved challenges in the field have been discussed with their possible solutions. PMID:26089024

  1. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  2. Popping of graphite oxide: application in preparing metal nanoparticle catalysts.

    PubMed

    Gao, Yongjun; Chen, Xi; Zhang, Jiaguang; Asakura, Hiroyuki; Tanaka, Tsunehiro; Teramura, Kentaro; Ma, Ding; Yan, Ning

    2015-08-26

    A popcorn-like transformation of graphite oxide (GO) is reported and used to synthesize metal nanoparticle catalysts. The popping step is unique and essential, not only generating a high-surface-area support but also partially decomposing the metal precursors to form well-separated metal oxide nuclei, which would further evolve into highly dispersed and uniform-sized nanoparticles in the subsequent reduction. PMID:26179983

  3. Shape Evolution of Metal Nanoparticles in Water Vapor Environment.

    PubMed

    Zhu, Beien; Xu, Zhen; Wang, Chunlei; Gao, Yi

    2016-04-13

    The structures of the metal nanoparticles are crucial for their catalytic activities. How to understand and even control the shape evolution of nanoparticles under reaction condition is a big challenge in heterogeneous catalysis. It has been proved that many reactive gases hold the capability of changing the structures and properties of metal nanoparticles. One interesting question is whether water vapor, such a ubiquitous environment, could induce the shape evolution of metal nanoparticles. So far this question has not received enough attention yet. In this work, we developed a model based on the density functional theory, the Wulff construction, and the Langmuir adsorption isotherm to explore the shape of metal nanoparticle at given temperature and water vapor pressure. By this model, we show clearly that water vapor could notably increase the fraction of (110) facets and decrease that of (111) facets for 3-8 nm Cu nanoparticles, which is perfectly consistent with the experimental observations. Further investigations indicate the water vapor has different effects on the different metal species (Cu, Au, Pt, and Pd). This work not only helps to understand the water vapor effect on the structures of metal nanoparticles but also proposes a simple but effective model to predict the shape of nanoparticles in certain environment.

  4. Marine microorganisms as potential biofactories for synthesis of metallic nanoparticles.

    PubMed

    Manivasagan, Panchanathan; Nam, Seung Yun; Oh, Junghwan

    2016-11-01

    The use of marine microorganisms as potential biofactories for green synthesis of metallic nanoparticles is a relatively new field of research with considerable prospects. This method is eco-friendly, time saving, and inexpensive and can be easily scaled up for large-scale synthesis. The increasing need to develop simple, nontoxic, clean, and environmentally safe production methods for nanoparticles and to decrease environmental impact, minimize waste, and increase energy productivity has become important in this field. Marine microorganisms are tiny organisms that live in marine ecosystems and account for >98% of biomass of the world's ocean. Marine microorganisms synthesize metallic nanoparticles either intracellularly or extracellularly. Marine microbially-produced metallic nanoparticles have received considerable attention in recent years because of their expected impact on various applications such as medicine, energy, electronic, and space industries. The present review discusses marine microorganisms as potential biofactories for the green synthesis of metallic nanoparticles and their potential applications. PMID:26920850

  5. Marine microorganisms as potential biofactories for synthesis of metallic nanoparticles.

    PubMed

    Manivasagan, Panchanathan; Nam, Seung Yun; Oh, Junghwan

    2016-11-01

    The use of marine microorganisms as potential biofactories for green synthesis of metallic nanoparticles is a relatively new field of research with considerable prospects. This method is eco-friendly, time saving, and inexpensive and can be easily scaled up for large-scale synthesis. The increasing need to develop simple, nontoxic, clean, and environmentally safe production methods for nanoparticles and to decrease environmental impact, minimize waste, and increase energy productivity has become important in this field. Marine microorganisms are tiny organisms that live in marine ecosystems and account for >98% of biomass of the world's ocean. Marine microorganisms synthesize metallic nanoparticles either intracellularly or extracellularly. Marine microbially-produced metallic nanoparticles have received considerable attention in recent years because of their expected impact on various applications such as medicine, energy, electronic, and space industries. The present review discusses marine microorganisms as potential biofactories for the green synthesis of metallic nanoparticles and their potential applications.

  6. Stabilization of Electrocatalytic Metal Nanoparticles at Metal-Metal Oxide-Graphene Triple Junction Points

    SciTech Connect

    Kou, Rong; Shao, Yuyan; Mei, Donghai; Nie, Zimin; Wang, Donghai; Wang, Chong M.; Viswanathan, Vilayanur V.; Park, Seh K.; Aksay, Ilhan A.; Lin, Yuehe; Wang, Yong; Liu, Jun

    2011-03-02

    Carbon-supported metal catalysts are widely used in heterogeneous catalysis and electrocatalysis. In this paper, we report a novel method to deposit metal catalysts and metal oxide nanoparticles on two-dimensional graphene sheets to improve the catalytic performance and stability of the catalyst materials. The new synthesis method allows indium tin oxide (ITO) nanocrystals to be directly grown on functionalized graphene sheets forming the ITO-graphene hybrids. Pt nanoparticles are then deposited to form a special triple-junction structure (Pt-ITO-graphene). Both experimental study and periodic density functional theory calculations show that the supported Pt nanoparticles are stable at Pt-ITO-graphene triple junction points. The new catalyst materials were tested for oxygen reduction for potential applications in polymer electrolyte membrane fuel cells, and they exhibited greatly enhanced stability and activity. The reasons for the high stability and activity of Pt-ITO-graphene are analyzed.

  7. Interference between nanoparticles and metal homeostasis

    NASA Astrophysics Data System (ADS)

    Petit, A. N.; Aude Garcia, C.; Candéias, S.; Casanova, A.; Catty, P.; Charbonnier, P.; Chevallet, M.; Collin-Faure, V.; Cuillel, M.; Douki, T.; Herlin-Boime, N.; Lelong, C.; Luche, S.; Mintz, E.; Moulis, J. M.; Nivière, V.; Ollagnier de Choudens, S.; Rabilloud, T.; Ravanat, J. L.; Sauvaigo, S.; Carrière, M.; Michaud-Soret, I.

    2011-07-01

    The TiO2 nanoparticles (NPs) are now produced abundantly and widely used in a variety of consumer products. Due to the important increase in the production of TiO2-NPs, potential widespread exposure of humans and environment may occur during both the manufacturing process and final use. Therefore, the potential toxicity of TiO2-NPs on human health and environment has attracted particular attention. Unfortunately, the results of the large number of studies on the toxicity of TiO2-NPs differ significantly, mainly due to an incomplete characterization of the used nanomaterials in terms of size, shape and crystalline structure and to their unknown state of agglomeration/aggregation. The purpose of our project entitled NanoBioMet is to investigate if interferences between nanoparticles and metal homeostasis could be observed and to study the toxicity mechanisms of TiO2-NPs with well-characterized physicochemical parameters, using proteomic and molecular approaches. A perturbation of metal homeostasis will be evaluated upon TiO2-NPs exposure which could generate reactive oxygen species (ROS) production. Moreover, oxidative stress consequences such as DNA damage and lipid peroxidation will be studied. The toxicity of TiO2-NPs of different sizes and crystalline structures will be evaluated both in prokaryotic (E. coli) and eukaryotic cells (A549 human pneumocytes, macrophages, and hepatocytes). First results of the project will be presented concerning the dispersion of TiO2-NPs in bacterial medium, proteomic studies on total extracts of macrophages and genotoxicity on pneumocytes.

  8. Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle.

    PubMed

    Fang, Zheyu; Zhen, Yu-Rong; Neumann, Oara; Polman, Albert; García de Abajo, F Javier; Nordlander, Peter; Halas, Naomi J

    2013-04-10

    When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor-a "nanobubble"-surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications.

  9. Ancient Metal Mirror Alloy Revisited: Quasicrystalline Nanoparticles Observed

    NASA Astrophysics Data System (ADS)

    Sekhar, J. A.; Mantri, A. S.; Yamjala, S.; Saha, Sabyasachi; Balamuralikrishnan, R.; Rao, P. Rama

    2015-12-01

    This article presents, for the first time, evidence of nanocrystalline structure, through direct transmission electron microscopy (TEM) observations, in a Cu-32 wt.% Sn alloy that has been made by an age-old, uniquely crafted casting process. This alloy has been used as a metal mirror for centuries. The TEM images also reveal five-sided projections of nano-particles. The convergent beam nano-diffraction patterns obtained from the nano-particles point to the nano-phase being quasicrystalline, a feature that has never before been reported for a copper alloy, although there have been reports of the presence of icosahedral `clusters' within large unit cell intermetallic phases. This observation has been substantiated by x-ray diffraction, wherein the observed peaks could be indexed to an icosahedral quasi-crystalline phase. The mirror alloy casting has been valued for its high hardness and high reflectance properties, both of which result from its unique internal microstructure that include nano-grains as well as quasi-crystallinity. We further postulate that this microstructure is a consequence of the raw materials used and the manufacturing process, including the choice of mold material. While the alloy consists primarily of copper and tin, impurity elements such as zinc, iron, sulfur, aluminum and nickel are also present, in individual amounts not exceeding one wt.%. It is believed that these trace impurities could have influenced the microstructure and, consequently, the properties of the metal mirror alloy.

  10. Temperature and size-dependent Hamaker constants for metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, K.; Pinchuk, P.

    2016-08-01

    Theoretical values of the Hamaker constant have been calculated for metal nanoparticles using Lifshitz theory. The theory describes the Hamaker constant in terms of the permittivity of the interacting bodies. Metal nanoparticles exhibit an internal size effect that alters the dielectric permittivity of the particle when its size falls below the mean free path of the conducting electrons. This size dependence of the permittivity leads to size-dependence of the Hamaker constant for metal nanoparticles. Additionally, the electron damping and the plasma frequency used to model the permittivity of the particle exhibit temperature-dependence, which lead to temperature dependence of the Hamaker constant. In this work, both the size and temperature dependence for gold, silver, copper, and aluminum nanoparticles is demonstrated. The results of this study might be of interest for studying the colloidal stability of nanoparticles in solution.

  11. Handwritten, Soft Circuit Boards and Antennas Using Liquid Metal Nanoparticles.

    PubMed

    Lin, Yiliang; Cooper, Christopher; Wang, Meng; Adams, Jacob J; Genzer, Jan; Dickey, Michael D

    2015-12-22

    Soft conductors are created by embedding liquid metal nanoparticles between two elastomeric sheets. Initially, the particles form an electrically insulating composite. Soft circuit boards can be handwritten by a stylus, which sinters the particles into conductive traces by applying localized mechanical pressure to the elastomeric sheets. Antennas with tunable frequencies are formed by sintering nanoparticles in microchannels.

  12. Future prospects of antibacterial metal nanoparticles as enzyme inhibitor.

    PubMed

    Ahmed, Khan Behlol Ayaz; Raman, Thiagarajan; Veerappan, Anbazhagan

    2016-11-01

    Nanoparticles are being widely used as antibacterial agents with metal nanoparticles emerging as the most efficient antibacterial agents. There have been many studies which have reported the mechanism of antibacterial activity of nanoparticles on bacteria. In this review we aim to emphasize on all the possible mechanisms which are involved in the antibacterial activity of nanoparticles and also to understand their mode of action and role as bacterial enzyme inhibitor by comparing their antibacterial mechanism to that of antibiotics with enzyme inhibition as a major mechanism. With the emergence of widespread antibiotic resistance, nanoparticles offer a better alternative to our conventional arsenal of antibiotics. Once the biological safety of these nanoparticles is addressed, these nanoparticles can be of great medical importance in our fight against bacterial infections. PMID:27524096

  13. Evaluation of metal nanoparticles for drug delivery systems.

    PubMed

    Adeyemi, Oluyomi S; Sulaiman, Faoziyat A

    2015-04-01

    Diminazene aceturate is a trypanocide with unwanted toxicity and limited efficacy. It was reasoned that conjugating diminazene aceturate to functionalized nanoparticle would lower untoward toxicity while improving selectivity and therapeutic efficacy. Silver and gold nanoparticles were evaluated for their capacities to serve as carriers for diminazene aceturate. The silver and gold nanoparticles were synthesized, functionalized and coupled to diminazene aceturate following established protocols. The nanoparticle conjugates were characterized. The free diminazene aceturate and drug conjugated nanoparticles were subsequently evaluated for cytotoxicity in vitro. The characterizations by transmission electron microscopy or UV/Vis spectroscopy revealed that conjugation of diminazene aceturate to silver or gold nanoparticles was successful. Evaluation for cytotoxic actions in vitro demonstrated no significance difference between free diminazene aceturate and the conjugates. Our data suggest that surface modified metal nanoparticles could be optimized for drug delivery systems.

  14. Noble metal-based bimetallic nanoparticles: the effect of the structure on the optical, catalytic and photocatalytic properties.

    PubMed

    Zaleska-Medynska, Adriana; Marchelek, Martyna; Diak, Magdalena; Grabowska, Ewelina

    2016-03-01

    Nanoparticles composed of two different metal elements show novel electronic, optical, catalytic or photocatalytic properties from monometallic nanoparticles. Bimetallic nanoparticles could show not only the combination of the properties related to the presence of two individual metals, but also new properties due to a synergy between two metals. The structure of bimetallic nanoparticles can be oriented in random alloy, alloy with an intermetallic compound, cluster-in-cluster or core-shell structures and is strictly dependent on the relative strengths of metal-metal bond, surface energies of bulk elements, relative atomic sizes, preparation method and conditions, etc. In this review, selected properties, such as structure, optical, catalytic and photocatalytic of noble metals-based bimetallic nanoparticles, are discussed together with preparation routes. The effects of preparation method conditions as well as metal properties on the final structure of bimetallic nanoparticles (from alloy to core-shell structure) are followed. The role of bimetallic nanoparticles in heterogeneous catalysis and photocatalysis are discussed. Furthermore, structure and optical characteristics of bimetallic nanoparticles are described in relation to the some features of monometallic NPs. Such a complex approach allows to systematize knowledge and to identify the future direction of research.

  15. Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities.

    PubMed

    Jin, Rongchao; Zeng, Chenjie; Zhou, Meng; Chen, Yuxiang

    2016-09-28

    Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles. PMID:27585252

  16. Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities.

    PubMed

    Jin, Rongchao; Zeng, Chenjie; Zhou, Meng; Chen, Yuxiang

    2016-09-28

    Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles.

  17. Transport of metal oxide nanoparticles and single-walled carbon nanotubes in human mucus.

    PubMed

    Jachak, Ashish; Lai, Samuel K; Hida, Kaoru; Suk, Jung Soo; Markovic, Nina; Biswal, Shyam; Breysse, Patrick N; Hanes, Justin

    2012-09-01

    Whether mucus layers lining entrance points into the body, including the lung airways, provide protection against the penetration of engineered nanoparticles remains poorly understood. We measured the diffusion coefficients of hundreds of individual nanoparticles of three different metal oxides (nMeOs) and two types of single-walled carbon nanotubes (SWCNTs) in undiluted human mucus. We found that the vast majority of these nanoparticles are efficiently trapped in human mucus and, further, that the mechanism of trapping is adhesive interactions as opposed to steric obstruction. However, a small fraction of zinc oxide (ZnO) nanoparticles moved at rates fast enough to penetrate airway mucus layers. We conclude that human mucus layers probably provide considerable protection for mucosal tissues from the penetration of most nMeOs and SWCNTs, and suggest that further investigation of the potential health risks of exposure to ZnO nanoparticles is warranted.

  18. Stabilization of electrocatalytic metal nanoparticles at metal-metal oxide-graphene triple junction points.

    PubMed

    Kou, Rong; Shao, Yuyan; Mei, Donghai; Nie, Zimin; Wang, Donghai; Wang, Chongmin; Viswanathan, Vilayanur V; Park, Sehkyu; Aksay, Ilhan A; Lin, Yuehe; Wang, Yong; Liu, Jun

    2011-03-01

    Carbon-supported precious metal catalysts are widely used in heterogeneous catalysis and electrocatalysis, and enhancement of catalyst dispersion and stability by controlling the interfacial structure is highly desired. Here we report a new method to deposit metal oxides and metal nanoparticles on graphene and form stable metal-metal oxide-graphene triple junctions for electrocatalysis applications. We first synthesize indium tin oxide (ITO) nanocrystals directly on functionalized graphene sheets, forming an ITO-graphene hybrid. Platinum nanoparticles are then deposited, forming a unique triple-junction structure (Pt-ITO-graphene). Our experimental work and periodic density functional theory (DFT) calculations show that the supported Pt nanoparticles are more stable at the Pt-ITO-graphene triple junctions. Furthermore, DFT calculations suggest that the defects and functional groups on graphene also play an important role in stabilizing the catalysts. These new catalyst materials were tested for oxygen reduction for potential applications in polymer electrolyte membrane fuel cells, and they exhibited greatly enhanced stability and activity.

  19. Stabilization of electrocatalytic metal nanoparticles at metal-metal oxide-graphene triple junction points.

    PubMed

    Kou, Rong; Shao, Yuyan; Mei, Donghai; Nie, Zimin; Wang, Donghai; Wang, Chongmin; Viswanathan, Vilayanur V; Park, Sehkyu; Aksay, Ilhan A; Lin, Yuehe; Wang, Yong; Liu, Jun

    2011-03-01

    Carbon-supported precious metal catalysts are widely used in heterogeneous catalysis and electrocatalysis, and enhancement of catalyst dispersion and stability by controlling the interfacial structure is highly desired. Here we report a new method to deposit metal oxides and metal nanoparticles on graphene and form stable metal-metal oxide-graphene triple junctions for electrocatalysis applications. We first synthesize indium tin oxide (ITO) nanocrystals directly on functionalized graphene sheets, forming an ITO-graphene hybrid. Platinum nanoparticles are then deposited, forming a unique triple-junction structure (Pt-ITO-graphene). Our experimental work and periodic density functional theory (DFT) calculations show that the supported Pt nanoparticles are more stable at the Pt-ITO-graphene triple junctions. Furthermore, DFT calculations suggest that the defects and functional groups on graphene also play an important role in stabilizing the catalysts. These new catalyst materials were tested for oxygen reduction for potential applications in polymer electrolyte membrane fuel cells, and they exhibited greatly enhanced stability and activity. PMID:21302925

  20. Synthesis and deposition of metal nanoparticles by gas condensation process

    SciTech Connect

    Maicu, Marina Glöß, Daniel; Frach, Peter; Schmittgens, Ralph; Gerlach, Gerald; Hecker, Dominic

    2014-03-15

    In this work, the synthesis of Pt and Ag nanoparticles by means of the inert gas phase condensation of sputtered atomic vapor is presented. The process parameters (power, sputtering time, and gas flow) were varied in order to study the relationship between deposition conditions and properties of the nanoparticles such as their quantity, size, and size distribution. Moreover, the gas phase condensation process can be combined with a plasma enhanced chemical vapor deposition procedure in order to deposit nanocomposite coatings consisting of metallic nanoparticles embedded in a thin film matrix material. Selected examples of application of the generated nanoparticles and nanocomposites are discussed.

  1. Biogenic synthesis of metallic nanoparticles and prospects toward green chemistry.

    PubMed

    Adil, Syed Farooq; Assal, Mohamed E; Khan, Mujeeb; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H; Liz-Marzán, Luis M

    2015-06-01

    The immense importance of nanoparticles and their applications is a strong motivation for exploring new synthetic techniques. However, due to strict regulations that manage the potential environmental impacts greener alternatives for conventional synthesis are the focus of intense research. In the scope of this perspective, a concise discussion about the use of green reducing and stabilizing agents toward the preparation of metal nanoparticles is presented. Reports on the synthesis of noble metal nanoparticles using plant extracts, ascorbic acid and sodium citrate as green reagents are summarized and discussed, pointing toward an urgent need of understanding the mechanistic aspects of the involved reactions. PMID:25633046

  2. Biogenic synthesis of metallic nanoparticles and prospects toward green chemistry.

    PubMed

    Adil, Syed Farooq; Assal, Mohamed E; Khan, Mujeeb; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H; Liz-Marzán, Luis M

    2015-06-01

    The immense importance of nanoparticles and their applications is a strong motivation for exploring new synthetic techniques. However, due to strict regulations that manage the potential environmental impacts greener alternatives for conventional synthesis are the focus of intense research. In the scope of this perspective, a concise discussion about the use of green reducing and stabilizing agents toward the preparation of metal nanoparticles is presented. Reports on the synthesis of noble metal nanoparticles using plant extracts, ascorbic acid and sodium citrate as green reagents are summarized and discussed, pointing toward an urgent need of understanding the mechanistic aspects of the involved reactions.

  3. Formation of Metal Selenide and Metal-Selenium Nanoparticles using Distinct Reactivity between Selenium and Noble Metals.

    PubMed

    Park, Se Ho; Choi, Ji Yong; Lee, Young Hwan; Park, Joon T; Song, Hyunjoon

    2015-07-01

    Small Se nanoparticles with a diameter of ≈20 nm were generated by the reduction of selenium chloride with NaBH4 at -10 °C. The reaction with Ag at 60 °C yielded stable Ag2 Se nanoparticles, which subsequently were transformed into M-Se nanoparticles (M=Cd, Zn, Pb) through cation exchange reactions with corresponding ions. The reaction with Pt formed Pt layers that were evenly coated on the surface of the Se nanoparticles, and the dissolution of the Se cores with hydrazine generated uniform Pt hollow nanoparticles. The reaction with Au generated tiny Au clusters on the Se surface, and eventually formed acorn-shaped Au-Se nanoparticles through heat treatment. These results indicate that small Se nanoparticles with diameters of ≈20 nm can be used as a versatile platform for the synthesis of metal selenide and metal-selenium hybrid nanoparticles with complex structures.

  4. In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

    PubMed

    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

  5. In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

    PubMed

    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

  6. Fabrication of Metal Nanoparticles from Fungi and Metal Salts: Scope and Application

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-02-01

    Fungi secrete enzymes and proteins as reducing agents which can be used for the synthesis of metal nanoparticles from metal salts. Large-scale production of nanoparticles from diverse fungal strains has great potential since they can be grown even in vitro. In recent years, various approaches have been made to maximize the yield of nanoparticles of varying shape, size, and stability. They have been characterized by thermogravimetric analysis, X-ray diffractometry, SEM/TEM, zeta potential measurements, UV-vis, and Fourier transform infrared (FTIR) spectroscopy. In this review, we focus on the biogenic synthesis of metal nanoparticles by fungi to explore the chemistry of their formation extracellularly and intracellularly. Emphasis has been given to the potential of metal nanoparticles as an antimicrobial agent to inhibit the growth of pathogenic fungi, and on other potential applications.

  7. Fabrication of Metal Nanoparticles from Fungi and Metal Salts: Scope and Application.

    PubMed

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-12-01

    Fungi secrete enzymes and proteins as reducing agents which can be used for the synthesis of metal nanoparticles from metal salts. Large-scale production of nanoparticles from diverse fungal strains has great potential since they can be grown even in vitro. In recent years, various approaches have been made to maximize the yield of nanoparticles of varying shape, size, and stability. They have been characterized by thermogravimetric analysis, X-ray diffractometry, SEM/TEM, zeta potential measurements, UV-vis, and Fourier transform infrared (FTIR) spectroscopy. In this review, we focus on the biogenic synthesis of metal nanoparticles by fungi to explore the chemistry of their formation extracellularly and intracellularly. Emphasis has been given to the potential of metal nanoparticles as an antimicrobial agent to inhibit the growth of pathogenic fungi, and on other potential applications.

  8. Observing single-molecule chemical reactions on metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Emory, Steven R.; Ambrose, W. Patrick; Goodwin, Peter M.; Keller, Richard A.

    2001-06-01

    We report on the study of the photodecomposition of single Rhodamine 6G (R6G) dye molecules adsorbed on silver nanoparticles. The nanoparticles were immobilized and spatially isolated on polylysine-derivatized glass coverslips, and confocal laser microspectroscopy was used to obtain surface-enhanced Raman scatters (SERS) spectra from individual R6G molecules. The photodecomposition of these molecules was observed with 150-ms temporal resolution. The photoproduct was identified as graphitic carbon based on the appearance of bread SERS vibrational bands at 1592 cm-1 and 1340 cm-1 observed in both bulk and averaged single-molecule photoproduct spectra. In contrast, when observed at the single-molecule level, the photoproduct yielded sharp SERS spectra. The inhomogeneous broadening of the bulk SERS spectra is due to a variety of photoproducts in different surface orientations and is a characteristic of ensemble-averaged measurement of disordered systems. These single-molecule studies indicate a photodecomposition pathway by which the R6G molecule desorbs from the metal surface, an excited-state photoreaction occurs, and the R6G photoproduct(s) readsorbs to the surface. A SERS spectrum is obtained when either the intact R6G or the R6G photoproduct(s) are adsorbed on a SERS-active site. This work further illustrates the power of single-molecule spectroscopy (SMS) to reveal unique behaviors of single molecules that are not discernable with bulk measurements.

  9. Observing single molecule chemical reactions on metal nanoparticles.

    SciTech Connect

    Emory, S. R.; Ambrose, W. Patrick; Goodwin, P. M.; Keller, Richard A.

    2001-01-01

    We report the study of the photodecomposition of single Rhodamine 6G (R6G) dye molecules adsorbed on silver nanoparticles. The nanoparticles were immobilized and spatially isolated on polylysine-derivatized glass coverslips, and confocal laser microspectroscopy was used to obtain surface-enhanced Raman scattering (SERS) spectra from individual R6G molecules. The photodecomposition of these molecules was observed with 150-ms temporal resolution. The photoproduct was identified as graphitic carbon based on the appearance of broad SERS vibrational bands at 1592 cm{sup -1} and 1340 cm{sup -1} observed in both bulk and averaged single-molecule photoproduct spectra. In contrast, when observed at the single-molecule level, the photoproduct yielded sharp SERS spectra. The inhomogeneous broadening of the bulk SERS spectra is due to a variety of photoproducts in different surface orientations and is a characteristic of ensemble-averaged measurements of disordered systems. These single-molecule studies indicate a photodecomposition pathway by which the R6G molecule desorbs from the metal surface, an excited-state photoreaction occurs, and the R6G photoproduct(s) readsorbs to the surface. A SERS spectrum is obtained when either the intact R6G or the R6G photoproduct(s) are adsorbed on a SERS-active site. This work further illustrates the power of single-molecule spectroscopy (SMS) to reveal unique behaviors of single molecules that are not discernable with bulk measurements.

  10. Toxicity of heavy metals and metal-containing nanoparticles on plants.

    PubMed

    Mustafa, Ghazala; Komatsu, Setsuko

    2016-08-01

    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock. PMID:26940747

  11. Toxicity of heavy metals and metal-containing nanoparticles on plants.

    PubMed

    Mustafa, Ghazala; Komatsu, Setsuko

    2016-08-01

    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.

  12. Effects of metal oxide nanoparticles on soil properties.

    PubMed

    Ben-Moshe, Tal; Frenk, Sammy; Dror, Ishai; Minz, Dror; Berkowitz, Brian

    2013-01-01

    In recent years the behavior and properties of nanoparticles released to the environment have been studied extensively to better assess the potential consequences of their broad use in commercial products. The fate, transport and mobility of nanoparticles in soil were shown to be strongly dependent on environmental conditions. However, little is known about the possible effects of nanoparticles on soil chemical, physical and biological properties. In this study, two types of metal oxide nanoparticles, CuO and Fe(3)O(4) were mixed into two types of soil and the effects of the nanoparticles on various soil properties were assessed. Metal oxide nanoparticles were shown previously to catalyze the oxidation of organic pollutants in aqueous suspensions, and they were therefore expected to induce changes in the organic material in the soil, especially upon addition of an oxidant. It was found that the nanoparticles did not change the total amount of organic materials in the soil or the total organic carbon in the soil extract; however, three-dimensional fluorescence spectroscopy demonstrated changes in humic substances. The nanoparticles also affected the soil bacterial community composition, based on denaturing gradient gel electrophoresis (DGGE) fingerprinting, but had little impact on the macroscopic properties of the soil.

  13. Enhanced Antimicrobial Activity Of Antibiotics Mixed With Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Kumar, Neeraj; Bhanjana, Gaurav; Thakur, Rajesh; Dilbaghi, Neeraj

    2011-12-01

    Current producers of antimicrobial technology have a long lasting, environmentally safe, non-leaching, water soluble solution that will eventually replace all poisons and heavy metals. The transition metal ions inevitably exist as metal complexes in biological systems by interaction with the numerous molecules possessing groupings capable of complexation or chelation. Nanoparticles of metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. the bacterial action of antibiotics like penicillin, erythryomycin, ampicillin, streptomycin, kanamycin etc. and that of a mixture of antibiotics and metal and metal oxide nanoparticles like zinc oxide, zirconium, silver and gold on microbes was examined by the agar-well-diffusion method, enumeration of colony-forming units (CFU) and turbidimetry.

  14. Noble metal nanoparticle@metal oxide core/yolk-shell nanostructures as catalysts: recent progress and perspective

    NASA Astrophysics Data System (ADS)

    Li, Guodong; Tang, Zhiyong

    2014-03-01

    Controllable integration of noble metals (e.g., Au, Ag, Pt, and Pd) and metal oxides (e.g., TiO2, CeO2, and ZrO2) into single nanostructures has attracted immense research interest in heterogeneous catalysis, because they not only combine the properties of both noble metals and metal oxides, but also bring unique collective and synergetic functions in comparison with single-component materials. Among many strategies recently developed, one of the most efficient ways is to encapsulate and protect individual noble metal nanoparticles by a metal oxide shell of a certain thickness to generate the core-shell or yolk-shell structure, which exhibits enhanced catalytic performance compared with conventional supported catalysts. In this review article, we summarize the state-of-the art progress in synthesis and catalytic application of noble metal nanoparticle@metal oxide core/yolk-shell nanostructures. We hope that this review will help the readers to obtain better insight into the design and application of well-defined nanocomposites in both the energy and environmental fields.

  15. Incorporation of metal nanoparticles into wood substrate and methods

    DOEpatents

    Rector, Kirk D; Lucas, Marcel

    2015-11-04

    Metal nanoparticles were incorporated into wood. Ionic liquids were used to expand the wood cell wall structure for nanoparticle incorporation into the cell wall structure. Nanoparticles of elemental gold or silver were found to be effective surface enhanced Raman spectroscopy (SERS) imaging contrast or sensing agents. Nanoparticles of elemental iron were found to be efficient microwave absorbers and caused localized heating for disrupting the integrity of the lignocellulosic matrix. Controls suggest that the localized heating around the iron nanoparticles reduces losses of cellulose in the form of water, volatiles and CO.sub.2. The ionic liquid is needed during the incorporation process at room temperature. The use of small amounts of ionic liquid combined with the absence of an ionic liquid purification step and a lower energy and water use are expected to reduce costs in an up-scaled pretreatment process.

  16. Photothermal effects of plasmonic metal nanoparticles in a fluid

    NASA Astrophysics Data System (ADS)

    Norton, Stephen J.; Vo-Dinh, Tuan

    2016-02-01

    There is a strong interest in the use of plasmonic metal nanoparticles in medical applications involving photothermal therapy. In this study, the problem of calculating the temperature elevation of a fluid arising from the absorption of light by a suspension of plasmonic nanoparticles is examined. The dependence of this temperature increase on the absorption cross section of nanoparticles of different shapes, in particular, nanospheres, nanospheroids, and nanostars, is studied. The nanoparticles behave as point sources of heat production and the time-dependent heat transfer equation is solved assuming that the nanoparticles are confined to a limited region. From this solution, the steady-state temperature of the fluid medium can be calculated and the time constant to achieve this temperature determined.

  17. Manipulation of metallic nanoparticle with evanescent vortex Bessel beam.

    PubMed

    Rui, Guanghao; Wang, Xiaoyan; Cui, Yiping

    2015-10-01

    In this work, we propose a novel strategy to optically trap and manipulate metallic nanoparticles using evanescent vortex Bessel beam (EVBB). A versatile method is presented to generate evanescent Bessel beam with tunable optical angular momentum by focusing a radially polarized vortex beam onto a one-dimensional photonics band gap structure. The behavior of a metallic nanoparticle in the EVBB is numerically studied. We show that such particle can be stably trapped near the surface. The orbital angular momentum drives the metallic nanoparticle to orbit around the beam axis, and the direction of the orbital motion is controlled by the handedness of the helical phase front. The technique demonstrated in this work may open up new avenues for optical manipulation, and the non-contact tunable orbiting dynamics of the trapped particle may find important applications in higher resolution imaging techniques. PMID:26480086

  18. Optical bistability in a nonlinear-shell-coated metallic nanoparticle

    PubMed Central

    Chen, Hongli; Zhang, Youming; Zhang, Baile; Gao, Lei

    2016-01-01

    We provide a self-consistent mean field approximation in the framework of Mie scattering theory to study the optical bistability of a metallic nanoparticle coated with a nonlinear shell. We demonstrate that the nanoparticle coated with a weakly nonlinear shell exhibits optical bistability in a broad range of incident optical intensity. This optical bistability critically relies on the geometry of the shell-coated nanoparticle, especially the fractional volume of the metallic core. The incident wavelength can also affect the optical bistability. Through an optimization-like process, we find a design with broader bistable region and lower threshold field by adjusting the size of the nonlinear shell, the fractional volume of the metallic core, and the incident wavelength. These results may find potential applications in optical bistable devices such as all-optical switches, optical transistors and optical memories. PMID:26907967

  19. Manipulation of metallic nanoparticle with evanescent vortex Bessel beam.

    PubMed

    Rui, Guanghao; Wang, Xiaoyan; Cui, Yiping

    2015-10-01

    In this work, we propose a novel strategy to optically trap and manipulate metallic nanoparticles using evanescent vortex Bessel beam (EVBB). A versatile method is presented to generate evanescent Bessel beam with tunable optical angular momentum by focusing a radially polarized vortex beam onto a one-dimensional photonics band gap structure. The behavior of a metallic nanoparticle in the EVBB is numerically studied. We show that such particle can be stably trapped near the surface. The orbital angular momentum drives the metallic nanoparticle to orbit around the beam axis, and the direction of the orbital motion is controlled by the handedness of the helical phase front. The technique demonstrated in this work may open up new avenues for optical manipulation, and the non-contact tunable orbiting dynamics of the trapped particle may find important applications in higher resolution imaging techniques.

  20. Metal nanoparticles as a conductive catalyst

    SciTech Connect

    Coker, Eric N.

    2010-08-03

    A metal nanocluster composite material for use as a conductive catalyst. The metal nanocluster composite material has metal nanoclusters on a carbon substrate formed within a porous zeolitic material, forming stable metal nanoclusters with a size distribution between 0.6-10 nm and, more particularly, nanoclusters with a size distribution in a range as low as 0.6-0.9 nm.

  1. Metal enhanced fluorescence with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Mattingly, Shaina LaRissa Strating

    A novel hybrid nanocomposite of Au nanoparticle-modified silicon nanowire was developed for surface enhanced fluorescence applications. The designed nanocomposite contained a silicon nanowire, gold nanoparticles and a silica layer doped with dye molecules. The hybrid nanomaterial was characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), fluorescence measurements, Fourier transform infrared (FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results showed that the gold nanoparticles were uniformly adhered on the silicon nanowires and covered by a thin silica layer. The nanostructure exhibited strong capacity for surface enhanced fluorescence. Different enhancement factors were obtained by changing synthetic conditions. The second goal of the project was to determine if the shape of gold nanoparticles affects the extent of its fluorescence enhancement under constant external factors. Two shapes of gold nanoparticles were synthesized and characterized by SEM, STEM, zeta potential and absorbance measurements. Then they were coated with fluorescent dye-doped silica and the fluorescence intensity was measured and compared to the pure fluorescent dye. Gold nanorods enhanced fluorescence more than gold nanostars and that the fluorescent dye Alexafluor 700 showed a greater fluorescence intensity change in the presence of nanoparticles than methylene blue.

  2. The electrochemisty of surface modified <10 nm metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Roberts, Joseph J. P.

    Chapter One provides a general introduction of the research on metal oxide nanoparticles (MOx), highlighting their synthesis, surface modification, and functionalization. Emphasis is given to the different synthetic route for producing small (<10 nm) MOx nanoparticles with narrow size distributions. Different methods for modifying their surface with small organic molecules are discussed with focus given to silanes and phosphates. Furthermore, functionalizing surface modified nanoparticles for specific functions is addressed, with markers for analytically relevant nanoscale quantification being the primary focus. Chapter Two describes in detail the thermal degradation synthesis used for the generation of small MOx nanoparticles. It demonstrates the versatile of the synthesis by successfully synthesizing ZrO 2 and IrO2 nanoparticles. Preliminary work involving the formation of Bi2S3, Bi2O3, and RuO2 nanomaterials is also addressed. The solvothermal synthesis of indium tin oxide (ITO) is also shown for comparison to ITO produced by thermal degradation. Chapter Three details the surface modification of ITO nanoparticles and subsequent electrochemical tagging with a ferrocene moiety. ITO nanoparticles were synthesized via thermal degradation. These nanoparticles underwent a ligand exchange with a covalently binding mondentate silane terminated with a primary amine. Acyl chloride coupling between the amine and chlorocarbonylferrocene provided an electrochemical tag to quantify the level of surface modification. Electrochemisty of the quasi-diffusing nanoparticles was evaluated via cyclic voltammetry (CV), chronoamperometry (CA), and mircodisk electrode (microE) experiments. Chapter Four investigates spectroscopic tagging of ITO and ZrO2 nanoparticles as well as electrochemical tagging of ZrO 2 and IrO2 nanoparticles. An unbound azo-dye was synthesized and attempts were made to attach the dye to the surface of ITO nanoparticles. Imine couple between a spectroscopic tag

  3. Formation of metal nanoparticles in silicon nanopores: Plasmon resonance studies

    NASA Astrophysics Data System (ADS)

    Polisski, S.; Goller, B.; Heck, S. C.; Maier, S. A.; Fujii, M.; Kovalev, D.

    2011-01-01

    We present a method for the formation of noble metal nanoparticle ensembles in nanostructured silicon. The key idea is based on the unique property of the large reduction potential of extended internal hydrogen-terminated porous silicon surfaces. The process of metal nanoparticle formation in porous silicon was experimentally traced using their optical plasmon resonance response. We also demonstrate that bimetallic compounds can be formed in porous silicon and that their composition can be controlled using this technique. Experimental results were found to contradict partially with considerations based on Mie theory.

  4. Laser fabrication of 2D and 3D metal nanoparticle structures and arrays.

    PubMed

    Kuznetsov, A I; Kiyan, R; Chichkov, B N

    2010-09-27

    A novel method for fabrication of 2D and 3D metal nanoparticle structures and arrays is proposed. This technique is based on laser-induced transfer of molten metal nanodroplets from thin metal films. Metal nanoparticles are produced by solidification of these nanodroplets. The size of the transferred nanoparticles can be controllably changed in the range from 180 nm to 1500 nm. Several examples of complex 2D and 3D microstructures generated form gold nanoparticles are demonstrated. PMID:20941016

  5. Towards stable catalysts by controlling collective properties of supported metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Prieto, Gonzalo; Zečević, Jovana; Friedrich, Heiner; de Jong, Krijn P.; de Jongh, Petra E.

    2013-01-01

    Supported metal nanoparticles play a pivotal role in areas such as nanoelectronics, energy storage/conversion and as catalysts for the sustainable production of fuels and chemicals. However, the tendency of nanoparticles to grow into larger crystallites is an impediment for stable performance. Exemplarily, loss of active surface area by metal particle growth is a major cause of deactivation for supported catalysts. In specific cases particle growth might be mitigated by tuning the properties of individual nanoparticles, such as size, composition and interaction with the support. Here we present an alternative strategy based on control over collective properties, revealing the pronounced impact of the three-dimensional nanospatial distribution of metal particles on catalyst stability. We employ silica-supported copper nanoparticles as catalysts for methanol synthesis as a showcase. Achieving near-maximum interparticle spacings, as accessed quantitatively by electron tomography, slows down deactivation up to an order of magnitude compared with a catalyst with a non-uniform nanoparticle distribution, or a reference Cu/ZnO/Al2O3 catalyst. Our approach paves the way towards the rational design of practically relevant catalysts and other nanomaterials with enhanced stability and functionality, for applications such as sensors, gas storage, batteries and solar fuel production.

  6. Towards stable catalysts by controlling collective properties of supported metal nanoparticles.

    PubMed

    Prieto, Gonzalo; Zečević, Jovana; Friedrich, Heiner; de Jong, Krijn P; de Jongh, Petra E

    2013-01-01

    Supported metal nanoparticles play a pivotal role in areas such as nanoelectronics, energy storage/conversion and as catalysts for the sustainable production of fuels and chemicals. However, the tendency of nanoparticles to grow into larger crystallites is an impediment for stable performance. Exemplarily, loss of active surface area by metal particle growth is a major cause of deactivation for supported catalysts. In specific cases particle growth might be mitigated by tuning the properties of individual nanoparticles, such as size, composition and interaction with the support. Here we present an alternative strategy based on control over collective properties, revealing the pronounced impact of the three-dimensional nanospatial distribution of metal particles on catalyst stability. We employ silica-supported copper nanoparticles as catalysts for methanol synthesis as a showcase. Achieving near-maximum interparticle spacings, as accessed quantitatively by electron tomography, slows down deactivation up to an order of magnitude compared with a catalyst with a non-uniform nanoparticle distribution, or a reference Cu/ZnO/Al(2)O(3) catalyst. Our approach paves the way towards the rational design of practically relevant catalysts and other nanomaterials with enhanced stability and functionality, for applications such as sensors, gas storage, batteries and solar fuel production. PMID:23142841

  7. Optical Properties and Biological Applications of Electromagnetically Coupled Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sheikholeslami, Sassan Nathan

    The optical properties of metallic particles change dramatically as the size shrinks to the nanoscale. The familiar mirror-like sheen of bulk metals is replaced by the bright, sharp, colorful plasmonic resonances of nanoparticles. The resonances of plasmonic metal nanoparticles are highly tunable throughout the visible spectrum, depending on the size, shape, local dielectric environment, and proximity to other optical resonances. Fundamental and applied research in the nanoscience community in the past few decades has sought to understand and exploit these phenomena for biological applications. In this work, discrete nanoparticle assemblies were produced through biomolecular interactions and studied at the single particle level with darkfield spectroscopy. Pairs of gold nanoparticles tethered by DNA were utilized as molecular rulers to study the dynamics of DNA bending by the restriction enzyme EcoRV. These results substantiated that nanoparticle rulers, deemed "plasmon rulers", could measure the dynamics of single biomolecules with high throughput, long lifetime, and high temporal resolution. To extend these concepts for live cell studies, a plasmon ruler comprised of peptide-linked gold nanoparticle satellites around a core particle was synthesized and utilized to optically follow cell signaling pathways in vivo at the single molecule level. The signal provided by these plasmon rulers allowed continuous observation of caspase-3 activation at the single molecule level in living cells for over 2 hours, unambiguously identifying early stage activation of caspase-3 in apoptotic cells. In the last section of this dissertation, an experimental and theoretical study of electomagnetic coupling in asymmetric metal nanoparticle dimers is presented. A "heterodimer" composed of a silver particle and a gold particle is observed to have a novel coupling between a plasmon mode (free electron oscillations) and an inter-band absorption process (bound electron transitions). The

  8. Ultrafast magnetization dynamics of cobalt nanoparticles and individual ferromagnetic dots

    NASA Astrophysics Data System (ADS)

    Bigot, Jean-Yves

    2009-03-01

    The ultrafast magnetization dynamics of magnetic materials can be investigated using femtosecond laser pulses to perform femtosecond magneto-optical Kerr and Faraday measurements [1]. In this talk, we will focus on the magnetization dynamics of cobalt nanoparticles which are either ferromagnetic or super-paramagnetic at room temperature and on the dynamics of individual ferromagnetic dots. In the first case (Co nanoparticles), we will demonstrate that the magnetization dynamics preceding the fluctuations over the anisotropy energy barrier is coherent but exhibits a strongly damped precession [2]. These results, which have been obtained with a three dimensional analysis of the magnetization vector [3] will be discussed in the context of the N'eel-Brown models involving the gyromagnetic character of the magnetization. We will also examine the dynamics of self-organized supra-crystals of cobalt nanoparticles [4]. In the second case, we will present the ultrafast magnetization dynamics of individual ferromagnetic dots (CoPt3, Permalloy, Nickel) made either by e-beam lithography or induced optically on thin films deposited on sapphire and glass substrates. The technique employed is the magneto-optical pump probe imaging (MOPPI) which allows performing time resolved magneto-optical Kerr images with with spatial and temporal resolutions of 300 nm and 150 fs [5]. The study of the demagnetization of the dots for different laser intensities shows that it is possible to write and read ultrafast monodomains on thin films. [3pt] [1] E. Beaurepaire, J.-C. Merle, A. Daunois, J.-Y. Bigot Phys. Rev. Lett., 76, 4250 (1996) [0pt] [2] L.H.F. Andrade, A. Laraoui, M. Vomir, D. Muller, J.-P. Stoquert, C. Estournès, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 97, 127401 (2006). [0pt] [3] M. Vomir, L. H.F. Andrade, L. Guidoni, E. Beaurepaire, J.-Y. Bigot Phys. Rev. Lett. 94, 237601 (2005). [0pt] [4] I. Lisiecki, V. Halt'e, C. Petit, M.-P. Pileni, J.-Y. Bigot Adv. Mater., 20, 4176 (2008

  9. Differential plasma protein binding to metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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 TiO2, 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 TiO2 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.

  10. Site-specific deposition of single gold nanoparticles by individual growth in electrohydrodynamically-printed attoliter droplet reactors

    NASA Astrophysics Data System (ADS)

    Schneider, Julian; Rohner, Patrik; Galliker, Patrick; Raja, Shyamprasad N.; Pan, Ying; Tiwari, Manish K.; Poulikakos, Dimos

    2015-05-01

    Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma ashing. With this non-contact technique, single particles with diameters tunable in the range of 5-35 nm and with narrow size distribution, high yield and alignment accuracy are generated on demand and patterned into arbitrary arrays. The nanoparticles feature good catalytic activity as shown by the exemplary growth of silicon nanowires from the nanoparticles and the etching of nanoholes by the printed nanoparticles.Gold nanoparticles with unique electronic, optical and catalytic properties can be efficiently synthesized in colloidal suspensions and are of broad scientific and technical interest and utility. However, their orderly integration on functional surfaces and devices remains a challenge. Here we show that single gold nanoparticles can be directly grown in individually printed, stabilized metal-salt ink attoliter droplets, using a nanoscale electrohydrodynamic printing method with a stable high-frequency dripping mode. This enables controllable sessile droplet nanoreactor formation and sustenance on non-wetting substrates, despite simultaneous rapid evaporation. The single gold nanoparticles can be formed inside such reactors in situ or by subsequent thermal annealing and plasma

  11. Metal nanoparticles in the presence of lipopolysaccharides trigger the onset of metal allergy in mice

    NASA Astrophysics Data System (ADS)

    Hirai, Toshiro; Yoshioka, Yasuo; Izumi, Natsumi; Ichihashi, Ko-Ichi; Handa, Takayuki; Nishijima, Nobuo; Uemura, Eiichiro; Sagami, Ko-Ichi; Takahashi, Hideki; Yamaguchi, Manami; Nagano, Kazuya; Mukai, Yohei; Kamada, Haruhiko; Tsunoda, Shin-Ichi; Ishii, Ken J.; Higashisaka, Kazuma; Tsutsumi, Yasuo

    2016-09-01

    Many people suffer from metal allergy, and the recently demonstrated presence of naturally occurring metal nanoparticles in our environment could present a new candidate for inducing metal allergy. Here, we show that mice pretreated with silver nanoparticles (nAg) and lipopolysaccharides, but not with the silver ions that are thought to cause allergies, developed allergic inflammation in response to the silver. nAg-induced acquired immune responses depended on CD4+ T cells and elicited IL-17A-mediated inflammation, similar to that observed in human metal allergy. Nickel nanoparticles also caused sensitization in the mice, whereas gold and silica nanoparticles, which are minimally ionizable, did not. Quantitative analysis of the silver distribution suggested that small nAg (≤10 nm) transferred to the draining lymph node and released ions more readily than large nAg (>10 nm). These results suggest that metal nanoparticles served as ion carriers to enable metal sensitization. Our data demonstrate a potentially new trigger for metal allergy.

  12. Absorption properties of metal-semiconductor hybrid nanoparticles.

    PubMed

    Shaviv, Ehud; Schubert, Olaf; Alves-Santos, Marcelo; Goldoni, Guido; Di Felice, Rosa; Vallée, Fabrice; Del Fatti, Natalia; Banin, Uri; Sönnichsen, Carsten

    2011-06-28

    The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

  13. Low-temperature metallic alloying of copper and silver nanoparticles with gold nanoparticles through digestive ripening.

    PubMed

    Smetana, Alexander B; Klabunde, Kenneth J; Sorensen, Christopher M; Ponce, Audaldo A; Mwale, Benny

    2006-02-01

    We describe a remarkable and simple alloying procedure in which noble metal intermetallic nanoparticles are produced in gram quantities via digestive ripening. This process involves mixing of separately prepared colloids of pure Au and pure Ag or Cu particles and then heating in the presence of an alkanethiol under reflux. The result after 1 h is alloy nanoparticles. Particles synthesized according to this procedure were characterized by UV-vis spectroscopy, EDX analysis, and high-resolution electron microscopy, the results of which confirm the formation of alloy particles. The particles of 5.6+/-0.5 nm diameter for Au/Ag and 4.8+/-1.0 nm diameter for Cu/Au undergo facile self-assembly to form 3-D superlattice ordering. It appears that during this digestive ripening process, the organic ligands display an extraordinary chemistry in which atom transfer between atomically pure copper, silver, and gold metal nanoparticles yields monodisperse alloy nanoparticles.

  14. Resonances of nanoparticles with poor plasmonic metal tips

    NASA Astrophysics Data System (ADS)

    Ringe, Emilie; Desantis, Christopher J.; Collins, Sean M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Skrabalak, Sara E.; Midgley, Paul A.

    2015-11-01

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

  15. Resonances of nanoparticles with poor plasmonic metal tips.

    PubMed

    Ringe, Emilie; DeSantis, Christopher J; Collins, Sean M; Duchamp, Martial; Dunin-Borkowski, Rafal E; Skrabalak, Sara E; Midgley, Paul A

    2015-11-30

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

  16. Improving proton therapy by metal-containing nanoparticles: nanoscale insights

    PubMed Central

    Schlathölter, Thomas; Eustache, Pierre; Porcel, Erika; Salado, Daniela; Stefancikova, Lenka; Tillement, Olivier; Lux, Francois; Mowat, Pierre; Biegun, Aleksandra K; van Goethem, Marc-Jan; Remita, Hynd; Lacombe, Sandrine

    2016-01-01

    The use of nanoparticles to enhance the effect of radiation-based cancer treatments is a growing field of study and recently, even nanoparticle-induced improvement of proton therapy performance has been investigated. Aiming at a clinical implementation of this approach, it is essential to characterize the mechanisms underlying the synergistic effects of nanoparticles combined with proton irradiation. In this study, we investigated the effect of platinum- and gadolinium-based nanoparticles on the nanoscale damage induced by a proton beam of therapeutically relevant energy (150 MeV) using plasmid DNA molecular probe. Two conditions of irradiation (0.44 and 3.6 keV/μm) were considered to mimic the beam properties at the entrance and at the end of the proton track. We demonstrate that the two metal-containing nanoparticles amplify, in particular, the induction of nanosize damages (>2 nm) which are most lethal for cells. More importantly, this effect is even more pronounced at the end of the proton track. This work gives a new insight into the underlying mechanisms on the nanoscale and indicates that the addition of metal-based nanoparticles is a promising strategy not only to increase the cell killing action of fast protons, but also to improve tumor targeting. PMID:27143877

  17. Oscillatory characteristics of metallic nanoparticles inside lipid nanotubes

    NASA Astrophysics Data System (ADS)

    Sadeghi, Fatemeh; Ansari, Reza; Darvizeh, Mansour

    2015-12-01

    This study is concerned with the oscillatory behavior of metallic nanoparticles, and in particular silver and gold nanoparticles, inside lipid nanotubes (LNTs) using the continuum approximation along with the 6-12 Lennard-Jones (LJ) potential function. The nanoparticle is modeled as a dense sphere and the LNT is assumed to be comprised of six layers including two head groups, two intermediate layers and two tail groups. To evaluate van der Waals (vdW) interactions, analytical expressions are first derived through undertaking surface and volume integrals which are then validated by a fully numerical scheme based on the differential quadrature (DQ) technique. Using the actual force distribution between the two interacting molecules, the equation of motion is directly solved utilizing the Runge-Kutta numerical integration scheme to arrive at the time history of displacement and velocity of the inner core. Also, a semi-analytical expression incorporating both geometrical parameters and initial conditions is introduced for the precise evaluation of oscillation frequency. A comprehensive study is conducted to gain an insight into the influences of nanoparticle radius, LNT length, head and tail group thicknesses and initial conditions on the oscillatory behavior of the metallic nanoparticles inside LNTs. It is found that the escape velocity and oscillation frequency of silver nanoparticles are higher than those of gold ones. It is further shown that the oscillation frequency is less affected by the tail group thickness when compared to the head group thickness.

  18. Resonance energy transfer: Dye to metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Wari, M. N.; Pujar, G. H.; Inamdar, S. R.

    2015-06-01

    In the present study, surface energy transfer (SET) from Coumarin 540A (C540 A) to Gold nanoparticle (Au) is demonstrated. The observed results show pronounced effect on the photoluminescence intensity and shortening of the lifetime of Coumarin 540A upon interaction with the spherical gold nanoparticle, also there are measured effects on radiative rate of the dye. Experimental results are analyzed with fluorescence resonance energy transfer (FRET) and SET theories. The results obtained from distance-dependent quenching provide experimental evidence that the efficiency curve slope and distance of quenching is best modeled by surface energy transfer process.

  19. Resonance energy transfer: Dye to metal nanoparticles

    SciTech Connect

    Wari, M. N.; Pujar, G. H.; Inamdar, S. R.

    2015-06-24

    In the present study, surface energy transfer (SET) from Coumarin 540A (C540 A) to Gold nanoparticle (Au) is demonstrated. The observed results show pronounced effect on the photoluminescence intensity and shortening of the lifetime of Coumarin 540A upon interaction with the spherical gold nanoparticle, also there are measured effects on radiative rate of the dye. Experimental results are analyzed with fluorescence resonance energy transfer (FRET) and SET theories. The results obtained from distance-dependent quenching provide experimental evidence that the efficiency curve slope and distance of quenching is best modeled by surface energy transfer process.

  20. Synthesis of high purity metal oxide nanoparticles for optical applications

    NASA Astrophysics Data System (ADS)

    Baker, C.; Kim, W.; Friebele, E. J.; Villalobos, G.; Frantz, J.; Shaw, L. B.; Sadowski, B.; Fontana, J.; Dubinskii, M.; Zhang, J.; Sanghera, J.

    2014-09-01

    In this paper we present our recent research results in synthesizing various metal oxide nanoparticles for use as laser gain media (solid state as well as fiber lasers) and transparent ceramic windows via two separate techniques, co-precipitation and flame spray pyrolysis. The nanoparticles were pressed into ceramic discs that exhibited optical transmission approaching the theoretical limit and showed very high optical-to-optical lasing slope efficiency. We have also synthesized sesquioxide nanoparticles using a Flame Spray Pyrolysis (FSP) technique that leads to the synthesis of a metastable phase of sesquioxide which allows fabricating excellent optical quality transparent windows with very fine grain sizes. Finally, we present our research in the synthesis of rare earth doped boehmite nanoparticles where the rareearth ion is encased in a cage of aluminum and oxygen to prevent ion-ion proximity and energy transfer. The preforms have been drawn into fibers exhibiting long lifetimes and high laser efficiencies.

  1. Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents

    PubMed Central

    Rao, Pasupuleti Visweswara; Nallappan, Devi; Madhavi, Kondeti; Rahman, Shafiqur; Jun Wei, Lim; Gan, Siew Hua

    2016-01-01

    Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities. PMID:27057273

  2. Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents.

    PubMed

    Rao, Pasupuleti Visweswara; Nallappan, Devi; Madhavi, Kondeti; Rahman, Shafiqur; Jun Wei, Lim; Gan, Siew Hua

    2016-01-01

    Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities.

  3. Silica coated noble metal nanoparticle hydrosols as supported catalyst precursors.

    PubMed

    Kong, Tung Shing Adam; Yu, Kai Man Kerry; Tsang, Shik Chi

    2006-04-01

    Synthesis of well-defined nanoparticles has been intensively pursued not only for their fundamental scientific interest, but also for many technological applications. One important development of the nanomaterial is in the area of chemical catalysis. We have now developed a new aqueous-based method for the synthesis of silica encapsulated noble metal nanoparticles in controlled dimensions. Thus, colloid stable silica encapsulated approximately 5 nm platinum nanoparticle is synthesized by a multi-step method. The thickness of the silica coating could be controlled using a different amount of silica precursor. These particles supported on a high surface area alumina are also demonstrated to display a superior hydrogenation activity and stability against metal sintering after thermal activation.

  4. Unexpected magnetization in highly pure metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Hanna, C. B.; Alanko, Gordon; Beausoleil, Boone; Chess, Jordan; Thurber, Aaron; Punnoose, Alex

    2012-02-01

    We report the synthesis and characterization of a large set of highly pure metal oxide (CeO2, SnO2 and ZnO) nanoparticles of ultra-small size (2-10 nm). While the metal oxide systems in this study are non-magnetic as bulk materials, our prepared nanoparticles possess an unexpected small room-temperature ferromagnetic magnetization on the order of 0.001 emu/g. This magnetization is shown to not be a result of magnetic impurities, and is discussed in terms of modification of the electronic structure and crystal lattice. These nanoparticles were thoroughly characterized in their size and phase by x-ray diffraction, morphology by transmission electron microscopy, chemical state and elemental purity by x-ray photoelectron spectroscopy, electronic bandgap by UV-vis absorption spectroscopy, and magnetic properties by vibrating sample magnetometry and electron paramagnetic resonance.

  5. Plasmon-mediated Photoelectron Emission from Single, Supported Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Grubisic, Andrej; Nesbitt, David

    2014-03-01

    Coherent multiphoton photoelectron emission (MPPE) from supported metal nanoparticles/structures has been studied at a single-particle level via scanning photoemission imaging microscopy (SPIM). Resonant excitation of localized surface plasmons (LSPs) with ultrafast laser pulses is shown to greatly amplify the photoelectron emission rate from metallic nanoparticles. In the limit of a large number of plasmon excitations, the n-photon photoelectron current scales rapidly with the electromagnetic near-field enhancement factor (|E|/|E0|)2n, indicating coherent MPPE as an extremely sensitive probe of the particle near-field. Additionally, our velocity map imaging (VMI) measurements of angle- and energy- resolved photoelectron distributions emitted from single plasmonic nanoparticles will be highlighted, with results shedding light into the complex dynamics of plasmon-induced photoelectron emission. We gratefully acknowledge Air Force Office of Scientific Research, National Science Foundation, and the National Institute of Standards and Technology for support of this work.

  6. Antimicrobial activity of metal oxide nanoparticles supported onto natural clinoptilolite.

    PubMed

    Hrenovic, Jasna; Milenkovic, Jelena; Daneu, Nina; Kepcija, Renata Matonickin; Rajic, Nevenka

    2012-08-01

    The antimicrobial activity of Cu(2)O, ZnO and NiO nanoparticles supported onto natural clinoptilolite was investigated in the secondary effluent under dark conditions. After 24h of contact the Cu(2)O and ZnO nanoparticles reduced the numbers of viable bacterial cells of Escherichia coli and Staphylococcus aureus in pure culture for four to six orders of magnitude and showed consistent 100% of antibacterial activity against native E. coli after 1h of contact during 48 exposures. The antibacterial activity of NiO nanoparticles was less efficient. The Cu(2)O and NiO nanoparticles showed 100% of antiprotozoan activity against Paramecium caudatum and Euplotes affinis after 1h of contact, while ZnO nanoparticles were less efficient. The morphology and crystallinity of the nanoparticles were not affected by microorganisms. The metal oxide nanoparticles could find a novel application in the disinfection of secondary effluent and removal of pathogenic microorganisms in the tertiary stage of wastewater treatment.

  7. Kinetics of self-assembled monolayer formation on individual nanoparticles.

    PubMed

    Smith, Jeremy G; Jain, Prashant K

    2016-08-24

    Self-assembled monolayer (SAM) formation of alkanethiols on nanoparticle surfaces is an extensively studied surface reaction. But the nanoscale aspects of the rich microscopic kinetics of this reaction may remain hidden due to ensemble-averaging in colloidal samples, which is why we investigated in real-time how alkanethiol SAMs form on a single Ag nanoparticle. From single-nanoparticle trajectories obtained using in situ optical spectroscopy, the kinetics of SAM formation appears to be limited by the growth of the layer across the nanoparticle surface. A significant spread in the growth kinetics is seen between nanoparticles. The single-nanoparticle rate distributions suggest two distinct modes for SAM growth: spillover of adsorbed thiols from the initial binding sites on the nanoparticle and direct adsorption of thiol from solution. At low concentrations, wherein direct adsorption from solution is not prevalent and growth takes place primarily by adsorbate migration, the SAM formation rate was less variable from one nanoparticle to another. On the other hand, at higher thiol concentrations, when both modes of growth were operative, the population of nanoparticles with inherent variations in surface conditions and/or morphology exhibited a heterogeneous distribution of rates. These new insights into the complex dynamics of SAM formation may inform synthetic strategies for ligand passivation and functionalization of nanoparticles and models of reactive adsorption and catalysis on nanoparticles. PMID:27523488

  8. Applications of metal nanoparticles in environmental cleanup

    EPA Science Inventory

    Iron nanoparticles (INPs) are one of the fastest-developing fields. INPs have a number of key physicochemical properties, such as high surface area, reactivity, optical and magnetic properties, and oxidation and reduction capacities, that make them attractive for water purificati...

  9. Fabrication of metallic microstructures by micromolding nanoparticles

    DOEpatents

    Morales, Alfredo M.; Winter, Michael R.; Domeier, Linda A.; Allan, Shawn M.; Skala, Dawn M.

    2002-01-01

    A method is provided for fabricating metallic microstructures, i.e., microcomponents of micron or submicron dimensions. A molding composition is prepared containing an optional binder and nanometer size (1 to 1000 nm in diameter) metallic particles. A mold, such as a lithographically patterned mold, preferably a LIGA or a negative photoresist mold, is filled with the molding composition and compressed. The resulting microstructures are then removed from the mold and the resulting metallic microstructures so provided are then sintered.

  10. Recent nanoarchitectures in metal nanoparticle-modified electrodes for electroanalysis.

    PubMed

    Oyama, Munetaka

    2010-01-01

    Increasing attention has been devoted to the use of metal nanoparticles (NPs) for electroanalysis. To make the best use of the electrocatalytic and electron-conducting characteristics of metal NPs, various nanoarchitectures have been developed for modifying metal NPs on electrode surfaces. In this review, at first recent nanoarchitectures with metal NPs for modifying electrodes are summarized together with the results of electrochemical analysis. Then, the progress of a seed-mediated growth method that we developed for modifying electrode surfaces is shown as an example that the nanoarchitectures of metal NPs are possible without using organic linker molecules. This approach should be effective for further functional modifications of the surfaces of metal NPs as well as the electrochemical analysis with lower charge-transfer resistance.

  11. Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Cacha, Brian Joseph Gonda

    Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C60/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (Voc) by 160% and short circuit current (Jsc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

  12. Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor.

    PubMed

    Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-08-01

    Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication.

  13. Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor.

    PubMed

    Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-08-01

    Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication. PMID:25994368

  14. Polarizability of supported metal nanoparticles: Mehler-Fock approach

    NASA Astrophysics Data System (ADS)

    Jung, Jesper; Pedersen, Thomas G.

    2012-09-01

    Using toroidal coordinates and the Mehler-Fock transform, we present an analysis of the polarizability of a complex structure allowing for the study of arbitrarily truncated metal spheres including a dielectric substrate. Our analysis is based on an electrostatic approach, i.e., we are in the quasi-static limit, where we solve the Laplace equation for the potential. The derived method is used to analyze the behavior of localized surface plasmon resonances of truncated metal nanospheres including substrate effects. The method is fast, simple, easy to implement, and useful for analysis of experimental work on supported metal nanoparticles, e.g., within the area of plasmonic photovoltaics.

  15. Tailoring the Catalytic Properties of Metal Nanoparticles via Support Interactions.

    PubMed

    Ahmadi, M; Mistry, H; Roldan Cuenya, B

    2016-09-01

    The development of new catalysts for energy technology and environmental remediation requires a thorough knowledge of how the physical and chemical properties of a catalyst affect its reactivity. For supported metal nanoparticles (NPs), such properties can include the particle size, shape, composition, and chemical state, but a critical parameter which must not be overlooked is the role of the NP support. Here, we highlight the key mechanisms behind support-induced enhancement in the catalytic properties of metal NPs. These include support-induced changes in the NP morphology, stability, electronic structure, and chemical state, as well as changes in the support due to the NPs. Utilizing the support-dependent phenomena described in this Perspective may allow significant breakthroughs in the design and tailoring of the catalytic activity and selectivity of metal nanoparticles. PMID:27530730

  16. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

    NASA Astrophysics Data System (ADS)

    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.

  17. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels.

    PubMed

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

    2016-04-14

    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. PMID:26996157

  18. Bulk Metallic Glass-like Scattering Signal in Small Metallic Nanoparticles

    SciTech Connect

    Doan-Nguyen, VVT; Kimber, SAJ; Pontoni, D; Hickey, DR; Diroll, BT; Yang, XH; Miglierini, M; Murray, CB; Billinge, SJL

    2014-06-01

    The atomic structure of Ni-Pd nanoparticles has been studied using atomic pair distribution function (PDF) analysis of X-ray total scattering data and with transmission electron microscopy (TEM). Larger nanoparticles have PDFs corresponding to the bulk face-centered cubic packing. However, the smallest nanoparticles have PDFs that strongly resemble those obtained from bulk metallic glasses (BMGs). In fact, by simply scaling the distance axis by the mean metallic radius, the curves may be collapsed onto each other and onto the PDF from a metallic glass sample. In common with a wide range of BMG materials, the intermediate range order may be fit with a damped single-frequency sine wave. When viewed in high-resolution TEM, these nanoparticles exhibit atomic fringes typical of those seen in small metallic clusters with icosahedral or decahedral order. These two seemingly contradictory results are reconciled by calculating the PDFs of models of icosahedra that would be consistent with the fringes seen in TEM. These model PDFs resemble the measured ones when significant atom-position disorder is introduced, drawing together the two diverse fields of metallic nanoparticles and BMGs and supporting the view that BMGs may contain significant icosahedral or decahedral order.

  19. Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review.

    PubMed

    Miazek, Krystian; Iwanek, Waldemar; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

    2015-10-09

    Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed.

  20. Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review

    PubMed Central

    Miazek, Krystian; Iwanek, Waldemar; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

    2015-01-01

    Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed. PMID:26473834

  1. Building up strain in colloidal metal nanoparticle catalysts.

    PubMed

    Sneed, Brian T; Young, Allison P; Tsung, Chia-Kuang

    2015-08-01

    The focus on surface lattice strain in nanostructures as a fundamental research topic has gained momentum in recent years as scientists investigated its significant impact on the surface electronic structure and catalytic properties of nanomaterials. Researchers have begun to tell a more complete story of catalysis from a perspective which brings this concept to the forefront of the discussion. The nano-'realm' makes the effects of surface lattice strain, which acts on the same spatial scales, more pronounced due to a higher ratio of surface to bulk atoms. This is especially evident in the field of metal nanoparticle catalysis, where displacement of atoms on surfaces can significantly alter the sorption properties of molecules. In part, the concept of strain-engineering for catalysis opened up due to the achievements that were made in the synthesis of a more sophisticated nanoparticle library from an ever-expanding set of methodologies. Developing synthesis methods for metal nanoparticles with well-defined and strained architectures is a worthy goal that, if reached, will have considerable impact in the search for catalysts. In this review, we summarize the recent accomplishments in the area of surface lattice-strained metal nanoparticle synthesis, framing the discussion from the important perspective of surface lattice strain effects in catalysis.

  2. Bio-related noble metal nanoparticle structure property relationships

    NASA Astrophysics Data System (ADS)

    Leonard, Donovan Nicholas

    Structure property relationships of noble metal nanoparticles (NPs) can be drastically different than bulk properties of the same metals. This research study used state-of-the-art analytical electron microscopy and scanned probe microscopy to determine material properties on the nanoscale of bio-related Au and Pd NPs. Recently, it has been demonstrated the self-assembly of Au NPs on functionalized silica surfaces creates a conductive surface. Determination of the aggregate morphology responsible for electron conduction was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, changes in the electrical properties of the substrates after low temperature (<350°C) annealing was also studied. It was found that coalescence and densification of the Au NP aggregates disrupted the interconnected network which subsequently created a loss of conductivity. Investigation of bio-related Au/SiO2 core-shell NPs determined why published experimental results showed the sol-gel silica shell improved, by almost an order of magnitude, the detection efficiency of a DNA detection assay. Novel 360° rotation scanning TEM (STEM) imaging allowed study of individual NP surface morphology and internal structure. Electron energy loss spectroscopy (EELS) spectrum imaging determined optoelectronic properties and chemical composition of the silica shell used to encapsulate Au NPs. Results indicated the sol-gel deposited SiO2 had a band gap energy of ˜8.9eV, bulk plasmon-peak energy of ˜25.5eV and chemical composition of stoichiometric SiO2. Lastly, an attempt to elicit structure property relationships of novel RNA mediated Pd hexagon NPs was performed. Selected area electron diffraction (SAD), low voltage scanning transmission electron microscopy (LV-STEM), electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) were chosen for characterization of atomic ordering, chemical composition and optoelectronic properties of the novel

  3. Transport of metal oxide nanoparticles in saturated porous media.

    PubMed

    Ben-Moshe, Tal; Dror, Ishai; Berkowitz, Brian

    2010-09-01

    The behavior of four types of untreated metal oxide nanoparticles in saturated porous media was studied. The transport of Fe(3)O(4), TiO(2), CuO, and ZnO was measured in a series of column experiments. Vertical columns were packed with uniform, spherical glass beads. The particles were introduced as a pulse suspended in aqueous solutions and breakthrough curves at the outlet were measured using UV-vis spectrometry. Different factors affecting the mobility of the nanoparticles such as ionic strength, addition of organic matter (humic acid), flow rate and pH were investigated. The experiments showed that mobility varies strongly among the nanoparticles, with TiO(2) demonstrating the highest mobility. The mobility is also strongly affected by the experimental conditions. Increasing the ionic strength enhances the deposition of the nanoparticles. On the other hand, addition of humic acid increases the nanoparticle mobility significantly. Lower flow rates again led to reduced mobility, while changes in pH had little effect. Overall, in natural systems, it is expected that the presence of humic acid in soil and aquifer materials, and the ionic strength of the resident water, will be key factors determining nanoparticle mobility.

  4. Metal Nanoparticles Preparation In Supercritical Carbon Dioxide Solutions

    SciTech Connect

    Harry W. Rollins

    2004-04-01

    The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique properties of a supercritical fluid.(14&15) Through simple variations of temperature and pressure, the properties of a supercritical fluid can be continuously tuned from gas-like to liquid-like without undergoing a phase change. Nanoparticle preparation methods that utilize supercritical fluids are briefly reviewed below using the following categories: Rapid Expansion of Supercritical Solutions (RESS), Reactive Supercritical Fluid Processing, and Supercritical Fluid Microemulsions. Because of its easily accessible critical temperature and pressure and environmentally benign nature, carbon dioxide is the most widely used supercritical solvent. Supercritical CO2 is unfortunately a poor solvent for many polar or ionic species, which has impeded its use in the preparation of metal and semiconductor nanoparticles. We have developed a reactive supercritical fluid processing method using supercritical carbon dioxide for the preparation of metal and metal sulfide particles and used it to prepare narrowly distributed nanoparticles of silver (Ag) and silver sulfide

  5. Impact of metallic and metal oxide nanoparticles on wastewater treatment and anaerobic digestion.

    PubMed

    Yang, Yu; Zhang, Chiqian; Hu, Zhiqiang

    2013-01-01

    Metallic and metal oxide nanomaterials have been increasingly used in consumer products (e.g. sunscreen, socks), the medical and electronic industries, and environmental remediation. Many of them ultimately enter wastewater treatment plants (WWTPs) or landfills. This review paper discusses the fate and potential effects of four types of nanoparticles, namely, silver nanoparticles (AgNPs), nano ZnO, nano TiO2, and nano zero valent iron (NZVI), on waste/wastewater treatment and anaerobic digestion. The stabilities and chemical properties of these nanoparticles (NPs) result in significant differences in antimicrobial activities. Analysis of published data of metallic and metal oxide NPs suggests that oxygen is often a prerequisite for the generation of reactive oxygen species (ROS) for AgNPs and NZVI, while illumination is necessary for ROS generation for nano TiO2 and nano ZnO. Furthermore, such nanoparticles are capable of being oxidized or dissolved in water and can release metal ions, leading to metal toxicity. Therefore, AgNPs and nano TiO2 are chemically stable NPs that have no adverse effects on microbes under anaerobic conditions. Although the toxicity of nanomaterials has been studied intensively under aerobic conditions, more research is needed to address their fate in anaerobic waste/wastewater treatment systems and their long-term effects on the environment.

  6. Antimicrobial properties of metal and metal-halide nanoparticles and their potential applications

    NASA Astrophysics Data System (ADS)

    Torrey, Jason Robert

    Heavy metals, including silver and copper, have been known to possess antimicrobial properties against bacterial, fungal, and viral pathogens. Metal nanoparticles (aggregations of metal atoms 1-200 nm in size) have recently become the subject of intensive study for their increased antimicrobial properties. In the current studies, metal and metal-halide nanoparticles were evaluated for their antibacterial efficacy. Silver (Ag), silver bromide (AgBr), silver iodide (AgI), and copper iodide (CuI) nanoparticles significantly reduced bacterial numbers of the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus within 24 hours and were more effective against P. aeruginosa. CuI nanoparticles were found to be highly effective, reducing both organisms by >4.43 log 10 within 15 minutes at 60 ppm Cu. CuI nanoparticles formulated with different stabilizers (sodium dodecyl sulfate, SDS; polyvinyl pyrrolidone, PVP) were further tested against representative Gram-positive and Gram-negative bacteria, Mycobacteria, a fungus (Candida albicans ), and a non-enveloped virus (poliovirus). Both nanoparticles caused significant reductions in most of the Gram-negative bacteria within five minutes (>5.09-log10). The Gram-positive bacterial species and C. albicans were more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. In contrast, the acid-fast Mycobacterium smegmatis was more resistant to CuI-SDS than CuI-PVP nanoparticles. Poliovirus was more resistant than the other organisms tested except for Mycobacterium fortuitum, which displayed the greatest resistance to CuI nanoparticles. As an example of a real world antimicrobial application, polymer coatings embedded with various concentrations of CuI nanoparticles were tested for antibacterial efficacy against P. aeruginosa and S. aureus. Polyester-epoxy powder coatings were found to display superior uniformity, stability and antimicrobial properties against both organisms (>4.92 log 10 after six hours at

  7. Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts.

    PubMed

    Hunt, Sean T; Milina, Maria; Alba-Rubio, Ana C; Hendon, Christopher H; Dumesic, James A; Román-Leshkov, Yuriy

    2016-05-20

    We demonstrated the self-assembly of transition metal carbide nanoparticles coated with atomically thin noble metal monolayers by carburizing mixtures of noble metal salts and transition metal oxides encapsulated in removable silica templates. This approach allows for control of the final core-shell architecture, including particle size, monolayer coverage, and heterometallic composition. Carbon-supported Ti(0.1)W(0.9)C nanoparticles coated with Pt or bimetallic PtRu monolayers exhibited enhanced resistance to sintering and CO poisoning, achieving an order of magnitude increase in specific activity over commercial catalysts for methanol electrooxidation after 10,000 cycles. These core-shell materials provide a new direction to reduce the loading, enhance the activity, and increase the stability of noble metal catalysts.

  8. Is Neurotoxicity of Metallic Nanoparticles the Cascades of Oxidative Stress?

    NASA Astrophysics Data System (ADS)

    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.

  9. Is Neurotoxicity of Metallic Nanoparticles the Cascades of Oxidative Stress?

    PubMed

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

    2016-12-01

    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. PMID:27295259

  10. Design strategies of hybrid metallic nanoparticles for theragnostic applications

    NASA Astrophysics Data System (ADS)

    Gautier, J.; Allard-Vannier, E.; Hervé-Aubert, K.; Soucé, M.; Chourpa, I.

    2013-11-01

    Metallic nanoparticles (MNPs) such as iron oxide and gold nanoparticles are interesting platforms to build theragnostic nanocarriers which combine both therapeutic and diagnostic functions within a single nanostructure. Nevertheless, their surface must be functionalized to be suitable for in vivo applications. Surface functionalization also provides binding sites for targeting ligands, and for drug loading. This review focuses on the materials and surface chemistry used to build hybrid nanocarriers that are inorganic cores functionalized with organic materials. The surface state of the MNPs largely depends on their synthesis routes, and dictates the strategies used for functionalization. Two main strategies can be found in the literature: the design of core-shell nanosystems, or embedding nanoparticles in organic materials. Emerging tendencies such as the use of clusters or alternative coating materials are also described. To present both hydrophilic and lipophilic nanosystems, we chose the doxorubicin anticancer agent as an example, as the molecule presents an affinity for both types of materials.

  11. Supported metal nanoparticles on porous materials. Methods and applications.

    PubMed

    White, Robin J; Luque, Rafael; Budarin, Vitaliy L; Clark, James H; Macquarrie, Duncan J

    2009-02-01

    Nanoparticles are regarded as a major step forward to achieving the miniaturisation and nanoscaling effects and properties that have been utilised by nature for millions of years. The chemist is no longer observing and describing the behaviour of matter but is now able to manipulate and produce new types of materials with specific desired physicochemical characteristics. Such materials are receiving extensive attention across a broad range of research disciplines. The fusion between nanoparticle and nanoporous materials technology represents one of the most interesting of these rapidly expanding areas. The harnessing of nanoscale activity and selectivity, potentially provides extremely efficient catalytic materials for the production of commodity chemicals, and energy needed for a future sustainable society. In this tutorial review, we present an introduction to the field of supported metal nanoparticles (SMNPs) on porous materials, focusing on their preparation and applications in different areas. PMID:19169462

  12. Uncovering the design rules for peptide synthesis of metal nanoparticles.

    PubMed

    Tan, Yen Nee; Lee, Jim Yang; Wang, Daniel I C

    2010-04-28

    Peptides are multifunctional reagents (reducing and capping agents) that can be used for the synthesis of biocompatible metal nanoparticles under relatively mild conditions. However, the progress in peptide synthesis of metal nanoparticles has been slow due to the lack of peptide design rules. It is difficult to establish sequence-reactivity relationships from peptides isolated from biological sources (e.g., biomineralizing organisms) or selected by combinatorial display libraries because of their widely varying compositions and structures. The abundance of random and inactive amino acid sequences in the peptides also increases the difficulty in knowledge extraction. In this study, a "bottom-up" approach was used to formulate a set of rudimentary rules for the size- and shape-controlled peptide synthesis of gold nanoparticles from the properties of the 20 natural alpha-amino acids for AuCl(4)(-) reduction and binding to Au(0). It was discovered that the reduction capability of a peptide depends on the presence of certain reducing amino acid residues, whose activity may be regulated by neighboring residues with different Au(0) binding strengths. Another finding is the effect of peptide net charge on the nucleation and growth of the Au nanoparticles. On the basis of these understandings, several multifunctional peptides were designed to synthesize gold nanoparticles in different morphologies (nanospheres and nanoplates) and with sizes tunable by the strategic placement of selected amino acid residues in the peptide sequence. The methodology presented here and the findings are useful for establishing the scientific basis for the rational design of peptides for the synthesis of metal nanostructures. PMID:20355728

  13. Adsorption and desorption of bivalent metals to hematite nanoparticles.

    PubMed

    Grover, Valerie A; Hu, Jinxuan; Engates, Karen E; Shipley, Heather J

    2012-01-01

    The use of commercially prepared hematite nanoparticles (37.0 nm) was studied as an adsorbent in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) from aqueous solutions. Single-metal adsorption was studied as a function of metal and adsorbent concentrations, whereas binary metal competition was found to be dependent on the molar ratio between the competing metals. Competitive effects indicated that Pb had strong homogenous affinity to the nanohematite surface, and decreased adsorption of Cd, Cu, and Zn occurred when Pb was present in a binary system. Metal adsorption strength to nanohematite at pH 6.0 increased with metal electronegativity: Pb > Cu > Zn ∼ Cd. Equilibrium modeling revealed that the Langmuir-Freundlich composite isotherm adequately described the adsorption and competitive effects of metals to nanohematite, whereas desorption was best described by the Langmuir isotherm. The desorption of metals from nanohematite was found to be pH dependent, with pH 4.0 > pH 6.0 > pH 8.0, and results showed that greater than 65% desorption was achieved at pH 4.0 within three 24-h cycles for all metals.

  14. Carbon composites with metal nanoparticles for Alcohol fuel cells

    NASA Astrophysics Data System (ADS)

    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.

  15. Biocidal properties of metal oxide nanoparticles and their halogen adducts

    NASA Astrophysics Data System (ADS)

    Haggstrom, Johanna A.; Klabunde, Kenneth J.; Marchin, George L.

    2010-03-01

    Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (Δ Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores. The procedure consists of a membrane method. Transmission electron micrographs are used to compare nanoparticle-treated and untreated cells and spores. It is proposed that the abrasive character of the particles, the oxidative power of the halogens/interhalogens, and the electrostatic attraction between the metal oxides and the biological material are responsible for high biocidal activities. While some activity was demonstrated, bacterial endospores were more resistant to nanoparticle treatment than the vegetative bacteria.

  16. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  17. Central nervous system toxicity of metallic nanoparticles

    PubMed Central

    Feng, Xiaoli; Chen, Aijie; Zhang, Yanli; Wang, Jianfeng; Shao, Longquan; Wei, Limin

    2015-01-01

    Nanomaterials (NMs) are increasingly used for the therapy, diagnosis, and monitoring of disease- or drug-induced mechanisms in the human biological system. In view of their small size, after certain modifications, NMs have the capacity to bypass or cross the blood–brain barrier. Nanotechnology is particularly advantageous in the field of neurology. Examples may include the utilization of nanoparticle (NP)-based drug carriers to readily cross the blood–brain barrier to treat central nervous system (CNS) diseases, nanoscaffolds for axonal regeneration, nanoelectromechanical systems in neurological operations, and NPs in molecular imaging and CNS imaging. However, NPs can also be potentially hazardous to the CNS in terms of nano-neurotoxicity via several possible mechanisms, such as oxidative stress, autophagy, and lysosome dysfunction, and the activation of certain signaling pathways. In this review, we discuss the dual effect of NMs on the CNS and the mechanisms involved. The limitations of the current research are also discussed. PMID:26170667

  18. Metal nanoparticles amplify photodynamic effect on skin cells in vitro

    NASA Astrophysics Data System (ADS)

    Bauer, Brigitte; Chen, Si; Käll, Mikael; Gunnarsson, Linda; Ericson, Marica B.

    2011-03-01

    We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.

  19. Behavior of metal oxide nanoparticles in natural aqueous matrices

    NASA Astrophysics Data System (ADS)

    Keller, A. A.; Zhou, D.; Wang, H.

    2009-12-01

    The increasing use of nanomaterials in consumer products that are exposed to environmental media has led to a need to understand their fate and transport. In particular, metal oxide (MeO) nanoparticles, such as TiO2, ZnO and CeO2, are increasingly incorporated into a wide range of products, from sunscreens to paints and other coatings, and catalysts. With regard to their transport, it is important to determine how far these nanoparticles will travel in different ambient waters, such as rivers, lakes and seawater. There have been a number of studies that have addressed the aggregation of different nanoparticles in simpler aqueous solutions. However, it is important to understand the combined effect of pH, ionic strength, ionic composition, NOM and other characteristics of the aqueous media in which the nanoparticles will be dispersed, which may result in either aggregation and settling, or stabilization and transport. This also affects the bioavailability of the nanomaterials, and the phase (water column or sediments) in which the bulk of the particles are likely to reside. For this study we considered several natural aqueous matrices, including seawater, freshwater, groundwater, rainwater and treated wastewater, as well as two different water matrices used in micro- and mesocosm studies of nanoparticle toxicity. We determined that the two most important water quality characteristics controlling the rate of aggregation, relatively independent of particle composition, are [NOM] and ionic strength.

  20. Optics of metal nanoparticle aggregates with light induced motion.

    PubMed

    Drachev, Vladimir P; Perminov, Sergey V; Rautian, Sergey G

    2007-07-01

    Light-induced forces between metal nanoparticles change the geometry of the aggregates and affect their optical properties. Light absorption, scattering and scattering of a probe beam are numerically studied with Newton's equations and the coupled dipole equations for penta-particle aggregates. The relative changes in optical responses are large compared with the linear, low-intensity limit and relatively fast with nanosecond characteristic times. Time and intensity dependencies are shown to be sensitive to the initial potential of the aggregation forces.

  1. Giant coupling effect between metal nanoparticle chain and optical waveguide.

    PubMed

    Février, Mickaël; Gogol, Philippe; Aassime, Abdelhanin; Mégy, Robert; Delacour, Cécile; Chelnokov, Alexei; Apuzzo, Aniello; Blaize, Sylvain; Lourtioz, Jean-Michel; Dagens, Béatrice

    2012-02-01

    We demonstrate that the optical energy carried by a TE dielectric waveguide mode can be totally transferred into a transverse plasmon mode of a coupled metal nanoparticle chain. Experiments are performed at 1.5 μm. Mode coupling occurs through the evanescent field of the dielectric waveguide mode. Giant coupling effects are evidenced from record coupling lengths as short as ~560 nm. This result opens the way to nanometer scale devices based on localized plasmons in photonic integrated circuits. PMID:22251002

  2. Functional Application of Noble Metal Nanoparticles In Situ Synthesized on Ramie Fibers.

    PubMed

    Tang, Bin; Yao, Ya; Li, Jingliang; Qin, Si; Zhu, Haijin; Kaur, Jasjeet; Chen, Wu; Sun, Lu; Wang, Xungai

    2015-12-01

    Different functions were imparted to ramie fibers through treatment with noble metal nanoparticles including silver and gold nanoparticles. The in situ synthesis of silver and gold nanoparticles was achieved by heating in the presence of ramie fibers in the corresponding solutions of precursors. The unique optical property of synthesized noble metal nanoparticles, i.e., localized surface plasmon resonance, endowed ramie fibers with bright colors. Color strength (K/S) of fibers increased with heating temperature. Silver nanoparticles were obtained in alkaline solution, while acidic condition was conducive to gold nanoparticles. The optical properties of treated ramie fibers were investigated using UV-vis absorption spectroscopy. Scanning electron microscopy (SEM) was employed to observe the morphologies of silver and gold nanoparticles in situ synthesized on fibers. The ramie fibers treated with noble metal nanoparticles showed remarkable catalytic activity for reduction of 4-nitrophenol (4-NP) by sodium borohydride. Moreover, the silver nanoparticle treatment showed significant antibacterial property on ramie fibers. PMID:26383541

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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 the insulating matrix. These nanocomposites have been characterized by measuring the resistivity of the composite layer as a function of the implantation dose. The experimental results are compared with a model based on percolation theory, in which electron transport through the composite is explained by conduction through a random resistor network formed by the metallic nanoparticles. Excellent agreement is found between the experimental results and the predictions of the theory. We conclude in that the conductivity process is due only to percolation (when the conducting elements are in geometric contact) and that the contribution from tunneling conduction is negligible.

  4. Classical theory for second-harmonic generation from metallic nanoparticles

    SciTech Connect

    Zeng Yong; Liu Jinjie; Moloney, Jerome V.; Hoyer, Walter; Koch, Stephan W.

    2009-06-15

    In this paper, we develop a classical electrodynamic theory to study the optical nonlinearities of metallic nanoparticles. The quasi free electrons inside the metal are approximated as a classical Coulomb-interacting electron gas, and their motion under the excitation of an external electromagnetic field is described by the plasma equations. This theory is further tailored to study second-harmonic generation. Through detailed experiment-theory comparisons, we validate this classical theory as well as the associated numerical algorithm. It is demonstrated that our theory not only provides qualitative agreement with experiments but it also reproduces the overall strength of the experimentally observed second-harmonic signals.

  5. Rapid laser sintering of metal nano-particles inks

    NASA Astrophysics Data System (ADS)

    Ermak, Oleg; Zenou, Michael; Bernstein Toker, Gil; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-01

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  6. Rapid laser sintering of metal nano-particles inks.

    PubMed

    Ermak, Oleg; Zenou, Michael; Toker, Gil Bernstein; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-23

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  7. Rapid laser sintering of metal nano-particles inks.

    PubMed

    Ermak, Oleg; Zenou, Michael; Toker, Gil Bernstein; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-23

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased. PMID:27514079

  8. Metal nanoparticles with liquid-crystalline ligands: controlling nanoparticle superlattice structure and properties.

    PubMed

    Lewandowski, Wiktor; Wójcik, Michał; Górecka, Ewa

    2014-05-19

    Nanoparticle ordered aggregates are promising candidates for future application in a variety of sensing, optical and electronic technologies, mainly based on collective interactions between individual nano-building blocks. Physicochemical properties of such assemblies depend on nanoparticle spacing, therefore a lot of effort throughout the last years was put on development of assembly methods allowing control over aggregates structure. In this minireview we describe efficient self-assembly process based on the utilization of liquid-crystalline ligands grafted onto nanoparticle surface. We show strategies used to synthesize liquid-crystalline nanoparticles as well as discuss parameters influencing structural and thermal characteristic of aggregates. It is also demonstrated that the liquid-crystalline approach offers access to dynamic self-assembly and metamaterials with anisotropic plasmonic properties, which makes this strategy unique among others.

  9. Unveiling the chemistry behind the green synthesis of metal nanoparticles.

    PubMed

    Santos, Sónia A O; Pinto, Ricardo J B; Rocha, Sílvia M; Marques, Paula A A P; Pascoal Neto, Carlos; Silvestre, Armando J D; Freire, Carmen S R

    2014-09-01

    Nanobiotechnology has emerged as a fundamental domain in modern science, and metallic nanoparticles (NPs) are one of the largest classes of NPs studied because of their wide spectrum of possible applications in several fields. The use of plant extracts as reducing and stabilizing agents in their synthesis is an interesting and reliable alternative to conventional methodologies. However, the role of the different components of such extracts in the reduction/stabilization of metal ions has not yet been understood clearly. Here we studied the behavior of the main components of a Eucalyptus globulus Labill. bark aqueous extract during metal-ion reduction followed by advanced chromatographic techniques, which allowed us to establish their specific role in the process. The obtained results showed that phenolic compounds, particularly galloyl derivatives, are mainly responsible for the metal-ion reduction, whereas sugars are essentially involved in the stabilization of the NPs. PMID:25088383

  10. Unveiling the chemistry behind the green synthesis of metal nanoparticles.

    PubMed

    Santos, Sónia A O; Pinto, Ricardo J B; Rocha, Sílvia M; Marques, Paula A A P; Pascoal Neto, Carlos; Silvestre, Armando J D; Freire, Carmen S R

    2014-09-01

    Nanobiotechnology has emerged as a fundamental domain in modern science, and metallic nanoparticles (NPs) are one of the largest classes of NPs studied because of their wide spectrum of possible applications in several fields. The use of plant extracts as reducing and stabilizing agents in their synthesis is an interesting and reliable alternative to conventional methodologies. However, the role of the different components of such extracts in the reduction/stabilization of metal ions has not yet been understood clearly. Here we studied the behavior of the main components of a Eucalyptus globulus Labill. bark aqueous extract during metal-ion reduction followed by advanced chromatographic techniques, which allowed us to establish their specific role in the process. The obtained results showed that phenolic compounds, particularly galloyl derivatives, are mainly responsible for the metal-ion reduction, whereas sugars are essentially involved in the stabilization of the NPs.

  11. Serum protein adsorption and excretion pathways of metal nanoparticles

    PubMed Central

    Vinluan, Rodrigo D; Zheng, Jie

    2015-01-01

    While the synthesis of metal nanoparticles (NPs) with fascinating optical and electronic properties have progressed dramatically and their potential biomedical applications were also well demonstrated in the past decade, translation of metal NPs into the clinical practice still remains a challenge due to their severe accumulation in the body. Herein, we give a brief review on size-dependent material properties of metal NPs and their potential biomedical applications, followed by a summary of how structural parameters such as size, shape and charge influence their interactions with serum protein adsorption, cellular uptake and excretion pathways. Finally, the future challenges in minimizing serum protein adsorption and expediting clinical translation of metal NPs were also discussed. PMID:26377047

  12. Formation of oriented nanostructures in diamond using metallic nanoparticles.

    PubMed

    Mehedi, H-A; Hebert, C; Ruffinatto, S; Eon, D; Omnes, F; Gheeraert, E

    2012-11-16

    A simple, fast and cost-effective etching technique to create oriented nanostructures such as pyramidal and cylindrical shaped nanopores in diamond membranes by self-assembled metallic nanoparticles is proposed. In this process, a diamond film is annealed with thin metallic layers in a hydrogen atmosphere. Carbon from the diamond surface is dissolved into nanoparticles generated from the metal film, then evacuated in the form of hydrocarbons and, consequently, the nanoparticles enter the crystal volume. In order to understand and optimize the etching process, the role of different parameters such as type of catalyst (Ni, Co, Pt, and Au), hydrogen gas, temperature and time of annealing, and microstructure of diamond (polycrystalline and nanocrystalline) were investigated. With this technique, nanopores with lateral sizes in the range of 10-100 nm, and as deep as about 600 nm, in diamond membranes were produced without any need for a lithography process, which opens the opportunities for fabricating porous diamond membranes for chemical sensing applications. PMID:23090452

  13. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  14. Thermoelectric Performance Enhancement by Surrounding Crystalline Semiconductors with Metallic Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun-Jung; King, Glen C.; Park, Yeonjoon; Lee, Kunik; Choi, Sang H.

    2011-01-01

    Direct conversion of thermal energy to electricity by thermoelectric (TE) devices may play a key role in future energy production and utilization. However, relatively poor performance of current TE materials has slowed development of new energy conversion applications. Recent reports have shown that the dimensionless Figure of Merit, ZT, for TE devices can be increased beyond the state-of-the-art level by nanoscale structuring of materials to reduce their thermal conductivity. New morphologically designed TE materials have been fabricated at the NASA Langley Research Center, and their characterization is underway. These newly designed materials are based on semiconductor crystal grains whose surfaces are surrounded by metallic nanoparticles. The nanoscale particles are used to tailor the thermal and electrical conduction properties for TE applications by altering the phonon and electron transport pathways. A sample of bismuth telluride decorated with metallic nanoparticles showed less thermal conductivity and twice the electrical conductivity at room temperature as compared to pure Bi2Te3. Apparently, electrons cross easily between semiconductor crystal grains via the intervening metallic nanoparticle bridges, but phonons are scattered at the interfacing gaps. Hence, if the interfacing gap is larger than the mean free path of the phonon, thermal energy transmission from one grain to others is reduced. Here we describe the design and analysis of these new materials that offer substantial improvements in thermoelectric performance.

  15. Single metallic nanoparticle imaging for protein detection in cells.

    PubMed

    Cognet, L; Tardin, C; Boyer, D; Choquet, D; Tamarat, P; Lounis, B

    2003-09-30

    We performed a visualization of membrane proteins labeled with 10-nm gold nanoparticles in cells, using an all-optical method based on photothermal interference contrast. The high sensitivity of the method and the stability of the signals allows 3D imaging of individual nanoparticles without the drawbacks of photobleaching and blinking inherent to fluorescent markers. A simple analytical model is derived to account for the measurements of the signal amplitude and the spatial resolution. The photothermal interference contrast method provides an efficient, reproducible, and promising way to visualize low amounts of proteins in cells by optical means. PMID:13679586

  16. Three-dimensional imaging of localized surface plasmon resonances of metal nanoparticles.

    PubMed

    Nicoletti, Olivia; de la Peña, Francisco; Leary, Rowan K; Holland, Daniel J; Ducati, Caterina; Midgley, Paul A

    2013-10-01

    The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications. However, the precise interplay between the three-dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum imaging, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization, compressed sensing and electron tomography. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.

  17. Green nanochemistry: metal oxide nanoparticles and porous thin films from bare metal powders.

    PubMed

    Redel, Engelbert; Petrov, Srebri; Dag, Omer; Moir, Jonathon; Huai, Chen; Mirtchev, Peter; Ozin, Geoffrey A

    2012-01-01

    A universal, simple, robust, widely applicable and cost-effective aqueous process is described for a controlled oxidative dissolution process of micrometer-sized metal powders to form high-purity aqueous dispersions of colloidally stable 3-8 nm metal oxide nanoparticles. Their utilization for making single and multilayer optically transparent high-surface-area nanoporous films is demonstrated. This facile synthesis is anticipated to find numerous applications in materials science, engineering, and nanomedicine.

  18. In Situ Synthesis of Metal Sulfide Nanoparticles Based on 2D Metal-Organic Framework Nanosheets.

    PubMed

    Lu, Qipeng; Zhao, Meiting; Chen, Junze; Chen, Bo; Tan, Chaoliang; Zhang, Xiao; Huang, Ying; Yang, Jian; Cao, Feifei; Yu, Yifu; Ping, Jianfeng; Zhang, Zhicheng; Wu, Xue-Jun; Zhang, Hua

    2016-09-01

    A facile in situ synthetic method is developed to synthesize metal sulfide nanoparticles based on 2D M-TCPP (M = Cu, Cd, or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin)) metal-organic framework nanosheets. The obtained CuS/Cu-TCPP composite nanosheet is used as the active material in photoelectrochemical cells, showing notably increased photocurrent due to the improved exciton separation and charge carrier transport.

  19. Metal and Metal Carbide Nanoparticle Synthesis Using Electrical Explosion of Wires Coupled with Epoxide Polymerization Capping.

    PubMed

    Abdelkader, Elseddik M; Jelliss, Paul A; Buckner, Steven W

    2015-06-15

    In this study, metal-containing nanoparticles (NPs) were produced using electrical explosion of wires (EEW) in organic solvents. The explosion chamber was constructed from Teflon to withstand the shockwave, allow growth and reaction of the incipient NPs in various organic solvents containing dissolved ligands, and allow a constant flow of argon to maintain an inert environment. A survey of different transition d-block metals was conducted with metals from groups 4-8, affording metal carbide NPs, while metals from groups 9-12 gave elemental metallic NPs. Tungsten carbide phase WC1-x, which has not been previously isolated as a single-phase material, was exclusively formed during EEW. We used polymerization initiation by electron-rich metallic nanoparticles (PIERMEN) as a capping technique for the nascent NPs with an alkyl epoxide employed as the monomers. Transmission electron microscopy showed spherical particles with the metallic core embedded in a polymer matrix with predominantly smaller particles (<50 nm), but also a broad size distribution with some larger particles (>100 nm). Powder X-ray diffraction (PXRD) was used to confirm the identity of the metallic NPs. The capping agents were characterized using ATR-FTIR spectroscopy. No evidence is observed for the formation of crystalline oxides during EEW for any metals used. Differential scanning calorimetry/thermal gravimetric analysis was used to study the NP's behavior upon heating under an air flow up to 800 °C with the product oxides characterized by PXRD. The bifurcation between metal-carbide NPs and metal NPs correlates with the enthalpy of formation of the product carbides. We observed PIERMEN capping of elemental metal NPs only when the metal has negative standard electrode potentials (relative to a bis(biphenyl) chromium(I)/(0) reference electrode).

  20. Controlling the plasmon resonance of single metal nanoparticles by near-field anisotropic nanoscale photopolymerization.

    PubMed

    Ibn-El-Ahrach, H; Bachelot, R; Lérondel, G; Vial, A; Grimault, A-S; Plain, J; Royer, P; Soppera, O

    2008-03-01

    We propose a new approach for tuning the Surface Plasmon (SP) resonance wavelength using hybrid nanoparticles. Our approach is based on nanoscale photopolymerization around metal nanoparticles. The enhanced optical near-field of silver nanoparticles triggers local photopolymerization. As a result, atomic force microscopy reveals two nanoscale polymerized lobes around nanoparticles, with a controlled effective index distribution. A spectral breaking degeneracy of surface plasmon resonance of the nanoparticles has been demonstrated by polarized extinction spectroscopy.

  1. Synthesis and characterization of diazonium functionalized nanoparticles for deposition on metal surfaces.

    PubMed

    Joselevich, María; Williams, Federico J

    2008-10-21

    Silica nanoparticles were surface-functionalized with diazonium groups. The reaction steps leading to the formation of the diazonium functionality were followed with IR and XPS, and the structure of the diazonium-functionalized nanoparticle was confirmed with solid state NMR. Nanoparticle size distribution was determined with DLS, SEM, and TEM. The nanoparticles were then covalently bonded to gold and iron surfaces. Their spatial distribution over the metal surface was analyzed by SEM. Diazonium modification of nanoparticles represents a new method for the covalent attachment of nanoparticles to metal surfaces.

  2. Comparative study on size dependence of melting temperatures of pure metal and alloy nanoparticles

    SciTech Connect

    Chen, C. L.; Lee, J.-G.; Arakawa, K.; Mori, H.

    2011-07-04

    A comparative study on the size dependence of the melting temperatures of pure metal and alloy nanoparticles has been carried out. It was found that the melting temperatures of Bi-Sn, In-Sn, and Pb-Sn alloy nanoparticles decreased more rapidly with decreasing particle size than those of the constituent metal nanoparticles (Bi, In, Pb, Sn). Namely, the size dependence of the melting temperature was stronger for the alloy nanoparticles than that for the constituent metal nanoparticles. Results calculated with a thermodynamic model were in good agreement with the experimental observations.

  3. Nanoconstruction by welding individual metallic nanowires together using nanoscale solder

    NASA Astrophysics Data System (ADS)

    Peng, Y.; Cullis, A. G.; Inkson, B. J.

    2010-07-01

    This work presents a new bottom-up nanowelding technique enabling building blocks to be assembled and welded together into complex 3D nanostructures using nanovolumes of metal solder. The building blocks of gold nanowires, (Co72Pt28/Pt)n multilayer nanowires, and nanosolder Sn99Au1 alloy nanowires were successfully fabricated by a template technique. Individual metallic nanowires were picked up and assembled together. Conductive nanocircuits were then welded together using similar or dissimilar nanosolder material. At the weld sites, nanoscale volumes of a chosen metal are deposited using nanosolder of a sacrificial nanowire, which ensures that the nanoobjects to be bonded retain their structural integrity. The whole nanowelding process is clean, controllable and reliable, and ensures both mechanically strong and electrically conductive contacts.

  4. Nanochemistry of metals

    NASA Astrophysics Data System (ADS)

    Sergeev, Gleb B.

    2001-10-01

    The results of studies on the nanochemistry of metals published in recent years are generalised. Primary attention is centred on the methods for the synthesis of nanoparticles and their chemical reactions. The means of stabilisation of nanoparticles which involve individual metals and incorporate atoms of several metals are considered as well as their physicochemical properties. Self-assembling processes of nanoparticles are described. The prospects of using metal nanoparticles in semiconductor devices, catalysis, biology and medicine are discussed. The bibliography includes 165 references.

  5. Microbial preparation of metal-substituted magnetite nanoparticles.

    PubMed

    Moon, Ji-Won; Roh, Yul; Lauf, Robert J; Vali, Hojatollah; Yeary, Lucas W; Phelps, Tommy J

    2007-07-01

    A microbial process that exploits the ability of iron-reducing microorganisms to produce copious amounts of extra-cellular metal (M)-substituted magnetite nanoparticles using akaganeite and dopants of dissolved form has previously been reported. The objectives of this study were to develop methods for producing M-substituted magnetite nanoparticles with a high rate of metal substitution by biological processes and to identify factors affecting the production of nano-crystals. The thermophilic and psychrotolerant iron-reducing bacteria had the ability to form M-substituted magnetite nano-crystals (M(y)Fe(3-y)O(4)) from a doped precursor, mixed-M iron oxyhydroxide, (M(x)Fe(1-x)OOH, x< or =0.5, M is Mn, Zn, Ni, Co and Cr). Within the range of 0.01< or =x< or =0.3, using the mixed precursor material enabled the microbial synthesis of more heavily substituted magnetite compared to the previous method, in which the precursor was pure akaganeite and the dopants were present as soluble metal salts. The mixed precursor method was especially advantageous in the case of toxic metals such as Cr and Ni. Also this new method increased the production rate and magnetic properties of the product, while improving crystallinity, size control and scalability.

  6. Resonances of nanoparticles with poor plasmonic metal tips.

    PubMed

    Ringe, Emilie; DeSantis, Christopher J; Collins, Sean M; Duchamp, Martial; Dunin-Borkowski, Rafal E; Skrabalak, Sara E; Midgley, Paul A

    2015-01-01

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd. PMID:26617270

  7. Resonances of nanoparticles with poor plasmonic metal tips

    PubMed Central

    Ringe, Emilie; DeSantis, Christopher J.; Collins, Sean M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Skrabalak, Sara E.; Midgley, Paul A.

    2015-01-01

    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd. PMID:26617270

  8. Removal of Trichloroethylene and Heavy Metals by Zerovalent Iron Nanoparticles

    NASA Astrophysics Data System (ADS)

    Boparai, H. K.; O'Carroll, D. M.

    2009-05-01

    Heavy metals combined with chlorinated solvents are one class of mixed waste found at various hazardous waste sites in North America. Nano zerovalent iron (nZVI), an emerging technology, is being successfully used for treating chlorinated solvents and heavy metals independently, however comparatively little research has investigated the remediation of the wastes when they are present in the same mixture. The remediation of trichloroethylene (TCE)/heavy metal waste mixtures via nZVI has been investigated in the present study. Results suggest that some metals are reduced by nZVI to their zerovalent state and thus precipitate on nZVI particles. This improves the contaminant removal performance of nZVI by forming bimetallic iron nanoparticles. Other metals are directly precipitated or adsorbed on the nZVI particles in their original oxidation state and are rendered immobile. In some cases the presence of the heavy metals in the waste mixture enhanced the dechlorination of TCE while in other cases it did not. This study suggests that nano zerovalent iron particles can be effectively used for the remediation of mixed contamination of heavy metals and chlorinated solvents. Results have been supported by a variety of techniques including X-ray photoelectron spectroscopy (XPS) analysis.

  9. Nanoparticles reduce nickel allergy by capturing metal ions.

    PubMed

    Vemula, Praveen Kumar; Anderson, R Rox; Karp, Jeffrey M

    2011-05-01

    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation. PMID:21460828

  10. Nanoparticles reduce nickel allergy by capturing metal ions

    NASA Astrophysics Data System (ADS)

    Vemula, Praveen Kumar; Anderson, R. Rox; Karp, Jeffrey M.

    2011-05-01

    Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

  11. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    SciTech Connect

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  12. Functionalized magnetite particles for adsorption of colloidal noble metal nanoparticles.

    PubMed

    Lopes, Joana L; Marques, Karine L; Girão, Ana V; Pereira, Eduarda; Trindade, Tito

    2016-08-01

    Magnetite (inverse spinel type) particles have been surface-modified with siliceous shells enriched in dithiocarbamate groups. The deposition of colloidal noble metal nanoparticles (Au, Ag, Pt, Pd) onto the modified magnetites can be performed by treating the respective hydrosols with the magnetic sorbents, thus allowing their uptake from water under a magnetic gradient. In particular, for Au colloids, these magnetic particles are very efficient sorbents that we ascribe to the strong affinity of sulfur-containing groups at the magnetite surfaces for this metal. Considering the extensive use of Au colloids in laboratorial and industrial contexts, the approach described here might have an impact on the development of nanotechnologies to recover this precious metal. En route to these findings, we varied several operational parameters in order to investigate this strategy as a new bottom-up assembly method for producing plasmonic-magnetic nanoassemblies. PMID:27156089

  13. Functionalized magnetite particles for adsorption of colloidal noble metal nanoparticles.

    PubMed

    Lopes, Joana L; Marques, Karine L; Girão, Ana V; Pereira, Eduarda; Trindade, Tito

    2016-08-01

    Magnetite (inverse spinel type) particles have been surface-modified with siliceous shells enriched in dithiocarbamate groups. The deposition of colloidal noble metal nanoparticles (Au, Ag, Pt, Pd) onto the modified magnetites can be performed by treating the respective hydrosols with the magnetic sorbents, thus allowing their uptake from water under a magnetic gradient. In particular, for Au colloids, these magnetic particles are very efficient sorbents that we ascribe to the strong affinity of sulfur-containing groups at the magnetite surfaces for this metal. Considering the extensive use of Au colloids in laboratorial and industrial contexts, the approach described here might have an impact on the development of nanotechnologies to recover this precious metal. En route to these findings, we varied several operational parameters in order to investigate this strategy as a new bottom-up assembly method for producing plasmonic-magnetic nanoassemblies.

  14. Electron beam synthesis of metal and semiconductor nanoparticles using metal-organic frameworks as ordered precursors

    NASA Astrophysics Data System (ADS)

    Jacobs, Benjamin W.; Houk, Ronald J. T.; Wong, Bryan M.; Talin, A. Alec; Allendorf, Mark D.

    2011-09-01

    We demonstrate a versatile, bottom-up method of forming metal and semiconducting nanoparticles by exposing precursor metal-organic frameworks (MOFs) to an electron beam. Using a transmission electron microscope to initiate and observe growth, we show that the composition, size, and morphology of the nanoparticles are determined by the chemistry and structure of the MOF, as well as the electron beam properties. Zinc oxide, metallic indium and copper particles were produced with narrow and tunable size distributions comparable to those obtained from state-of-the-art methods. This method represents a first step toward the fabrication of nanoscale heterostructures using the highly controlled environment of the MOF pores as a scaffold or template.

  15. Metal-Enhanced Fluorescence: Ultrafast Energy Transfer from Dyes in a Polymer Film to Metal Nanoparticles.

    PubMed

    Lee, Jaebeom; Pang, Yoonsoo

    2016-02-01

    Fluorescence from dye molecules dispersed in thin polymer layers increases by 20-25 times when a silver island film exists beneath the layer. Polymer layers of <100 nm thick cover the silver island film to minimize emission quenching from direct contact and also keep the dye molecules in close proximity to the metal nanosurface for possible fluorescence enhancements by silver island film. We report an ultrafast radiation process of ~400 ps lifetime from the surface plasmons of silver nanoparticles observed in time-resolved fluorescence of rhodamine 6G and DCM in thin polymer films coated on silver island surface. The ultrafast energy transfer and fluorescence from metal nanoparticles might be strongly related to the efficiency of metal-enhanced fluorescence. PMID:27433635

  16. Fabrication of Metal and Metal Oxide Nanoparticles by Algae and their Toxic Effects

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-08-01

    Of all the aquatic organisms, algae are a good source of biomolecules. Since algae contain pigments, proteins, carbohydrates, fats, nucleic acids and secondary metabolites such as alkaloids, some aromatic compounds, macrolides, peptides and terpenes, they act as reducing agents to produce nanoparticles from metal salts without producing any toxic by-product. Once the algal biomolecules are identified, the nanoparticles of desired shape or size may be fabricated. The metal and metal oxide nanoparticles thus synthesized have been investigated for their antimicrobial activity against several gram-positive and gram-negative bacterial strains and fungi. Their dimension is controlled by temperature, incubation time, pH and concentration of the solution. In this review, we have attempted to update the procedure of nanoparticle synthesis from algae, their characterization by UV-vis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectroscopy, dynamic light scattering and application in cutting-edge areas.

  17. Fabrication of Metal and Metal Oxide Nanoparticles by Algae and their Toxic Effects.

    PubMed

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-12-01

    Of all the aquatic organisms, algae are a good source of biomolecules. Since algae contain pigments, proteins, carbohydrates, fats, nucleic acids and secondary metabolites such as alkaloids, some aromatic compounds, macrolides, peptides and terpenes, they act as reducing agents to produce nanoparticles from metal salts without producing any toxic by-product. Once the algal biomolecules are identified, the nanoparticles of desired shape or size may be fabricated. The metal and metal oxide nanoparticles thus synthesized have been investigated for their antimicrobial activity against several gram-positive and gram-negative bacterial strains and fungi. Their dimension is controlled by temperature, incubation time, pH and concentration of the solution. In this review, we have attempted to update the procedure of nanoparticle synthesis from algae, their characterization by UV-vis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectroscopy, dynamic light scattering and application in cutting-edge areas. PMID:27530743

  18. Size distributions of metal nanoparticles in polyelectrolyte gels

    NASA Astrophysics Data System (ADS)

    Svergun, D. I.; Shtykova, E. V.; Dembo, A. T.; Bronstein, L. M.; Platonova, O. A.; Yakunin, A. N.; Valetsky, P. M.; Khokhlov, A. R.

    1998-12-01

    Small-angle x-ray scattering is used to study size distributions of noble metal nanoparticles embedded in polyelectrolyte hydrogels with oppositely charged surfactants. A procedure is proposed to subtract matrix scattering and to extract pure scattering due to the nanoparticles allowing to evaluate their size distribution functions by means of a regularization technique. Two kinds of collapsed gel-surfactant complexes were studied: a complex of a cationic gel of poly(diallyldimethylammonium chloride) with an anionic surfactant sodium dodecyl sulfate (PDADMACl/SDS), and that of an anionic gel of poly(methacrylic acid) with a cationic surfactant cetylpyridinium chloride (PMA/CPC). Addition of a gold compound (HAuCl4ṡ3H2O) to the PDADMACl/SDS system forms the metal compound clusters and leads to a partial distortion of the gel structure. After subsequent reduction of the gold compound with sodium borohydride (NaBH4) ordering in the gel disappears and gold nanoparticles are formed. Their size distribution includes a fraction of small particles with approximately the same size as the compound clusters before reduction and a fraction of larger particles with the radii up to 40 nm. For the collapsed PDADMACl/SDS gels, aging does not change the size distribution profile; for the noncollapsed PDADMACl gels without surfactant, metal particles are found to grow with time. This suggests that the aggregation of metal colloids is prevented by the ordering in the collapsed gel-surfactant complex. The addition of HAuCl4ṡ3H2O and the subsequent reduction of the metal ions in the PMA/CPC system does not distort the gel structure as the degree of incorporation of AuCl4- ions is very low. Particle sizes in the PMA/CPC system are found to be somewhat larger than those in the PDADMACl/SDS system. The PDADMACl/SDS gels loaded with the PtCl4 compound were also studied to analyze the influence of the reducing agent type on the particle size distribution distributions. Fast reduction

  19. Organic nano-floating-gate transistor memory with metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Van Tho, Luu; Baeg, Kang-Jun; Noh, Yong-Young

    2016-04-01

    Organic non-volatile memory is advanced topics for various soft electronics applications as lightweight, low-cost, flexible, and printable solid-state data storage media. As a key building block, organic field-effect transistors (OFETs) with a nano-floating gate are widely used and promising structures to store digital information stably in a memory cell. Different types of nano-floating-gates and their various synthesis methods have been developed and applied to fabricate nanoparticle-based non-volatile memory devices. In this review, recent advances in the classes of nano-floating-gate OFET memory devices using metal nanoparticles as charge-trapping sites are briefly reviewed. Details of device fabrication, characterization, and operation mechanisms are reported based on recent research activities reported in the literature.

  20. Few-cycle plasmon oscillations controlling photoemission from metal nanoparticles

    SciTech Connect

    Földi, Péter; Márton, István; Német, Nikolett; Dombi, Péter; Ayadi, Viktor

    2015-01-05

    Few-cycle optical excitation of nanosystems holds promise of fundamental discoveries and applications in ultrafast nanoscience, the development of nanostructured photocathodes, and many more. For these, surface plasmon generation on unprecedented timescales needs to be controlled. For this, few-cycle plasmon oscillations on a metal nanoparticle can be generated by keeping considerable electric field enhancement factors. As an initial application of such a high spatiotemporal localization of an ultrashort laser pulse, we numerically demonstrate the control of photoelectrons on a true sub-fs timescale in nanometric spatial domains. We show that it is only off-resonant nanoparticles that can provide few-cycle plasmons and electron control on this timescale.

  1. Extracellular synthesis of magnetite and metal-substituted magnetite nanoparticles.

    PubMed

    Roh, Y; Vali, H; Phelps, T J; Moon, J W

    2006-11-01

    We have developed a novel microbial process that exploits the ability of Fe(III)-reducing microorganisms to produce copious amounts of extracellular magentites and metal-substituted magnetite nanoparticles. The Fe(III)-reducing bacteria (Theroanaerobacter ethanolicus and Shewanella sp.) have the ability to reduce Fe(III) and various metals in aqueous media and form various sized magnetite and metal-substituted magnetite nano-crystals. The Fe(III)-reducing bacteria formed metalsubstituted magnetites using iron oxide plus metals (e.g., Co, Cr, Mn, Ni) under conditions of relatively low temperature (<70 degrees C), ambient pressure, and pH values near neutral to slightly basic (pH = 6.5 to 9). Precise biological control over activation and regulation of the biosolid-state processes can produce magnetite particles of well-defined size (typically tens of nanometers) and crystallographic morphology, containing selected dopant metals into the magnetite (Fe(3-y)XyO4) structure (where X = Co, Cr, Mn, Ni). Magnetite yields of up to 20 g/L per day have been observed in 20-L vessels. Water-based ferrofluids were formed with the nanometer sized, magnetite, and metal-substituted biomagnetite particles.

  2. Nanoparticle imaging. 3D structure of individual nanocrystals in solution by electron microscopy.

    PubMed

    Park, Jungwon; Elmlund, Hans; Ercius, Peter; Yuk, Jong Min; Limmer, David T; Chen, Qian; Kim, Kwanpyo; Han, Sang Hoon; Weitz, David A; Zettl, A; Alivisatos, A Paul

    2015-07-17

    Knowledge about the synthesis, growth mechanisms, and physical properties of colloidal nanoparticles has been limited by technical impediments. We introduce a method for determining three-dimensional (3D) structures of individual nanoparticles in solution. We combine a graphene liquid cell, high-resolution transmission electron microscopy, a direct electron detector, and an algorithm for single-particle 3D reconstruction originally developed for analysis of biological molecules. This method yielded two 3D structures of individual platinum nanocrystals at near-atomic resolution. Because our method derives the 3D structure from images of individual nanoparticles rotating freely in solution, it enables the analysis of heterogeneous populations of potentially unordered nanoparticles that are synthesized in solution, thereby providing a means to understand the structure and stability of defects at the nanoscale. PMID:26185247

  3. Apoferritin Templated Synthesis of Metal Phosphate Nanoparticle Labels for Electrochemical Immunoassay

    SciTech Connect

    Liu, Guodong; Wu, Hong; Wang, Jun; Lin, Yuehe

    2006-08-29

    W have introduced template-synthesized metal phosphate nanoparticle labels for electrochemical immunoassay. Such use of an apoferritin template offers a simple and convenient route to prepare metallic nanoparticle labels for electrochemical immunoassays and avoid the complicated and time-consuming nanoparticle synthesis process (QD synthesis). Releasing metal ions from metal phosphate in an acetate buffer (pH 4.6) eliminates the harsh condition in the traditional metallic nanoparticle dissolution (e.g., strong acid dissolution of QDs and gold nanoparticles). This method is ultrasensitive and its DL is low to 77fM. The simultaneous detection of multiple protein targets is easily performed by using different metal phosphate nanoparticle labels (cadmium phosphate and lead phosphate). This approach can be extended to prepare multiple metal (such as zinc, lead, cadmium, copper, indium, gold, silver) phosphate nanoparticle labels or hybrid metal (bimetallic or trimetallic with predetermined ratios) phosphate nanoparticle labels for a multiplex electrochemical immunoassay. The new nanoparticle labels could be applicable to other electrochemical bioassays, such as DNA, and is thus expected to lead to wide applications for protein diagnostics and for bioanalysis in general.

  4. Individual and competitive removal of heavy metals using capacitive deionization.

    PubMed

    Huang, Zhe; Lu, Lu; Cai, Zhenxiao; Ren, Zhiyong Jason

    2016-01-25

    This study presents the viability and preference of capacitive deionization (CDI) for removing different heavy metal ions in various conditions. The removal performance and mechanisms of three ions, cadmium (Cd(2+)), lead (Pb(2+)) and chromium (Cr(3+)) were investigated individually and as a mixture under different applied voltages and ion concentrations. It was found that CDI could effectively remove these metals, and the performance was positively correlated with the applied voltage. When 1.2 V was applied into solution containing 0.5mM individual ions, the Cd(2+), Pb(2+), and Cr(3+) removal was 32%, 43%, and 52%, respectively, and the electrosorption played a bigger role in Cd(2+) removal than for the other two ions. Interestingly, while the removal of Pb(2+) and Cr(3+) remained at a similar level of 46% in the mixture of three ions, the Cd(2+) removal significantly decreased to 14%. Similar patterns were observed when 0.05 mM was used to simulate natural contaminated water condition, but the removal efficiencies were much higher, with the removal of Pb(2+), Cr(3+), and Cd(2+) increased to 81%, 78%, and 42%, respectively. The low valence charge and lack of physical sorption of Cd(2+) were believed to be the reason for the removal behavior, and advanced microscopic analysis showed clear deposits of metal ions on the cathode surface after operation.

  5. Redistribution of elements of metals in plant tissues under treatment by non-ionic colloidal solution of biogenic metal nanoparticles

    PubMed Central

    2014-01-01

    The content of metal elements in plant tissues of 10-day wheat seedlings after seed pre-treatment and foliar treatment with non-ionic colloidal solution of metal nanoparticles (Fe, Mn, Cu, Zn) was determined by an atomic absorption spectrometer. It was shown that metal nanoparticles due to their physical properties (nanoscale and uncharged state) were capable of penetrating rapidly into plant cells and optimizing plant metabolic processes at the early stages of growth and development. PMID:25114646

  6. Optical scattering from isolated metal nanoparticles and arrays.

    SciTech Connect

    Wurtz, G. A.; Im, J. S.; Gray, S. K.; Wiederrecht, G. P.; Chemistry

    2003-12-25

    Near-field scanning optical microscopy (NSOM) is used to explore the optical scattering from isolated metal nanoparticles (MNPs) and arrays of MNPs. The optical excitation source is an evanescent wave created through total internal reflection of a continuous wave laser beam at the sample-air interface. For optical excitation of isolated Ag and Au MNPs, experimental results show that the scattered light propagates into the far field at an angle of 19{sup o} from the substrate. Finite-difference time-domain (FDTD) calculations are used to study simpler but related metallic nanowire systems under evanescent wave excitation. The FDTD results are found to be similar to the experimental results, indicating the generality of the scattering phenomenon. NSOM characterization of plasmonic arrays that consist of closely spaced Ag MNPs are subsequently reported. Confined optical signals within the array are observed along with a reduction in the far-field scattered signal. Simultaneous collection of the atomic force microscopy signal and near-field signals also shows that the spatial distribution of the near-field is strongly modified in the arrays compared to isolated MNPs. FDTD studies on arrays of nanowires also show large differences from the isolated metal nanoparticle calculations, including a decrease in the forward scattered angle (with chain length) and diminished overall forward scattering.

  7. Anisotropic metal nanoparticles: Synthesis, assembly, and optical applications.

    PubMed

    Murphy, Catherine J; Sau, Tapan K; Gole, Anand M; Orendorff, Christopher J; Gao, Jinxin; Gou, Linfeng; Hunyadi, Simona E; Li, Tan

    2005-07-28

    This feature article highlights work from the authors' laboratories on the synthesis, assembly, reactivity, and optical applications of metallic nanoparticles of nonspherical shape, especially nanorods. The synthesis is a seed-mediated growth procedure, in which metal salts are reduced initially with a strong reducing agent, in water, to produce approximately 4 nm seed particles. Subsequent reduction of more metal salt with a weak reducing agent, in the presence of structure-directing additives, leads to the controlled formation of nanorods of specified aspect ratio and can also yield other shapes of nanoparticles (stars, tetrapods, blocks, cubes, etc.). Variations in reaction conditions and crystallographic analysis of gold nanorods have led to insight into the growth mechanism of these materials. Assembly of nanorods can be driven by simple evaporation from solution or by rational design with molecular-scale connectors. Short nanorods appear to be more chemically reactive than long nanorods. Finally, optical applications in sensing and imaging, which take advantage of the visible light absorption and scattering properties of the nanorods, are discussed. PMID:16852739

  8. Behavior of metallic nanoparticles in Al matrix under high electronic energy deposition

    NASA Astrophysics Data System (ADS)

    Rizza, G.; Dunlop, A.; Dezellus, A.

    2007-03-01

    Metallic nanoparticles (Pb and Bi) embedded in a crystalline Al matrix were irradiated with 30 MeV C60 cluster ions at 300 K. Experimental evidence of partial amorphization of bismuth nanoparticles is observed. On the other hand, Pb inclusions remain crystalline. The condition under which embedded nanoparticles can be amorphized is discussed.

  9. Oil Phase Evaporation Induced Self-Assembly of Hydrophobic Nanoparticles into Spherical Clusters with Controlled Surface Chemistry in an Oil-in-Water Dispersion and Comparison of Behaviors of Individual and Clustered Iron Oxide Nanoparticles

    PubMed Central

    Qiu, Penghe; Jensen, Christina; Charity, Njoku; Towner, Rheal; Mao, Chuanbin

    2010-01-01

    We report a general method for preparing nanoparticle clusters (NPCs) in an oil-in-water emulsion system mediated by cetyl trimethylammonium bromide (CTAB) where previously, only individual nanoparticles were obtained. NPCs of magnetic, metallic and semiconductor nanoparticles have been prepared to demonstrate the generality of the method. The NPCs were spherical and composed of densely packed individual nanoparticles. The number density of nanoparticles in the oil phase was found to be critical for the formation, morphology and yield of NPCs. The method developed here is scalable and can produce NPCs in nearly 100% yield at a concentration of 5 mg/ml in water which is approximately 5 times higher than the highest value reported in literature. The surface chemistry of NPCs can also be controlled by replacing CTAB with polymers containing different functional groups via a similar procedure. The reproducible production of NPCs with well defined shapes has allowed us to compare the properties of individual and clustered iron oxide nanoparticles including magnetization, magnetic moments and contrast enhancement in magnetic resonance imaging (MRI). We found that due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in MRI. PMID:21117657

  10. Present status and future outlook of selective metallization for electronics industry by laser irradiation to metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira

    2015-03-01

    Recently an alternative to conventional methods based on vacuum processes such as evaporation or sputtering is desired to reduce the energy consumption and the environmental impact. Printed electronics has been developed as a one of the candidates, which is based on wet processes using soluble functional materials such as organic semiconductors, inorganic nanomaterials, organic-inorganic hybrids, and so on. Although inkjet printing has been studied widely as a core technology of printed electronics, the limitation of resolution is around 20 micrometer. The combination of the inkjet printing with other selective metallization process is necessary because the resolution of several micrometers is required in some optical and electrical devices. The laser processing has emerged as an attractive technique in microelectronics because of the fascinating features such as high resolution, high degree of flexibility to control the resolution and size of the micro-patterns, high speed, and a little environmental pollution. In this paper, the present status and future outlook of selective metallization for interconnection and the formation of transparent conductive film based on the laser processing using metal nanoparticles were reported. The laser beam irradiation to metal nanoparticles causes the fast and efficient sintering by plasmon resonance of metal nanoparticle, where the absorbed energy is confined in a nanoparticle and the nanoparticle acts as a nano-heater. The laser irradiation to metal nanoparticles was applied to the laser direct writing of metal wiring and micropatterns using silver and copper nanoparticles.

  11. A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles.

    PubMed

    Abedini, Alam; Daud, Abdul Razak; Abdul Hamid, Muhammad Azmi; Kamil Othman, Norinsan; Saion, Elias

    2013-01-01

    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.

  12. Copper oxide nanoparticles are highly toxic: a comparison between metal oxide nanoparticles and carbon nanotubes.

    PubMed

    Karlsson, Hanna L; Cronholm, Pontus; Gustafsson, Johanna; Möller, Lennart

    2008-09-01

    Since the manufacture and use of nanoparticles are increasing, humans are more likely to be exposed occupationally or via consumer products and the environment. However, so far toxicity data for most manufactured nanoparticles are limited. The aim of this study was to investigate and compare different nanoparticles and nanotubes regarding cytotoxicity and ability to cause DNA damage and oxidative stress. The study was focused on different metal oxide particles (CuO, TiO2, ZnO, CuZnFe2O4, Fe3O4, Fe2O3), and the toxicity was compared to that of carbon nanoparticles and multiwalled carbon nanotubes (MWCNT). The human lung epithelial cell line A549 was exposed to the particles, and cytotoxicity was analyzed using trypan blue staining. DNA damage and oxidative lesions were determined using the comet assay, and intracellular production of reactive oxygen species (ROS) was measured using the oxidation-sensitive fluoroprobe 2',7'-dichlorofluorescin diacetate (DCFH-DA). The results showed that there was a high variation among different nanoparticles concerning their ability to cause toxic effects. CuO nanoparticles were most potent regarding cytotoxicity and DNA damage. The toxicity was likely not explained by Cu ions released to the cell medium. These particles also caused oxidative lesions and were the only particles that induced an almost significant increase (p = 0.058) in intracellular ROS. ZnO showed effects on cell viability as well as DNA damage, whereas the TiO2 particles (a mix of rutile and anatase) only caused DNA damage. For iron oxide particles (Fe3O4, Fe2O3), no or low toxicity was observed, but CuZnFe2O4 particles were rather potent in inducing DNA lesions. Finally, the carbon nanotubes showed cytotoxic effects and caused DNA damage in the lowest dose tested. The effects were not explained by soluble metal impurities. In conclusion, this study highlights the in vitro toxicity of CuO nanoparticles.

  13. Ballistic-diffusive approximation for the thermal dynamics of metallic nanoparticles in nanocomposite materials

    SciTech Connect

    Shirdel-Havar, A. H. Masoudian Saadabad, R.

    2015-03-21

    Based on ballistic-diffusive approximation, a method is presented to model heat transfer in nanocomposites containing metal nanoparticles. This method provides analytical expression for the temperature dynamics of metallic nanoparticles embedded in a dielectric medium. In this study, nanoparticles are considered as spherical shells, so that Boltzmann equation is solved using ballistic-diffusive approximation to calculate the electron and lattice thermal dynamics in gold nanoparticles, while thermal exchange between the particles is taken into account. The model was used to investigate the influence of particle size and metal concentration of the medium on the electron and lattice thermal dynamics. It is shown that these two parameters are crucial in determining the nanocomposite thermal behavior. Our results showed that the heat transfer rate from nanoparticles to the matrix decreases as the nanoparticle size increases. On the other hand, increasing the metal concentration of the medium can also decrease the heat transfer rate.

  14. Selective Catalysis in Nanoparticle Metal-Organic Framework Composites

    NASA Astrophysics Data System (ADS)

    Stephenson, Casey Justin

    The design of highly selective catalysts are becoming increasingly important, especially as chemical and pharmaceutical industries seek to improve atom economy and minimize energy intensive separations that are often required to separate side products from the desired product. Enzymes are among the most selective of all catalysts, generally operating through molecular recognition whereby an active site analogous to a lock and the substrate is analogous to a key. The assembly of a porous, crystalline material around a catalytically active metal particle could serve as an artificial enzyme. In this vein, we first synthesized the polyvinylpyrrolidone (PVP) coated nanoparticles of interest and then encapsulated them within zeolitic imidazolate framework 8 or ZIF-8. 2.8 nm Pt-PVP nanoparticles, which were encapsulated within ZIF-8 to form Pt ZIF-8 composite. Pt ZIF-8 was inactive for the hydrogenation of cyclic olefins such as cis-cyclooctene and cis-cyclohexene while the composite proved to be a highly selective catalyst for the hydrogenation of terminal olefins, hydrogenating trans-1,3-hexadiene to 3-hexene in 95% selectivity after 24 hours under 1 bar H2. We extended our encapsulation method to sub-2 nm Au nanoparticles to form Au ZIF-8. Au ZIF-8 served as a highly chemoselective catalyst for the hydrogenation of crotonaldehyde an alpha,beta-unsaturated aldehyde, to crotyl alcohol an alpha,beta-unsaturated alcohol, in 90-95% selectivity. In order to investigate nanoparticle size effects on selectivity, 6-10 nm Au nanoparticles were encapsulated within ZIF-8 to form Au6 ZIF-8. Control catalysts with nanoparticles supported on the surface of ZIF-8 were synthesized as well, Au/ZIF-8 and Au6/ZIF-8. Au6 ZIF-8 hydrogenated crotonaldehyde in 85% selectivity towards the unsaturated alcohol. Catalysts with nanoparticles supported on the exterior of ZIF-8 were far less selective towards the unsaturated alcohol. Post-catalysis transmission electron microscopy analysis of Au ZIF

  15. Coupling of Acoustic Vibrations to Plasmon Resonances in Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahmed, Aftab; Pelton, Matthew; Guest, Jeffrey

    Measurements of acoustic vibrations in nanoparticles provide a unique opportunity to study mechanical phenomena at nanometer length scales and picosecond time scales. Phonon vibrations of plasmonic nanoparticles are of particular interest, due to their large extinction efficiencies, and high sensitivity to surrounding medium. There are two mechanisms that transduce the mechanical oscillations into plasmon resonance shift: (1) changes in polarizability; and (2) changes in electron density. These mechanisms have been used to explain qualitatively the origin of the transient-absorption signals, however, a quantitative connection has not yet been made except for simple geometries. Here, we present a method to quantitatively determine the coupling between vibrational modes and plasmon modes in noble-metal nanoparticles including spheres, shells, rods and cubes. We separately determine the parts of the optical response that are due to shape changes and to changes in electron density, and we relate the optical signals to the symmetries of the vibrational and plasmon modes. These results clarify reported experimental results, and should help guide the optimization of future experiments.

  16. Incorporation of Metallic Nanoparticles into Conducting Polymer Actuator Films

    NASA Astrophysics Data System (ADS)

    Costa, Alexsandro Santos; Li, Kwong-Chi; Kilmartin, Paul A.; Travas-Sejdic, Jadranka

    2009-07-01

    Nanocomposites of conducting polymer films (CP) with metal nanoparticles have been prepared. Electropolymerization of pyrrole on stainless steel electrodes was undertaken galvanostatically until the thickness of the polypyrrole (PPy) film reached around 7.5 μm, which is suitable for the future application of these films in micropumps and microvalves. Subsequently platinum nanoparticles were deposited from a solution of a platinum precursor (K2PtCl6) onto the PPy coated stainless steel electrodes by applying a potential of -0.1 V for between 3 and 15 s. The length of the deposition time led to significant differences in the morphology and size of the particles obtained. The actuation of the free standing films was studied by electrochemomechanical deformation measurements (ECMD) on strips of films cycled in NaPF6. Depending upon the test conditions, the strain rate and ultimate strain of films containing Pt nanoparticles could be increased by a factor of 2 or more compared to those of pristine PPy films.

  17. Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism

    PubMed Central

    Margeat, Olivier; Lecante, Pierre; Chaudret, Bruno

    2010-01-01

    Summary The results of the investigation of the structural and magnetic (static and dynamic) properties of an assembly of metallic Fe nanoparticles synthesized by an organometallic chemical method are described. These nanoparticles are embedded in a polymer, monodisperse, with a diameter below 2 nm, which corresponds to a number of around 200 atoms. The X-ray absorption near-edge structure and Mössbauer spectrum are characteristic of metallic Fe. The structural studies by wide angle X-ray scattering indicate an original polytetrahedral atomic arrangement similar to that of β-Mn, characterized by a short-range order. The average magnetic moment per Fe atom is raised to 2.59 µB (for comparison, bulk value of metallic Fe: 2.2 µB). Even if the spontaneous magnetization decreases rapidly as compared to bulk materials, it remains enhanced even up to room temperature. The gyromagnetic ratio measured by ferromagnetic resonance is of the same order as that of bulk Fe, which allows us to conclude that the orbital and spin contributions increase at the same rate. A large magnetic anisotropy for metallic Fe has been measured up to (3.7 ± 1.0)·105 J/m3. Precise analysis of the low temperature Mössbauer spectra, show a broad distribution of large hyperfine fields. The largest hyperfine fields display the largest isomer shifts. This indicates a progressive increase of the magnetic moment inside the particle from the core to the outer shell. The components corresponding to the large hyperfine fields with large isomer shifts are indeed characteristic of surface atoms. PMID:21977400

  18. Deposition of metal nanoparticles on phospholipid multilayer membranes modified by gramicidin.

    PubMed

    Han, Won Bae; Kim, Yongdeok; An, Hyeun Hwan; Kim, Hee-Soo; Yoon, Chong Seung

    2013-10-29

    A planar dipalmitoyl phosphatidylcholine (DPPC) multilayer phospholipid membrane was structurally modified by introducing a transmembrane protein, gramicidin (up to 25 mol %), to study its effect on the metal nanoparticles deposited on the membrane. Without gramicidin, when 3-nm-thick Ag, Sn, Al, and Au were deposited, the nanoparticles hardly nucleated on the DPPC membrane in rigid gel state (except for Au); however, the gramicidin addition dramatically enhanced the DPPC membrane surface's affinity for metal atoms so that a dense array of metal (Ag, Sn, and Au) or metal-oxide (Al-oxide) nanoparticles was produced on the membrane surface. The particle sizes ranged from 3 to 15 nm depending on the metal and gramicidin concentration, whereas the particle density was strongly dictated by the gramicidin concentration. The proposed method provides a convenient, generally applicable synthesis route for preparing different metal or metal-oxide nanoparticles on a relatively robust biocompatible membrane.

  19. Systematic investigation of the synthesis, characterization and switching mechanism of metal oxide nanoparticle resists

    NASA Astrophysics Data System (ADS)

    Siauw, Meiliana; Du, Ke; Valade, David; Trefonas, Peter; Thackeray, James W.; Whittaker, Andrew; Blakey, Idriss

    2016-03-01

    Metal oxide nanoparticle resists have recently emerged as next generation photoresist materials which exhibit promising performance for extreme ultraviolet lithography. In this present work, we are able to show our ability to synthesize and well characterize small uniform metal oxide nanoparticles, to present stability study of the nanoparticles in the resist solvent over time, to pattern ~20 nm features by electron beam lithography, and to provide an insight into the insolubilization mechanism of the resist system.

  20. Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rupam; Huang, Zhi-Feng; Nadgorny, Boris

    2014-10-01

    Multiple percolation transitions are observed in a binary system of RuO2-CaCu3Ti4O12 metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO2 metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.

  1. Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

    SciTech Connect

    Mukherjee, Rupam; Huang, Zhi-Feng; Nadgorny, Boris

    2014-10-27

    Multiple percolation transitions are observed in a binary system of RuO{sub 2}-CaCu{sub 3}Ti{sub 4}O{sub 12} metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO{sub 2} metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.

  2. Laser induced mechanisms controlling the size distribution of metallic nanoparticles.

    PubMed

    Liu, Zeming; Vitrant, Guy; Lefkir, Yaya; Bakhti, Said; Destouches, Nathalie

    2016-09-21

    This paper describes a model to simulate changes in the size distribution of metallic nanoparticles (NPs) in TiO2 films upon continuous wave light excitation. Interrelated laser induced physical and chemical processes initiated directly by photon absorption or by plasmon induced thermal heating are considered. Namely the model takes into account the NP coalescence, Ostwald ripening, the reduction of silver ions and the oxidation of metallic NPs, competitive mechanisms that can lead to counter-intuitive behaviors depending on the exposure conditions. Theoretical predictions are compared successfully to the experimental results deduced from a thorough analysis of scanning transmission electron microscopy (STEM) pictures of Ag:TiO2 films processed with a scanning visible laser beam at different speeds. Ag:TiO2 systems are considered for many applications in solar energy conversion, photocatalysis or secured data printing. Numerical investigations of such a system provide a better understanding of light induced growth and shrinking processes and open up prospects for designing more efficient photocatalytic devices based on metal NP doped TiO2 or for improving the size homogeneity in self-organized metallic NP patterns, for instance. PMID:27539293

  3. Greener syntheses of metallic nanoparticles and zinc oxide nanopowders

    NASA Astrophysics Data System (ADS)

    Samson, Jacopo

    In recent years, nanotechnology and nanomaterials synthesis have attracted a great deal of attention in the scientific community. Nanomaterials display size and morphology-related optical properties that differ from their bulk counterparts and therefore can be used for many applications in different fields such as biomedicine, electronics, antibacterial agents, and energy. Attempts to fabricate different morphologies of metallic and metal oxide nanoparticles (NPs) have successfully yielded attractive nanostructures such as particles, rods, helices, combs, tetra-pods, and flowers, all displaying properties mainly related to their enhanced surface area and/or aspect ratios. Most of the above mentioned nanomaterials productions have employed harsh synthetic routes such as high temperatures, low pressures, and the use of costly equipments. Here we show how a greener approach to nanomaterials synthesis is feasible with both minimization of aqueous precursors, energy and employment of a multi-block heater for temperature control. We present in this thesis several methods for the preparation of NPs of several materials that focus on minimizing the environmental impact of the synthesis itself. First, we describe the use of the toroidal form of plasmid DNA as a rigid narrowly dispersed bio-polymeric nanocavity, which mold the formation of disc-shaped nanoparticles of several types of metals. This approach exploits several properties of plasmid DNA: (a) DNA affinity for metal cations, (b) toroidal plasmid DNA structures which are favored by metal ionic binding, and (c) the ability to vary plasmid size. Herein, we present a complementary synthetic method based on a kinetic approach wherein the plasmid DNA acts as a template to initiate and control the formation of Au and other metallic NPs by incubation at elevated temperatures. Also reported herein is a simple, scalable hydrothermal method to make ZnO NPs that exploits temperature to precisely control the range of pH values

  4. Nickel and platinum group metal nanoparticle production by Desulfovibrio alaskensis G20.

    PubMed

    Capeness, M J; Edmundson, M C; Horsfall, L E

    2015-12-25

    Desulfovibrio alaskensis G20 is an anaerobic sulfate reducing bacteria. While Desulfovibrio species have previously been shown to reduce palladium and platinum to the zero-state, forming nanoparticles in the process; there have been no reports that D. alaskensis is able to form these nanoparticles. Metal nanoparticles have properties that make them ideal for use in many industrial and medical applications, such as their size and shape giving them higher catalytic activity than the bulk form of the same metal. Nanoparticles of the platinum group metals in particular are highly sought after for their catalytic ability and herein we report the formation of both palladium and platinum nanoparticles by D. alaskensis and the biotransformation of solvated nickel ions to nanoparticle form.

  5. Investigation of laser heating effect of metallic nanoparticles on cancer treatment

    NASA Astrophysics Data System (ADS)

    Shan, G. S.; Liu, X. M.; Chen, H. J.; Yu, J. S.; Chen, X. D.; Yao, Y.; Qi, L. M.; Chen, Z. J.

    2016-07-01

    Metallic nanoparticles can be applied for hyperthermia therapy of cancer treatment to enhance the efficacy because of their high absorption rate. The absorption of laser energy by metallic nanoparticles is strongly dependent on the concentration, shape, material of nanoparticles and the wavelength of the laser. However, there is no systematic investigation on the heating effect involving different material, concentration and laser wavelength. In this paper, gold nanoparticles (AuNPs), sliver nanoparticles (AgNPs) and sliver nanowires (AgNWs) with different concentrations are heated by 450nm and 532nm wavelength laser to investigate the heating effect. The result shows that the temperature distribution of heated metallic nanoparticles is non-uniform.

  6. Charge Transfer Stabilization of Late Transition Metal Oxide Nanoparticles on a Layered Niobate Support.

    PubMed

    Strayer, Megan E; Senftle, Thomas P; Winterstein, Jonathan P; Vargas-Barbosa, Nella M; Sharma, Renu; Rioux, Robert M; Janik, Michael J; Mallouk, Thomas E

    2015-12-30

    Interfacial interactions between late transition metal/metal oxide nanoparticles and oxide supports impact catalytic activity and stability. Here, we report the use of isothermal titration calorimetry (ITC), electron microscopy and density functional theory (DFT) to explore periodic trends in the heats of nanoparticle-support interactions for late transition metal and metal oxide nanoparticles on layered niobate and silicate supports. Data for Co(OH)2, hydroxyiridate-capped IrOx·nH2O, Ni(OH)2, CuO, and Ag2O nanoparticles were added to previously reported data for Rh(OH)3 grown on nanosheets of TBA0.24H0.76Ca2Nb3O10 and a layered silicate. ITC measurements showed stronger bonding energies in the order Ag < Cu ≈ Ni ≈ Co < Rh < Ir on the niobate support, as expected from trends in M-O bond energies. Nanoparticles with exothermic heats of interaction were stabilized against sintering. In contrast, ITC measurements showed endothermic interactions of Cu, Ni, and Rh oxide/hydroxide nanoparticles with the silicate and poor resistance to sintering. These trends in interfacial energies were corroborated by DFT calculations using single-atom and four-atom cluster models of metal/metal oxide nanoparticles. Density of states and charge density difference calculations reveal that strongly bonded metals (Rh, Ir) transfer d-electron density from the adsorbed cluster to niobium atoms in the support; this mixing is absent in weakly binding metals, such as Ag and Au, and in all metals on the layered silicate support. The large differences between the behavior of nanoparticles on niobate and silicate supports highlight the importance of d-orbital interactions between the nanoparticle and support in controlling the nanoparticles' stability. PMID:26651875

  7. Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

    PubMed Central

    Schmidt, Cédric; Riporto, Jérémy; Uldry, Aline; Rogov, Andrii; Mugnier, Yannick; Dantec, Ronan Le; Wolf, Jean-Pierre; Bonacina, Luigi

    2016-01-01

    We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors. PMID:27140074

  8. Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

    NASA Astrophysics Data System (ADS)

    Schmidt, Cédric; Riporto, Jérémy; Uldry, Aline; Rogov, Andrii; Mugnier, Yannick; Dantec, Ronan Le; Wolf, Jean-Pierre; Bonacina, Luigi

    2016-05-01

    We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors.

  9. Metal-Based Nanoparticles and the Immune System: Activation, Inflammation, and Potential Applications

    PubMed Central

    Luo, Yueh-Hsia; Chang, Louis W.; Lin, Pinpin

    2015-01-01

    Nanomaterials, including metal-based nanoparticles, are used for various biological and medical applications. However, metals affect immune functions in many animal species including humans. Different physical and chemical properties induce different cellular responses, such as cellular uptake and intracellular biodistribution, leading to the different immune responses. The goals of this review are to summarize and discuss the innate and adaptive immune responses triggered by metal-based nanoparticles in a variety of immune system models. PMID:26125021

  10. A general phase transfer protocol for synthesizing alkylamine-stabilized nanoparticles of noble metals.

    PubMed

    Yang, J; Lee, Jim Yang; Too, Heng-Phon

    2007-04-01

    The ethanol-mediated phase transfer protocol was extended herein to prepare alkylamine-stabilized nanoparticles of several noble metals by transferring them from aqueous environment into toluene. This method relies on the use of ethanol as a mediator to provide and maintain adequate contact between dodecylamine and metal nanoparticles during the transfer process and involves first mixing the metal hydrosols and an ethanol solution of dodecylamine and then extracting the dodecylamine-stabilized metal nanoparticles into toluene. Alkylamine-stabilized Ag, Pd, Rh, Ir and Os nanoparticles with 7.09, 3.45, 6.89, 2.42 and 4.52 nm in diameter, respectively, could be prepared this way. The self-assembly of dodecylamine-stabilized Ag and Rh nanoparticles was also detected by transmission electron microscopy (TEM).

  11. Dynamics of laser induced metal nanoparticle and pattern formation

    SciTech Connect

    Peláez, R. J. Kuhn, T.; Rodríguez, C. E.; Afonso, C. N.

    2015-02-09

    Discontinuous metal films are converted into either almost round, isolated, and randomly distributed nanoparticles (NPs) or fringed patterns of alternate non transformed film and NPs by exposure to single pulses (20 ns pulse duration and 193 nm wavelength) of homogeneous or modulated laser beam intensity. The dynamics of NPs and pattern formation is studied by measuring in real time the transmission and reflectivity of the sample upon homogeneous beam exposure and the intensity of the diffraction orders 0 and 1 in transmission configuration upon modulated beam exposure. The results show that laser irradiation induces melting of the metal either completely or at regions around intensity maxima sites for homogeneous and modulated beam exposure, respectively, within ≤10 ns. The aggregation and/or coalescence of the initially irregular metal nanostructures is triggered upon melting and continues after solidification (estimated to occur at ≤80 ns) for more than 1 μs. The present results demonstrate that real time transmission rather than reflectivity measurements is a valuable and easy-to-use tool for following the dynamics of NPs and pattern formation. They provide insights on the heat-driven processes occurring both in liquid and solid phases and allow controlling in-situ the process through the fluence. They also evidence that there is negligible lateral heat release in discontinuous films upon laser irradiation.

  12. Encapsulation of Mono- or Bimetal Nanoparticles Inside Metal-Organic Frameworks via In situ Incorporation of Metal Precursors.

    PubMed

    Chen, Liyu; Chen, Xiaodong; Liu, Hongli; Li, Yingwei

    2015-06-10

    A facile, in situ metal precursor incorporation strategy is established for good control over the location and composition of metal nanoparticles within metal-organic frameworks (MOFs). This one-step metal precursor incorporation route is successfully applied to the fabrication of ultrafine Pd, Ni, and PdNi alloys to be selectively encapsulated inside the pores of MOFs, achieving superior catalytic activity and stability in the hydrogenation of nitrobenzene.

  13. Role of metal nanoparticles on porosification of silicon by metal induced etching (MIE)

    NASA Astrophysics Data System (ADS)

    Saxena, Shailendra K.; Yogi, Priyanka; Yadav, Pooja; Mishra, Suryakant; Pandey, Haardik; Rai, Hari Mohan; Kumar, Vivek; Sagdeo, Pankaj R.; Kumar, Rajesh

    2016-06-01

    Porosification of silicon (Si) by metal induced etching (MIE) process has been studied here to understand the etching mechanism. The etching mechanism has been discussed on the basis of electron transfer from Si to metal ion (Ag+) and metal to H2O2. Role of silver nanoparticles (AgNPs) in the etching process has been investigated by studying the effect of AgNPs coverage on surface porosity. A quantitative analysis of SEM images, done using Image J, shows a direct correlation between AgNPs coverage and surface porosity after the porosification. Density of Si nanowires (NWs) also varies as a function of AgNPs fractional coverage which reasserts the fact that AgNPs governs the porosification process during MIE. The Raman and PL spectrum show the presence of Si NSs in the samples.

  14. Engineered metal nanoparticles in the sub-nanomolar levels kill cancer cells

    PubMed Central

    Vodyanoy, Vitaly; Daniels, Yasmine; Pustovyy, Oleg; MacCrehan, William A; Muramoto, Shin; Stan, Gheorghe

    2016-01-01

    Background Small metal nanoparticles obtained from animal blood were observed to be toxic to cultured cancer cells, whereas noncancerous cells were much less affected. In this work, engineered zinc and copper metal nanoparticles were produced from bulk metal rods by an underwater high-voltage discharge method. The metal nanoparticles were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The metal nanoparticles, with estimated diameters of 1 nm–2 nm, were determined to be more than 85% nonoxidized. A cell viability assay and high-resolution light microscopy showed that exposure of RG2, cultured rat brain glioma cancer cells, to the zinc and copper nanoparticles resulted in cell morphological changes, including decreased cell adherence, shrinking/rounding, nuclear condensation, and budding from cell bodies. The metal-induced cell injuries were similar to the effects of staurosporine, an active apoptotic reagent. The viability experiments conducted for zinc and copper yielded values of dissociation constants of 0.22±0.08 nmol/L (standard error [SE]) and 0.12±0.02 nmol/L (SE), respectively. The noncancerous astrocytes were not affected at the same conditions. Because metal nanoparticles were lethal to the cancer cells at sub-nanomolar concentrations, they are potentially important as nanomedicine. Purpose Lethal concentrations of synthetic metal nanoparticles reported in the literature are a few orders of magnitude higher than the natural, blood-isolated metal nanoparticles; therefore, in this work, engineered metal nanoparticles were examined to mimic the properties of endogenous metal nanoparticles. Materials and methods RG2, rat brain glioma cells CTX TNA2 brain rat astrocytes, obtained from the American Type Culture Collection, high-voltage discharge, atomic force microscope, X-ray photoelectron spectroscopy, high-resolution light microscopy, zeta potential measurements, and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium

  15. Salt-Driven Deposition of Thermoresponsive Polymer-Coated Metal Nanoparticles on Solid Substrates.

    PubMed

    Zhang, Zhiyue; Maji, Samarendra; da Fonseca Antunes, André B; De Rycke, Riet; Hoogenboom, Richard; De Geest, Bruno G

    2016-06-13

    Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble-metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer-like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt-free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion-induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer-coated nanoparticles and a hydrophobic substrate. PMID:27142455

  16. Effect of metal-liquid interface composition on the adsorption of a cyanine dye onto gold nanoparticles.

    PubMed

    Guerrini, Luca; Jurasekova, Zuzana; del Puerto, Elena; Hartsuiker, Liesbeth; Domingo, Concepcion; Garcia-Ramos, Jose Vicente; Otto, Cees; Sanchez-Cortes, Santiago

    2013-01-29

    Synthesis of asymmetric nanoparticles, such as gold nanorods, with tunable optical properties providing metal structures with improved SERS performance is playing a critical role in expanding the use of SERS to imaging and sensing applications. However, the synthetic methods usually require surfactants or polymers as shape-directing agents. These chemicals normally remain firmly bound to the metal after the synthesis, preventing the direct adsorption of a large number of potential analytes and often hampering the chemical functionalization of the surface unless extended, and critical for the nanoparticle stability, postremoval steps were performed. For this reason, it is of great importance for the full exploitation of these nanostructures to gain a deeper insight into the dependence of the analyte-metal interaction to the metal-liquid interface composition. In this article, we investigated in detail the role played by each component of the gold nanorod (GNR) interface in the adsorption of indocyanine green (ICG) as a probe molecule. Citrate-reduced gold nanospheres were used as a model substrate since the negative citrate anions adsorbed onto the metal surface can be easily displaced by those chemicals usually involved in the GNR synthesis, allowing the GNR-like interface composition to be progressively rebuilt and modified at will on the citrate-capped nanoparticles. The obtained results provide a meticulous description of the role played by each individual component of the metal-liquid interface on the ICG interaction with the metal, illustrating how apparently minor experimental changes can dramatically modify the affinity and optical properties of the ICG probe adsorbed onto the nanoparticle.

  17. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    NASA Astrophysics Data System (ADS)

    Akman, O.; Kavas, H.; Baykal, A.; Toprak, M. S.; Çoruh, Ali; Aktaş, B.

    2013-02-01

    Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications.

  18. Synthesis and optical properties of anisotropic metal nanoparticles.

    PubMed

    Hao, Encai; Schatz, George C; Hupp, Joseph T

    2004-07-01

    In this paper we overview our recent studies of anisotropic noble metal (e.g. gold and silver) nanoparticles, in which a combination of theory and experiment has been used to elucidate the extinction spectra of the particles, as well as information related to their surface enhanced Raman spectroscopy. We used wet-chemical methods to generate several structurally well-defined nanostructures other than solid spheres, including silver nanodisks and triangular nanoprisms, and gold nanoshells and multipods. When solid spheres are transformed into one of these shapes, the surface plasmon resonances in these particles are strongly affected, typically red-shifting and even splitting into distinctive dipole and quadrupole plasmon modes. In parallel, we have developed computational electrodynamics methods based on the discrete dipole approximation (DDA) method to determine the origins of these intriguing optical features. This has resulted in considerable insight concerning the variation of plasmon wavelength with nanoparticle size, shape and dielectric environment, as well as the use of these particles for optical sensing applications. PMID:15617376

  19. Inhomogeneous depletion of oxygen ions in metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vykhodets, Vladimir B.; Jarvis, Emily A. A.; Kurennykh, Tatiana E.; Beketov, Igor V.; Obukhov, Sviatoslav I.; Samatov, Oleg M.; Medvedev, Anatoly I.; Davletshin, Andrey E.; Whyte, Travis H.

    2016-02-01

    Zirconia and yttria stabilized zirconia (YSZ) have multiple uses, including catalysis, fuel cells, dental applications, and thermal coatings. We employ nuclear reaction analysis to determine elemental composition of YSZ nanoparticles synthesized by laser evaporation including 18O studies to distinguish between oxide and adsorbed oxygen content as a function of surface area. We see dramatic deviation from stoichiometry that can be traced to loss of oxygen from the oxide near the surface of these nanopowders. Density functional calculations are coupled with these experimental studies to explore the electronic structure of nonstoichiometric surfaces achieved through depletion of oxygen. Our results show oxygen-depleted surfaces present under oxygen potentials where stoichiometric, oxygen-terminated surfaces would be favored thermodynamically for crystalline systems. Oxygen depletion at nanopowder surfaces can create effective two-dimensional surface metallic states while maintaining stoichiometry in the underlying nanoparticle core. This insight into nanopowder surfaces applies to dissimilar oxides of aluminum and zirconium indicating synthesis conditions may be more influential than the inherent oxide properties and displaying need for distinct models for nanopowders of these important engineering materials where surface chemistry dominates performance.

  20. Plasmon-induced hot carriers in metallic nanoparticles.

    PubMed

    Manjavacas, Alejandro; Liu, Jun G; Kulkarni, Vikram; Nordlander, Peter

    2014-08-26

    Plasmon-induced hot carrier formation is attracting an increasing research interest due to its potential for applications in photocatalysis, photodetection and solar energy harvesting. However, despite very significant experimental effort, a comprehensive theoretical description of the hot carrier generation process is still missing. In this work we develop a theoretical model for the plasmon-induced hot carrier process and apply it to spherical silver nanoparticles and nanoshells. In this model, the conduction electrons of the metal are described as free particles in a finite spherical potential well, and the plasmon-induced hot carrier production is calculated using Fermi’s golden rule. We show that the inclusion of many-body interactions has only a minor influence on the results. Using the model we calculate the rate of hot carrier generation, finding that it closely follows the spectral profile of the plasmon. Our analysis reveals that particle size and hot carrier lifetime play a central role in determining both the production rate and the energy distribution of the hot carriers. Specifically, larger nanoparticle sizes and shorter lifetimes result in higher carrier production rates but smaller energies, and vice versa. We characterize the efficiency of the hot carrier generation process by introducing a figure of merit that measures the number of high energy carriers generated per plasmon. Furthermore, we analyze the spatial distribution and directionality of these excitations. The results presented here contribute to the basic understanding of plasmon-induced hot carrier generation and provide insight for optimization of the process.

  1. Polymer waveguide couplers based on metal nanoparticle-polymer nanocomposites.

    PubMed

    Signoretto, M; Suárez, I; Chirvony, V S; Abargues, R; Rodríguez-Cantó, P J; Martínez-Pastor, J

    2015-11-27

    In this work Au nanoparticles (AuNPs) are incorporated into poly(methyl methacrylate) (PMMA) waveguides to develop optical couplers that are compatible with planar organic polymer photonics. A method for growing AuNPs (of 10 to 100 nm in size) inside the commercially available Novolak resist is proposed with the intention of tuning the plasmon resonance and the absorption/scattering efficiencies inside the patterned structures. The refractive index of the MNP-Novolak nanocomposite (MNPs: noble metal nanoparticles) is carefully analysed both experimentally and numerically in order to find the appropriate fabrication conditions (filling factor and growth time) to optimize the scattering cross section at a desired wavelength. Then the nanocomposite is patterned inside a PMMA waveguide to exploit its scattering properties to couple and guide a normal incident laser light beam along the polymer. In this way, light coupling is experimentally demonstrated in a broad wavelength range (404-780 nm). Due to the elliptical shape of the MNPs the nanocomposite demonstrates a birefringence, which enhances the coupling to the TE mode up to efficiencies of around 1%. PMID:26526708

  2. Star-like copolymer stabilized noble-metal nanoparticle powders.

    PubMed

    Cao, Peng-Fei; Yan, Yun-Hui; Mangadlao, Joey Dacula; Rong, Li-Han; Advincula, Rigoberto

    2016-04-14

    The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials.

  3. Directed liquid phase assembly of highly ordered metallic nanoparticle arrays

    SciTech Connect

    Wu, Yueying; Dong, Nanyi; Fu, Shaofang; Fowlkes, Jason D.; Kondic, Lou; Vincenti, Maria A.; de Ceglia, Domenico; Rack, Philip D.

    2014-04-01

    Directed assembly of nanomaterials is a promising route for the synthesis of advanced materials and devices. We demonstrate the directed-assembly of highly ordered two-dimensional arrays of hierarchical nanostructures with tunable size, spacing and composition. The directed assembly is achieved on lithographically patterned metal films that are subsequently pulse-laser melted; during the brief liquid lifetime, the pattened nanostructures assemble into highly ordered primary and secondary nanoparticles, with sizes below that which was originally patterned. Complementary fluid-dynamics simulations emulate the resultant patterns and show how the competition of capillary forces and liquid metal–solid substrate interaction potential drives the directed assembly. Lastly, as an example of the enhanced functionality, a full-wave electromagnetic analysis has been performed to identify the nature of the supported plasmonic resonances.

  4. Directed liquid phase assembly of highly ordered metallic nanoparticle arrays

    DOE PAGES

    Wu, Yueying; Dong, Nanyi; Fu, Shaofang; Fowlkes, Jason D.; Kondic, Lou; Vincenti, Maria A.; de Ceglia, Domenico; Rack, Philip D.

    2014-04-01

    Directed assembly of nanomaterials is a promising route for the synthesis of advanced materials and devices. We demonstrate the directed-assembly of highly ordered two-dimensional arrays of hierarchical nanostructures with tunable size, spacing and composition. The directed assembly is achieved on lithographically patterned metal films that are subsequently pulse-laser melted; during the brief liquid lifetime, the pattened nanostructures assemble into highly ordered primary and secondary nanoparticles, with sizes below that which was originally patterned. Complementary fluid-dynamics simulations emulate the resultant patterns and show how the competition of capillary forces and liquid metal–solid substrate interaction potential drives the directed assembly. Lastly, asmore » an example of the enhanced functionality, a full-wave electromagnetic analysis has been performed to identify the nature of the supported plasmonic resonances.« less

  5. Asymmetries in transition metal XPS spectra: metal nanoparticle structure, and interaction with the graphene-structured substrate surface.

    PubMed

    Sacher, E

    2010-03-16

    Transition-metal XPS spectra have traditionally been considered to possess a natural asymmetry, extending to the high-binding-energy side. This is based on the fact that these spectra have generally been found experimentally to have such an asymmetry, as well as on the confirmation of asymmetry offered by the Doniach-Sunjić equation, an equation based on the proposal that the conduction electron scattering amplitude for interband absorption or emission in metals, at the Fermi level, is a singularity. Our discovery that metal nanoparticles, prepared under vacuum and characterized without exposure to air, have symmetric peaks, which become asymmetric with time, informed us that these peak asymmetries have other sources. On the basis of our belief that all metal spectra are composed of symmetric peaks, where the asymmetries are attributed to overlapping minor peaks that are consistent with known physical and chemical phenomena associated with that metal, we have shown that, for the metals that we have studied, these asymmetries contain much information, otherwise unavailable, on the structures, contaminants, oxidation, and interfacial interactions of nanoparticle surfaces. The existence of this information has been demonstrated for several metals, and its value is shown by its use in explaining the strong interfacial bonding of the nanoparticles with substrates having graphene structures. A possible future research direction is offered in the field of metal-metal interactions in nanoparticle alloys.

  6. Synthesis of Metal Nanoparticle-decorated Carbon Nanotubes under Ambient Conditions

    NASA Technical Reports Server (NTRS)

    Lin, Yi; Watson, Kent A.; Ghose, Sayata; Smith, Joseph G.; Connell, John W.

    2008-01-01

    This viewgraph presentation reviews the production of Metal Nanoparticle-decorated carbon Nanotubes. Multi-walled carbon nanotubes (MWCNTs) were efficiently decorated with metal nanoparticles (e.g. Ag, Pt, etc.) using the corresponding metal acetate in a simple mixing process without the need of chemical reagents or further processing. The conversion of acetate compounds to the corresponding metal reached over 90%, forming nanoparticles with average diameters less than 10 nm under certain conditions. The process was readily scalable allowing for the convenient preparation of multi-gram quantities of metal nanoparticle-decorated MWCNTs in a matter of a few minutes. These materials are under evaluation for a variety of electrical and catalytic applications. The preparation and characterization of these materials will be presented. The microscopic views of the processed MWCNTs are shown

  7. Development of structure-activity relationship for metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Rong; Zhang, Hai Yuan; Ji, Zhao Xia; Rallo, Robert; Xia, Tian; Chang, Chong Hyun; Nel, Andre; Cohen, Yoram

    2013-05-01

    Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions.Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were

  8. Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites

    SciTech Connect

    Scarselli, M.; Camilli, L.; Castrucci, P.; De Crescenzi, M.; Matthes, L.; Pulci, O.; Gatto, E.; Venanzi, M.

    2012-12-10

    In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle-nanotube interactions and electronic charge transfer at the interface.

  9. Solution synthesis of mixed-metal chalcogenide nanoparticles and spray deposition of precursor films

    DOEpatents

    Schulz, Douglas L.; Curtis, Calvin J.; Ginley, David S.

    2000-01-01

    A colloidal suspension comprising metal chalcogenide nanoparticles and a volatile capping agent. The colloidal suspension is made by reacting a metal salt with a chalcogenide salt in an organic solvent to precipitate a metal chalcogenide, recovering the metal chalcogenide, and admixing the metal chalcogenide with a volatile capping agent. The colloidal suspension is spray deposited onto a substrate to produce a semiconductor precursor film which is substantially free of impurities.

  10. One-pot synthesized hierarchical zeolite supported metal nanoparticles for highly efficient biomass conversion.

    PubMed

    Wang, Darui; Ma, Bing; Wang, Bo; Zhao, Chen; Wu, Peng

    2015-10-21

    Hierarchically porous zeolite supported metal nanoparticles are successfully prepared through a base-assisted chemoselective interaction between the silicon species on the zeolite crystal surface and metal salts, in which in situ construction of mesopores and high dispersion of metal species are realized simultaneously. PMID:26361087

  11. Aqueous phase synthesis of copper nanoparticles: a link between heavy metal resistance and nanoparticle synthesis ability in bacterial systems.

    PubMed

    Ramanathan, Rajesh; Field, Matthew R; O'Mullane, Anthony P; Smooker, Peter M; Bhargava, Suresh K; Bansal, Vipul

    2013-03-21

    We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu(2+) ions provides new insights into the mechanistic aspect of Cu(2+) ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms.

  12. Tailored Composite Polymer-Metal Nanoparticles by Miniemulsion Polymerization and Thiol-ene Functionalization

    PubMed Central

    van Berkel, Kim Y.

    2010-01-01

    A simple and modular synthetic approach, based on miniemulsion polymerization, has been developed for the fabrication of composite polymer-metal nanoparticle materials. The procedure produces well-defined composite structures consisting of gold, silver or MnFe2O4 nanoparticles (∼10 nm in diameter) encapsulated within larger spherical nanoparticles of poly(divinylbenzene) (∼100 nm in diameter). This methodology readily permits the incorporation of multiple metal domains into a single polymeric particle, while still preserving the useful optical and magnetic properties of the metal nanoparticles. The morphology of the composite particles is retained upon increasing the inorganic content, and also upon redispersion in organic solvents. Finally, the ability to tailor the surface chemistry of the composite nanoparticles and incorporate steric stabilizing groups using simple thiol-ene chemistry is demonstrated. PMID:20657708

  13. High-performance heterogeneous catalysis with surface-exposed stable metal nanoparticles

    PubMed Central

    Huang, Ning; Xu, Yanhong; Jiang, Donglin

    2014-01-01

    Protection of metal nanoparticles from agglomeration is critical for their functions and applications. The conventional method for enhancing their stability is to cover them with passivation layers to prevent direct contact. However, the presence of a protective shell blocks exposure of the metal species to reactants, thereby significantly impeding the nanoparticles' utility as catalysts. Here, we report that metal nanoparticles can be prepared and used in a surface-exposed state that renders them inherently catalytically active. This strategy is realised by spatial confinement and electronic stabilisation with a dual-module mesoporous and microporous three-dimensional π-network in which surface-exposed nanoparticles are crystallised upon in situ reduction. The uncovered palladium nanoparticles serve as heterogeneous catalysts that are exceptionally active in water, catalyse unreactive aryl chlorides for straightforward carbon–carbon bond formation and are stable for repeated use in various types of cross couplings. Therefore, our results open new perspectives in developing practical heterogeneous catalysts. PMID:25427425

  14. Study of metallic fibrous nanoparticle aggregate produced using femtosecond laser radiation under ambient conditions

    NASA Astrophysics Data System (ADS)

    Sivakumar, M.; Venkatakrishnan, Krishnan; Tan, B.

    2010-06-01

    In this study, we report formation of weblike fibrous nanoparticle aggregate due to irradiation of bulk iron, aluminium and titanium samples using femtosecond laser radiation at MHz pulse repetition frequency in air at atmospheric pressure. Electron microscopy analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanoparticle diameter varies between 5 and 40 nm and they are covered with an oxide layer of a few nanometres thick. X-ray diffraction and micro-Raman analysis revealed metallic and oxide phases in the nanostructure. The formation of a nanoparticle aggregate is explained by nucleation and condensation of vapour in the plasma plume and by phase explosion. Moreover the laser interaction time plays a significant role in the generation of nanostructure from bulk metals. This study provides evidence that femtosecond laser irradiation can be an ambient condition physical method for metallic fibrous nanoparticle aggregate generation.

  15. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.

    PubMed

    Li, Zihui; Sai, Hiroaki; Warren, Scott C; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules.

  16. Condensation Dynamics on Mimicked Metal Matrix Hydrophobic Nanoparticle-Composites

    NASA Astrophysics Data System (ADS)

    Damle, Viraj; Sun, Xiaoda; Rykaczewski, Konrad

    2014-11-01

    Use of hydrophobic surfaces promotes condensation in the dropwise mode, which is significantly more efficient than the common filmwise mode. However, limited longevity of hydrophobic surface modifiers has prevented their wide spread use in industry. Recently, metal matrix composites (MMCs) having microscale hydrophobic heterogeneities dispersed in hydrophilic metal matrix have been proposed as durable and self-healing alternative to hydrophobic surface coatings interacting with deposited water droplets. While dispersion of hydrophobic microparticles in MMC is likely to lead to surface flooding during condensation, the effect of dispersion of hydrophobic nanoparticles (HNPs) with size comparable to water nuclei critical radii and spacing is not obvious. To this end, we fabricated highly ordered arrays of Teflon nanospheres on silicon substrates that mimic the top surface of the MMCs with dispersed HNPs. We used light and electron microscopy to observe breath figures resulting from condensation on these surfaces at varied degrees of subcooling. Here, we discuss the relation between the droplet size distribution, Teflon nanosphere diameter and spacing, and condensation mode. KR acknowledges startup funding from ASU.

  17. Carbon nanomaterials combined with metal nanoparticles for theranostic applications

    PubMed Central

    Modugno, Gloria; Ménard-Moyon, Cécilia; Prato, Maurizio; Bianco, Alberto

    2015-01-01

    Among targeted delivery systems, platforms with nanosize dimensions, such as carbon nanomaterials (CNMs) and metal nanoparticles (NPs), have shown great potential in biomedical applications. They have received considerable interest in recent years, especially with respect to their potential utilization in the field of cancer diagnosis and therapy. The many functions of nanomaterials provide opportunities to use them as multimodal agents for theranostics, a combination of therapy and diagnosis. Carbon nanotubes and graphene are some of the most widely used CNMs because of their unique structural and physicochemical properties. Their high specific surface area allows for efficient drug loading and the possibility of functionalization with various bioactive molecules. In addition, CNMs are ideal platforms for the attachment of NPs. In the biomedical field, NPs have also shown tremendous potential for use in drug delivery, non-invasive tumour imaging and early detection due to their optical and magnetic properties. NP/CNM hybrids not only combine the unique properties of the NPs and CNMs but they also exhibit new properties arising from interactions between the two entities. In this review, the preparation of CNMs conjugated to different types of metal NPs and their applications in diagnosis, imaging, therapy and theranostics are presented. PMID:25323135

  18. Optical properties and circular dichroism of chiral metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyuan; Govorov, Alexander; OU Team

    2013-03-01

    In nature, biological systems are built up by homochiral building blocks, such as a sugar and protein. Circular dichroism (CD) is an effective tool of resolving molecular conformations. It utilizes circularly polarized light to detect differential absorption of chiral materials. In medicine, it will help us to develop new drugs and therapies, if we understand the connection between the physical or chemical properties of drug molecules and their conformations. With the rapid development of nanotechnologies, chiral nanomaterials attract lots of attention nowadays. CD signals of chiral molecules can be enhanced or shifted to the visible band in the presence of plasmonic nanocrystals. Here we present a plasmonic CD mechanism from a single chiral metal nanocrystal. The mechanism is essentially different from the dipolar plasmon-plasmon interaction in a chiral NP assembly, which mimics the CD mechanism of chiral molecules. Chiral metal nanocrystals are expected to have promising applications in biosensing. Recently a few experimental papers reported successful realizations of chiral nanocrystals in a macroscopic ensemble in solution. Particularly the paper described silver nanoparticles grown on chiral template molecules and demonstrating characteristic CD signals at a plasmonic wavelength. The plasmonic CD signals in Ref. can come from a dipolar plasmon-molecule interaction or from a chiral shape of nanocrystals. This work was supported by the NSF (project: CBET- 0933782) and by the Volkswagen Foundation.

  19. Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.

    PubMed

    Alabastri, Alessandro; Yang, Xiao; Manjavacas, Alejandro; Everitt, Henry O; Nordlander, Peter

    2016-04-26

    The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures.

  20. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly

    PubMed Central

    Li, Zihui; Sai, Hiroaki; Warren, Scott C.; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M.; Wiesner, Ulrich

    2010-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules. PMID:21103025

  1. Carbon nanomaterials combined with metal nanoparticles for theranostic applications.

    PubMed

    Modugno, Gloria; Ménard-Moyon, Cécilia; Prato, Maurizio; Bianco, Alberto

    2015-02-01

    Among targeted delivery systems, platforms with nanosize dimensions, such as carbon nanomaterials (CNMs) and metal nanoparticles (NPs), have shown great potential in biomedical applications. They have received considerable interest in recent years, especially with respect to their potential utilization in the field of cancer diagnosis and therapy. The many functions of nanomaterials provide opportunities to use them as multimodal agents for theranostics, a combination of therapy and diagnosis. Carbon nanotubes and graphene are some of the most widely used CNMs because of their unique structural and physicochemical properties. Their high specific surface area allows for efficient drug loading and the possibility of functionalization with various bioactive molecules. In addition, CNMs are ideal platforms for the attachment of NPs. In the biomedical field, NPs have also shown tremendous potential for use in drug delivery, non-invasive tumour imaging and early detection due to their optical and magnetic properties. NP/CNM hybrids not only combine the unique properties of the NPs and CNMs but they also exhibit new properties arising from interactions between the two entities. In this review, the preparation of CNMs conjugated to different types of metal NPs and their applications in diagnosis, imaging, therapy and theranostics are presented.

  2. Aqueous phase synthesis of copper nanoparticles: a link between heavy metal resistance and nanoparticle synthesis ability in bacterial systems

    NASA Astrophysics Data System (ADS)

    Ramanathan, Rajesh; Field, Matthew R.; O'Mullane, Anthony P.; Smooker, Peter M.; Bhargava, Suresh K.; Bansal, Vipul

    2013-02-01

    We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu2+ ions provides new insights into the mechanistic aspect of Cu2+ ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms.We demonstrate aqueous phase biosynthesis of phase-pure metallic copper nanoparticles (CuNPs) using a silver resistant bacterium Morganella morganii. This is particularly important considering that there has been no report that demonstrates biosynthesis and stabilization of pure copper nanoparticles in the aqueous phase. Electrochemical analysis of bacterial cells exposed to Cu2+ ions provides new insights into the mechanistic aspect of Cu2+ ion reduction within the bacterial cell and indicates a strong link between the silver and copper resistance machinery of bacteria in the context of metal ion reduction. The outcomes of this study take us a step closer towards designing rational strategies for biosynthesis of different metal nanoparticles using microorganisms. Electronic supplementary information (ESI) available: Sequence similarity analysis of proteins involved in the silver and copper resistance machinery of bacteria. See DOI: 10.1039/c2nr32887a

  3. Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles

    SciTech Connect

    Djerdj, Igor Arcon, Denis; Jaglicic, Zvonko; Niederberger, Markus

    2008-07-15

    The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO{sub 2} nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed. - Graphical abstract: In the first part of this article, nonaqueous sol-gel routes to ternary metal oxide nanoparticles are briefly reviewed, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the appearance of an unprecedented superstructure in MnO nanoparticles. In the second part, doping experiments of TiO{sub 2} with Fe and Co are presented, along with their characterization including magnetic measurements.

  4. Metal Nanoparticles as Targeted Carriers Circumventing the Blood-Brain Barrier.

    PubMed

    Sintov, A C; Velasco-Aguirre, C; Gallardo-Toledo, E; Araya, E; Kogan, M J

    2016-01-01

    Metal nanoparticles have been proposed as a carrier and a therapeutic agent in biomedical field because of their unique physiochemical properties. Due to these physicochemical properties, they can be used in different fields of biomedicine. In relation to this, plasmonic nanoparticles can be used for detection and photothermal destruction of tumor cells or toxic protein aggregates, and magnetic iron nanoparticles can be used for imaging and for hyperthermia of tumor cells. In addition, both therapy and imaging can be combined in one nanoparticle system, in a process called theranostics. Metal nanoparticles can be synthesized to modulate their size and shape, and conjugated with different ligands, which allow their application in drug delivery, diagnostics, and treatment of central nervous system diseases. This review is focused on the potential applications of metal nanoparticles and their capability to circumvent the blood-brain barrier (BBB). Although many articles have demonstrated delivery of metal nanoparticles to the brain by crossing the BBB after systemic administration, the percentage of the injected dose that reaches this organ is low in comparison to others, especially the liver and spleen. In connection with this drawback, we elaborate the architecture of the BBB and review possible mechanisms to cross this barrier by engineered nanoparticles. The potential uses of metal nanoparticles for treatment of disorders as well as related neurotoxicological considerations are also discussed. Finally, we bring up for discussion a direct and relatively simpler solution to the problem. We discuss this in detail after having proposed the use of the intranasal administration route as a way to circumvent the BBB. This route has not been extensively studied yet for metal nanoparticles, although it could be used as a research tool for mechanistic understanding and toxicity as well as an added value for medical practice. PMID:27678178

  5. Alkylamine capped metal nanoparticle "inks" for printable SERS substrates, electronics and broadband photodetectors.

    PubMed

    Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Yu, Kuai; Ang, Priscilla Kailian; Cao, Hanh Duyen; Balapanuru, Janardhan; Loh, Kian Ping; Xu, Qing-Hua

    2011-05-01

    We report a facile and general method for the preparation of alkylamine capped metal (Au and Ag) nanoparticle "ink" with high solubility. Using these metal nanoparticle "inks", we have demonstrated their applications for large scale fabrication of highly efficient surface enhanced Raman scattering (SERS) substrates by a facile solution processing method. These SERS substrates can detect analytes down to a few nM. The flexible plastic SERS substrates have also been demonstrated. The annealing temperature dependent conductivity of the nanoparticle films indicated a transition temperature above which high conductivity was achieved. The transition temperature could be tailored to the plastic compatible temperatures by using proper alkylamine as the capping agent. The ultrafast electron relaxation studies of the nanoparticle films demonstrated that faster electron relaxation was observed at higher annealing temperatures due to stronger electronic coupling between the nanoparticles. The applications of these highly concentrated alkylamine capped metal nanoparticle inks for the printable electronics were demonstrated by printing the oleylamine capped gold nanoparticles ink as source and drain for the graphene field effect transistor. Furthermore, the broadband photoresponse properties of the Au and Ag nanoparticle films have been demonstrated by using visible and near-infrared lasers. These investigations demonstrate that these nanoparticle "inks" are promising for applications in printable SERS substrates, electronics, and broadband photoresponse devices.

  6. Theoretical study and pathways for nanoparticle capture during solidification of metal melt

    NASA Astrophysics Data System (ADS)

    Xu, J. Q.; Chen, L. Y.; Choi, H.; Li, X. C.

    2012-06-01

    Nanocomposites can provide exciting physical, chemical, and mechanical properties for numerous applications. The solidification processing method has great potential for economical fabrication of bulk nanocomposites, especially for those with crystalline materials as the matrix, such as metal matrix nanocomposites (MMNCs). However, it is extremely difficult to effectively capture nanoparticles (less than 100 nm) into the solidification fronts during solidification. It is thus very important to initiate a theoretical study to examine the physics that governs the interactions between nanoparticles and the solidification front, and to provide enabling pathways for effective nanoparticle capture during solidification. The aim of this paper is to establish a theoretical framework for the fundamental understanding of nanoparticle capture during solidification of metal melt in order to obtain bulk MMNCs. A thermodynamically favorable condition is set as the starting point for further theoretical analysis of the three-party model system, namely a nanoparticle-metal-melt-solidification front. Three key interaction potentials, the interfacial energy at short range (0.2-0.4 nm), the van der Waals potential (especially at a longer range beyond 0.4 nm and up to ˜10 nm) and the Brownian potential, were studied. Three possible pathways for nanoparticle capture were thus devised: viscous capture, Brownian capture and spontaneous capture. Spontaneous capture is proposed as the most favorable for nanoparticle capture during solidification of metal melt. The theoretical model of nanoparticle capture from this study will serve as a powerful tool for future experimental studies to realize exciting functionalities offered by bulk MMNCs.

  7. Metal nanoparticle deposited inorganic nanostructure hybrids, uses thereof and processes for their preparation

    DOEpatents

    Tenne, Reshef; Tsverin, Yulia; Burghaus, Uwe; Komarneni, Mallikharjuna Rao

    2016-01-26

    This invention relates to a hybrid component comprising at least one nanoparticle of inorganic layered compound (in the form of fullerene-like structure or nanotube), and at least one metal nanoparticle, uses thereof as a catalyst, (e.g. photocatalysis) and processes for its preparation.

  8. Synthesis of well dispersed polymer grafted metal-organic framework nanoparticles.

    PubMed

    Xie, K; Fu, Q; He, Y; Kim, J; Goh, S J; Nam, E; Qiao, G G; Webley, P A

    2015-11-01

    Novel polymer grafted metal-organic framework (MOF) nanoparticles were synthesized. The formed core/shell nanoparticles exhibit outstanding water dispersity and pH sensitivity, and show their catalytic effect for the reduction reaction of 4-nitrophenol (NP) to 4-aminophenol (AP) when loaded with Pd(0) catalyst.

  9. Self-healing metal wire using electric field trapping of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Koshi, Tomoya; Iwase, Eiji

    2015-06-01

    We propose a self-healing metal wire using electric field trapping of gold nanoparticles by a dielectrophoresis force. A cracked gold wire can retrieve its conductivity through the self-healing function. In this paper, we examine the healing voltage causing the electric field trapping and determine the healing time, which is relevant to future device applications. First, the forces acting on a nanoparticle are analyzed and a theoretical healing voltage curve is calculated. Then, gold wires with 200- to 1,600-nm-wide cracks are fabricated on glass substrate and the self-healing function is verified through healing experiments. As a result, gold wires with cracks of up to 1,200 nm in width are successfully healed by applying less than ∼2.5 V (on average), and the experimental results correspond almost exactly with the calculated healing voltage curve. The average healing times are 10 to 285 s for 200- to 1,200-nm-wide cracks. Through scanning electron microscope analysis after the healing experiments, we confirm that the cracks are healed by assembled nanoparticles.

  10. Green synthesis of metal nanoparticles: biodegradable polymers and enzymes in stabilization and surface functionalization

    EPA Science Inventory

    Current breakthroughs in green nanotechnology are capable to transform many of the existing processes and products that enhance environmental quality, reduce pollution, and conserve natural and non-renewable resources. Noteworthy, successful use of metal nanoparticles and 10 nano...

  11. Effect of Percolation on the Cubic Susceptibility of Metal Nanoparticle Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Bender, Matthew W.; Boyd, Robert W.

    1998-01-01

    Generalized two-dimensional and three-dimensional Maxwell Garnett and Bruggeman geometries reveal that a sign reversal in the cubic susceptibility occurs for metal nanoparticle composites near the percolation threshold.

  12. A Bioanalytical Chemistry Experiment for Undergraduate Students: Biosensors Based on Metal Nanoparticles

    ERIC Educational Resources Information Center

    Niagi, John; Warner, John; Andreesco, Silvana

    2007-01-01

    The study describes the development of new biosensors based on metal nanoparticles because of its high surface area and large binding ability. The adopted procedure is extremely simple and versatile and can be used in various applications of electrochemistry.

  13. The Raman spectrum of graphene oxide decorated with different metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Irene Ling; Chen, Si Fan; Zhai, Jian Pang

    2015-10-01

    It is interesting to investigate the nature of interactions between metal nanoparticles and graphene oxide (GO), which is the fundamental of the potential applications of the GO. Resonant Raman technique provides a useful way to explore the influence of metal nanoparticles on the electronic structure of GO. For this purpose, GO has been decorated by nanoparticles of metals such as silver (Ag), gold (Au) and palladium (Pd), and then measured using micro Raman spectroscopy. Several different laser lines are used in the experiment. There is a red shift in the D-band as well as the G-band in addition to the changes in the Raman bandwidth. Comparing the changes in the Raman spectra of the GO caused by the different metal nanoparticles, we find that the effect of Ag on GO is large. On the other hand, Au nanoparticles cause small changes. Such difference is related to the intrinsic properties of the metal nanoparticles which have different ionization energies. When the laser wavelength increases, the ratio between the intensities of the D-band and G-band (ID/IG) increases. And the Raman enhancement effects of Pd, Ag, and Au nanoparticles are different since they have different surface plasmon resonance frequencies.

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

    PubMed Central

    Kahru, Anne; Dubourguier, Henri-Charles; Blinova, Irina; Ivask, Angela; Kasemets, Kaja

    2008-01-01

    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.

  15. Electrocatalytic reduction of carbon dioxide on post-transition metal and metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    White, James L.

    The electroreduction of carbon dioxide to liquid products is an important component in the utilization of CO2 and in the high-density storage of intermittent renewable energy in the form of chemical bonds. Materials based on indium and tin, which yield predominantly formic acid, have been investigated in order to gain a greater understanding of the electrochemically active species and the mechanism of CO2 reduction on these heavy post-transition metals, since prior studies on the bulk metals did not provide thermodynamically sensible reaction pathways. Nanoparticles of the oxides and hydroxides of tin and indium have been prepared and characterized by transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and various electrochemical methods in order to obtain structural information and analyze the role of various surface species on the CO2 reduction pathway. On both indium and tin, metastable surface-bound hydroxides bound CO2 and formed metal carbonates, which can then be reduced electrochemically. The relevant oxidation state of tin was suggested to be SnII rather than SnIV, necessitating a pre reduction to generate the CO2-binding species. Metallic indium nanoparticles partially oxidized in air and became highly efficient CO2 reduction electrocatalysts. Unit Faradaic efficiencies for formate, much higher than on bulk indium, were achieved with only 300 mV of overpotential on these particles, which possessed an oxyhydroxide shell surrounding a conductive metallic core. Alloys and mixed-metal oxide and hydroxide particles of tin and indium have also been studied for their carbon dioxide electrocatalytic capabilities, especially in comparison to the pure metal species. Additionally, a solar-driven indium-based CO2 electrolyzer was developed to investigate the overall efficiency for intermittent energy storage. The three flow cells were powered by a commercial photovoltaic array and had a maximum conversion efficiency of incident

  16. 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

    NASA Astrophysics Data System (ADS)

    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.

  17. An expeditious synthesis of early transition metal carbide nanoparticles on graphitic carbons.

    PubMed

    Ressnig, Debora; Moldovan, Simona; Ersen, Ovidiu; Beaunier, Patricia; Portehault, David; Sanchez, Clément; Carenco, Sophie

    2016-08-01

    An expeditious synthesis of metal carbide nanoparticles onto various carbon supports is demonstrated. The procedure is versatile and readily yields TiC, VC, Mo2C and W2C nanoparticles on different types of carbons. The reaction is initiated at room temperature and proceeds within seconds. This novel synthetic route paves the way for a large variety of metal carbide-carbon nanocomposites that may be implemented in emerging nanotechnology fields.

  18. An expeditious synthesis of early transition metal carbide nanoparticles on graphitic carbons.

    PubMed

    Ressnig, Debora; Moldovan, Simona; Ersen, Ovidiu; Beaunier, Patricia; Portehault, David; Sanchez, Clément; Carenco, Sophie

    2016-08-01

    An expeditious synthesis of metal carbide nanoparticles onto various carbon supports is demonstrated. The procedure is versatile and readily yields TiC, VC, Mo2C and W2C nanoparticles on different types of carbons. The reaction is initiated at room temperature and proceeds within seconds. This novel synthetic route paves the way for a large variety of metal carbide-carbon nanocomposites that may be implemented in emerging nanotechnology fields. PMID:27383864

  19. Reactive aluminum metal nanoparticles within a photodegradable poly(methyl methacrylate) matrix

    NASA Astrophysics Data System (ADS)

    Patel, Ashish; Becic, Jasmin; Buckner, Steven W.; Jelliss, Paul A.

    2014-01-01

    We report here on new photoreactive core-matrix reactive metal nanoparticles. Poly(methyl methacrylate)-capped aluminum nanoparticles (PMMA-Al NPs) were synthesized and demonstrated air stability on the order of 2 months. Upon exposure of the PMMA-Al NPs to UV radiation the composite reacts more rapidly to release H2 gas from alkaline solution. FTIR spectroscopy indicates that the PMMA cap degrades under UV irradiation, exposing the reactive metal core.

  20. A model for the latent heat of melting in free standing metal nanoparticles

    SciTech Connect

    Shin, Jeong-Heon; Deinert, Mark R.

    2014-04-28

    Nanoparticles of many metals are known to exhibit scale dependent latent heats of melting. Analytical models for this phenomenon have so far failed to completely capture the observed phenomena. Here we present a thermodynamic analysis for the melting of metal nanoparticles in terms of their internal energy and a scale dependent surface tension proposed by Tolman. The resulting model predicts the scale dependence of the latent heat of melting and is confirmed using published data for tin and aluminum.

  1. Countering drug resistance, infectious diseases, and sepsis using metal and metal oxides nanoparticles: Current status.

    PubMed

    Khan, Shams Tabrez; Musarrat, Javed; Al-Khedhairy, Abdulaziz A

    2016-10-01

    One fourth of the global mortalities is still caused by microbial infections largely due to the development of resistance against conventional antibiotics among pathogens, the resurgence of old infectious diseases and the emergence of hundreds of new infectious diseases. The lack of funds and resources for the discovery of new antibiotics necessitates the search for economic and effective alternative antimicrobial agents. Metal and metal oxide nanoparticles including silver and zinc oxide exhibit remarkable antimicrobial activities against pathogens and hence are one of the most propitious alternative antimicrobial agents. These engineered nanomaterials are approved by regulatory agencies such as USFDA and Korea's FITI, for use as antimicrobial agents, supplementary antimicrobials, food packaging, skin care products, oral hygiene, and for fortifying devices prone to microbial infections. Nevertheless, detailed studies, on molecular and biochemical mechanisms underlying their antimicrobial activity are missing. To take the full advantage of this emerging technology selective antimicrobial activity of these nanoparticles against pathogens should be studied. Optimization of these nanomaterials through functionalization to increase their efficacy and biocompatibility is also required. Urgent in vivo studies on the toxicity of nanomaterials at realistic doses are also needed before their clinical translation. PMID:27259161

  2. Hydrothermal synthesis of platinum-group-metal nanoparticles by using HEPES as a reductant and stabilizer.

    PubMed

    So, Man-Ho; Ho, Chi-Ming; Chen, Rong; Che, Chi-Ming

    2010-06-01

    Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 degrees C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8+/-0.2, Os: 1.6+/-0.2, Rh: 4.5+/-0.5, Ir: 2.0+/-0.3, Pd: 3.8+/-0.4, Pt: 1.9+/-0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum-group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes. PMID:20512785

  3. Star-like copolymer stabilized noble-metal nanoparticle powders

    NASA Astrophysics Data System (ADS)

    Cao, Peng-Fei; Yan, Yun-Hui; Mangadlao, Joey Dacula; Rong, Li-Han; Advincula, Rigoberto

    2016-03-01

    The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials.The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials. Electronic supplementary information (ESI) available: Synthesis scheme and the 1H NMR spectrum of PEI

  4. Pharyngeal aspiration of metal oxide nanoparticles showed potential of allergy aggravation effect to inhaled ovalbumin.

    PubMed

    Horie, Masanori; Stowe, Mayumi; Tabei, Miki; Kuroda, Etsushi

    2015-02-01

    The inhalation of manufactured metal oxide nanoparticles may lead to pulmonary toxicity. For instance, ZnO nanoparticles are known to induce pulmonary oxidative stress and inflammation. On the other hand, the pulmonary toxicity of TiO2 nanoparticles is less than that of ZnO nanoparticles. Although, there have been some investigations concerning the induction of pulmonary oxidative stress and inflammation caused by manufactured metal oxide nanoparticles. And, although, it has reported that some nanoparticles cause aggravation of allergic reactions, there have so far been no reports regarding allergy aggravation effects of manufactured metal oxide nanoparticles. In this study, three types of nanoparticles, TiO2, ZnO and SiO2, were administered to mouse lungs by pharyngeal aspiration. Subsequently, the mice inhaled ovalbumin (OVA) a total of eight times over 3 weeks. After inhalation of OVA, the concentrations of total IgE, OVA-specific IgE and OVA-specific IgG1 in serum increased in the mice treated with ZnO. TiO2 and SiO2 nanoparticles did not affect the OVA-specific IgE and IgG1 levels. These results suggest that ZnO nanoparticles have the potential to aggravate allergic reactions. The results also suggest that Zn(2+) release from ZnO nanoparticles is involved in the aggravation potential of allergies. However, pharyngeal aspiration of ZnCl2 solution was not able to aggravate allergic reactions. Continuous Zn(2+) release from ZnO nanoparticles to the lung is necessary for the aggravation of allergic reactions.

  5. High-Frequency Waves in a Random Distribution of Metallic Nanoparticles in an External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2016-09-01

    Propagation of magnetoplasma waves at an angle to a static magnetic field is studied for a random distribution of spherical metallic nanoparticles. A general analytical expression for dispersion relation of the system is derived and useful expressions are obtained in the limiting cases. It is found that the interaction between longitudinal and transverse modes leads to coupled modes in the vicinity of the frequency √ {f + ξ } {ω _p}, where ξ is the ratio of the volume occupied by all the nanoparticles to the entire volume, ωp the plasma frequency of electrons inside a nanoparticle, and f a geometrical factor of order unity (1/3 for spherical nanoparticles).

  6. Preparation of transition metal nanoparticles and surfaces modified with (CO) polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-10-25

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surface modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a collidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as fuctionalization with a variety of different chemical groups, expanding their utility and application.

  7. Preparation of transition metal nanoparticles and surfaces modified with (co)polymers synthesized by RAFT

    DOEpatents

    McCormick, III, Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2011-12-27

    A new, facile, general one-phase method of generating thiol-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the steps of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  8. Preparation of transition metal nanoparticles and surfaces modified with (CO)polymers synthesized by RAFT

    DOEpatents

    McCormick, III., Charles L.; Lowe, Andrew B.; Sumerlin, Brent S.

    2006-11-21

    A new, facile, general one-phase method of generating thio-functionalized transition metal nanoparticles and surfaces modified by (co)polymers synthesized by the RAFT method is described. The method includes the stops of forming a (co)polymer in aqueous solution using the RAFT methodology, forming a colloidal transition metal precursor solution from an appropriate transition metal; adding the metal precursor solution or surface to the (co)polymer solution, adding a reducing agent into the solution to reduce the metal colloid in situ to produce the stabilized nanoparticles or surface, and isolating the stabilized nanoparticles or surface in a manner such that aggregation is minimized. The functionalized surfaces generated using these methods can further undergo planar surface modifications, such as functionalization with a variety of different chemical groups, expanding their utility and application.

  9. Enhanced two-photon emission in coupled metal nanoparticles induced by conjugated polymers.

    PubMed

    Guan, Zhenping; Polavarapu, Lakshminarayana; Xu, Qing-Hua

    2010-12-01

    Interactions between noble metal (Ag and Au) nanoparticles and conjugated polymers as well as their one- and two-photon emission have been investigated. Ag and Au nanoparticles exhibited extraordinary quenching effects on the fluorescence of cationic poly(fluorinephenylene). The quenching efficiency by 37-nm Ag nanoparticles is ∼19 times more efficient than that by 13-nm Au nanoparticles, and 9-10 orders of magnitude more efficient than typical small molecule dye-quencher pairs. On the other hand, the cationic conjugated polymers induce the aggregate formation and plasmonic coupling of the metal nanoparticles, as evidenced by transmission electron microscopy images and appearance of a new longitudinal plasmon band in the near-infrared region. The two-photon emissions of Ag and Au nanoparticles were found to be significantly enhanced upon addition of conjugated polymers, by a factor of 51-times and 9-times compared to the isolated nanoparticles for Ag and Au, respectively. These studies could be further extended to the applications of two-photon imaging and sensing of the analytes that can induce formation of metal nanoparticle aggregates, which have many advantages over the conventional one-photon counterparts.

  10. Wavelength-band-tuning photodiodes by using various metallic nanoparticles.

    PubMed

    Hwang, J D; Chan, Y D; Chou, T C

    2015-11-20

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD. PMID:26508114

  11. Wavelength-band-tuning photodiodes by using various metallic nanoparticles.

    PubMed

    Hwang, J D; Chan, Y D; Chou, T C

    2015-11-20

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD.

  12. Wavelength-band-tuning photodiodes by using various metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hwang, J. D.; Chan, Y. D.; Chou, T. C.

    2015-11-01

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD.

  13. A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

    PubMed Central

    2013-01-01

    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose. PMID:24225302

  14. Structural characterization of rotavirus-directed synthesis and assembly of metallic nanoparticle arrays.

    PubMed

    Plascencia-Villa, Germán; Medina, Ariosto; Palomares, Laura A; Ramírez, Octavio T; Ascencio, Jorge A

    2013-08-01

    Self-assembled structures derived of viral proteins display sophisticated structures that are difficult to obtain with even advanced synthesis methods and the use of protein nanotubes for synthesis and organization of inorganic nanoarrays into well-defined architectures are here reported. Nanoparticle arrays derived of rotavirus VP6 nanotubes were synthesized by in situ functionalization with silver and gold nanoparticles. The size and morphology of metal nanoparticles were characterized by transmission electron microscopy (TEM) and high resolution TEM (HR-TEM). Processing of micrographs to obtain fast Fourier transforms (FFT) patterns of nanoparticles shown that the preferred morphologies are fcc-like and multiple twinned ones. Micrographs were used to assign structure and orientation, and the elemental composition analysis was performed with energy dispersive spectroscopy (EDS). Structural characterization of functionalized rotavirus VP6 demonstrated its utility for directed construction of hybrid anisotropic nanomaterials formed by arrays of metallic nanoparticles.

  15. Carbon Materials Embedded with Metal Nanoparticles as Anode in Lithium-Ion Batteries

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh

    2002-01-01

    Carbon materials containing metal nanoparticles that can form an alloy with lithium were tested for their capacity and cycle life to store and release lithium electrochemically. Metal nanoparticles may provide the additional lithium storage capacity as well as additional channels to conduct lithium in carbon. The cycle life of this carbon-metal composite can be long because the solid-electrolyte interface (SEI) on the carbon surface may protect both lithium and the metal particles in the carbon interior. In addition, the voids in the carbon interior may accommodate the nanoparticle's volume change, and such volume change may not cause much internal stress due to small sizes of the nanoparticles. This concept of improving carbon's performance to store and release lithium was demonstrated using experimental cells of C(Pd)/0.5M Lil-50/50 (vol.%) EC and DMC/Li, where C(Pd) was graphitized carbon fibers containing palladium nanoparticles, EC was ethylene carbonate, and DMC was dimethyl carbonate. However, such improvement was not observed if the Pd nanoparticles are replaced by aluminum, possibly because the aluminum nanoparticles were oxidized in air during storage, resulting in an inert oxide of aluminum. Further studies are needed to use this concept for practical applications.

  16. Nanostructured target fabrication with metal and semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Antici, P.

    2015-10-01

    The development of ultra-intense high-energy (≫1 J) short (<1 ps) laser pulses in the last decade has enabled the acceleration of high-energy short-pulse proton beams. A key parameter for enhancing the acceleration regime is the laser-to-target absorption, which heavily depends on the target structure and material. In this work, we present the realization of a nanostructured target with a sub-laser wavelength nano-layer in the front surface as a possible candidate for improving the absorption. The nanostructured film was realized by a simpler and cheaper method than using conventional lithographic techniques: A colloidal solution of metallic or semiconductor nanoparticles (NPs) was produced by laser ablation and, after a heating and sonication process, was spray-dried on the front surface of an aluminum target. The obtained nanostructured film with a thickness of 1 μm appears, at morphological and chemical analysis, uniformly nanostructured and distributed on the target surface without the presence of oxides or external contaminants. Finally, the size of the NPs can be tuned from tens to hundreds of nanometers simply by varying the growth parameters (i.e., irradiation time, fluence, and laser beam energy).

  17. Metallic photonic crystals based on solution-processible gold nanoparticles.

    PubMed

    Zhang, Xinping; Sun, Baoquan; Friend, Richard H; Guo, Hongcang; Nau, Dietmar; Giessen, Harald

    2006-04-01

    We demonstrate the fabrication of metallic photonic crystals, in the form of a periodic array of gold nanowires on a waveguide, by spin-coating a colloidal gold suspension onto a photoresist mask and subsequent annealing. The photoresist mask with a period below 500 nm is manufactured by interference lithography on an indium tin oxide (ITO) glass substrate, where the ITO layer has a thickness around 210 nm and acts as the waveguide. The width of the nanowires can be controlled from 100 to 300 nm by changing the duty cycle of the mask. During evaporation of solvent, the gold nanoparticles are drawn to the grooves of the grating with apparently complete dewetting off the photoresist for channels less than 2 microm in width, which therefore form nanowires after the annealing process. Strong coupling between the waveguide mode and the plasmon resonance of the nanowires, which is dependent on the polarization and incidence angle of the light wave, is demonstrated by optical extinction measurements. Continuity of the nanowires is confirmed by conductivity properties. Simplicity, high processing speed, and low cost are the main advantages of this method, which may have a plethora of applications in telecommunication, all-optical switching, sensors, and semiconductor devices.

  18. Electrochemical Characterization of Ultrathin Cross-Linked Metal Nanoparticle Films.

    PubMed

    Han, Chu; Percival, Stephen J; Zhang, Bo

    2016-09-01

    Here we report the preparation, characterization, and electrochemical study of conductive, ultrathin films of cross-linked metal nanoparticles (NPs). Nanoporous films ranging from 40 to 200 nm in thickness composed of gold and platinum NPs of ∼5 nm were fabricated via a powerful layer-by-layer spin coating process. This process allows preparation of uniform NP films as large as 2 × 2 cm(2) with precise control over thickness, structure, and electrochemical and electrocatalytic properties. Gold, platinum, and bimetallic NP films were fabricated and characterized using cyclic voltammetry, scanning electron microscopy, and conductance measurements. Their electrocatalytic activity toward the oxygen reduction reaction (ORR) was investigated. Our results show that the electrochemical activity of such NP films is initially hindered by the presence of dense thiolate cross-linking ligands. Both electrochemical cycling and oxygen plasma cleaning are effective means in restoring their electrochemical activity. Gold NP films have higher electric conductivity than platinum possibly due to more uniform film structure and closer particle-particle distance. The electrochemical and electrocatalytic performance of platinum NP films can be greatly enhanced by the incorporation of gold NPs. This work focuses on electrochemical characterization of cross-linked NP films and demonstrates several unique properties. These include quick and easy preparation, ultrathin and uniform film thickness, tunable structure and composition, and transferability to many other substrates.

  19. Comparative responses to metal oxide nanoparticles in marine phytoplankton.

    PubMed

    Castro-Bugallo, Alexandra; González-Fernández, África; Guisande, Cástor; Barreiro, Aldo

    2014-11-01

    A series of experiments was undertaken on three different marine microalgae to compare the effect of two metal oxide nanoparticles (NPs) on different physiological responses to stress: zinc oxide (ZnO), a known toxic compound for microalgae, and the never before tested yttrium oxide (Y₂O3). The effect of these potential pollutants was estimated for different physiological variables and temporal scales: Growth, carbon content, carbon-to-nitrogen (C:N) ratio, and chlorophyll fluorescence were evaluated in long-term assays, and reactive oxygen species (ROS) production was evaluated in a short-term assay. Population growth was the most susceptible variable to the acute toxic effects of both NPs as measured in terms of number of cells and of biomass. Although Phaeodactylum tricornutum and Alexandrium minutum were negatively affected by ZnO NPs, this effect was not detected in Tetraselmis suecica, in which cell growth was significantly decreased by Y₂O₃ NPs. Biomass per cell was negatively affected in the most toxic treatments in T. suecica but was positively affected in A. minutum. ZnO treatments induced a sharper decrease in chlorophyll fluorescence and higher ROS than did Y₂O₃ treatments. The pronounced differences observed in the responses between the species and the physiological variables tested highlight the importance of analyzing diverse groups of microalgae and various physiological levels to determine the potential effects of environmental pollutants.

  20. Metallic nanoparticles functionalizing carbon nanotube networks for gas sensing applications.

    PubMed

    Abdelhalim, Ahmed; Abdellah, Alaa; Scarpa, Giuseppe; Lugli, Paolo

    2014-02-01

    We report the fabrication of carbon nanotube (CNT) based gas sensors functionalized with different metallic nanoparticles (NPs) (Au, Pd, Ag) with exceptionally high responses towards four test gases (NH3, CO2, CO and ethanol). The CNT networks were fabricated through a low cost spray deposition process while the NPs were deposited by a thermal evaporation process. CNT based gas sensors functionalized with Au with a nominal thickness of 1.0 nm showed superior response towards NH3, CO and ethanol. The sensors' normalized responses reached 92%, 22% and 32% with concentrations of 100 ppm, 50 ppm and 100 ppm for NH3, CO and ethanol respectively. CNT based gas sensors functionalized with Pd with a nominal thickness of 1.5 nm showed the best performance with CO2. The normalized response reached 3%, 6%, 12% and 17% with concentrations of 500 ppm, 1000 ppm, 2500 ppm and 5000 ppm of CO2 respectively. We also investigated the morphological and optical changes that occur to the NPs upon thermal treatment. Functionalization of CNT films deposited on glass with Au and Ag showed surface plasmon resonance effects that are dependent on the nominal thickness of the functionalization layer. PMID:24407105

  1. Comparative Metal Oxide Nanoparticle Toxicity Using Embryonic Zebrafish

    PubMed Central

    Wehmas, Leah C.; Anders, Catherine; Chess, Jordan; Punnoose, Alex; Pereira, Cliff B.; Greenwood, Juliet A.; Tanguay, Robert L.

    2015-01-01

    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 hour 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. PMID:26029632

  2. Quantum dynamical simulations of local field enhancement in metal nanoparticles.

    PubMed

    Negre, Christian F A; Perassi, Eduardo M; Coronado, Eduardo A; Sánchez, Cristián G

    2013-03-27

    Field enhancements (Γ) around small Ag nanoparticles (NPs) are calculated using a quantum dynamical simulation formalism and the results are compared with electrodynamic simulations using the discrete dipole approximation (DDA) in order to address the important issue of the intrinsic atomistic structure of NPs. Quite remarkably, in both quantum and classical approaches the highest values of Γ are located in the same regions around single NPs. However, by introducing a complete atomistic description of the metallic NPs in optical simulations, a different pattern of the Γ distribution is obtained. Knowing the correct pattern of the Γ distribution around NPs is crucial for understanding the spectroscopic features of molecules inside hot spots. The enhancement produced by surface plasmon coupling is studied by using both approaches in NP dimers for different inter-particle distances. The results show that the trend of the variation of Γ versus inter-particle distance is different for classical and quantum simulations. This difference is explained in terms of a charge transfer mechanism that cannot be obtained with classical electrodynamics. Finally, time dependent distribution of the enhancement factor is simulated by introducing a time dependent field perturbation into the Hamiltonian, allowing an assessment of the localized surface plasmon resonance quantum dynamics.

  3. Association of the physical and chemical properties and the cytotoxicity of metal oxide nanoparticles: metal ion release, adsorption ability and specific surface area.

    PubMed

    Horie, Masanori; Fujita, Katsuhide; Kato, Haruhisa; Endoh, Shigehisa; Nishio, Keiko; Komaba, Lilian Kaede; Nakamura, Ayako; Miyauchi, Arisa; Kinugasa, Shinichi; Hagihara, Yoshihisa; Niki, Etsuo; Yoshida, Yasukazu; Iwahashi, Hitoshi

    2012-04-01

    Association of cellular influences and physical and chemical properties were examined for 24 kinds of industrial metal oxide nanoparticles: ZnO, CuO, NiO, Sb(2)O(3), CoO, MoO(3), Y(2)O(3), MgO, Gd(2)O(3), SnO(2), WO(3), ZrO(2), Fe(2)O(3), TiO(2), CeO(2), Al(2)O(3), Bi(2)O(3), La(2)O(3), ITO, and cobalt blue pigments. We prepared a stable medium dispersion for each nanoparticle and examined the influence on cell viability and oxidative stress together with physical and chemical characterizations. ZnO, CuO, NiO, MgO, and WO(3) showed a large amount of metal ion release in the culture medium. The cellular influences of these soluble nanoparticles were larger than insoluble nanoparticles. TiO(2), SnO(2), and CeO(2) nanoparticles showed strong protein adsorption ability; however, cellular influences of these nanoparticles were small. The primary particle size and the specific surface area seemed unrelated to cellular influences. Cellular influences of metal oxide nanoparticles depended on the kind and concentrations of released metals in the solution. For insoluble nanoparticles, the adsorption property was involved in cellular influences. The primary particle size and specific surface area of metal oxide nanoparticles did not affect directly cellular influences. In conclusion the most important cytotoxic factor of metal oxide nanoparticles was metal ion release.

  4. Simultaneous removal of PAHs and metal contaminants from water using magnetic nanoparticle adsorbents.

    PubMed

    Huang, Yuxiong; Fulton, Aaron N; Keller, Arturo A

    2016-11-15

    Many industrial wastewaters are contaminated with both heavy metal ions and organic compounds, posing a major threat to public health and the environment. In this study, magnetic nanoparticle adsorbents, namely Mag-PCMA-T, which contain a maghemite core and a silica mesoporous layer that permanently confines surfactant micelles within the mesopores, were synthesized to achieve simultaneous removal of polycyclic aromatic hydrocarbons (PAHs) (1mg/L) and metal contaminants (1mg/L). The individual removal efficiency of Cd(2+) and acenaphthene using Mag-PCMA-T was evaluated under a range of initial ion concentrations and adsorbent dosages, as well as the competitive adsorption with Cd(2+) and acenaphthene simultaneously present. The isotherms and kinetics of Cd(2+) and acenaphthene sorption onto Mag-PCMA-T were determined. Mag-PCMA-T removed >85% of the acenaphthene in <30min, with relatively high sorption capacity (up to 1060mg/kg). Mag-PCMA-T also exhibited high sorption capacity for Cd(2+) (up to 2250mg/kg). The simultaneous sorption performance was stable across a wide pH range (4-9) as well as in the presence of competitive metal ions (Ca(2+) and Mg(2+)) or natural organic matters. The Mag-PCMA-T can be regenerated and reused, providing a sustainable, fast, convenient, and efficient approach for water treatment. PMID:27450251

  5. Fabrication of porous silicon by metal-assisted etching using highly ordered gold nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Scheeler, Sebastian P.; Ullrich, Simon; Kudera, Stefan; Pacholski, Claudia

    2012-08-01

    A simple method for the fabrication of porous silicon (Si) by metal-assisted etching was developed using gold nanoparticles as catalytic sites. The etching masks were prepared by spin-coating of colloidal gold nanoparticles onto Si. An appropriate functionalization of the gold nanoparticle surface prior to the deposition step enabled the formation of quasi-hexagonally ordered arrays by self-assembly which were translated into an array of pores by subsequent etching in HF solution containing H2O2. The quality of the pattern transfer depended on the chosen preparation conditions for the gold nanoparticle etching mask. The influence of the Si surface properties was investigated by using either hydrophilic or hydrophobic Si substrates resulting from piranha solution or HF treatment, respectively. The polymer-coated gold nanoparticles had to be thermally treated in order to provide a direct contact at the metal/Si interface which is required for the following metal-assisted etching. Plasma treatment as well as flame annealing was successfully applied. The best results were obtained for Si substrates which were flame annealed in order to remove the polymer matrix - independent of the substrate surface properties prior to spin-coating (hydrophilic or hydrophobic). The presented method opens up new resources for the fabrication of porous silicon by metal-assisted etching. Here, a vast variety of metal nanoparticles accessible by well-established wet-chemical synthesis can be employed for the fabrication of the etching masks.

  6. Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery.

    PubMed

    Rai, Mahendra; Ingle, Avinash P; Gupta, Indarchand; Brandelli, Adriano

    2015-12-30

    The unique properties of nanomaterials can be applied to solve different problems including new ways of drug delivery. Noble metal nanoparticles are most promising because they have been used for medicinal purposes since ancient time. It is evident from the past studies that the metallic nanoparticles are much more effective against various microorganisms when compared to their conventional counterparts. However, decoration of such nanoparticles with biomaterials add more advantages to their antimicrobial activity. Decoration of metal nanoparticles with biopolymers is a quite new area of research. Studies performed hitherto shown that nanoparticles of noble metals like silver, gold and platinum demonstrated better antibacterial, antifungal and antiviral activities when conjugated with biopolymers. The development of such technology has potential to develop materials that are more effective in the field of health science. Considering the importance and uniqueness of this concept, the present review aims to discuss the use of biopolymer-decorated metal nanoparticles for combating various diseases caused by microbial pathogens. Moreover, the nanotoxicity aspect has also been discussed. PMID:26520406

  7. Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery.

    PubMed

    Rai, Mahendra; Ingle, Avinash P; Gupta, Indarchand; Brandelli, Adriano

    2015-12-30

    The unique properties of nanomaterials can be applied to solve different problems including new ways of drug delivery. Noble metal nanoparticles are most promising because they have been used for medicinal purposes since ancient time. It is evident from the past studies that the metallic nanoparticles are much more effective against various microorganisms when compared to their conventional counterparts. However, decoration of such nanoparticles with biomaterials add more advantages to their antimicrobial activity. Decoration of metal nanoparticles with biopolymers is a quite new area of research. Studies performed hitherto shown that nanoparticles of noble metals like silver, gold and platinum demonstrated better antibacterial, antifungal and antiviral activities when conjugated with biopolymers. The development of such technology has potential to develop materials that are more effective in the field of health science. Considering the importance and uniqueness of this concept, the present review aims to discuss the use of biopolymer-decorated metal nanoparticles for combating various diseases caused by microbial pathogens. Moreover, the nanotoxicity aspect has also been discussed.

  8. Observation of intrinsic size effects in the optical response of individual gold nanoparticles.

    PubMed

    Berciaud, Stéphane; Cognet, Laurent; Tamarat, Philippe; Lounis, Brahim

    2005-03-01

    The photothermal heterodyne imaging method is used to study for the first time the absorption spectra of individual gold nanoparticles with diameters down to 5 nm. Intrinsic size effects that result in a broadening of the surface plasmon resonance are unambiguously observed. Dispersions in the peak energies and homogeneous widths of the single-particle resonances are revealed. The experimental results are analyzed within the frame of Mie theory. PMID:15755105

  9. SINGLE-PARTICLE ICPMS FOR CHARACTERIZING METAL-BASED NANOPARTICLES IN THE ENVIRONMENT - ADVANCES AND CHALLENGES

    EPA Science Inventory

    As engineered metal-based nanomaterials become widely used in consumer and industrial products, the amount of these materials introduced into the environment by a variety of paths will increase. The concentration of metal associated with these engineered nanoparticles will be s...

  10. Floating AC-DEP (dielectrophoretic) manipulations of fluorescent nanoparticle at metal nanostructure for plasmonic applications

    NASA Astrophysics Data System (ADS)

    Kim, J.; Shin, H. J.; Hwang, K. S.; Park, J. H.

    2014-11-01

    We propose the fluorescent nanoparticle manipulations at nano-metal structures with floating AC-DEP force for plasmonic applications. The electrode gap was optimized to induce enough DEP force around the nano-structure for manipulation of the nanoparticles. 10um wide gap of electrode was acquired to apply the floating AC-DEP force at various designed metal nano-structure such as nanowire, y-branch and vortex. The all shape of nano-metal structures are formed at the gap of microelectrode and not connected with microelectrode. The gold nano-structures in the gap of microelectrode were fabricated with e-beam lithography and lift-off process. Before the formation of metal nanostructure, micro electrodes for applying the electric field around the metal nano-structures were fabricated with photolithography and lift-off process. Cadmium selenide (CdSe/ZnS) QDs (0.8 nM, emission wavelength of 605 nm) with a 25 nm zinc sulfide capping layer and 100nm polystyrene nano bead (1 nM, emission wavelength of 610nm) were used as fluorescent nanoparticles. We applied the 8 Vpp, 3 MHz sine wave for the positive DEP force, and it resulted in 108 V/m electric field and 1011 V/m electric field gradient around gold nanowire with floating AC. The fluorescent nanoparticle's attachment at the nanowire is confirmed by the fluorescent optical analysis. The fluorescent nanoparticles are located successfully at designed metal nano-structures for plasmonic applications.

  11. Plasma - enhanced dispersion of metal and ceramic nanoparticles in polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Maguire, Paul; Liu, Yazi; Askari, Sadegh; Patel, Jenish; Macia-Montero, Manuel; Mitra, Somak; Zhang, Richao; Sun, Dan; Mariotti, Davide

    2015-09-01

    In this work we demonstrate a facile method to synthesize a nanoparticle/PEDOT:PSS hybrid nanocomposite material in aqueous solution through atmospheric pressure direct current (DC) plasma processing at room temperature. Both metal (Au) and ceramic (TiO2) nanoparticle composite films have been fabricated. Nanoparticle dispersion is enhanced considerable and remains stable. TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased nanoparticle/PEDOT:PSS nanocomposite electrical conductivity has been observed. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma processed Au or TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are thought to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer bonding. This is expected to have a significant benefit in materials processing with inorganic nanoparticles for applications in energy storage, photocatalysis and biomedical sensors. Engineering and Physical Sciences Research Council (EPSRC: EP/K006088/1, EP/K006142, Nos. EP/K022237/1).

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

    NASA Astrophysics Data System (ADS)

    Heidmann, I.

    2013-04-01

    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.

  13. Managing light polarization via plasmon-molecule interactions within an asymmetric metal nanoparticle trimer

    SciTech Connect

    Shegai, Timur; Li, Zhipeng; Zhang, Zhenyu; Xu, Hongxing; Haran, Gilad

    2008-01-01

    The interaction of light with metal nanoparticles leads to novel phenomena mediated by surface plasmon excitations. In this paper we use single molecules to characterize the interaction of surface plasmons with light, and show that such interaction can strongly modulate the polarization of the emitted light. The simplest nanostructures that enable such polarization modulation are asymmetric silver nanocrystal trimers, where individual Raman scattering molecules are located in the gap between two of the nanoparticles. The third particle breaks the dipolar symmetry of the two-particle junction, generating a wavelength-dependent polarization pattern. Indeed, the scattered light becomes elliptically polarized and its intensity pattern is rotated in the presence of the third particle. We use a combination of spectroscopic observations on single molecules, scanning electron microscope imaging, and generalized Mie theory calculations to provide a full picture of the effect of particles on the polarization of the emitted light. Furthermore, our theoretical analysis allows us to show that the observed phenomenon is very sensitive to the size of the trimer particles and their relative position, suggesting future means for precise control of light polarization on the nanoscale.

  14. A Genetically Modified Tobacco Mosaic Virus that can Produce Gold Nanoparticles from a Metal Salt Precursor

    PubMed Central

    Love, Andrew J.; Makarov, Valentine V.; Sinitsyna, Olga V.; Shaw, Jane; Yaminsky, Igor V.; Kalinina, Natalia O.; Taliansky, Michael E.

    2015-01-01

    We genetically modified tobacco mosaic virus (TMV) to surface display a characterized peptide with potent metal ion binding and reducing capacity (MBP TMV), and demonstrate that unlike wild type TMV, this construct can lead to the formation of discrete 10–40 nm gold nanoparticles when mixed with 3 mM potassium tetrachloroaurate. Using a variety of analytical physicochemical approaches it was found that these nanoparticles were crystalline in nature and stable. Given that the MBP TMV can produce metal nanomaterials in the absence of chemical reductants, it may have utility in the green production of metal nanomaterials. PMID:26617624

  15. Stabilized metal nanoparticles from organometallic precursors for low temperature fuel cells.

    PubMed

    Ramirez-Meneses, E; Dominguez-Crespo, M A; Torres-Huerta, A M

    2013-01-01

    In this work, a review of articles and patents related to the utilization of colloidal metal nanoparticles produced by the decomposition of organometallic precursors as supported electrocatalysts in different electrochemical reactions including hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) is discussed. In the case of stabilized metal nanoparticles, the kind of functional group contained in the stabilizer as well as the metal/stabilizer ratio, to evaluate the effect of particle size on the electrochemical performance, were also debated. Potential applications and perspectives of these electrocatalysts in proton exchange membrane fuel cells (PEMFC) are contended with reference to the role played by the coordination compounds and costs.

  16. A Genetically Modified Tobacco Mosaic Virus that can Produce Gold Nanoparticles from a Metal Salt Precursor.

    PubMed

    Love, Andrew J; Makarov, Valentine V; Sinitsyna, Olga V; Shaw, Jane; Yaminsky, Igor V; Kalinina, Natalia O; Taliansky, Michael E

    2015-01-01

    We genetically modified tobacco mosaic virus (TMV) to surface display a characterized peptide with potent metal ion binding and reducing capacity (MBP TMV), and demonstrate that unlike wild type TMV, this construct can lead to the formation of discrete 10-40 nm gold nanoparticles when mixed with 3 mM potassium tetrachloroaurate. Using a variety of analytical physicochemical approaches it was found that these nanoparticles were crystalline in nature and stable. Given that the MBP TMV can produce metal nanomaterials in the absence of chemical reductants, it may have utility in the green production of metal nanomaterials. PMID:26617624

  17. Super adsorption capability from amorphousization of metal oxide nanoparticles for dye removal

    PubMed Central

    Li, L. H.; Xiao, J.; Liu, P.; Yang, G. W.

    2015-01-01

    Transitional metal oxide nanoparticles as advanced environment and energy materials require very well absorption performance to apply in practice. Although most metal oxides are based on crystalline, high activities can also be achieved with amorphous phases. Here, we reported the adsorption behavior and mechanism of methyl blue (MB) on the amorphous transitional metal oxide (Fe, Co and Ni oxides) nanoparticles, and we demonstrated that the amorphousization of transitional metal oxide (Fe, Co and Ni oxides) nanoparticles driven by a novel process involving laser irradiation in liquid can create a super adsorption capability for MB, and the maximum adsorption capacity of the fabricated NiO amorphous nanostructure reaches up to 10584.6 mgg−1, the largest value reported to date for all MB adsorbents. The proof-of-principle investigation of NiO amorphous nanophase demonstrated the broad applicability of this methodology for obtaining new super dyes adsorbents. PMID:25761448

  18. An electrodynamics-Langevin dynamics (ED-LD) approach to simulate metal nanoparticle interactions and motion.

    PubMed

    Sule, N; Rice, S A; Gray, S K; Scherer, N F

    2015-11-16

    Understanding the formation of electrodynamically interacting assemblies of metal nanoparticles requires accurate computational methods for determining the forces and propagating trajectories. However, since computation of electromagnetic forces occurs on attosecond to femtosecond timescales, simulating the motion of colloidal nanoparticles on milliseconds to seconds timescales is a challenging multi-scale computational problem. Here, we present a computational technique for performing accurate simulations of laser-illuminated metal nanoparticles. In the simulation, we self-consistently combine the finite-difference time-domain method for electrodynamics (ED) with Langevin dynamics (LD) for the particle motions. We demonstrate the ED-LD method by calculating the 3D trajectories of a single 100-nm-diameter Ag nanoparticle and optical trapping and optical binding of two and three 150-nm-diameter Ag nanoparticles in simulated optical tweezers. We show that surface charge on the colloidal metal nanoparticles plays an important role in their optically driven self-organization. In fact, these simulations provide a more complete understanding of the assembly of different structures of two and three Ag nanoparticles that have been observed experimentally, demonstrating that the ED-LD method will be a very useful tool for understanding the self-organization of optical matter.

  19. Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

    SciTech Connect

    Guidelli, Eder José Baffa, Oswaldo

    2014-11-07

    Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

  20. Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

    NASA Astrophysics Data System (ADS)

    Guidelli, Eder José; Baffa, Oswaldo

    2014-11-01

    Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

  1. An electrodynamics-Langevin dynamics (ED-LD) approach to simulate metal nanoparticle interactions and motion.

    PubMed

    Sule, N; Rice, S A; Gray, S K; Scherer, N F

    2015-11-16

    Understanding the formation of electrodynamically interacting assemblies of metal nanoparticles requires accurate computational methods for determining the forces and propagating trajectories. However, since computation of electromagnetic forces occurs on attosecond to femtosecond timescales, simulating the motion of colloidal nanoparticles on milliseconds to seconds timescales is a challenging multi-scale computational problem. Here, we present a computational technique for performing accurate simulations of laser-illuminated metal nanoparticles. In the simulation, we self-consistently combine the finite-difference time-domain method for electrodynamics (ED) with Langevin dynamics (LD) for the particle motions. We demonstrate the ED-LD method by calculating the 3D trajectories of a single 100-nm-diameter Ag nanoparticle and optical trapping and optical binding of two and three 150-nm-diameter Ag nanoparticles in simulated optical tweezers. We show that surface charge on the colloidal metal nanoparticles plays an important role in their optically driven self-organization. In fact, these simulations provide a more complete understanding of the assembly of different structures of two and three Ag nanoparticles that have been observed experimentally, demonstrating that the ED-LD method will be a very useful tool for understanding the self-organization of optical matter. PMID:26698479

  2. Catalytic role of traditional enzymes for biosynthesis of biogenic metallic nanoparticles: a mini-review.

    PubMed

    Durán, Marcela; Silveira, Camila P; Durán, Nelson

    2015-10-01

    Although the formation mechanism of biogenically metallic nanoparticles is broadly associated to enzyme mediation, major attention has been given to the role of proteins and peptides in oxido-reduction of metallic ions leading to these nanostructures. Among the wide range of biomolecules that can act not only as capping agents but also as non-enzymatic agents to form nanoparticles, disulphide bridge-containing peptides and amino acids particularly stand out. The literature proposes that they actively participate in the process of nanoparticles' synthesis, with thiols groups and disulphide bridge moieties as the reaction catalytic sites. Similarly, denaturated enzymes containing exposed S-S or S-H moieties are also able to reduce metallic ions to form nanoparticles. This mini-review is focused on the biogenic synthesis of metallic nanoparticles such as gold, silver, copper, platinum, palladium, lead and selenium, in which proteins, peptides, reductases and even oxido-reductases act as non-enzymatic catalysts of the reduction reaction, opening economically and ecologically favourable perspectives in the nanoparticles synthesis field. PMID:26435286

  3. Catalytic role of traditional enzymes for biosynthesis of biogenic metallic nanoparticles: a mini-review.

    PubMed

    Durán, Marcela; Silveira, Camila P; Durán, Nelson

    2015-10-01

    Although the formation mechanism of biogenically metallic nanoparticles is broadly associated to enzyme mediation, major attention has been given to the role of proteins and peptides in oxido-reduction of metallic ions leading to these nanostructures. Among the wide range of biomolecules that can act not only as capping agents but also as non-enzymatic agents to form nanoparticles, disulphide bridge-containing peptides and amino acids particularly stand out. The literature proposes that they actively participate in the process of nanoparticles' synthesis, with thiols groups and disulphide bridge moieties as the reaction catalytic sites. Similarly, denaturated enzymes containing exposed S-S or S-H moieties are also able to reduce metallic ions to form nanoparticles. This mini-review is focused on the biogenic synthesis of metallic nanoparticles such as gold, silver, copper, platinum, palladium, lead and selenium, in which proteins, peptides, reductases and even oxido-reductases act as non-enzymatic catalysts of the reduction reaction, opening economically and ecologically favourable perspectives in the nanoparticles synthesis field.

  4. Metallic oxide nanoparticle translocation across the human bronchial epithelial barrier

    NASA Astrophysics Data System (ADS)

    George, Isabelle; Naudin, Grégoire; Boland, Sonja; Mornet, Stéphane; Contremoulins, Vincent; Beugnon, Karine; Martinon, Laurent; Lambert, Olivier; Baeza-Squiban, Armelle

    2015-02-01

    Inhalation is the most frequent route of unintentional exposure to nanoparticles (NPs). Our aim was to quantify the translocation of different metallic NPs across human bronchial epithelial cells and to determine the factors influencing this translocation. Calu-3 cells forming a tight epithelial barrier when grown on a porous membrane in a two compartment chamber were exposed to fluorescently labelled NPs to quantify the NP translocation. NP translocation and uptake by cells were also studied by confocal and transmission electron microscopy. Translocation was characterized according to NP size (16, 50, or 100 nm), surface charge (negative or positive SiO2), composition (SiO2 or TiO2), presence of proteins or phospholipids and in an inflammatory context. Our results showed that NPs can translocate through the Calu-3 monolayer whatever their composition (SiO2 or TiO2), but this translocation was increased for the smallest and negatively charged NPs. Translocation was not associated with an alteration of the integrity of the epithelial monolayer, suggesting a transcytosis of the internalized NPs. By modifying the NP corona, the ability of NPs to cross the epithelial barrier differed depending on their intrinsic properties, making positively charged NPs more prone to translocate. NP translocation can be amplified by using agents known to open tight junctions and to allow paracellular passage. NP translocation was also modulated when mimicking an inflammatory context frequently found in the lungs, altering the epithelial integrity and inducing transient tight junction opening. This in vitro evaluation of NP translocation could be extended to other inhaled NPs to predict their biodistribution.Inhalation is the most frequent route of unintentional exposure to nanoparticles (NPs). Our aim was to quantify the translocation of different metallic NPs across human bronchial epithelial cells and to determine the factors influencing this translocation. Calu-3 cells forming a

  5. Catalytic and photocatalytic transformations on metal nanoparticles with targeted geometric and plasmonic properties.

    PubMed

    Linic, Suljo; Christopher, Phillip; Xin, Hongliang; Marimuthu, Andiappan

    2013-08-20

    Heterogeneous catalysis by metals was among the first enabling technologies that extensively relied on nanoscience. The early intersections of catalysis and nanoscience focused on the synthesis of catalytic materials with high surface to volume ratio. These synthesis strategies mainly involved the impregnation of metal salts on high surface area supports. This would usually yield quasi-spherical nanoparticles capped by low-energy surface facets, typically with closely packed metal atoms. These high density areas often function as the catalytically active surface sites. Unfortunately, strategies to control the functioning surface facet (i.e., the geometry of active sites that performs catalytic turnover) are rare and represent a significant challenge in our ability to fine-tune and optimize the reactive surfaces. Through recent developments in colloidal chemistry, chemists have been able to synthesize metallic nanoparticles of both targeted size and desired shape. This has opened new possibilities for the design of heterogeneous catalytic materials, since metal nanoparticles of different shapes are terminated with different surface facets. By controlling the surface facet exposed to reactants, we can start affecting the chemical transformations taking place on the metal particles and changing the outcome of catalytic processes. Controlling the size and shape of metal nanoparticles also allows us to control the optical properties of these materials. For example, noble metals nanoparticles (Au, Ag, Cu) interact with UV-vis light through an excitation of localized surface plasmon resonance (LSPR), which is highly sensitive to the size and shape of the nanostructures. This excitation is accompanied by the creation of short-lived energetic electrons on the surface of the nanostructure. We showed recently that these energetic electrons could drive photocatalytic transformations on these nanostructures. The photocatalytic, electron-driven processes on metal nanoparticles

  6. Metallic oxide nanoparticle translocation across the human bronchial epithelial barrier.

    PubMed

    George, Isabelle; Naudin, Grégoire; Boland, Sonja; Mornet, Stéphane; Contremoulins, Vincent; Beugnon, Karine; Martinon, Laurent; Lambert, Olivier; Baeza-Squiban, Armelle

    2015-03-14

    Inhalation is the most frequent route of unintentional exposure to nanoparticles (NPs). Our aim was to quantify the translocation of different metallic NPs across human bronchial epithelial cells and to determine the factors influencing this translocation. Calu-3 cells forming a tight epithelial barrier when grown on a porous membrane in a two compartment chamber were exposed to fluorescently labelled NPs to quantify the NP translocation. NP translocation and uptake by cells were also studied by confocal and transmission electron microscopy. Translocation was characterized according to NP size (16, 50, or 100 nm), surface charge (negative or positive SiO2), composition (SiO2 or TiO2), presence of proteins or phospholipids and in an inflammatory context. Our results showed that NPs can translocate through the Calu-3 monolayer whatever their composition (SiO2 or TiO2), but this translocation was increased for the smallest and negatively charged NPs. Translocation was not associated with an alteration of the integrity of the epithelial monolayer, suggesting a transcytosis of the internalized NPs. By modifying the NP corona, the ability of NPs to cross the epithelial barrier differed depending on their intrinsic properties, making positively charged NPs more prone to translocate. NP translocation can be amplified by using agents known to open tight junctions and to allow paracellular passage. NP translocation was also modulated when mimicking an inflammatory context frequently found in the lungs, altering the epithelial integrity and inducing transient tight junction opening. This in vitro evaluation of NP translocation could be extended to other inhaled NPs to predict their biodistribution.

  7. Two-phase equilibrium states in individual Cu–Ni nanoparticles: size, depletion and hysteresis effects

    PubMed Central

    2015-01-01

    Summary In isolated bimetallic nanoscale systems the limit amount of matter and surface-induced size effects can change the thermodynamics of first-order phase transformation. In this paper we present theoretical modification of Gibbs free energy concept describing first-order phase transformation of binary alloyed nanoparticles taking into account size effects as well as depletion and hysteresis effects. In such a way the hysteresis in a form of nonsymmetry for forth and back transforming paths takes place; compositional splitting and the loops-like splitted path on the size dependent temperature–composition phase diagram occur. Our calculations for individual Cu–Ni nanoparticle show that one must differentiate the solubility curves and the equilibrium loops (discussed here in term of solidification and melting loops). For the first time we have calculated and present here on the temperature–composition phase diagram the nanomelting loop at the size of 80 nm and the nanosolidification loop at the size of 25 nm for an individual Cu–Ni nanoparticle. So we observe the difference between the size-dependent phase diagram and solubility diagram, between two-phase equilibrium curves and solubility curves; also intersection of nanoliquidus and nanosolidus is available. These findings lead to the necessity to reconsider such basic concepts in materials science as phase diagram and solubility diagram. PMID:26425433

  8. A simple urea-based route to ternary metal oxynitride nanoparticles

    SciTech Connect

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

    2009-01-15

    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{sub 2}N (M=Ca, Sr or Ba), MNbO{sub 2}N (M=Sr or Ba), LaTiO{sub 2}N and SrMoO{sub 3-x}N{sub 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{sub 2}N so obtained and the insets show the SAED pattern and HREM image of the nanoparticles.

  9. Carbon Materials Metal/Metal Oxide Nanoparticle Composite and Battery Anode Composed of the Same

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2006-01-01

    A method of forming a composite material for use as an anode for a lithium-ion battery is disclosed. The steps include selecting a carbon material as a constituent part of the composite, chemically treating the selected carbon material to receive nanoparticles, incorporating nanoparticles into the chemically treated carbon material and removing surface nanoparticles from an outside surface of the carbon material with incorporated nanoparticles. A material making up the nanoparticles alloys with lithium.

  10. Potential for metal contamination by direct sonication of nanoparticle suspensions

    EPA Science Inventory

    There is a growing need to examine the potential toxicity of engineered nanoparticles (ENPs) to establish regulations protective of environmental health and safety. During a series of experiments to evaluate the toxicity of titanium dioxide (TiO2) nanoparticles on terrestrial pla...

  11. Electrospinning-thermal treatment synthesis: a general strategy to decorate highly porous nanotubes on both internal and external side-walls with metal oxide/noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Haitao; Lu, Bingan; Xu, Jing; Xie, Erqing; Wang, Taihong; Xu, Zhi

    2013-03-01

    The hybrid structure of nanoparticle-decorated highly porous nanotubes combines the advantages of large specific surface areas of nanoparticles and anisotropic properties of highly porous nanotubes, which is desirable for many applications, including batteries, photoelectrochemical water splitting, and catalysis. Here, we report a novel emulsion electrospinning-thermal treatment method to synthesize the nanoparticles deposited on both side walls of nanotubes with two unique characteristics: (1) large loading amount of nanoparticles per highly porous nanotubes (with the morphology of nanoparticles); (2) intimate contact between nanoparticles and highly porous nanotubes. Both features are advantageous for the above applications that involve both surface reactions and charge transportation processes. Moreover, the emulsion electrospinning-thermal treatment method is simple and straightforward, with which we have successfully decorated various highly porous metal oxide nanotubes with metal oxide or noble metal nanoparticles. The new method will have an impact on diverse technologies such as lithium ion batteries, catalysts, and photoelectrochemical devices.The hybrid structure of nanoparticle-decorated highly porous nanotubes combines the advantages of large specific surface areas of nanoparticles and anisotropic properties of highly porous nanotubes, which is desirable for many applications, including batteries, photoelectrochemical water splitting, and catalysis. Here, we report a novel emulsion electrospinning-thermal treatment method to synthesize the nanoparticles deposited on both side walls of nanotubes with two unique characteristics: (1) large loading amount of nanoparticles per highly porous nanotubes (with the morphology of nanoparticles); (2) intimate contact between nanoparticles and highly porous nanotubes. Both features are advantageous for the above applications that involve both surface reactions and charge transportation processes. Moreover, the

  12. Dialkyldiselenophosphinato-metal complexes - a new class of single source precursors for deposition of metal selenide thin films and nanoparticles

    NASA Astrophysics Data System (ADS)

    Malik, Sajid N.; Akhtar, Masood; Revaprasadu, Neerish; Qadeer Malik, Abdul; Azad Malik, Mohammad

    2014-08-01

    We report here a new synthetic approach for convenient and high yield synthesis of dialkyldiselenophosphinato-metal complexes. A number of diphenyldiselenophosphinato-metal as well as diisopropyldiselenophosphinato-metal complexes have been synthesized and used as precursors for deposition of semiconductor thin films and nanoparticles. Cubic Cu2-xSe and tetragonal CuInSe2 thin films have been deposited by AACVD at 400, 450 and 500 °C whereas cubic PbSe and tetragonal CZTSe thin films have been deposited through doctor blade method followed by annealing. SEM investigations revealed significant differences in morphology of the films deposited at different temperatures. Preparation of Cu2-xSe and In2Se3 nanoparticles using diisopropyldiselenophosphinato-metal precursors has been carried out by colloidal method in HDA/TOP system. Cu2-xSe nanoparticles (grown at 250 °C) and In2Se3 nanoparticles (grown at 270 °C) have a mean diameter of 5.0 ± 1.2 nm and 13 ± 2.5 nm, respectively.

  13. Superparamagnetic silica nanoparticles with immobilized metal affinity ligands for protein adsorption

    NASA Astrophysics Data System (ADS)

    Ma, Zhiya; Guan, Yueping; Liu, Huizhou

    2006-06-01

    Superparamagnetic silica-coated magnetite (Fe 3O 4) nanoparticles with immobilized metal affinity ligands were prepared for protein adsorption. First, magnetite nanoparticles were synthesized by co-precipitating Fe 2+ and Fe 3+ in an ammonia solution. Then silica was coated on the Fe 3O 4 nanoparticles using a sol-gel method to obtain magnetic silica nanoparticles. The condensation product of 3-Glycidoxypropyltrimethoxysilane (GLYMO) and iminodiacetic acid (IDA) was immobilized on them and after charged with Cu 2+, the magnetic silica nanoparticles with immobilized Cu 2+ were applied for the adsorption of bovine serum albumin (BSA). Scanning electron micrograph showed that the magnetic silica nanoparticles with an average size of 190 nm were well dispersed without aggregation. X-ray diffraction showed the spinel structure for the magnetite particles coated with silica. Magnetic measurement revealed the magnetic silica nanoparticles were superparamagnetic and the saturation magnetization was about 15.0 emu/g. Protein adsorption results showed that the nanoparticles had high adsorption capacity for BSA (73 mg/g) and low nonspecific adsorption. The regeneration of these nanoparticles was also studied.

  14. The biomechanisms of metal and metal-oxide nanoparticles' interactions with cells.

    PubMed

    Teske, Sondra S; Detweiler, Corrella S

    2015-02-01

    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.

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

    PubMed

    Testino, Andrea; Pilger, Frank; Lucchini, Mattia Alberto; Quinsaat, Jose Enrico Q; Stähli, Christoph; Bowen, Paul

    2015-01-01

    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-x)NixC2O4·2H2O, 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(PO4)2 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. PMID:26060919

  16. Metal sulfide nanoparticles synthesized via enzyme treatment of biopolymer stabilized nanosuspensions

    NASA Astrophysics Data System (ADS)

    Kim, Yi-Yeoun; Walsh, Dominic

    2010-02-01

    Nanoparticles of CuS, CuxS, Ag2S and CdS were successfully prepared using a novel general and green synthetic process to give dextran biopolymer stabilised metal sulfifde nanosuspensions. Following preparation, dextranase enzyme was used to remove the bulk of the bound dextran to give pure stable metal sulfide nanocrystals for application in for example aspects of medicine, photonics and solar cells. Particles of good homogeneity were obtained and the CuS nanoparticle size was controlled to 9-27 nm by adjusting the reaction conditions. Cu2S nanoparticles were 14 nm, Ag2S nanoparticles were 20-50 nm and CdS nanoparticles were 9 nm is size. The complexing mechanism of nanoparticle sulfides to dextrans was further studied using carboxylmethyl dextran as a complexing agent and crosslinked Sephadex (dextran) `beads as substrate. Particles were characterized by TEM, XRD, TGA, FT-IR and zeta-potential measurement, and their UV-vis spectroscopic absorption properties were determined. Stabilization of the sulfide nanoparticles with soluble hydroxylated biopolymers such as dextran is previously unreported and is here interpreted in terms of viscosity, pH of the system and weak polar S-H or S(metal)OH2+ interactions with dextran depending on the material. Notably, the complexing mechanism appears to differ significantly from that taking place in known dextran-metal oxide systems. The process shown here has good potential for scale-up as a biosynthetic route for a range of functional sulfide nanoparticles.Nanoparticles of CuS, CuxS, Ag2S and CdS were successfully prepared using a novel general and green synthetic process to give dextran biopolymer stabilised metal sulfifde nanosuspensions. Following preparation, dextranase enzyme was used to remove the bulk of the bound dextran to give pure stable metal sulfide nanocrystals for application in for example aspects of medicine, photonics and solar cells. Particles of good homogeneity were obtained and the CuS nanoparticle size

  17. Recent progress in studies of metallic nickel and nickel-based nanoparticles' genotoxicity and carcinogenicity.

    PubMed

    Magaye, Ruth; Zhao, Jinshun

    2012-11-01

    Recently, nanoparticles have been the focus of many research and innovation. Metallic nickel and nickel-based nanoparticles are among those being exploited. Nickel fine particles are known to be genotoxic and carcinogenic. It has been discovered that many properties of nano sized elements and materials are not present in their bulk states. The nano size of these particles renders them the ability to be easily transported into biological systems, thus raising the question of their effects on the susceptible system. Therefore scientific research on the effects of nickel nanoparticles is important. This mini-review intends to summarize the current knowledge on the genotoxicity and carcinogenicity potential of metallic nickel and nickel-based nanoparticles implicated in in vitro and in vivo mammalian studies. PMID:23000472

  18. Synthesis and characterization of metal-carbon core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, He

    Superparamagnetic nanoparticles have been actively investigated as the contrast agents for Magnetic Resonance Imaging (MRI) since the last decade owing to their relatively high magnetic susceptibility, longer retention in the blood stream and better toxicity profile compared to gadolinium-based contrast agents. Most research in this regard has been focused on iron oxides primarily because nanoparticles made of materials that have higher saturation magnetization are usually prone to degradation due to oxidation and are difficult to retain under ambient conditions. Attempts to preserve the high saturation magnetization phases have been made through passivating the surface of the nanoparticles with Au or oxides. However, these approaches are not very effective. In this work, the synthesis, structures, compositions, magnetic properties and potential applications of some metallic nanoparticles, stabilized with protective graphitic carbons, have been studied. Fe, Co, FexCo(1-x) and AuxFe (1-x) alloy nanoparticles encapsulated by graphitic carbon are synthesized by chemical vapor deposition. Transmission electron microscopy (TEM) reveals that the nanoparticles are mostly about 10 nm in diameter and each nanoparticle is enclosed by at least one layer of graphitic carbon. Phase identification by high resolution TEM indicates the metallic phases were indeed obtained and preserved, even after three years of exposure to ambient conditions. The Fe-containing nanoparticles were found to be either BCC or FCC or Fe 3C, the Co nanoparticles being FCC, the FexCo(1-x) (0.1 < x < 0.6) nanoparticles being BCC alloys and AuxFe (1-x) (0.2 < x < 0.8) nanoparticles being FCC alloys. Energy dispersive spectrometry analysis of the Au0.67Fe0.33 nanoparticles indicates the composition of nanoparticles is consistent with the molar ratio of metal precursors, while quantitative EELS analysis suggest that the composition distribution of FexCo(1-x) rather wide. Preliminary Energy-Filtered TEM

  19. Phase diagrams of microemulsions containing reducing agents and metal salts as bases for the synthesis of metallic nanoparticles.

    PubMed

    Najjar, Reza; Stubenrauch, Cosima

    2009-03-01

    We studied the phase diagrams of microemulsions with a view to using these systems for the synthesis of metallic Pt, Pb, and Bi nanoparticles as well as of intermetallic Pt/Pb and Pt/Bi nanoparticles. The microemulsions consisted of H(2)O/salt-n-decane-SDS-1-butanol. The salt was either one metal precursor (H(2)PtCl(6) x 6 H(2)O, Pb(NO(3))(2), or Bi(NO(3))(3) x 5 H(2)O), a mixture of two metal precursors (H(2)PtCl(6) x 6 H(2)O + Pb(NO(3))(2) or H(2)PtCl(6) x 6 H(2)O + Bi(NO(3))(3) x 5 H(2)O), or the reducing agent (NaBH(4)). In addition, other salts needed to be added in order to solubilize the metal precursors, to stabilize the reducing agent, and to adjust the ionic strength. Combining the microemulsion (mu e1) that contains the metal precursor(s) with the microemulsion (mu e2) that contains the reducing agent leads to metallic nanoparticles. To study systematically how the shape and size of the synthesized metallic nanoparticles depend on the size and shape of the respective microemulsion droplets, first of all one has to find those conditions under which mu e1 and mu e2 have the same structure. For that purpose we determined the water emulsification failure boundary (wefb) of each microemulsion as it is at the wefb where the water droplets are known to be spherical. We found that the ionic strength (I) of the aqueous phase as well as the hard acid and hard base properties of the ions are the key tuning parameters for the location of the wefb.

  20. Formation of metal nanoparticles by short-distance sputter deposition in a reactive ion etching chamber

    SciTech Connect

    Nie Min; Meng, Dennis Desheng; Sun Kai

    2009-09-01

    A new method is reported to form metal nanoparticles by sputter deposition inside a reactive ion etching chamber with a very short target-substrate distance. The distribution and morphology of nanoparticles are found to be affected by the distance, the ion concentration, and the sputtering time. Densely distributed nanoparticles of various compositions were fabricated on the substrates that were kept at a distance of 130 mum or smaller from the target. When the distance was increased to 510 mum, island structures were formed, indicating the tendency to form continuous thin film with longer distance. The observed trend for nanoparticle formation is opposite to the previously reported mechanism for the formation of nanoparticles by sputtering. A new mechanism based on the seeding effect of the substrate is proposed to interpret the experimental results.

  1. Characterization of magnetite-organic complex nanoparticles by metal-reducing bacteria.

    PubMed

    Kim, Yumi; Jang, Heedong; Suh, Yongjae; Roh, Yul

    2011-08-01

    Magnetite nanoparticles exhibit clear technological potential for biomedical applications. The objectives of this study were to synthesize magnetite-organic complex nanoparticles through the use of metal-reducing bacteria and characterize the mineralogical and surface chemical properties of these nanoparticles as well as to test their potential applications in biomedical technology with regards to their protein immobilization capacity. The microbially formed magnetite nanoparticles had a size of around 10 nm with a spherical shape and were coated with organics containing an abundance of reactive carboxyl groups without any chemical process for functionalizing them. These microbial processes may lead to a simple preparation of functional magnetite-organic complex nanoparticles which have benefits for biomedical applications.

  2. Structure and optical properties of noble metal and oxide nanoparticles dispersed in various polysaccharide biopolymers

    NASA Astrophysics Data System (ADS)

    Djoković, V.; Božanic, D. K.; Vodnik, V. V.; Krsmanović, R. M.; Trandafilovic, L. V.; Dimitrijević-Branković, S.

    2011-10-01

    We present the results on the structure and the optical properties of noble metal (Ag, Au) and oxide (ZnO) nanoparticles synthesized by various methods in different polysaccharide matrices such as chitosan, glycogen, alginate and starch. The structure of the obtained nanoparticles was studied in detail with microscopic techniques (TEM, SEM), while the XPS spectroscopy was used to investigate the effects at the nanoparticle-biomolecule interfaces. The antimicrobial activity of the nanocomposite films with Ag nanoparticles was tested against the Staphylococcus aureus, Escherichia coli and Candida albicans pathogens. In addition, we will present the results on the structure and optical properties of the tryptophan amino acid functionalized silver nanoparticles dispersed in water soluble polymer matrices.

  3. Decoration of diatom biosilica with noble metal and semiconductor nanoparticles (<10 nm): assembly, characterization, and applications.

    PubMed

    Jantschke, Anne; Herrmann, Anne-Kristin; Lesnyak, Vladimir; Eychmüller, Alexander; Brunner, Eike

    2012-01-01

    Diatom-templated noble metal (Ag, Pt, Au) and semiconductor (CdTe) nanoparticle arrays were synthesized by the attachment of prefabricated nanoparticles of defined size. Two different attachment techniques-layer-by-layer deposition and covalent linking-could successfully be applied. The synthesized arrays were shown to be useful for surface-enhanced Raman spectroscopy (SERS) of components, for catalysis, and for improved image quality in scanning electron microscopy (SEM).

  4. Removal of Heavy Metals from Aqueous Systems with Thiol Functionalized Superparamagnetic Nanoparticles

    SciTech Connect

    Yantasee, Wassana; Warner, Cynthia L.; Sangvanich, Thanapon; Addleman, Raymond S.; Carter, Timothy G.; Wiacek, Robert J.; Fryxell, Glen E.; Timchalk, Chuck; Warner, Marvin G.

    2007-06-09

    We have shown that superparamagnetic iron oxide (Fe3O4) nanoparticles with a surface functionalization of dimercaptosuccinic acid is an effective, magnetic, sorbent material for toxic metals such as Hg, Ag, Pb, Cd and other soft cations. The chemical affinity, stability, capacity and kinetics of the functionalized nanoparticles has been explored and compared to conventional resin based sorbents and nanoporous silica materials with similar surface chemistries.

  5. Metal sulfide nanoparticles synthesized via enzyme treatment of biopolymer stabilized nanosuspensions.

    PubMed

    Kim, Yi-Yeoun; Walsh, Dominic

    2010-02-01

    Nanoparticles of CuS, Cu(x)S, Ag(2)S and CdS were successfully prepared using a novel general and green synthetic process to give dextran biopolymer stabilised metal sulfifde nanosuspensions. Following preparation, dextranase enzyme was used to remove the bulk of the bound dextran to give pure stable metal sulfide nanocrystals for application in for example aspects of medicine, photonics and solar cells. Particles of good homogeneity were obtained and the CuS nanoparticle size was controlled to 9-27 nm by adjusting the reaction conditions. Cu(2)S nanoparticles were 14 nm, Ag(2)S nanoparticles were 20-50 nm and CdS nanoparticles were 9 nm is size. The complexing mechanism of nanoparticle sulfides to dextrans was further studied using carboxylmethyl dextran as a complexing agent and crosslinked Sephadex (dextran) ;beads as substrate. Particles were characterized by TEM, XRD, TGA, FT-IR and zeta-potential measurement, and their UV-vis spectroscopic absorption properties were determined. Stabilization of the sulfide nanoparticles with soluble hydroxylated biopolymers such as dextran is previously unreported and is here interpreted in terms of viscosity, pH of the system and weak polar S-H or S(metal)OH(2)(+) interactions with dextran depending on the material. Notably, the complexing mechanism appears to differ significantly from that taking place in known dextran-metal oxide systems. The process shown here has good potential for scale-up as a biosynthetic route for a range of functional sulfide nanoparticles.

  6. Current [corrected] trends in phytosynthesis of metal nanoparticles.

    PubMed

    Rai, Mahendra; Yadav, Alka; Gade, Aniket

    2008-01-01

    Nanotechnology is emerging as a field of applied science and technology. Synthesis of nanoparticles is done by various physical and chemical methods but the biological system is gaining attention as an eco-friendly technique. The biosynthetic method employing plant parts is proving as a simple and cost-effective method for the synthesis of nanoparticles. The present mini review focuses on the different systems utilized for the synthesis of nanoparticles with special emphasis on the use of plants for the synthesis process, its applications and future directions.

  7. High-Performance, Superparamagnetic, Nanoparticle-Based Heavy Metal Sorbents for Removal of Contaminants from Natural Waters

    SciTech Connect

    Warner, Cynthia L.; Addleman, Shane; Cinson, Anthony D.; Droubay, Timothy C.; Engelhard, Mark H.; Nash, Michael A.; Yantasee, Wassana; Warner, Marvin G.

    2010-06-01

    We describe the synthesis and characterization of superparamagnetic iron oxide nanoparticle based heavy metal sorbents with various surface chemistries that demonstrate an excellent affinity for the separation of heavy metals in contaminated water systems (i.e. spiked Columbia river water). The magnetic nanoparticle sorbents are prepared from an easy to synthesize iron oxide precursor, followed by a simple, one-step ligand exchange technique to introduce the organic surface functionality of interest chosen to target either specific or broader classes of heavy metals. Functionalized superparamagnetic nanoparticles are excellent sorbent materials for the extraction of heavy metal contaminants from environmental and clinical samples since they are easily removed from the media once bound to the contaminant by simply applying a magnetic field. These engineered magnetic nanoparticle sorbents have an inherently high active surface area (often > 100 m2/g), allowing for increased binding capacity. To demonstrate the potential sorbent performance of each of the surface modified magnetic nanoparticles, river water was spiked with Hg, Pb, Cd, Ag, Co, Cu, and Tl and exposed to low concentrations of the functionalized nanoparticles. The samples were analyzed to determine the metal content before and after exposure to the magnetic nanoparticle sorbents. In almost all cases reported here the nanoparticles were found to be superior to commercially available sorbents binding a wide range of different heavy metals with extremely high affinity. Detailed characterization of the functionalized magnetic nanoparticle sorbents including FT-IR, BET surface analysis, TGA, XPS and VSM as well as the heavy metal removal experiments are presented.

  8. High-harmonic generation by nonlinear resonant excitation of surface plasmon modes in metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hurst, Jérôme; Haas, Fernando; Manfredi, Giovanni; Hervieux, Paul-Antoine

    2014-04-01

    The nonlinear electron dynamics in metallic nanoparticles is studied using a hydrodynamic model that incorporates most quantum many-body features, including spill-out and nonlocal effects as well as electron exchange and correlations. We show that, by irradiating the nanoparticle with a chirped laser pulse of modest intensity (autoresonance), it is possible to drive the electron dynamics far into the nonlinear regime, leading to enhanced energy absorption and complete ionization of the nanoparticle on a time scale of the order of 100 fs. The accompanying radiated power spectrum is rich in high-order harmonics.

  9. Revealing the nanoparticles aspect ratio in the glass-metal nanocomposites irradiated with femtosecond laser

    PubMed Central

    Chervinskii, S.; Drevinskas, R.; Karpov, D. V.; Beresna, M.; Lipovskii, A. A.; Svirko, Yu. P.; Kazansky, P. G.

    2015-01-01

    We studied a femtosecond laser shaping of silver nanoparticles embedded in soda-lime glass. Comparing experimental absorption spectra with the modeling based on Maxwell Garnett approximation modified for spheroidal inclusions, we obtained the mean aspect ratio of the re-shaped silver nanoparticles as a function of the laser fluence. We demonstrated that under our experimental conditions the spherical shape of silver nanoparticles changed to a prolate spheroid with the aspect ratio as high as 3.5 at the laser fluence of 0.6 J/cm2. The developed approach can be employed to control the anisotropy of the glass-metal composites. PMID:26348691

  10. Potential to raise the efficiency of neutron and neutron-photon therapy using metal nonradioactive nanoparticles

    NASA Astrophysics Data System (ADS)

    Shmatov, M. L.

    2016-07-01

    The use of metal nonradioactive nanoparticles (specifically, gold ones) in neutron and neutron-photon cancer therapy is proposed. The minimum therapeutically effective average density of gold within a tumor subjected to neutron irradiation is estimated as a value on the order of 10-5-10-4 g/cm3. Potential benefits of the use of data obtained when using Peteosthor (a drug containing 224Ra and colloidal platinum) and Thorotrast (a radiopaque contrast agent containing thorium oxide nanoparticles) and its analogues in the analysis of safety and efficiency of application of nonradioactive nanoparticles in radiation therapy and diagnostics are discussed.

  11. Gold nanoparticles with cyclic phenylazomethines: one-pot synthesis and metal ion sensing.

    PubMed

    Shomura, Ryo; Chung, Keum Jee; Iwai, Hideo; Higuchi, Masayoshi

    2011-07-01

    New gold nanoparticles covered with cyclic phenylazomethine (CPA) were obtained by a one-pot synthesis. It is confirmed by XPS that imines of CPA in the nanoparticles (Au-CPA) are partially reduced to amines. The amine part of CPA in Au-CPA is attached to the surfaces of gold nanoparticles, and the imine part works as a redox-active site. A glassy carbon electrode modified with Au-CPA was revealed to work as an electrochemical probe for metal ion sensing.

  12. A new bio-inspired route to metal-nanoparticle-based heterogeneous catalysts.

    PubMed

    Debecker, Damien P; Faure, Chrystel; Meyre, Marie-Edith; Derré, Alain; Gaigneaux, Eric M

    2008-10-01

    Onion-type multilamellar vesicles are made of concentric bilayers of organic surfactant and are mainly known for their potential applications in biotechnology. They can be used as microreactors for the spontaneous and controlled production of metal nanoparticles. This process does not require any thermal treatment and, hence, it is also attractive for material sciences such as heterogeneous catalysis. In this paper, silver-nanoparticle-based catalysts are prepared by transferring onion-grown silver nanoparticles onto inorganic supports. The resulting materials are active in the total oxidation of benzene, attesting that this novel bio-inspired concept is promising in inorganic catalysis. PMID:18844300

  13. A review of chemical and physical characterisation of atmospheric metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sanderson, Paul; Delgado-Saborit, Juana Maria; Harrison, Roy M.

    2014-09-01

    Knowledge of the human health impacts associated with airborne nanoparticle exposure has led to considerable research activity aimed at better characterising these particles and understanding which particle properties are most important in the context of effects on health. Knowledge of the sources, chemical composition, physical structure and ambient concentrations of nanoparticles has improved significantly as a result. Given the known toxicity of many metals and the contribution of nanoparticles to their oxidative potential, the metallic content of the nanoparticulate burden is likely to be an important factor to consider when attempting to assess the impact of nanoparticle exposure on health. This review therefore seeks to draw together the existing knowledge of metallic nanoparticles in the atmosphere and discuss future research priorities in the field. The article opens by outlining the reasons behind the current research interest in the field, and moves on to discuss sources of nanoparticles to the atmosphere. The next section reviews ambient concentrations, covering spatial and temporal variation, mass and number size distributions, air sampling and measurement techniques. Further sections discuss the chemical and physical composition of particles. The review concludes by summing up the current state of research in the area and considering where future research should be focused.

  14. Comparison of Doxorubicin Anticancer Drug Loading on Different Metal Oxide Nanoparticles

    PubMed Central

    Javed, Khalid Rashid; Ahmad, Munir; Ali, Salamat; Butt, Muhammad Zakria; Nafees, Muhammad; Butt, Alvina Rafiq; Nadeem, Muhammad; Shahid, Abubakar

    2015-01-01

    Abstract Nanomaterials are being vigorously investigated for their use in anticancer drug delivery regimes or as biomarkers agents and are considered to be a candidate to provide a way to combat severe weaknesses of anticancer drug pharmacokinetics, such as their nonspecificity. Because of this weakness, a bigger proportion of the drug-loaded nanomaterials flow toward healthy tissues and result in undesirable side effects. It is very important to evaluate drug loading and release efficiency of various nanomaterials to find out true pharmacokinetics of these drugs. This observational study aims to evaluate various surface functionalized and naked nanomaterials for their drug loading capability and consequently strengthens the Reporting of Observational Studies in Epidemiology (STROBE). We analyzed naked and coated nanoparticles of transition metal oxides for their further loading with doxorubicin, a representative water-soluble anticancer drug. Various uncoated and polyethylene glycol-coated metal oxide nanoparticles were synthesized and loaded with anticancer drug using simple stirring of the nanoparticles in a saturated aqueous solution of the drug. Results showed that surface-coated nanoparticles have higher drug-loading capabilities; however, certain naked metal oxide nanoparticles, such as cobalt oxide nanoparticles, can load a sufficient amount of drug. PMID:25789952

  15. Comparison of doxorubicin anticancer drug loading on different metal oxide nanoparticles.

    PubMed

    Javed, Khalid Rashid; Ahmad, Munir; Ali, Salamat; Butt, Muhammad Zakria; Nafees, Muhammad; Butt, Alvina Rafiq; Nadeem, Muhammad; Shahid, Abubakar

    2015-03-01

    Nanomaterials are being vigorously investigated for their use in anticancer drug delivery regimes or as biomarkers agents and are considered to be a candidate to provide a way to combat severe weaknesses of anticancer drug pharmacokinetics, such as their nonspecificity. Because of this weakness, a bigger proportion of the drug-loaded nanomaterials flow toward healthy tissues and result in undesirable side effects. It is very important to evaluate drug loading and release efficiency of various nanomaterials to find out true pharmacokinetics of these drugs.This observational study aims to evaluate various surface functionalized and naked nanomaterials for their drug loading capability and consequently strengthens the Reporting of Observational Studies in Epidemiology (STROBE). We analyzed naked and coated nanoparticles of transition metal oxides for their further loading with doxorubicin, a representative water-soluble anticancer drug.Various uncoated and polyethylene glycol-coated metal oxide nanoparticles were synthesized and loaded with anticancer drug using simple stirring of the nanoparticles in a saturated aqueous solution of the drug. Results showed that surface-coated nanoparticles have higher drug-loading capabilities; however, certain naked metal oxide nanoparticles, such as cobalt oxide nanoparticles, can load a sufficient amount of drug. PMID:25789952

  16. Comparative study on the uptake and bioimpact of metal nanoparticles released into environment

    NASA Astrophysics Data System (ADS)

    Andries, Maria; Pricop, Daniela; Grigoras, Marian; Lupu, Nicoleta; Sacarescu, Liviu; Creanga, Dorina; Iacomi, Felicia

    2015-12-01

    Metallic particles of very small size are ubiquitously released in the air, water and soil from various natural and artificial sources - the last ones with enhanced extent since nanotechnology development accelerated exponentially. In this study we focused on the impact of metal nanoparticles in vegetal species of agroindustrial interest namely the maize (Zea mais L.). Laboratory simulation of environmental pollution was carried out by using engineered nanoparticles of two types: iron oxides with magnetic properties and gold nanoparticles supplied in the form of dilutes stable suspensions in the culture medium of maize seedlings. Magnetic nanoparticle (MNPs) preparation was performed by applying chemical route from iron ferric and ferrous precursor salts in alkali reaction medium at relatively high temperature (over 80 °C). Gold nanoparticles (GNPs) synthesis was accomplished from auric hydrochloride acid in alkali reaction medium in similar temperature conditions. In both types of metallic nanoparticles citrate ions were used as coating shell with role of suspension stabilization. Plantlet response was assessed at the level of assimilatory pigment contents in green tissue of seedlings in early ontogenetic stages.

  17. Catalytically Active Bimetallic Nanoparticles Supported on Porous Carbon Capsules Derived From Metal-Organic Framework Composites.

    PubMed

    Yang, Hui; Bradley, Siobhan J; Chan, Andrew; Waterhouse, Geoffrey I N; Nann, Thomas; Kruger, Paul E; Telfer, Shane G

    2016-09-14

    We report a new methodology for producing monometallic or bimetallic nanoparticles confined within hollow nitrogen-doped porous carbon capsules. The capsules are derived from metal-organic framework (MOF) crystals that are coated with a shell of a secondary material comprising either a metal-tannic acid coordination polymer or a resorcinol-formaldehyde polymer. Platinum nanoparticles are optionally sandwiched between the MOF core and the shell. Pyrolysis of the MOF-shell composites produces hollow capsules of porous nitrogen-doped carbon that bear either monometallic (Pt, Co, and Ni) or alloyed (PtCo and PtNi) metal nanoparticles. The Co and Ni components of the bimetallic nanoparticles are derived from the shell surrounding the MOF crystals. The hollow capsules prevent sintering and detachment of the nanoparticles, and their porous walls allow for efficient mass transport. Alloyed PtCo nanoparticles embedded in the capsule walls are highly active, selective, and recyclable catalysts for the hydrogenation of nitroarenes to anilines. PMID:27575666

  18. Transition-metal-doped ZnO nanoparticles: synthesis, characterization and photocatalytic activity under UV light.

    PubMed

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-15

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  19. Noble metal nanoparticles embedding into polymeric materials: From fundamentals to applications.

    PubMed

    Prakash, Jai; Pivin, J C; Swart, H C

    2015-12-01

    This review covers some key concepts related to embedding of the noble metal nanoparticles in polymer surfaces. The metal nanoparticles embedded into the polymer matrix can provide high-performance novel materials that find applications in modern nanotechnology. In particular, the origin of various processes that drive the embedding phenomenon, growth of the nanostructure at the surface, factors affecting the embedding including role of surface, interface energies and thermodynamic driving forces with emphasis on the fundamental and technological applications, under different conditions (annealing and ion beams) have been discussed. In addition to the conventional thermal process for embedding which includes the measure of fundamental polymer surface properties with relevant probing techniques, this review discusses the recent advances carried out in the understanding of embedding phenomenon starting from thin metal films to growth of the nanoparticles and embedded nanostructures using novel ion beam techniques. PMID:26584861

  20. Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Fratoddi, Ilaria; Venditti, Iole; Battocchio, Chiara; Polzonetti, Giovanni; Cametti, Cesare; Russo, Maria Vittoria

    2011-12-01

    Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

  1. Highly stable, water-dispersible metal-nanoparticle-decorated polymer nanocapsules and their catalytic applications.

    PubMed

    Yun, Gyeongwon; Hassan, Zahid; Lee, Jiyeong; Kim, Jeehong; Lee, Nam-Suk; Kim, Nam Hoon; Baek, Kangkyun; Hwang, Ilha; Park, Chan Gyung; Kim, Kimoon

    2014-06-16

    A facile synthesis of highly stable, water-dispersible metal-nanoparticle-decorated polymer nanocapsules (M@CB-PNs: M=Pd, Au, and Pt) was achieved by a simple two-step process employing a polymer nanocapsule (CB-PN) made of cucurbit[6]uril (CB[6]) and metal salts. The CB-PN serves as a versatile platform where various metal nanoparticles with a controlled size can be introduced on the surface and stabilized to prepare new water-dispersible nanostructures useful for many applications. The Pd nanoparticles on CB-PN exhibit high stability and dispersibility in water as well as excellent catalytic activity and recyclability in carbon-carbon and carbon-nitrogen bond-forming reactions in aqueous medium suggesting potential applications as a green catalyst.

  2. Polymer thin films embedded with metal nanoparticles for electrochemical biosensors applications.

    PubMed

    Prakash, S; Chakrabarty, Tina; Singh, Ajay K; Shahi, Vinod K

    2013-03-15

    Currently, polymer thin films embedded with metal nanoparticles provided the suitable microenvironment for biomolecules immobilization retaining their biological activity with desired orientation, to facilitate electron transfer between the immobilized enzymes and electrode surfaces, better conformation and high biological activity, resultant in enhanced sensing performance. This article reviews focus on various methods for brief discussion of fabrication of metal nanoparticles-polymer hybrid materials and their applications in different electrochemical biosensors. The performance of hybrid materials based electrochemical biosensor can be improved by synergic properties of the metal nanoparticles and polymer network with biomolecules interface via engineering of morphology, particle size, effective surface area, functionality, adsorption capability and electron-transfer properties. These attractive features to hybrid materials are expected to find applications in a new generation of miniaturized, smart biochip devices. PMID:23083910

  3. Electrochemical synthesis of elongated noble metal nanoparticles, such as nanowires and nanorods, on high-surface area carbon supports

    DOEpatents

    Adzic, Radoslav; Blyznakov, Stoyan; Vukmirovic, Miomir

    2015-08-04

    Elongated noble-metal nanoparticles and methods for their manufacture are disclosed. The method involves the formation of a plurality of elongated noble-metal nanoparticles by electrochemical deposition of the noble metal on a high surface area carbon support, such as carbon nanoparticles. Prior to electrochemical deposition, the carbon support may be functionalized by oxidation, thus making the manufacturing process simple and cost-effective. The generated elongated nanoparticles are covalently bound to the carbon support and can be used directly in electrocatalysis. The process provides elongated noble-metal nanoparticles with high catalytic activities and improved durability in combination with high catalyst utilization since the nanoparticles are deposited and covalently bound to the carbon support in their final position and will not change in forming an electrode assembly.

  4. In Vitro Vascular Toxicity of Metal Oxide Nanoparticles

    EPA Science Inventory

    Engineered nanoparticles (NPs) are designed to possess unique physicochemical properties, but may also produce atypical and unforeseen exposure scenarios with adverse health effects. The ability ofNPs to translocate into systemic circulation following either inhalation or ingesti...

  5. Synthesizing metallic to superconducting ceramic nanoparticles using optimized microemulsion systems

    NASA Astrophysics Data System (ADS)

    Li, Fang

    A microemulsion system with cetyltrimethylammonium bromide (CTAB) as surfactant, 1-butanol as cosurfactant and n-octane as the oil phase was optimized to produce nanoparticles. Based on the results of conductivity and droplet size, oil/surfactant weight ratio of 1.5 was chosen to perform the study due to its higher solubilization and droplet stability. Nanoparticles of monometallic Fe, bimetallic Fe/Ni, oxide Y2O3, complex oxide Y 2BaCuO5 (Y211) and YBa2Cu3O7-x (Y123) have been successfully synthesized using the water-in-oil microemulsion method. The size of amorphous Fe, Fe/Ni nanoparticles were about 10 nm and 5 nm respectively. The reduction rate of trichloroethylene (TCE, a model contaminant) by the Fe produced from the microemulsion system was the highest compared to the solution product and the commercial product. In the case of Fe/Ni nanoparticles, the initial degradation rate is four times faster than for Fe nanoparticles. Nanocrystalline Y2O3 particles were flake shaped with dimension in the range of 16--30 nm. Y2BaCuO5 and YBa2Cu3O7-x nanoparticles (˜110 nm) produced using the microemulsion method had lower processing temperature than other processing methods due to their smaller particle size. As the reaction time was shortened, the Y211 particle size reduced from larger than 100 nm to the 30--100 nm range. Superconductivity of Y123 nanoparticles was verified using magnetic measurements and the critical transition temperature was 91 K. In the melt-textured Y123 disk, a single domain with a maximum trapped field of 0.14 T was successfully fabricated with the addition of 30% Y211 nanoparticles produced by the microemulsion method. The JC and size distribution of Y211 grain in the Y123 matrix were slightly better than in conventional samples.

  6. Controlling Magnetism of a Complex Metallic System Using Atomic Individualism

    NASA Astrophysics Data System (ADS)

    Mudryk, Y.; Paudyal, D.; Pecharsky, V. K.; Gschneidner, K. A., Jr.; Misra, S.; Miller, G. J.

    2010-08-01

    When the complexity of a metallic compound reaches a certain level, a specific location in the structure may be critically responsible for a given fundamental property of a material while other locations may not play as much of a role in determining such a property. The first-principles theory has pinpointed a critical location in the framework of a complex intermetallic compound—Gd5Ge4—that resulted in a controlled alteration of the magnetism of this compound using precise chemical tools.

  7. Lathe Operator. Coordinator's Guide. Individualized Study Guide. General Metal Trades.

    ERIC Educational Resources Information Center

    East Texas State Univ., Commerce. Occupational Curriculum Lab.

    This guide provides information to enable coordinators to direct learning activities for students using an individualized study guide on operating a lathe. The study material is designed for students enrolled in cooperative part-time training and employed, or desiring to be employed, as lathe operators. Contents include a sample progress chart,…

  8. Welder's Helper. Coordinator's Guide. Individualized Study Guide. General Metal Trades.

    ERIC Educational Resources Information Center

    Dean, James W.

    This guide provides information to enable coordinators to direct learning activities for students using an individualized study guide on being a welder's helper. The study material is designed for students enrolled in cooperative part-time training and employed, or desiring to be employed, as welders' helpers. Contents include a sample progress…

  9. Modelling the transport of engineered metallic nanoparticles in the river Rhine.

    PubMed

    Markus, A A; Parsons, J R; Roex, E W M; de Voogt, P; Laane, R W P M

    2016-03-15

    As engineered nanoparticles of zinc oxide, titanium dioxide and silver, are increasingly used in consumer products, they will most probably enter the natural environment via wastewater, atmospheric deposition and other routes. The aim of this study is to predict the concentrations of these nanoparticles via wastewater emissions in a typical river system by means of a numerical model. The calculations rely on estimates of the use of nanomaterials in consumer products and the removal efficiency in wastewater treatment plants as well as model calculations of the fate and transport of nanoparticles in a riverine system. The river Rhine was chosen for this work as it is one of the major and best studied rivers in Europe. The study gives insight in the concentrations that can be expected and, by comparing the model results with measurements of the total metal concentrations, of the relative contribution of these emerging contaminants. Six scenarios were examined. Two scenarios concerned the total emission: in the first it was assumed that nanoparticles are only released via wastewater (treated or untreated) and in the second it was assumed that in addition nanoparticles can enter the river system via runoff from the application of sludge as a fertilizer. In both cases the assumption was that the nanoparticles enter the river system as free, unattached particles. Four additional scenarios, based on the total emissions from the second scenario, were examined to highlight the consequences of the assumption of free nanoparticles and the uncertainties about the aggregation processes. If all nanoparticles enter as free particles, roughly a third would end up attached to suspended particulate matter due to the aggregation processes nanoparticles are subject to. For the other scenarios the contribution varies from 20 to 45%. Since the Rhine is a fast flowing river, sedimentation is unlikely to occur, except at the floodplains and the lakes in the downstream regions, as in fact

  10. Green processing of metal oxide core-shell nanoparticles as low-temperature dielectrics in organic thin-film transistors.

    PubMed

    Portilla, Luis; Etschel, Sebastian H; Tykwinski, Rik R; Halik, Marcus

    2015-10-21

    TiO2 , Fe3 O4, AlOx , ITO (indium tin oxide), and CeO2 nanoparticles are tailored to exhibit excellent dispersability in deionized water and alcohols. The latter provides an ecofriendly solution for processing metal oxide nanoparticles at a neutral pH. Water-processed dielectrics from the metal oxide nanoparticles are incorporated into organic thin-film transistors fabricated on rigid and flexible substrates. PMID:26308740

  11. Green processing of metal oxide core-shell nanoparticles as low-temperature dielectrics in organic thin-film transistors.

    PubMed

    Portilla, Luis; Etschel, Sebastian H; Tykwinski, Rik R; Halik, Marcus

    2015-10-21

    TiO2 , Fe3 O4, AlOx , ITO (indium tin oxide), and CeO2 nanoparticles are tailored to exhibit excellent dispersability in deionized water and alcohols. The latter provides an ecofriendly solution for processing metal oxide nanoparticles at a neutral pH. Water-processed dielectrics from the metal oxide nanoparticles are incorporated into organic thin-film transistors fabricated on rigid and flexible substrates.

  12. Eddy current effects in the magnetization dynamics of ferromagnetic metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Denisov, S. I.; Lyutyy, T. V.; Pedchenko, B. O.; Babych, H. V.

    2014-07-01

    We develop an analytical model for describing the magnetization dynamics in ferromagnetic metal nanoparticles, which is based on the coupled system of the Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's equations in the quasi-static approximation and finding the magnetic field of eddy currents, we derive the closed LLG equation for the magnetization that fully accounts for the effects of conductivity. We analyze the difference between the LLG equations in metallic and dielectric nanoparticles and show that these effects can strongly influence the magnetization dynamics. As an example illustrating the importance of eddy currents, the phenomenon of precessional switching of magnetization is considered.

  13. Study on metal nanoparticles induced third-order optical nonlinearity in phenylhydrazone derivatives with DFWM technique

    SciTech Connect

    Sudheesh, P.; Chandrasekharan, K.; Rao, D. Mallikharjuna

    2014-01-28

    The third-order nonlinear optical properties of newly synthesized phenylhydrazone derivatives and the influence of noble metal nanoparticles (Ag and Au) on their nonlinear optical responses were investigated by employing Degenerate Four wave Mixing (DFWM) technique with a 7 nanosecond, 10Hz Nd: YAG laser pulses at 532nm. Metal nanoparticles were prepared by laser ablation and the particle formation was confirmed using UV-Visible spectroscopy, Transmission Electron Microscopy (TEM). The nonlinear optical susceptibility were measured and found to be of the order 10{sup −13}esu. The results are encouraging and conclude that the materials are promising candidate for future optical device applications.

  14. Colloidal metal nanoparticles: New building blocks for materials and amplification reagents for immunoassays

    NASA Astrophysics Data System (ADS)

    Musick, Michael David

    This thesis describes new analytical uses for colloidal metal nanoparticles. Investigations into the ligand directed self-assembly of new materials from metal nanoparticles and applications of metal nanoparticle arrays in electrochemistry and immunosensing have addressed several issues; These include (i) the development of a stepwise method to assemble materials composed of metal nanoparticles entirely from solution, (ii) characterization of morphological, optical and electrical properties of these materials, and (iii) potential applications for nanoparticle materials such as biocompatible electrodes, microband electrodes, and patterned arrays. Also discussed are (iv) interactions of colloidal metal particle arrays with surface plasmons, and (v) a new motif for ultrasensitive detection of immunological binding events. A novel method of layer-by-layer film formation from solution of metal nanoparticles film generation was developed and investigated. Atomic force microscopy of multilayered structures revealed an underlying porous nanostructure and a lack of inter- and intra particle order. Optical properties and DC resistance were monitored as a function of colloid coverage and bifunctional crosslinker. High coverage films were similar to evaporated discontinuous metal films in transmission properties (uv-vis/NIR) and in appearance by eye these films resembled their bulk metal counterparts. The measured resistivity was only 100 times greater than bulk Au. Applications in electrochemistry and the construction of a microband electrode of nanometer dimensions, is discussed and detailed further in chapter 4. Chapter 5 encompasses probing nanoparticle assemblies with surface plasmon resonance and the applications of colloidal Au nanoparticles as signal amplification reagents in a sandwich immunoassay. The binding of anti-human IgG:Au colloid conjugate to human IgG immobilized on an Au film produced a enhanced shift in plasmon angle over unconjugated antibody. Detection

  15. The challenges of testing metal and metal oxide nanoparticles in algal bioassays: titanium dioxide and gold nanoparticles as case studies.

    PubMed

    Hartmann, Nanna B; Engelbrekt, Christian; Zhang, Jingdong; Ulstrup, Jens; Kusk, Kresten Ole; Baun, Anders

    2013-09-01

    Aquatic toxicology of engineered nanoparticles is challenged by methodological difficulties stemming partly from highly dynamic and poorly understood behavior of nanoparticles in biological test systems. In this paper scientific and technical challenges of testing not readily soluble nanoparticles in standardised algal growth inhibition tests are highlighted with specific focus on biomass quantification methods. This is illustrated through tests with TiO2 and Au nanoparticles, for which cell-nanoparticle interactions and behavior was studied during incubation. Au NP coating layers changed over time and TiO2 nanoparticle aggregation/agglomeration increased as a function of concentration. Three biomass surrogate measuring techniques were evaluated (coulter counting, cell counting in haemocytometer, and fluorescence of pigment extracts) and out of these the fluorometric methods was found to be most suitable. Background correction was identified as a key issue for biomass quantification, complicated by algae-particle interactions and nanoparticle transformation. Optimisation of the method is needed to reduce further particle interference on measurements.

  16. Facile green synthesis of variable metallic gold nanoparticle using Padina gymnospora, a brown marine macroalga

    NASA Astrophysics Data System (ADS)

    Singh, M.; Kalaivani, R.; Manikandan, S.; Sangeetha, N.; Kumaraguru, A. K.

    2013-04-01

    The process of development of reliable and eco-friendly metallic nanoparticles is an important step in the field of nanotechnology. To achieve this, use of natural sources like biological systems becomes essential. In the present work, extracellular biosynthesis of gold nanoparticles using Padina gymnospora has been attempted and achieved rapid formation of gold nanoparticles in a short duration. The UV-vis spectrum of the aqueous medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. Scanning electron microscopy showed the formation of well-dispersed gold nanoparticles. FTIR spectra of brown alga confirmed that hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. AFM analysis showed the results of particle sizes (53-67 nm) and average height of the particle roughness (60.0 nm). X-ray diffraction (XRD) spectrum of the gold nanoparticles exhibited Bragg reflections corresponding to gold nanoparticles. This environment-friendly method of biological gold nanoparticle synthesis can be applied potentially in various products that directly come in contact with the human body, such as cosmetics, and foods and consumer goods, besides medical applications.

  17. Case studies in surface photochemistry on metal nanoparticles

    SciTech Connect

    Menzel, Dietrich; Hyun Kim, Ki; Mulugeta, Daniel; Watanabe, Kazuo

    2013-09-15

    The authors give a survey of their work on photochemical processes at silver nanoparticles carried out in Berlin in the past decade. Using well established procedures for the preparation of silver nanoparticles (Ag NPs) supported on ultrathin alumina layers on NiAl single crystals, they have investigated the photoreactions of adsorbed (NO){sub 2} and of Xe induced by laser pulses. The authors examined the influences of photon energy (2.3, 3.5, and 4.7 eV) and polarization, mean particle size (2–10 nm), and pulse length (5 ns and 100 fs) on yields and cross sections, and on photoreaction mechanisms. Comparison with Ag(111) was made throughout. For the NO dimer layer, the authors find general agreement with known results on bulk Ag(111) in terms of possible reactions (NO desorption and NO monomer formation as well as conversion into adsorbed N{sub 2}O and O) and predominant mechanism (via transient negative ion formation, TNI); NO desorption is the strongest channel. However, on the NPs, the cross sections show selective enhancement in particular under conditions of excitation of the Mie plasmon due to the field enhancement caused by it, but—more weakly—also under off-resonant conditions which the authors interpret by excitation confinement in the NPs. For ns laser pulses, the desorption yield responds linearly to photon flux so that the cross sections are independent of laser fluence. Using fs laser pulses, nonlinear yield response is found under plasmon excitation which is interpreted as due to re-excitation of hot electrons in the NPs during a single laser pulse. The dynamics of the individual process, however, stay the same under almost all conditions, as indicated by constant energy distributions over translational, rotational, and vibrational energies of the desorbing NO molecules, even in the nonlinear range. Only for the highest photon energy (i.e., off-resonance) and the smallest particles, a new channel is observed with higher translational energy

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

    NASA Astrophysics Data System (ADS)

    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 < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the nanoparticles after 48 h of incubation. It is concluded from the present study that, the PDDS-Fe3O4 showed good antiplasmodial activity and it might be used for the development of antiplasmodial drugs.

  19. Contaminant-induced changes to soil properties: From general overview to study of metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Ben Moshe, T.; Dror, I.; Yaron, B.; Berkowitz, B.

    2011-12-01

    A contemporary metapedogenetic process in which anthropogenic contaminants become an additional soil-forming factor is presented. Several examples that link contamination and modification of soil properties from the existing literature are reviewed. Also, recent experimental results that show possible soil property modifications as a result of application of metal oxide nanoparticles to natural soils are shown. Research results published in literature on chemical contaminant-soil interactions show that in some cases, irreversible changes to the soil matrix and properties may occur. In such cases, a pristine soil may become the parent material for a newly-formed soil. In contrast to natural processes over geological time scales, contaminant-induced soil modification occurs over much shorter time scales. In recent years, the effects of soil on the behavior and properties of nanoparticles released to the environment have been studied extensively. The behavior, transport and mobility of nanoparticles were shown to be strongly dependent on environmental conditions. However, little is known about the possible effects of nanoparticles on soil properties. In this study, two types of metal oxide nanoparticles, CuO and Fe3O4 were mixed with two types of soil and the effects of the nanoparticles on various soil properties were assessed. Metal oxide nanoparticles were previously shown to catalyze the oxidation of organic pollutants in aqueous suspensions, and they were therefore expected to induce changes in the organic material in the soil, especially upon addition of an oxidant. It was found that the nanoparticles did not change the total amount of organic materials in the soil or the total organic carbon in the soil extract; however, three-dimensional fluorescence spectroscopy demonstrated changes in humic substances.

  20. Metal nanoparticle-induced micronuclei and oxidative DNA damage in mice

    PubMed Central

    Song, Ming-Fen; Li, Yun-Shan; Kasai, Hiroshi; Kawai, Kazuaki

    2012-01-01

    Several mechanisms regarding the adverse health effects of nanomaterials have been proposed. Among them, oxidative stress is considered to be one of the most important. Many in vitro studies have shown that nanoparticles generate reactive oxygen species, deplete endogenous antioxidants, alter mitochondrial function and produce oxidative damage in DNA. 8-Hydroxy-2'-deoxyguanosine is a major type of oxidative DNA damage, and is often analyzed as a marker of oxidative stress in human and animal studies. In this study, we focused on the in vivo toxicity of metal oxide and silver nanoparticles. In particular, we analyzed the induction of micronucleated reticulocyte formation and oxidative stress in mice treated with nanoparticles (CuO, Fe3O4, Fe2O3, TiO2, Ag). For the micronucleus assay, peripheral blood was collected from the tail at 0, 24, 48 and 72 h after an i.p. injection of nanoparticles. Following the administration of nanoparticles by i.p. injection to mice, the urinary 8-hydroxy-2'-deoxyguanosine levels were analyzed by the HPLC-ECD method, to monitor the oxidative stress. The levels of 8-hydroxy-2'-deoxyguanosine in liver DNA were also measured. The results showed increases in the reticulocyte micronuclei formation in all nanoparticle-treated groups and in the urinary 8-hydroxy-2'-deoxyguanosine levels. The 8-hydroxy-2'-deoxyguanosine levels in the liver DNA of the CuO-treated group increased in a dose-dependent manner. In conclusion, the metal nanoparticles caused genotoxicity, and oxidative stress may be responsible for the toxicity of these metal nanoparticles. PMID:22573923

  1. Metallic nanoparticles and their medicinal potential. Part II: aluminosilicates, nanobiomagnets, quantum dots and cochleates.

    PubMed

    Loomba, Leena; Scarabelli, Tiziano

    2013-09-01

    Metallic miniaturization techniques have taken metals to nanoscale size where they can display fascinating properties and their potential applications in medicine. In recent years, metal nanoparticles such as aluminium, silicon, iron, cadmium, selenium, indium and calcium, which find their presence in aluminosilicates, nanobiomagnets, quantum dots (Q-dots) and cochleates, have caught attention of medical industries. The increasing impact of metallic nanoparticles in life sciences has significantly advanced the production techniques for these nanoparticles. In this Review, the various methods for the synthesis of nanoparticles are outlined, followed by their physicochemical properties, some recent applications in wound healing, diagnostic imaging, biosensing, assay labeling, antimicrobial activity, cancer therapy and drug delivery are listed, and finally their toxicological impacts are revised. The first half of this article describes the medicinal uses of two noble nanoparticles - gold and silver. This Review provides further information on the ability of aluminum, silicon, iron, selenium, indium, calcium and zinc to be used as nanoparticles in biomedical sciences. Aluminosilicates find their utility in wound healing and antibacterial growth. Iron-oxide nanoparticles enhance the properties of MRI contrast agents and are also used as biomagnets. Cadmium, selenium, tellurium and indium form the core nanostructures of tiny Q-dots used in cellular assay labeling, high-resolution cell imaging and biosensing. Cochleates have the bivalent nano ions calcium, magnesium or zinc imbedded in their structures and are considered to be highly effective agents for drug and gene delivery. The aluminosilicates, nanobiomagnets, Q-dots and cochleates are discussed in the light of their properties, synthesis and utility.

  2. Associations between iron oxyhydroxide nanoparticle growth and metal adsorption/structural incorporation

    SciTech Connect

    Kim, C.S.; Lentini, C.J.; Waychunas, G.A.

    2008-09-15

    The interaction of metal ions and oxyanions with nanoscale mineral phases has not yet been extensively studied despite the increased recognition of their prevalence in natural systems as a significant component of geomedia. A combination of macroscopic uptake studies to investigate the adsorption behavior of As(V), Cu(II), Hg(II), and Zn(II) onto nanoparticulate goethite ({alpha}-FeOOH) as a function of aging time at elevated temperature (75 C) and synchrotron-based X-ray studies to track changes in both the sorption mode and the rate of nanoparticle growth reveal the effects that uptake has on particle growth. Metal(loid) species which sorb quickly to the iron oxyhydroxide particles (As(V), Cu(II)) appear to passivate the particle surface, impeding the growth of the nanoparticles with progressive aging; in contrast, species that sorb more slowly (Hg(II), Zn(II)) have considerably less impact on particle growth. Progressive changes in the speciation of these particular metals with time suggest shifts in the mode of metal uptake with time, possibly indicating structural incorporation of the metal(loid) into the nanoparticle; this is supported by the continued increase in uptake concomitant with particle growth, implying that metal species may transform from surface-sorbed species to more structurally incorporated forms. This type of incorporation would have implications for the long-term fate and mobility of metals in contaminated regions, and affect the strategy for potential remediation/modeling efforts.

  3. Association rule mining of cellular responses induced by metal and metal oxide nanoparticles.

    PubMed

    Liu, Rong; France, Bryan; George, Saji; Rallo, Robert; Zhang, Haiyuan; Xia, Tian; Nel, Andre E; Bradley, Kenneth; Cohen, Yoram

    2014-03-01

    Relationships among fourteen different biological responses (including ten signaling pathway activities and four cytotoxicity effects) of murine macrophage (RAW264.7) and bronchial epithelial (BEAS-2B) cells exposed to six metal and metal oxide nanoparticles (NPs) were analyzed using both statistical and data mining approaches. Both the pathway activities and cytotoxicity effects were assessed using high-throughput screening (HTS) over an exposure period of up to 24 h and concentration range of 0.39-200 mg L(-1). HTS data were processed by outlier removal, normalization, and hit-identification (for significantly regulated cellular responses) to arrive at reliable multiparametric bioactivity profiles for the NPs. Association rule mining was then applied to the bioactivity profiles followed by a pruning process to remove redundant rules. The non-redundant association rules indicated that "significant regulation" of one or more cellular responses implies regulation of other (associated) cellular response types. Pairwise correlation analysis (via Pearson's χ(2) test) and self-organizing map clustering of the different cellular response types indicated consistency with the identified non-redundant association rules. Furthermore, in order to explore the potential use of association rules as a tool for data-driven hypothesis generation, specific pathway activity experiments were carried out for ZnO NPs. The experimental results confirmed the association rule identified for the p53 pathway and mitochondrial superoxide levels (via MitoSox reagent) and further revealed that blocking of the transcriptional activity of p53 lowered the MitoSox signal. The present approach of using association rule mining for data-driven hypothesis generation has important implications for streamlining multi-parameter HTS assays, improving the understanding of NP toxicity mechanisms, and selection of endpoints for the development of nanomaterial structure-activity relationships.

  4. Palladium Nanoparticle Incorporated Porous Activated Carbon: Electrochemical Detection of Toxic Metal Ions.

    PubMed

    Veerakumar, Pitchaimani; Veeramani, Vediyappan; Chen, Shen-Ming; Madhu, Rajesh; Liu, Shang-Bin

    2016-01-20

    A facile method has been developed for fabricating selective and sensitive electrochemical sensors for the detection of toxic metal ions, which invokes incorporation of palladium nanoparticles (Pd NPs) on porous activated carbons (PACs). The PACs, which were derived from waste biomass feedstock (fruit peels), possess desirable textural properties and porosities favorable for dispersion of Pd NPs (ca. 3-4 nm) on the graphitic PAC substrate. The Pd/PAC composite materials so fabricated were characterized by a variety of different techniques, such as X-ray diffraction, field-emission transmission electron microscopy, gas physisorption/chemisorption, thermogravimetric analysis, and Raman, Fourier-transform infrared, and X-ray photon spectroscopies. The Pd/PAC-modified glassy carbon electrodes (GCEs) were exploited as electrochemical sensors for the detection of toxic heavy metal ions, viz., Cd(2+), Pb(2+), Cu(2+), and Hg(2+), which showed superior performances for both individual as well as simultaneous detections. For simultaneous detection of Cd(2+), Pb(2+), Cu(2+), and Hg(2+), a linear response in the ion concentration range of 0.5-5.5, 0.5-8.9, 0.5-5.0, and 0.24-7.5 μM, with sensitivity of 66.7, 53.8, 41.1, and 50.3 μA μM(-1) cm(-2), and detection limit of 41, 50, 66, and 54 nM, respectively, was observed. Moreover, the Pd/PAC-modified GCEs also show perspective applications in detection of metal ions in real samples, as illustrated in this study for a milk sample.

  5. Crystallography Without Crystals: Determining the Structure of Individual Biological Molecules and Nanoparticles

    ScienceCinema

    Ourmazd, Abbas [University of Wisconsin, Milwaukee, Wisconsin, USA

    2016-07-12

    Ever shattered a valuable vase into 10 to the 6th power pieces and tried to reassemble it under a light providing a mean photon count of 10 minus 2 per detector pixel with shot noise? If you can do that, you can do single-molecule crystallography. This talk will outline how this can be done in principle. In more technical terms, the talk will describe how the combination of scattering physics and Bayesian algorithms can be used to reconstruct the 3-D diffracted intensity distribution from a collection of individual 2-D diffiraction patterns down to a mean photon count of 10 minus 2 per pixel, the signal level anticipated from the Linac Coherent Light Source, and hence determine the structure of individual macromolecules and nanoparticles.

  6. Preparation of metallic nanoparticles by irradiation in starch aqueous solution

    SciTech Connect

    Nemţanu, Monica R. Braşoveanu, Mirela Iacob, Nicuşor

    2014-11-24

    Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔE{sub ab} (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle h{sup o} was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.

  7. Preparation of metallic nanoparticles by irradiation in starch aqueous solution

    NASA Astrophysics Data System (ADS)

    NemÅ£anu, Monica R.; Braşoveanu, Mirela; Iacob, Nicuşor

    2014-11-01

    Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔEab (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle ho was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.

  8. GOLD NANOPARTICLES: A REVIVAL IN PRECIOUS METAL ADMINISTRATION TO PATIENTS

    PubMed Central

    Thakor, AS; Jokerst, J; Zaveleta, C; Massoud, TF; Gambhir, SS

    2011-01-01

    Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods whilst concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, bio-distribution, metabolism and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed. PMID:21846107

  9. Submicron writing by laser irradiation on metal nano-particle dispersed films toward flexible electronics

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira; Aminuzzaman, Mohammod; Miyashita, Tokuji

    2009-02-01

    The requirement for microwiring technology by a wet process has significantly increased recently toward the achievement of printable and flexible electronics. We have developed the metal microwiring with a resolution higher than 1 μm by the laser direct writing technique using Ag and Cu nano-particle-dispersed films as precursors. The technique was applied to the microwiring on a flexible and transparent polymer film. The metallization is caused in a micro-region by focused laser beam, which reduces the thermal damage of the flexible polymer substrate during the metallization process. The laser direct writing technique is based on the efficient and fast conversion of photon energy to thermal energy by direct excitation of the plasmon absorption of a metal nano-particle, which provides Cu microwiring with a low resistivity owing to the inhibition of the surface oxidation of the Cu nano-particle.

  10. The unexpected role of metal nanoparticles and nanonetworks in alloy degradation.

    SciTech Connect

    Zeng, Z.; Natesan, K.; Cai, Z.; Darling, S. B.

    2008-08-01

    Oxide scale, which is essential to protect structural alloys from high-temperature degradation such as oxidation, carburization and metal dusting, is usually considered to consist simply of oxide phases. Here, we report on a nanobeam X-ray and magnetic force microscopy investigation that reveals that the oxide scale actually consists of a mixture of oxide materials and metal nanoparticles. The metal nanoparticles self-assemble into nanonetworks, forming continuous channels for carbon transport through the oxide scales. To avoid the formation of these metallic particles in the oxide scale, alloys must develop a scale without spinel phase. We have designed a novel alloy that has been tested in a high-carbon-activity environment. Our results show that the incubation time for carbon transport through the oxide scale of the new alloy is more than an order of magnitude longer compared with commercial alloys with similar chromium content.

  11. Novel mechanochemical approaches for the synthesis of surface-functionalized metal nanoparticles

    NASA Astrophysics Data System (ADS)

    McMahon, Brandon Wade

    A novel mechanochemical milling technique, homogeneous media milling (HMM) is used to generate copious nanoparticles from a metal, parent media. Through the addition of surface-active capping agents, this method removes material from inch-scale parent material, via spallation and abrasion, resulting in gram-scale quantities of nanoparticles. Based on the principal of lowering a materials surface free energy through the chemisorption of a liquid or gaseous reagent, ductile and malleable metals can now be effectively and efficiently reduced to the nano scale. Acetonitrile was discovered to be an exceptionally good reagent for producing active aluminum nanoparticles, and oleic acid could be used to subsequently functionalize the particle surface, rendering them air-stable and hydrocarbon-fuel dispersible. In the interest of generality this process was used to make iron and copper nanoparticles via a similar method. It was discovered that acetonitrile decomposes on the surface of aluminum during HMM, resulting in the liberation of methyl group and hydrogen, which was detected as H2, CH4, and C2H6 in the headspace of the milling jar. Ammonia and methylamine, in gaseous form, are also reported to be highly effective surface-active milling agents for the production of aluminum nanoparticles. Methylamine, in particular, produced active, pyrophoric nanoparticles. For both acetonitrile and methylamine evidence of a stable surface adduct can be detected post milling using X-Ray photoelectron spectroscopy.

  12. Metal nanoparticles in diesel exhaust derived by in-cylinder melting of detached engine fragments

    NASA Astrophysics Data System (ADS)

    Liati, Anthi; Pandurangi, Sushant Sunil; Boulouchos, Konstantinos; Schreiber, Daniel; Arroyo Rojas Dasilva, Yadira

    2015-01-01

    A wide range of environmental and health effects are linked to combustion-generated pollutants related to traffic. Nanoparticles, in particular, are a major concern for humans since they can be inhaled and have potentially toxic effects. The variability and sources of combustion-related nanoparticle pollutants remain inadequately investigated. Here we report the presence of ca. 5-100 nm large Fe3O4 nanoparticles, in form of agglomerates, in diesel exhaust. The mode of occurrence of these nanoparticles, in combination with their chemical composition matching that of steel indicate that they derive by melting of engine fragments in the combustion chamber and subsequent crystallization during cooling. To evaluate this hypothesis, we applied CFD simulations of material transport in the cylinder of a diesel engine, assuming detachment of steel fragments from various sites of the cylinder. The CFD results show that fragments ≤20 μm in size dislodged from the piston surface or from the fuel nozzle interior can be indeed transported to such hot areas of the combustion chamber where they can melt. The simulation results concur with the experimental observations and point out that metal nanoparticle formation by in-cylinder melting of engine fragments can occur in diesel engines. The present study proposes a hitherto neglected formation mechanism of metal nanoparticle emissions from internal combustion engines raising possible environmental and health concerns, especially in urban areas.

  13. Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture.

    PubMed

    Swain, P; Nayak, S K; Sasmal, A; Behera, T; Barik, S K; Swain, S K; Mishra, S S; Sen, A K; Das, J K; Jayasankar, P

    2014-09-01

    The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag-TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.

  14. Mechanism of electrochemical charge transport in individual transition metal complexes.

    PubMed

    Albrecht, Tim; Guckian, Adrian; Kuznetsov, Alexander M; Vos, Johannes G; Ulstrup, Jens

    2006-12-27

    We used electrochemical scanning tunneling microscopy (STM) and spectroscopy (STS) to elucidate the mechanism of electron transport through individual pyridyl-based Os complexes. Our tunneling data obtained by two-dimensional electrochemical STS and STM imaging lead us to the conclusion that electron transport occurs by thermally activated hopping. The conductance enhancement around the redox potential of the complex, which is reminiscent of switching and transistor characterics in electronics, is reflected both in the STM imaging contrast and directly in the tunneling current. The latter shows a biphasic distance dependence, in line with a two-step electron hopping process. Under conditions where the substrate/molecule electron transfer (ET) step is dominant in determining the overall tunneling current, we determined the conductance of an individual Os complex to be 9 nS (Vbias = 0.1 V). We use theoretical approaches to connect the single-molecule conductance with electrochemical kinetics data obtained from monolayer experiments. While the latter leave some controversy regarding the degree of electronic coupling, our results suggest that electron transport occurs in the adiabatic limit of strong electronic coupling. Remarkably, and in contrast to established ET theory, the redox-mediated tunneling current remains strongly distance dependent due to the electronic coupling, even in the adiabatic limit. We exploit this feature and apply it to electrochemical single-molecule conductance data. In this way, we attempt to paint a unified picture of electrochemical charge transport at the single-molecule and monolayer levels. PMID:17177467

  15. Towards cost effective metal precursor sources for future photovoltaic material synthesis: CTS nanoparticles

    NASA Astrophysics Data System (ADS)

    Lokhande, A. C.; Gurav, K. V.; Jo, Eunjin; He, Mingrui; Lokhande, C. D.; Kim, Jin Hyeok

    2016-04-01

    Copper tin sulfide (CTS) is an emerging candidate for solar application due to its favorable band gap and higher optical absorption coefficient. Kuramite-Tetragonal Cu3SnS4 (CTS) monodisperse nanoparticles are prepared by hot injection technique involving cost effective sulfate metal precursor source. A protocol for controlled crystal structure has been demonstrated by variation of cationic Cu:Sn ratio. The crystal structure, size, phase purity, atomic composition, oxidation state and optical properties of the nanoparticles are confirmed from X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroscopy, respectively. Hexagonal shaped particles within the size distribution of 7-9 nm with an optimal band gap of 1.28 eV are obtained. XPS study shows the Cu1+, Sn4+ and S2- oxidation states. The effects of influential factors such as metal precursor ratio, metal precursor source, reaction time, heating rate and solvents have been demonstrated systematically on the synthesis of CTS nanoparticles. The plausible mechanism of the formation of CTS nanoparticles has been proposed. The obtained results provide new insight for applying CTS nanoparticles in photovoltaic applications.

  16. High-resolution investigation of metal nanoparticle growth on an insulating surface

    NASA Astrophysics Data System (ADS)

    Mativetsky, Jeffrey M.; Fostner, Shawn; Burke, Sarah A.; Grutter, Peter

    2009-07-01

    The three-dimensional nanoparticle morphology and the nanoparticle-substrate relationship during the submonolayer growth of three metals (gold, tantalum, and palladium) on the alkali halide KBr (001) surface is investigated by combining in situ high-resolution noncontact atomic force microscopy and ex situ transmission electron microscopy approaches. Highly varied growth behavior between the metals is revealed. Gold produces nearly spherical multiply twinned nanoparticles at room temperature and an increasing number of epitaxial particles at elevated temperatures. In contrast, the tantalum grows as relatively flat fractal particles, despite the square symmetry of the substrate lattice, a condition which normally precludes fractal growth. The tantalum also exhibits a strong affinity for KBr surface steps, leading to one-dimensional chains of nanoparticles. The deposition of palladium results in the creation of protruding substrate distortions and monolayer-high rectangular KBr islands in addition to the growth of palladium nanoparticles. It is hypothesized that the unusual growth observed in the palladium-KBr system is caused by the interdiffusion of palladium under the KBr surface. The range of growth behavior in the three systems is described in terms of the surface and interface energies, yielding bounds on the metal/KBr interface energies.

  17. Anchoring and promotion effects of metal oxides on silica supported catalytic gold nanoparticles.

    PubMed

    Luo, Jingjie; Ersen, Ovidiu; Chu, Wei; Dintzer, Thierry; Petit, Pierre; Petit, Corinne

    2016-11-15

    The understanding of the interactions between the different components of supported metal doped gold catalysts is of crucial importance for selecting and designing efficient gold catalysts for reactions such as CO oxidation. To progress in this direction, a unique supported nano gold catalyst Au/SS was prepared, and three doped samples (Au/SS@M) were elaborated. The samples before and after test were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). It is found that the doping metal species prefer to be located on the surface of gold nanoparticles and that a small amount of additional reductive metal leads to more efficient reaction. During the catalytic test, the nano-structure of the metal species transforms depending on its chemical nature. This study allows one to identify and address the contribution of each metal on the CO reaction in regard to oxidative species of gold, silica and dopants. Metal doping leads to different exposure of interface sites between Au and metal oxide, which is one of the key factors for the change of the catalytic activity. The metal oxides help the activation of oxygen by two actions: mobility inside the metal bulk and transfer of water species onto of gold nanoparticles.

  18. Anchoring and promotion effects of metal oxides on silica supported catalytic gold nanoparticles.

    PubMed

    Luo, Jingjie; Ersen, Ovidiu; Chu, Wei; Dintzer, Thierry; Petit, Pierre; Petit, Corinne

    2016-11-15

    The understanding of the interactions between the different components of supported metal doped gold catalysts is of crucial importance for selecting and designing efficient gold catalysts for reactions such as CO oxidation. To progress in this direction, a unique supported nano gold catalyst Au/SS was prepared, and three doped samples (Au/SS@M) were elaborated. The samples before and after test were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). It is found that the doping metal species prefer to be located on the surface of gold nanoparticles and that a small amount of additional reductive metal leads to more efficient reaction. During the catalytic test, the nano-structure of the metal species transforms depending on its chemical nature. This study allows one to identify and address the contribution of each metal on the CO reaction in regard to oxidative species of gold, silica and dopants. Metal doping leads to different exposure of interface sites between Au and metal oxide, which is one of the key factors for the change of the catalytic activity. The metal oxides help the activation of oxygen by two actions: mobility inside the metal bulk and transfer of water species onto of gold nanoparticles. PMID:27501036

  19. Plasmonic Enhancement of Optical Properties by Isolated and Coupled Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Greg; Khurgin, Jacob B.

    2012-12-01

    In this chapter we present a simple and comprehensive explanation of the mechanisms that can so dramatically modify the optical properties of atoms, molecules, or other quantum-size objects placed in the vicinity of metal nanoparticles. We develop a simple model that describes surface plasmon modes supported by the metal nanoparticles and describes them using just three key parameters -- effective volume, Q-factor, and radiative decay rate. We subsequently apply this model to the tasks of estimating the enhancement of optical radiation, electroluminescence, and photoluminescence absorbed or emitted by the optically active objects in the presence of an isolated single nanoparticle. Using the example of gold nanospheres embedded in GaN dielectric, we show that enhancement for each case depends strongly on the nanoparticle size enabling optimization for each combination of absorption cross section, original radiative efficiency, and separation between the object and metal sphere. We then expand the model for single metal nanoparticles to coupled metal nanostructures. We show that complex structures can be treated as coupled multipole modes with highest enhancements obtained due to the superposition of these modes mainly in small particles. This model allows for optimization of the structures for the largest possible field enhancements, which depends on the quality factor Q of the metal and can be as high as Q2 for two spherical particles. The "hot spot" can occur either in the nano-gaps between the particles or near the smaller particles. We trace the optimal field enhancement mechanism to the fact that the extended dipole modes of larger particles act as the efficient antennas while the modes in the gaps or near the smaller particles act as the compact sub-wavelength cavities. The physically-transparent, comprehensive analytical approach developed in this chapter not only offers a quick route for optimization but also can be conveniently extended to incorporate large

  20. Direct imaging of the magnetic polarity and reversal mechanism in individual Fe(3-x)O4 nanoparticles.

    PubMed

    Moya, Carlos; Iglesias-Freire, Óscar; Pérez, Nicolás; Batlle, Xavier; Labarta, Amilcar; Asenjo, Agustina

    2015-05-01

    This work reports on the experimental characterization of the magnetic domain configurations in cubic, isolated Fe3-xO4 nanoparticles with a lateral size of 25-30 nm. The magnetic polarity at remanence of single domain ferrimagnetic Fe3-xO4 nanoparticles deposited onto a carbon-silicon wafer is observed by magnetic force microscopy. The orientations of these domains provide a direct observation of the magneto-crystalline easy axes in each individual nanoparticle. Furthermore, the change in the domain orientation with an external magnetic field gives evidence of particle magnetization reversal mediated by a coherent rotation process that is also theoretically predicted by micromagnetic calculations.

  1. Effects of metal oxide nanoparticles on the stability of dispersions of weakly charged colloids.

    PubMed

    Herman, David; Walz, John Y

    2015-05-01

    The stability behavior of dispersions of weakly charged silica colloids was studied in the presence of highly charged metal oxide nanoparticles. Experiments were performed using 5 nm zirconia as well as 10 nm alumina nanoparticles (both positively charged), which were added to 0.1 vol % suspensions of 1.0 μm silica microparticles at the silica IEP. Both types of nanoparticles provided effective stabilization of the silica; i.e., the silica suspensions were stabilized for longer than the observation period (greater than 12 h). Stability was observed at zirconia concentrations as low as 10(-4) vol % and at an alumina concentration of 10(-2) vol %. The nanoparticles adsorbed onto the microparticle surfaces (confirmed via SEM imaging), which increased the zeta-potential of the silica. Force profile measurements performed with colloidal probe atomic force microscopy showed that the adsorption was effectively irreversible.

  2. Stability and aggregation of metal oxide nanoparticles in natural aqueous matrices.

    PubMed

    Keller, Arturo A; Wang, Hongtao; Zhou, Dongxu; Lenihan, Hunter S; Cherr, Gary; Cardinale, Bradley J; Miller, Robert; Ji, Zhaoxia

    2010-03-15

    There is a pressing need for information on the mobility of nanoparticles in the complex aqueous matrices found in realistic environmental conditions. We dispersed three different metal oxide nanoparticles (TiO(2), ZnO and CeO(2)) in samples taken from eight different aqueous media associated with seawater, lagoon, river, and groundwater, and measured their electrophoretic mobility, state of aggregation, and rate of sedimentation. The electrophoretic mobility of the particles in a given aqueous media was dominated by the presence of natural organic matter (NOM) and ionic strength, and independent of pH. NOM adsorbed onto these nanoparticles significantly reduces their aggregation, stabilizing them under many conditions. The transition from reaction to diffusion limited aggregation occurs at an electrophoretic mobility from around -2 to -0.8 microm s(-1) V(-1) cm. These results are key for designing and interpreting nanoparticle ecotoxicity studies in various environmental conditions. PMID:20151631

  3. Effects of metal oxide nanoparticles on the stability of dispersions of weakly charged colloids.

    PubMed

    Herman, David; Walz, John Y

    2015-05-01

    The stability behavior of dispersions of weakly charged silica colloids was studied in the presence of highly charged metal oxide nanoparticles. Experiments were performed using 5 nm zirconia as well as 10 nm alumina nanoparticles (both positively charged), which were added to 0.1 vol % suspensions of 1.0 μm silica microparticles at the silica IEP. Both types of nanoparticles provided effective stabilization of the silica; i.e., the silica suspensions were stabilized for longer than the observation period (greater than 12 h). Stability was observed at zirconia concentrations as low as 10(-4) vol % and at an alumina concentration of 10(-2) vol %. The nanoparticles adsorbed onto the microparticle surfaces (confirmed via SEM imaging), which increased the zeta-potential of the silica. Force profile measurements performed with colloidal probe atomic force microscopy showed that the adsorption was effectively irreversible. PMID:25860256

  4. The fate of metal (Fe) during diesel combustion: Morphology, chemistry, and formation pathways of nanoparticles

    SciTech Connect

    Miller, Art; Kittelson, David; Zachariah, Michael

    2007-04-15

    This report describes an investigation in which we used iron-doped diesel fuel to generate metal-bearing diesel particles and a subsequent analysis of the particles using transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). For this study, DPM was generated by a 1.5-L diesel engine and the fuel was doped with ferrocene to enhance the level of iron in the system. The exhaust particles were collected on TEM grids and analyzed using the Philips CM12 TEM/EDS instrument. Results show that when the iron-to-carbon (soot) ratio (Fe/C) in the engine is low, the exhaust particles have morphologies similar to those for the undoped case, but at a threshold Fe/C value of 0.013 (for this engine), homogeneously nucleated metallic nanoparticles are formed and begin agglomerating. The number and size of these nanoparticles increase with level of doping. Metal-bearing particles that span a wider size range are also formed. Agglomeration of metallic and carbon particles is observed in two distinct modes: attachment of iron primary particles (5-10 nm in diameter) to carbon agglomerates, and coagulation of iron agglomerates (20-200 nm in diameter) with carbon agglomerates. Results of this work imply that as new engine technologies reduce soot levels in the engine and/or levels of trace metals in the fuel are increased, the generation of metallic nanoparticles may ensue, creating a potential health concern. (author)

  5. Significantly enhanced sensitivity of surface plasmon resonance sensor with self-assembled metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Hong-Seung; Lee, Byeong-Hyeon; Oh, Geum-Yoon; Lee, Tae-Kyeong; Kim, Doo-Gun; Kim, Tae-Ryong; Choi, Young-Wan

    2016-04-01

    A surface plasmon resonance (SPR) sensor hybridized with self-assembled metallic nanoparticles is proposed and experimentally demonstrated. The measured sensitivity of the proposed SPR sensor is 110.77 deg/RIU, while that of a conventional SPR sensor is 84.75 deg/RIU. The enhanced sensitivity is attributed to the strong localized surface plasmons and the increased surface interaction area by the nanoparticles. Angle variation measurement, which is an easy detection method using bulk optics, is possible with this structure because a supplementary metallic thin film layer on the nanoparticles leads to utilization of the sensitive variation of the strong localized field by the change of the refractive index. Furthermore, the proposed structure can be fabricated with a very simple three-step nonlithographic process.

  6. Effect of particle size on the thermal conductivity of nanofluids containing metallic nanoparticles

    PubMed Central

    2011-01-01

    A one-parameter model is presented for the thermal conductivity of nanofluids containing dispersed metallic nanoparticles. The model takes into account the decrease in thermal conductivity of metal nanoparticles with decreasing size. Although literature data could be correlated well using the model, the effect of the size of the particles on the effective thermal conductivity of the nanofluid could not be elucidated from these data. Therefore, new thermal conductivity measurements are reported for six nanofluids containing silver nanoparticles of different sizes and volume fractions. The results provide strong evidence that the decrease in the thermal conductivity of the solid with particle size must be considered when developing models for the thermal conductivity of nanofluids. PMID:21711761

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

    PubMed

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

    2013-05-31

    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 Cu₂O 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, Cu₂O supported on reduced GO was formed and showed superior catalytic ability for the degradation of a model dye pollutant, methylene blue. PMID:23619742

  8. A Method for Promoting Assembly of Metallic and Nonmetallic Nanoparticles into Interfacial Monolayer Films.

    PubMed

    Xu, Yikai; Konrad, Magdalena P; Lee, Wendy W Y; Ye, Ziwei; Bell, Steven E J

    2016-08-10

    Two-dimensional metal nanoparticle arrays are normally constructed at liquid-oil interfaces by modifying the surfaces of the constituent nanoparticles so that they self-assemble. Here we present a general and facile new approach for promoting such interfacial assembly without any surface modification. The method use salts that have hydrophobic ions of opposite charge to the nanoparticles, which sit in the oil layer and thus reduce the Coulombic repulsion between the particles in the organic phase, allowing the particles to sit in close proximity to each other at the interface. The advantage of this method is that because it does not require the surface of the particles to be modified it allows nonmetallic particles including TiO2 and SiO2 to be assembled into dense interfacial layers using the same procedure as is used for metallic particles. This opens up a route to a new family of nanostructured functional materials. PMID:27454020

  9. Carrier transfer from InAs quantum dots to ErAs metal nanoparticles

    SciTech Connect

    Haughn, C. R.; Chen, E. Y.; Zide, J. M. O.; Doty, M. F.; Steenbergen, E. H.; Bissell, L. J.; Eyink, K. G.

    2014-09-08

    Erbium arsenide (ErAs) is a semi-metallic material that self-assembles into nanoparticles when grown in GaAs via molecular beam epitaxy. We use steady-state and time-resolved photoluminescence to examine the mechanism of carrier transfer between indium arsenide (InAs) quantum dots and ErAs nanoparticles in a GaAs host. We probe the electronic structure of the ErAs metal nanoparticles (MNPs) and the optoelectronic properties of the nanocomposite and show that the carrier transfer rates are independent of pump intensity. This result suggests that the ErAs MNPs have a continuous density of states and effectively act as traps. The absence of a temperature dependence tells us that carrier transfer from the InAs quantum dots to ErAs MNPs is not phonon assisted. We show that the measured photoluminescence decay rates are consistent with a carrier tunneling model.

  10. Spatio-temporal Modeling of Lasing Action in Core–Shell Metallic Nanoparticles

    PubMed Central

    2016-01-01

    Nanoscale laser sources based on single metallic nanoparticles (spasers) have attracted significant interest for their fundamental implications and technological potential. Here we theoretically investigate the spatio-temporal dynamics of lasing action in core–shell metallic nanoparticles that include optically pumped four-level gain media. By using detailed semiclassical simulations based on a time-domain generalization of the finite-element method, we study the evolution of the lasing dynamics when going from a spherical case to an elongated nanorod configuration. Our calculations show that there exists an optimal nanoparticle elongation that exhibits significantly improved lasing threshold and slope efficiency over those obtained for its spherical counterpart. These results are accounted for in terms of a coupled-mode theory analysis of the variation with elongation of the light confinement properties of localized surface plasmons. This work could be of importance for further development of nanoscale light sources based on localized surface plasmon resonances. PMID:27785457

  11. Fabrication of novel cryomill for synthesis of high purity metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kumar, Nirmal; Biswas, Krishanu

    2015-08-01

    The successful preparation of free standing metal nanoparticles with high purity in bulk quantity is the pre-requisite for any potential application. This is possible by using ball milling at cryogenic temperature. However, the most of ball mills available in the market do not allow preparing high purity metal nanoparticles by this route. In addition, it is not possible to carry out in situ measurements of process parameters as well as diagnostic of the process. In the present investigation, we present a detailed study on the fabrication of a cryomill, which is capable of avoiding contaminations in the product. It also provides in situ measurements and diagnostic of the low temperature milling process. Online monitoring of the milling temperature and observation of ball motion are the important aspects in the newly designed mill. The nanoparticles prepared using this fabricated mill have been found to be free standing and also free from contaminations.

  12. Plasmon-Induced Water Splitting Using Metallic-Nanoparticle-Loaded Photocatalysts and Photoelectrodes.

    PubMed

    Ueno, Kosei; Oshikiri, Tomoya; Misawa, Hiroaki

    2016-01-18

    Visible- and near-infrared-light-driven water splitting, which splits water molecules to generate hydrogen and oxygen gases, is a significant subject in artificial photosynthesis with the goal of achieving a low-carbon society. In recent years, considerable attention has been paid to studies on the development of a plasmon-induced water-splitting system responding to visible light. In this review, we categorized water-splitting systems as gold-nanoparticle-loaded semiconductor photocatalytic particles system and metallic-nanoparticles-loaded semiconductor photoelectrode systems, and introduce the latest studies according to these categories. Especially, we describe the studies that optimize a material or a structural design of metallic-nanoparticle-loaded semiconductor photoelectrodes and consider a whole water-splitting system, including a cathode design. Furthermore, we discuss important points when studying plasmon-induced water splitting, and we describe a methodology that enhances plasmon-induced water-splitting efficiency.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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 Cu2O 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, Cu2O supported on reduced GO was formed and showed superior catalytic ability for the degradation of a model dye pollutant, methylene blue.

  14. Synthesis of metallic nanoparticles through X-ray radiolysis using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akinobu; Okada, Ikuo; Fukuoka, Takao; Sakurai, Ikuya; Utsumi, Yuichi

    2016-05-01

    The potential to fabricate metallic nanoparticles directly on silicon substrates from liquid solutions is ideal for three-dimensional lithography systems, drug delivery materials, and sensing applications. Here, we report the successful synthesis of Au, Cu, and Fe nanoparticles from the corresponding liquid solutions [gold(I) trisodium disulphite, copper(II) sulfate, and potassium ferricyanide] by synchrotron (SR) X-ray irradiation. The deposition of gold nanoparticles in the gold(I) trisodium disulphite solution was performed by monochromatic X-ray exposure from synchrotron radiation. The use of ethanol as an additive enabled the nucleation and growth of Cu particles, while no Cu particles were produced in the copper sulfate solution without ethanol with polychromatic SR X-ray irradiation. Fe particles were generated by direct polychromatic SR X-ray irradiation. These results demonstrate the behavior of three-dimensional printers, enabling us to build composite material structures with metallic and plastic materials.

  15. Liposome supported metal oxide nanoparticles: interaction mechanism, light controlled content release, and intracellular delivery.

    PubMed

    Wang, Feng; Liu, Juewen

    2014-10-15

    Zwitterionic phosphotydylcholine lipo-somes stably adsorb a number of metal oxide nanoparticles via its phosphate group. This is different from physisorption and fusion with SiO2. The hybrid materials can be internalized by cancer cells and TiO2 allows light controlled liposome content release.

  16. Metallic nanoparticles deposited on carbon microspheres: novel materials for combinatorial electrochemistry and electroanalysis.

    PubMed

    Baron, Ronan; Wildgoose, Gregory G; Compton, Richard G

    2009-04-01

    This review deals with the preparation of metallic nanoparticles on glassy carbon microspheres and the use of these new hybrid materials for combinatorial electrochemistry and electroanalysis. First, the preparation of gold, silver and palladium nanoparticles on glassy carbon microspheres by a simple electroless procedure is described. Then, different types of electrodes modified with glassy carbon microspheres are described. These are: (i) glassy carbon electrodes modified by a composite film of glassy carbon microspheres and multi-walled carbon nanotubes, (ii) basal plane pyrolylic graphite electrodes modified by the abrasive attachment of glassy carbon microspheres and (iii) carbon-epoxy composite electrodes loaded with glassy carbon microspheres. The three types of electrode architectures described consist of metallic nanoparticles embedded in a carbon matrix and each of the electrode macrodisc surfaces actually correspond to a random metallic nanoelectrode array. Carbon-epoxy composite electrodes have good characteristics for their use as practical sensors. Furthermore, the use of several kinds of metallic nanoparticles allows the construction of a multi-analyte electrode and the screening of electroactive materials by following a combinatorial approach.

  17. Evolution of the Surface Science of Catalysis from Single Crystals to Metal Nanoparticles under Pressure

    SciTech Connect

    Somorjai, Gabor A.; Park, Jeong Y.

    2008-03-06

    Vacuum studies of metal single crystal surfaces using electron and molecular beam scattering revealed that the surface atoms relocate when the surface is clean (reconstruction) and when it is covered by adsorbates (adsorbate induced restructuring). It was also discovered that atomic steps and other low coordination surface sites are active for breaking chemical bonds (H-H, O=O, C-H, C=O and C-C) with high reaction probability. Investigations at high reactant pressures using sum frequency generation (SFG)--vibrational spectroscopy and high pressure scanning tunneling microscopy (HPSTM) revealed bond breaking at low reaction probability sites on the adsorbate-covered metal surface, and the need for adsorbate mobility for continued turnover. Since most catalysts (heterogeneous, enzyme and homogeneous) are nanoparticles, colloid synthesis methods were developed to produce monodispersed metal nanoparticles in the 1-10 nm range and controlled shapes to use them as new model catalyst systems in two-dimensional thin film form or deposited in mesoporous three-dimensional oxides. Studies of reaction selectivity in multipath reactions (hydrogenation of benzene, cyclohexene and crotonaldehyde) showed that reaction selectivity depends on both nanoparticle size and shape. The oxide-metal nanoparticle interface was found to be an important catalytic site because of the hot electron flow induced by exothermic reactions like carbon monoxide oxidation.

  18. Conventional and microwave hydrothermal synthesis of monodispersed metal oxide nanoparticles at liquid-liquid interface

    EPA Science Inventory

    Monodispersed nanoparticles of metal oxide including ferrites MFe2O4 (M=, Ni, Co, Mn) and γ-Fe2O3, Ta2O5 etc. have been synthesized using a water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure uses readily availab...

  19. In Situ Growth and Characterization of Metal Oxide Nanoparticles within Polyelectrolyte Membranes.

    PubMed

    Landers, John; Colon-Ortiz, Jonathan; Zong, Kenneth; Goswami, Anandarup; Asefa, Tewodros; Vishnyakov, Aleksey; Neimark, Alexander V

    2016-09-12

    This study describes a novel approach for the in situ synthesis of metal oxide-polyelectrolyte nanocomposites formed via impregnation of hydrated polyelectrolyte films with binary water/alcohol solutions of metal salts and consecutive reactions that convert metal cations into oxide nanoparticles embedded within the polymer matrix. The method is demonstrated drawing on the example of Nafion membranes and a variety of metal oxides with an emphasis placed on zinc oxide. The in situ formation of nanoparticles is controlled by changing the solvent composition and conditions of synthesis that for the first time allows one to tailor not only the size, but also the nanoparticle shape, giving a preference to growth of a particular crystal facet. The high-resolution TEM, SEM/EDX, UV-vis and XRD studies confirmed the homogeneous distribution of crystalline nanoparticles of circa 4 nm and their aggregates of 10-20 nm. The produced nanocomposite films are flexible, mechanically robust and have a potential to be employed in sensing, optoelectronics and catalysis. PMID:27539360

  20. FDTD/TDSE study of surface-enhanced infrared absorption by metal nanoparticles.

    SciTech Connect

    Chang, S.-H.; Schatz, G. C.; Gray, S. K.; Chemistry; Northwestern Univ.; National Cheng-Kung Univ.

    2006-01-01

    We study surface-enhanced infrared absorption, including multiphoton processes, due to the excitation of surface plasmons on metal nanoparticles. The time-dependent Schroedinger equation and finite-difference time-domain method are self-consistently coupled to treat the problem.

  1. Optical response of a quantum dot-metal nanoparticle hybrid interacting with a weak probe field.

    PubMed

    Kosionis, Spyridon G; Terzis, Andreas F; Sadeghi, Seyed M; Paspalakis, Emmanuel

    2013-01-30

    We study optical effects in a hybrid system composed of a semiconductor quantum dot and a spherical metal nanoparticle that interacts with a weak probe electromagnetic field. We use modified nonlinear density matrix equations for the description of the optical properties of the system and obtain a closed-form expression for the linear susceptibilities of the quantum dot, the metal nanoparticle, and the total system. We then investigate the dependence of the susceptibility on the interparticle distance as well as on the material parameters of the hybrid system. We find that the susceptibility of the quantum dot exhibits optical transparency for specific frequencies. In addition, we show that there is a range of frequencies of the applied field for which the susceptibility of the semiconductor quantum dot leads to gain. This suggests that in such a hybrid system quantum coherence can reverse the course of energy transfer, allowing flow of energy from the metallic nanoparticle to the quantum dot. We also explore the susceptibility of the metal nanoparticle and show that it is strongly influenced by the presence of the quantum dot.

  2. The versatile colour gamut of coatings of plasmonic metal nanoparticles.

    PubMed

    Kealley, Catherine S; Cortie, Michael B; Maaroof, Abbas I; Xu, Xiaoda

    2009-07-28

    We have investigated the colour gamut of coatings produced by the growth of plasmonically-active coatings of cap-shaped Au or Ag nanoparticles on a transparent substrate. The control of colour and spectral selectivity that can be obtained by the manipulation of the rates of nucleation and growth were explored using a combination of experiment and calculation. In our experimental work the Au nanoparticles were grown in situ using a wet chemical electroless plating technique while the Ag nanoparticles were produced by physical vapour deposition. The optical properties were numerically simulated using the discrete dipole approximation. The resulting measured or calculated transmission spectra were mapped to the CIE L-a -b colour space. The aspect ratio of the nanoparticles was the primary factor in determining the colours in both cases. However, increasing the nucleation rate of the particles resulted in them becoming more closely packed, which also red-shifted the optical extinction peak of the structure due to interactions of their near-fields. This caused an enhancement in the blue component of the transmitted light. Coatings of Ag particles had a significantly wider and brighter colour gamut than those of Au.

  3. Effect of Metallic Nanoparticle Decoration on Graphene Oxide Conductivity

    NASA Astrophysics Data System (ADS)

    Guliants, Elena; Fernando, Shiral; Watson, Venroy; Wang, Xifan; Gaugler, Elizabeth; Energy Technology and Materials Division Team

    2014-03-01

    Light and strong single-atom-thick carbon derivatives attract a wealth of attention from the research community due to their potential applications. Development of compatible satellite technologies for all-carbon nanoelectronic circuitry is vital for progress in practical applications. Graphene oxide (GO), the closest graphene relative, with its high surface area, unique atomic-layer properties, chemical inertness, and excellent bio-compatibility, has been tested for the applications in energy storage, flexible electronics, sensing technologies, and photovoltaics. GO conductivity enhancement by nanoparticle decoration can drastically improve the field effect transport of charge carriers in thin film transistors. In this study, GO, synthesized using modified Hummer's method, was functionalized with Ag nanoparticles using a two-step sonochemical procedure. Ag nanoparticles were shown to effectively migrate and redistribute when exposed to other carbon allotropies, such as carbon nanotubes and carbon dots. Studies of the effect of Ag precursor concentration and further nanoparticle migration on the conductivity of Ag/GO composites will be discussed within the context of charge carrier transport mechanisms.

  4. Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles.

    PubMed

    House, Stephen D; Bonifacio, Cecile S; Grieshaber, Ross V; Li, Long; Zhang, Zhongfan; Ciston, Jim; Stach, Eric A; Yang, Judith C

    2016-10-01

    High-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support - either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems - but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1-4nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles ≥1nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures. PMID:27421079

  5. QM/MD simulation of SWNT nucleation on transition-metal carbide nanoparticles.

    PubMed

    Page, Alister J; Yamane, Honami; Ohta, Yasuhito; Irle, Stephan; Morokuma, Keiji

    2010-11-10

    The mechanism and kinetics of single-walled carbon nanotube (SWNT) nucleation from Fe- and Ni-carbide nanoparticle precursors have been investigated using quantum chemical molecular dynamics (QM/MD) methods. The dependence of the nucleation mechanism and its kinetics on environmental factors, including temperature and metal-carbide carbon concentration, has also been elucidated. It was observed that SWNT nucleation occurred via three distinct stages, viz. the precipitation of the carbon from the metal-carbide, the formation of a "surface/subsurface" carbide intermediate species, and finally the formation of a nascent sp(2)-hybidrized carbon structure supported by the metal catalyst. The SWNT cap nucleation mechanism itself was unaffected by carbon concentration and/or temperature. However, the kinetics of SWNT nucleation exhibited distinct dependences on these same factors. In particular, SWNT nucleation from Ni(x)C(y) nanoparticles proceeded more favorably compared to nucleation from Fe(x)C(y) nanoparticles. Although SWNT nucleation from Fe(x)C(y) and Ni(x)C(y) nanoparticle precursors occurred via an identical route, the ultimate outcomes of these processes also differed substantially. Explicitly, the Ni(x)-supported sp(2)-hybridized carbon structures tended to encapsulate the catalyst particle itself, whereas the Fe(x)-supported structures tended to form isolated SWNT cap structures on the catalyst surface. These differences in SWNT nucleation kinetics were attributed directly to the relative strengths of the metal-carbon interaction, which also dictates the precipitation of carbon from the nanoparticle bulk and the longevity of the resultant surface/subsurface carbide species. The stability of the surface/subsurface carbide was also influenced by the phase of the nanoparticle itself. The observations agree well with experimentally available data for SWNT growth on iron and nickel catalyst particles.

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

    PubMed Central

    2011-01-01

    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. PMID:21371295

  7. Nanoparticle-based flow virometry for the analysis of individual virions.

    PubMed

    Arakelyan, Anush; Fitzgerald, Wendy; Margolis, Leonid; Grivel, Jean-Charles

    2013-09-01

    While flow cytometry has been used to analyze the antigenic composition of individual cells, the antigenic makeup of viral particles is still characterized predominantly in bulk. Here, we describe a technology, "flow virometry," that can be used for antigen detection on individual virions. The technology is based on binding magnetic nanoparticles to virions, staining the virions with monoclonal antibodies, separating the formed complexes with magnetic columns, and characterizing them with flow cytometers. We used this technology to study the distribution of two antigens (HLA-DR and LFA-1) that HIV-1 acquires from infected cells among individual HIV-1 virions. Flow virometry revealed that the antigenic makeup of virions from a single preparation is heterogeneous. This heterogeneity could not be detected with bulk analysis of viruses. Moreover, in two preparations of the same HIV-1 produced by different cells, the distribution of antigens among virions was different. In contrast, HIV-1 of two different HIV-1 genotypes replicating in the same cells became somewhat antigenically similar. This nanotechnology allows the study of virions in bodily fluids without virus propagation and in principle is not restricted to the analysis of HIV, but can be applied to the analysis of the individual surface antigenic makeup of any virus. PMID:23925291

  8. Individual and collective modes of surface magnetoplasmon in thiolate-protected silver nanoparticles studied by MCD spectroscopy

    NASA Astrophysics Data System (ADS)

    Yao, Hiroshi; Shiratsu, Taisuke

    2016-05-01

    Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiol (DT)-, azobenzenethiol (ABT)-, and ABT/DT mixed-monolayer-protected Ag nanoparticles. ABT-protected Ag nanoparticles are somewhat aggregated and thus exhibit a broad, collective mode of plasmonic absorption, whereas other samples with highly-dispersed nanoparticles show an individual mode of LSPR absorption. In all Ag nanoparticles, a derivative-like MCD signal is observed under an applied magnetic field of 1.6 T, which can be explained in terms of two circular modes of magnetoplasmon caused by the increase (or decrease) in the Lorentz force imparted on the free electrons that oscillate in the left (or right) circular orbits in the nanosphere. For the Ag nanoparticles exhibiting an individual LSPR mode, in particular, simultaneous deconvolution analysis of UV-vis absorption and MCD spectra reveal that (i) the amplitude of the magnetoplasmonic component with lower frequency (ω-), resulting from the reduction in the confinement strength of collective electrons by the Lorentz force, is stronger than that with a higher frequency (ω+) (ii) the accurate shift or cyclotron frequency between two magnetoplasmonic modes (ωc = ω+ - ω-) is size-dependent, and presents a very large value with implications for the apparent enhancement of the local magnetic-field in the Ag nanoparticles. These results strongly suggest that the Ag-thiolate layer or Ag-S bonding on the nanoparticle surface plays a significant role in the MO enhancement.Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD

  9. Metal deposition by electroless plating on polydopamine functionalized micro- and nanoparticles.

    PubMed

    Mondin, Giovanni; Wisser, Florian M; Leifert, Annika; Mohamed-Noriega, Nasser; Grothe, Julia; Dörfler, Susanne; Kaskel, Stefan

    2013-12-01

    A novel approach for the fabrication of metal coated micro- and nanoparticles by functionalization with a thin polydopamine layer followed by electroless plating is reported. The particles are initially coated with polydopamine via self-polymerization. The resulting polydopamine coated particles have a surface rich in catechols and amino groups, resulting in a high affinity toward metal ions. Thus, they provide an effective platform for selective electroless metal deposition without further activation and sensitization steps. The combination of a polydopamine-based functionalization with electroless plating ensures a simple, scalable, and cost-effective metal coating strategy. Silver-plated tungsten carbide microparticles, copper-plated tungsten carbide microparticles, and copper-plated alumina nanoparticles were successfully fabricated, showing also the high versatility of the method, since the polymerization of dopamine leads to the formation of an adherent polydopamine layer on the surface of particles of any material and size. The metal coated particles produced with this process are particularly well suited for the production of metal matrix composites, since the metal coating increases the wettability of the particles by the metal, promoting their integration within the matrix. Such composite materials are used in a variety of applications including electrical contacts, components for the automotive industries, magnets, and electromagnetic interference shielding. PMID:24041548

  10. Metal nanoparticles and IR laser applications in medicine for biotissue ablation and welding

    NASA Astrophysics Data System (ADS)

    Lalayan, A. A.; Israelyan, S. S.

    2016-05-01

    We report the possibility of laser welding and ablation of biotissue by using metal and hybrid metal nanoparticles (NPs) and infrared laser irradiation spectrally located far from plasmon resonances. A nanosecond YAG:Nd laser of wavelength 1064 nm has been used for synthesis of metal NPs. The Ag, Au, Cu, Ti and Ni, as well as Au–Ag and Au–Cu hybrid metal colloidal NPs were formed in a liquid medium. The diagnostic technique of second harmonic generation (SHG) has been applied to determine the biotissue ablation area after IR laser irradiation. The effectiveness of biotissue ablation was 4–5 times larger in the case of a tissue sample colored with metal NPs than for an uncolored sample. IR laser welding has been demonstrated for deep-located biotissue layers colored by metal NPs.

  11. Controlled Dealloying of Alloy Nanoparticles toward Optimization of Electrocatalysis on Spongy Metallic Nanoframes.

    PubMed

    Li, Guangfang Grace; Villarreal, Esteban; Zhang, Qingfeng; Zheng, Tingting; Zhu, Jun-Jie; Wang, Hui

    2016-09-14

    Atomic-level understanding of the structural transformations of multimetallic nanoparticles triggered by external stimuli is of vital importance to the enhancement of our capabilities to fine-tailor the key structural parameters and thereby to precisely tune the properties of the nanoparticles. Here, we show that, upon thermal annealing in a reducing atmosphere, Au@Cu2O core-shell nanoparticles transform into Au-Cu alloy nanoparticles with tunable compositional stoichiometries that are predetermined by the relative core and shell dimensions of their parental core-shell nanoparticle precursors. The Au-Cu alloy nanoparticles exhibit distinct dealloying behaviors that are dependent upon their Cu/Au stoichiometric ratios. For Au-Cu alloy nanoparticles with Cu atomic fractions above the parting limit, nanoporosity-evolving percolation dealloying occurs upon exposure of the alloy nanoparticles to appropriate chemical etchants, resulting in the formation of particulate spongy nanoframes with solid/void bicontinuous morphology composed of hierarchically interconnected nanoligaments. The nanoporosity evolution during percolation dealloying is synergistically guided by two intertwining structural rearrangement processes, ligament domain coarsening driven by thermodynamics and framework expansion driven by Kirkendall effects, both of which can be maneuvered by controlling the Cu leaching rates during the percolation dealloying. The dealloyed nanoframes possess large open surface areas accessible by the reactant molecules and high abundance of catalytically active undercoordinated atoms on the ligament surfaces, two unique structural features highly desirable for high-performance electrocatalysis. Using the room temperature electro-oxidation of methanol as a model reaction, we further demonstrate that, through controlled percolation dealloying of Au-Cu alloy nanoparticles, both the electrochemically active surface areas and the specific activity of the dealloyed metallic

  12. Surface interactions of gold nanorods and polysaccharides: From clusters to individual nanoparticles.

    PubMed

    de Barros, Heloise Ribeiro; Piovan, Leandro; Sassaki, Guilherme L; de Araujo Sabry, Diego; Mattoso, Ney; Nunes, Ábner Magalhães; Meneghetti, Mario R; Riegel-Vidotti, Izabel C

    2016-11-01

    Gold nanorods (AuNRs) are suitable for constructing self-assembled structures for the development of biosensing devices and are usually obtained in the presence of cetyltrimethylammonium bromide (CTAB). Here, a sulfated chitosan (ChiS) and gum arabic (GA) were employed to encapsulate CTAB/AuNRs with the purpose of studying the interactions of the polysaccharides with CTAB, which is cytotoxic and is responsible for the instability of nanoparticles in buffer solutions. The presence of a variety of functional groups such as the sulfate groups in ChiS and the carboxylic groups in GA, led to efficient interactions with CTAB/AuNRs as evidenced through UV-vis and FTIR spectroscopies. Electron microscopies (HR-SEM and TEM) revealed that nanoparticle clusters were formed in the GA-AuNRs sample, whereas individual AuNRs, surrounded by a dense layer of polysaccharides, were observed in the ChiS-AuNRs sample. Therefore, the presented work contributes to the understanding of the driving forces that control the surface interactions of the studied materials, providing useful information in the building-up of gold self-assembled nanostructures. PMID:27516295

  13. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    PubMed Central

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-01-01

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science. PMID:25650004

  14. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering.

    PubMed

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-01-01

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born's approximation and is remarkably efficient-opening up new routes in ultrafast nanophysics and free-electron laser science. PMID:25650004

  15. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    DOE PAGES

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; et al

    2015-02-04

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncoveredmore » from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science« less

  16. The 3D-architecture of individual free silver nanoparticles captured by X-ray scattering

    SciTech Connect

    Barke, Ingo; Hartmann, Hannes; Rupp, Daniela; Flückiger, Leonie; Sauppe, Mario; Adolph, Marcus; Schorb, Sebastian; Bostedt, Christoph; Treusch, Rolf; Peltz, Christian; Bartling, Stephan; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Möller, Thomas

    2015-02-04

    The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born’s approximation and is remarkably efficient—opening up new routes in ultrafast nanophysics and free-electron laser science

  17. Effect of clustering on the surface plasmon band in thin films of metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Pereira, Rui M. S.; Borges, Joel; Peres, Filipa C. R.; Pereira, Paulo A. S.; Smirnov, Georgi V.; Vaz, Filipe; Cavaleiro, Albano; Vasilevskiy, Mikhail I.

    2015-01-01

    We theoretically investigate the optical response of ensembles of polarizable metallic nanoparticles (NPs) that form (1) submonolayer films of particles adsorbed on a dielectric substrate, considered as two-dimensional (2-D) systems, and (2) thin three-dimensional (3-D) films, where NPs are embedded in a dielectric matrix. For system (1), the effect of NPs' distance to the substrate is taken into account. In both cases, we find that short-range clustering leads to a broadening and a spectral shift of the absorption band related to the surface plasmon resonance (SPR) in individual NPs. We show that the clustering can help in achieving spectrally broad SPR bands, especially if NPs aggregate into fractal clusters, which can be interesting for some applications such as surface-enhanced Raman scattering. In particular, submonolayer films on NPs generated using the diffusion-limited aggregation algorithm produce sizable and spectrally broad absorption, which can be tuned to the visible range by choosing an appropriate capping and/or substrate material. Calculated results for thin 3-D films are compared with experimental data obtained for Au/TiO2 nanocomposite layers produced by reactive cosputtering.

  18. Photoreactive surfactants: a facile and clean route to oxide and metal nanoparticles in reverse micelles.

    PubMed

    de Oliveira, Rodrigo J; Brown, Paul; Correia, Gemima B; Rogers, Sarah E; Heenan, Richard; Grillo, Isabelle; Galembeck, André; Eastoe, Julian

    2011-08-01

    A new class of photoreactive surfactants (PRSs) is presented here, consisting of amphiphiles that can also act as reagents in photochemical reactions. An example PRS is cobalt 2-ethylhexanoate (Co(EH)(2)), which forms reverse micelles (RMs) in a hydrocarbon solvent, as well as mixed reversed micelles with the standard surfactant Aerosol-OT (AOT). Small-angle neutron scattering (SANS) data show that mixed AOT/PRS RMs have a spherical structure and size similar to that of pure AOT micelles. Excitation of the ligand-to-metal charge transfer (LMCT) band in the PRSs promotes electron transfer from PRS to associated metal counterions, leading to the generation of metal and metal-oxide nanoparticles inside the RMs. This work presents proof of concept for employing PRSs as precursors to obtain nearly monodisperse inorganic nanoparticles: here both Co(3)O(4) and Bi nanoparticles have been synthesized at high metal concentration (10(-2) M) by simply irradiating the RMs. These results point toward a new approach of photoreactive self-assembly, which represents a clean and straightforward route to the generation of nanomaterials.

  19. Ligand Control over the Electronic Properties within the Metallic Core of Gold Nanoparticles.

    PubMed

    Cirri, Anthony; Silakov, Alexey; Lear, Benjamin J

    2015-09-28

    The behavior of electrons within the metallic core of gold nanoparticles (AuNPs) can be controlled by the nature of the surface chemistry of the AuNPs. Specifically, the conduction electron spin resonance (CESR) spectra of AuNPs of diameter 1.8-1.9 nm are sensitive to ligand exchange of hexanethiol for 4-bromothiophenol on the surface of the nanoparticle. Chemisorption of the aromatic ligand leads to a shift in the metallic electron's g-factor toward the value expected for pure gold systems, suggesting an increase in metallic character for the electrons within the gold core. Analysis by UV/Vis absorption spectroscopy reveals a concomitant bathochromic shift of the surface plasmon resonance band of the AuNP, indicating that other electronic properties of AuNPs are also affected by the ligand exchange. In total, our results demonstrate that the chemical nature of the ligand controls the valence band structure of AuNPs.

  20. Towards understanding mechanisms governing cytotoxicity of metal oxides nanoparticles: hints from nano-QSAR studies.

    PubMed

    Gajewicz, Agnieszka; Schaeublin, Nicole; Rasulev, Bakhtiyor; Hussain, Saber; Leszczynska, Danuta; Puzyn, Tomasz; Leszczynski, Jerzy

    2015-05-01

    The production of nanomaterials increases every year exponentially and therefore the probability these novel materials that they could cause adverse outcomes for human health and the environment also expands rapidly. We proposed two types of mechanisms of toxic action that are collectively applied in a nano-QSAR model, which provides governance over the toxicity of metal oxide nanoparticles to the human keratinocyte cell line (HaCaT). The combined experimental-theoretical studies allowed the development of an interpretative nano-QSAR model describing the toxicity of 18 nano-metal oxides to the HaCaT cell line, which is a common in vitro model for keratinocyte response during toxic dermal exposure. The comparison of the toxicity of metal oxide nanoparticles to bacteria Escherichia coli (prokaryotic system) and a human keratinocyte cell line (eukaryotic system), resulted in the hypothesis that different modes of toxic action occur between prokaryotic and eukaryotic systems.

  1. A single-source route for the synthesis of metal oxide nanoparticles using vegetable oil solvents.

    PubMed

    Pereira, Angela S; Silva, Nuno J O; Trindade, Tito; Pereira, Sergio

    2012-12-01

    We report a general method for the synthesis of metal oxide colloidal nanocrystals in sunflower oil using single-source precursors. In this research, iron oxide nanocrystals have been synthesized and characterized though this method can be extended to the synthesis of other common metal oxides such as ZnO and also to other types of vegetable oils as solvents. Using this method, nanoparticles with average diameters of 7 nm and 3 nm were obtained respectively for iron oxide and zinc oxide. The magnetic iron oxide phase was identified using powder XRD, surface enhanced Raman spectroscopy and magnetic measurements as maghemite as the main component. The magnetic measurements demonstrate the superparamagnetic behavior of the iron oxide nanoparticles. This synthetic approach is an interesting way to synthesize metal oxide nanocrystals in eco-friendly solvents of natural origin.

  2. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10-5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  3. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10‑5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  4. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-16

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  5. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-16

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains. PMID:27487089

  6. Electronic Coupling and Optimal Gap Size Between Two Metal Nanoparticles

    SciTech Connect

    Zhao, Ke; Troparevsky, Claudia; Xiao, Di; Eguiluz, Adolfo G; Zhang, Zhenyu

    2009-01-01

    We study the electronic coupling between two silver nanoparticles using ab initio density functional theory for real atoms. We show that the electronic coupling depends on both the gap size of the dimer system and the relative orientation of the particles. As the two particles are separated from touching contact, the dimer undergoes a bond-breaking step, which also establishes the striking existence of an optimal gap size dened by a maximal static polarizability of the dimer. For some dimers, the electronic coupling before the bond breaking can be strong enough to give rise to a net magnetic moment of the dimer, even though the isolated particles are nonmagnetic. These ndings may prove to be instrumental in understanding and controlling the optical, magnetic, electrical, and chemical properties of closely-packed nanoparticle aggregates.

  7. Metal nanoparticle-graphene oxide composites: Photophysical properties and sensing applications

    NASA Astrophysics Data System (ADS)

    Murphy, Sean J.

    Composite nanomaterials allow for attractive properties of multiple functional components to be combined. Fundamental understanding of the interaction between different nanomaterials, their surroundings, and nearby molecular species is pertinent for implementation into devices. Metal nanoparticles have been used for their optical properties in many applications including stained glass, cancer therapy, solar steam generation, surface enhanced Raman spectroscopy (SERS), and catalysis. Carbon-based nanomaterials such as graphene and carbon nanotubes show potential for a wide variety of applications including solar energy harvesting, chemical sensors, and electronics. Combining useful and in some cases new properties of composite nanomaterials offers exciting opportunities in fundamental science and device development. In this dissertation, I aim to address understanding photoinduced interaction between porphyrin and silver nanoparticles, inter-sheet interaction between stacked graphene oxide (GO) sheets in thin films, complexation of reduced GO with Raman active target molecule in SERS applications, and efficacy of graphene-metal nanoparticle composites for sensing applications. Molecule-metal nanoparticle composite material made up of photoactive porphyrin and silver nanoparticles was studied using various spectroscopic tools. UV-visible absorption and surface enhanced Raman spectroscopic results suggest formation of a charge-transfer complex for porphyrin-silver nanoparticle composite. Ultrafast transient absorption and fluorescence upconversion spectroscopies further corroborate electronic interaction by providing evidence for excited state electron transfer between porphyrin and silver nanoparticles. Understanding electronic interaction between adsorbed photoactive molecules and metal nanoparticles may be of use for applications in photocatalysis or light-energy harvesting. Graphene oxide (GO) thin films have been prepared and studied using transient absorption

  8. Comparison of characteristics of selected metallic and metal oxide nanoparticles produced by picosecond laser ablation at 532 and 1064 nm wavelengths

    NASA Astrophysics Data System (ADS)

    Hamad, Abubaker; Li, Lin; Liu, Zhu

    2016-10-01

    Picosecond laser generation of nanoparticles was only recently reported. The effect of laser wavelength in picosecond laser generation of nanoparticles is not yet fully understood. This investigation reports the new findings comparing the characteristics of Au, Ag, Ag-TiO2, TiO2, ZnO and iron oxide nanoparticles generated by picosecond laser ablation in deionised water at 532 and 1064 nm laser wavelengths. The laser ablation was carried out at a fixed pulse width of 10 ps, a repetition rate of 400 kHz and a scan speed of 250 mm/s. The nanoparticles were characterised by UV-Vis optical spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The work shows that there is no noticeable difference in the size of the metal oxide nanoparticles produced at 532 and 1064 nm, especially for the TiO2 and ZnO nanoparticles; however, a considerable size difference can be seen for metallic (e.g. Au) and metallic compound (e.g. Ag-TiO2) nanoparticles at the two wavelengths. It demonstrates that noble metals are more profoundly affected by laser wavelengths. The reasons behind these results are discussed. In addition, the work shows that there are different crystalline structures of the TiO2 nanoparticles at 1064 and 532 nm wavelengths.

  9. The Transport and Impact of Metal Nanoparticles in Soil

    NASA Astrophysics Data System (ADS)

    Dror, Ishai; Berkowitz, Brian

    2014-05-01

    The fate, transport and mobility of nanoparticles in soil are strongly dependent on environmental conditions. In this study we present the effect of soil properties on the transport of silver nanoparticles (AgNPs) in a set of laboratory column experiments, using different combinations of size fractions of a Mediterranean sandy clay soil. AgNPs are shown to have high mobility in soil with outlet relative concentrations ranging from 30% to 70%, depending on experimental conditions. The AgNP mobility through the column decreases when the fraction of smaller soil aggregates is larger. An early breakthrough pattern was found for the AgNP but not observed for AgNPs in pure quartz columns nor for bromide tracer in soil columns, suggesting that early breakthrough is related to the nature of AgNP transport in natural soils. Micro-CT and image analysis used to investigate structural features of the soil, suggest that soil aggregate size strongly affects AgNP transport in natural soil. These findings point to the importance of AgNP-soil chemical interactions as a retention mechanism, and demonstrate the need to employ natural soils rather than glass beads or quartz in representative experimental investigations. It is further noted that little is known about the possible effects of nanoparticles on soil chemical, physical and biological properties. Here we show that although copper oxide nanoparticles (nCuO) had little impact on the macroscopic properties of the soil, they did cause changes to humic substance structure and affected the soil bacterial community composition. In particular, the nCuO was found to have a strong effect on bacterial hydrolytic activity, oxidative potential, community composition and size in Bet-Dagan soil. These results indicate that CuO NPs are potentially harmful to soil environments. Furthermore, the results suggest that the clay fraction and organic matter in different soils interact with the nCuO and reduce its toxicity.

  10. Metallic nanoparticles as optoacoustic contrast agents for medical imaging

    NASA Astrophysics Data System (ADS)

    Conjusteau, Andre; Ermilov, Sergey A.; Lapotko, Dmitri; Liao, Hongwei; Hafner, Jason; Eghtedari, Mohammad; Motamedi, Massoud; Kotov, Nicholas; Oraevsky, Alexander A.

    2006-02-01

    A contrast agent for optoacoustic imaging and laser therapy of early tumors is being developed based on gold nanocolloids strongly absorbing visible and near-infrared light. The optoacoustic signals obtained from gold nanospheres and gold nanorods solutions are studied. In the case of 100 nm nanospheres as an example, a sharp increase in the total area under the curve of the optoacoustic signal is observed when the laser fluence is increased beyond a threshold value of about 0.1 J/cm2. The change in the optoacoustic signal profile is attributed to the formation of water vapor bubbles around heated nanoparticles, as evidenced via thermoacoustic microscopy experiments. It has been determined that, surprisingly, gold nanoparticles fail to generate detectable nanobubbles upon irradiation at the laser fluence of ~2 mJ/cm2, which heats the nanoparticles up to 374°C, the critical temperature of water. Only when the estimated temperature of the particle reaches about 10,000°C, a marked increase of the optoacoustic pressure amplitude and a changed profile of the optoacoustic signals indicate nanobubble formation. A nanoparticle based contrast agent is the most effective if it can be activate by laser pulses with low fluence attainable in the depth of tissue. With this goal in mind, we develop targeting protocols that form clusters of gold nanocolloid in the target cells in order to lower the bubble formation threshold below the level of optical fluence allowed for safe laser illumination of skin. Experiments and modeling suggest that formation of clusters of nanocolloids may improve the sensitivity of optoacoustic imaging in the detection of early stage tumors.

  11. Evaluation of the thermodynamic properties of hydrated metal oxide nanoparticles by INS techniques

    SciTech Connect

    Spencer, Elinor; Ross, Dr. Nancy; Parker, Stewart F.; Kolesnikov, Alexander I

    2013-01-01

    In this contribution we will present a detailed methodology for the elucidation of the following aspects of the thermodynamic properties of hydrated metal oxide nanoparticles from high-resolution, low-temperature inelastic neutron scattering (INS) data: (i) the isochoric heat capacity and entropy of the hydration layers both chemi- and physisorbed to the particle surface; (ii) the magnetic contribution to the heat capacity of the nanoparticles. This will include the calculation of the vibrational density of states (VDOS) from the raw INS spectra, and the subsequent extraction of the thermodynamic data from the VDOS. This technique will be described in terms of a worked example namely, cobalt oxide (Co3O4 and CoO). To complement this evaluation of the physical properties of metal oxide nanoparticle systems, we will emphasise the importance of high-resolution, high-energy INS for the determination of the structure and dynamics of the water species, namely molecular (H2O) and dissociated water (OH, hydroxyl), confined to the oxide surfaces. For this component of the chapter we will focus on INS investigations of hydrated isostructural rutile (a-TiO2) and cassiterite (SnO2) nanoparticles. We will complete this discussion of nanoparticle analysis by including an appraisal of the INS instrumentation employed in such studies with particular focus on TOSCA [ISIS, Rutherford Appleton Laboratory (RAL), U.K.] and the newly developed spectrometer SEQUOIA [SNS, Oak Ridge National Laboratory (ORNL), U.S.A].

  12. Far-field optical nanothermometry using individual sub-50 nm upconverting nanoparticles.

    PubMed

    Kilbane, Jacob D; Chan, Emory M; Monachon, Christian; Borys, Nicholas J; Levy, Elizabeth S; Pickel, Andrea D; Urban, Jeffrey J; Schuck, P James; Dames, Chris

    2016-06-01

    We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er(3+) and 20% Yb(3+). Isolated 20 × 20 × 40 nm(3) particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications. PMID:27216164

  13. Heavy metal removal from wastewater using zero-valent iron nanoparticles.

    PubMed

    Chen, S Y; Chen, W H; Shih, C J

    2008-01-01

    Because of having a high reduction potential, the zero-valent iron (ZVI) is often applied for the remediation of wastewater or groundwater with heavy metals. The purpose of this study was aimed to investigate the reaction behavior of heavy metals with ZVI nanoparticles in the wastewater. The affecting factors, such as initial pH, dosage of nanoscale ZVI and initial concentration of heavy metal, on the removal efficiency of heavy metals by ZVI in the wastewater were examined by the batch experiments in this study. It was found that the removal of heavy metals was affected by initial pH. The rate and efficiency of metal removal increased with decreasing initial pH. Greater than 90% of the heavy metals were removed when the initial pH was controlled at 2. In addition, the rate and efficiency of metal removal increased as the dosage of nanoscale ZVI increased. The removal efficiency of heavy metal was higher than 80% when 2.0 g/L of ZVI was added in the wastewater. On the other hand, the slow rate and low efficiency of metal removal from the wastewater treated by nanoscale ZVI was found in the wastewater with high concentration of heavy metal.

  14. An experimental assessment of toxic potential of nanoparticle preparation of heavy metals in streptozotocin induced diabetes.

    PubMed

    Gandhi, Sonia; Srinivasan, B P; Akarte, Atul Sureshrao

    2013-11-01

    Nanoparticle preparations of heavy metals have attracted enormous scientific and technological interest. Biologically produced nanoparticle preparations of heavy metals are elaborately described in traditional texts and being widely prescribed. The underlying interactions of nano preparations within the physiological fluids are key feature to understand their biological impact. In this perspective, we performed an experimental assessment of the toxicity potential of a marketed metallic preparation named Vasant Kusumakar Ras (VKR), wherein different heavy metals in composite form are reduced to nanoparticle size to produce the desired effect in diabetes and its complications. VKR (50mg/kg) was administered to Albino Wistar rats rendered diabetic using streptozotocin (90mg/kg) in 2 days old neonates. Anti-hyperglycemic effect was observed with VKR along with increased levels of plasma insulin. Renal variables including total proteins and albumin along with glomerular filtration rate were found to improve biochemically. The results were supplemented by effects on different inflammatory and growth factors like TNF-α, nitric oxide, TGF-β and VEGF. However, the results observed in kidney histopathology were not in accordance with the biochemical parameters. Inflammation observed in kidney was confirmed by immunostaining metallothionein, which was due to the accumulation of heavy metals. Furthermore, mercury accumulation in kidney further confirmed by autometallography, which activated mononuclear phagocyte system, which generated an immune response. This was further supported by increase in the extent of apoptosis in kidney tissues. In conclusion, nanoparticle preparations of heavy metals can be toxic to kidney if it is not regulated with respect to its surface chemistry and dosage.

  15. Far-field optical nanothermometry using individual sub-50 nm upconverting nanoparticles

    NASA Astrophysics Data System (ADS)

    Kilbane, Jacob D.; Chan, Emory M.; Monachon, Christian; Borys, Nicholas J.; Levy, Elizabeth S.; Pickel, Andrea D.; Urban, Jeffrey J.; Schuck, P. James; Dames, Chris

    2016-06-01

    We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er3+ and 20% Yb3+. Isolated 20 × 20 × 40 nm3 particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications.We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er3+ and 20% Yb3+. Isolated 20 × 20 × 40 nm3 particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K. A standard Arrhenius model widely used for larger particles can still be accurately applied to these sub-50 nm particles, with good particle-to-particle uniformity (response coefficients exhibited standard deviations below 5%). With its spatial resolution on the order of 50 nm when imaging a single particle, far below the diffraction limit, this technique has potential applications for both fundamental thermal measurements and nanoscale metrology in industrial applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01479h

  16. Direct quantification of rare earth doped titania nanoparticles in individual human cells.

    PubMed

    Jeynes, J C G; Jeynes, C; Palitsin, V; Townley, H E

    2016-07-15

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically. PMID:27255758

  17. Direct quantification of rare earth doped titania nanoparticles in individual human cells

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Jeynes, C.; Palitsin, V.; Townley, H. E.

    2016-07-01

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

  18. Well-Dispersed and Size-Controlled Supported Metal Oxide Nanoparticles Derived from MOF Composites and Further Application in Catalysis.

    PubMed

    Liu, Hong; Zhang, Suoying; Liu, Yayuan; Yang, Zhuhong; Feng, Xin; Lu, Xiaohua; Huo, Fengwei

    2015-07-01

    Supported metal oxide nanoparticles are important in heterogeneous catalysis; however, the ability to tailor their size, structure, and dispersion remains a challenge. A strategy to achieve well-dispersed and size-controlled supported metal oxides through the manageable growth of a metal organic framework (Cu-BTC) on TiO2 followed by pyrolysis is described.

  19. Metal Oxide Nanoparticles: The Importance of Size, Shape, Chemical Composition, and Valence State in Determining Toxicity

    NASA Astrophysics Data System (ADS)

    Dunnick, Katherine

    Nanoparticles, which are defined as a structure with at least one dimension between 1 and 100 nm, have the potential to be used in a variety of consumer products due to their improved functionality compared to similar particles of larger size. Their small size is associated with increased strength, improved catalytic properties, and increased reactivity; however, their size is also associated with increased toxicity in vitro and in vivo. Numerous toxicological studies have been conducted to determine the properties of nanomaterials that increase their toxicity in order to manufacture new nanomaterials with decreased toxicity. Data indicates that size, shape, chemical composition, and valence state of nanomaterials can dramatically alter their toxicity profile. Therefore, the purpose of this dissertation was to determine how altering the shape, size, and chemical composition of various metal oxide nanoparticles would affect their toxicity. Metal oxides are used in variety of consumer products, from spray-sun screens, to food coloring agents; thus, understanding the toxicity of metal oxides and determining which aspects affect their toxicity may provide safe alternatives nanomaterials for continued use in manufacturing. Tungstate nanoparticles toxicity was assessed in an in vitro model using RAW 264.7 cells. The size, shape, and chemical composition of these nanomaterials were altered and the effect on reactive oxygen species and general cytotoxicity was determined using a variety of techniques. Results demonstrate that shape was important in reactive oxygen species production as wires were able to induce significant reactive oxygen species compared to spheres. Shape, size, and chemical composition did not have much effect on the overall toxicity of these nanoparticles in RAW 264.7 cells over a 72 hour time course, implicating that the base material of the nanoparticles was not toxic in these cells. To further assess how chemical composition can affect toxicity

  20. Metallic oxide nanoparticles stimulate blood coagulation independent of their surface charge.

    PubMed

    Steuer, Heiko; Krastev, Rumen; Lembert, Nicolas

    2014-07-01

    Positively charged metallic oxides prevent blood coagulation whereas negatively charged metallic oxides are thrombogenic. This study was performed to examine whether this effect extends to metallic oxide nanoparticles. Oscillation shear rheometry was used to study the effect of zinc oxide and silicon dioxide nanoparticles on thrombus formation in human whole blood. Our data show that oscillation shear rheometry is a sensitive and robust technique to analyze thrombogenicity induced by nanoparticles. Blood without previous contact with nanoparticles had a clotting time (CT) of 16.7 ± 1.0 min reaching a maximal clot strength (CS) of 16 ± 14 Pa (G') after 30 min. ZnO nanoparticles (diameter 70 nm, +37 mV zeta-potential) at a concentration of 1 mg/mL prolonged CT to 20.8 ± 3.6 min and provoked a weak clot (CS 1.5 ± 1.0 Pa). However, at a lower concentration of 100 µg/mL the ZnO particles dramatically reduced CT to 6.0 ± 0.5 min and increased CS to 171 ± 63 Pa. This procoagulant effect decreased at lower concentrations reaching the detection limit at 10 ng/mL. SiO2 nanoparticles (diameter 232 nm, -28 mV zeta-potential) at high concentrations (1 mg/mL) reduced CT (2.1 ± 0.2 min) and stimulated CS (249 ± 59 Pa). Similar to ZnO particles, this procoagulant effect reached a detection limit at 10 ng/mL. Nanoparticles in high concentrations reproduce the surface charge effects on blood coagulation previously observed with large particles or solid metal oxides. However, nanoparticles with different surface charges equally well stimulate coagulation at lower concentrations. This stimulation may be an effect which is not directly related to the surface charge.

  1. Decay of dark and bright plasmonic modes in a metallic nanoparticle dimer

    NASA Astrophysics Data System (ADS)

    Brandstetter-Kunc, Adam; Weick, Guillaume; Weinmann, Dietmar; Jalabert, Rodolfo A.

    2015-01-01

    We develop a general quantum theory of the coupled plasmonic modes resulting from the near-field interaction between localized surface plasmons in a heterogeneous metallic nanoparticle dimer. In particular, we provide analytical expressions for the frequencies and decay rates of the bright and dark plasmonic modes. We show that, for sufficiently small nanoparticles, the main decay channel for the dark plasmonic mode, which is weakly coupled to light and, hence, immune to radiation damping, is of nonradiative origin and corresponds to Landau damping, i.e., decay into electron-hole pairs.

  2. Self-focusing of an intense laser pulse interacting with a periodic lattice of metallic nanoparticle

    SciTech Connect

    Sepehri Javan, N.

    2015-09-15

    The motivation for the present work is the study of self-focusing of an intense laser beam propagating through a periodic array of metallic nanoparticle. Using a perturbative method, a wave equation describing the nonlinear interaction of a laser beam with nanoparticles is derived. Evolution of laser spot size with the Gaussian profile for the circular and linear polarizations is considered. It is found that, in the same intensity, the linear polarization in a special interval of frequency resonantly acts better than the circular one.

  3. Nanoscale optical properties of metal nanoparticles probed by Second Harmonic Generation microscopy.

    PubMed

    Shen, Hong; Nguyen, Ngoc; Gachet, David; Maillard, Vincent; Toury, Timothée; Brasselet, Sophie

    2013-05-20

    We report spatial and vectorial imaging of local fields' confinement properties in metal nanoparticles with branched shapes, using Second Harmonic Generation (SHG) microscopy. Taking advantage of the coherent nature of this nonlinear process, the technique provides a direct evidence of the coupling between the excitation polarization and both localization and polarization specificities of local fields at the sub-diffraction scale. These combined features, which are governed by the nanoparticles' symmetry, are not accessible using other contrasts such as linear optical techniques or two-photon luminescence.

  4. A simple approach to obtain hybrid Au-loaded polymeric nanoparticles with a tunable metal load

    NASA Astrophysics Data System (ADS)

    Luque-Michel, Edurne; Larrea, Ane; Lahuerta, Celia; Sebastian, Víctor; Imbuluzqueta, Edurne; Arruebo, Manuel; Blanco-Prieto, María J.; Santamaría, Jesús

    2016-03-01

    A new strategy to nanoengineer multi-functional polymer-metal hybrid nanostructures is reported. By using this protocol the hurdles of most of the current developments concerning covalent and non-covalent attachment of polymers to preformed inorganic nanoparticles (NPs) are overcome. The strategy is based on the in situ reduction of metal precursors using the polymeric nanoparticle as a nanoreactor. Gold nanoparticles and poly(dl-lactic-co-glycolic acid), PLGA, are located in the core and shell, respectively. This novel technique enables the production of PLGA NPs smaller than 200 nm that bear either a single encapsulated Au NP or several smaller NPs with tunable sizes and a 100% loading efficiency. In situ reduction of Au ions inside the polymeric NPs was achieved on demand by using heat to activate the reductive effect of citrate ions. In addition, we show that the loading of the resulting Au NPs inside the PLGA NPs is highly dependent on the surfactant used. Electron microscopy, laser irradiation, UV-Vis and fluorescence spectroscopy characterization techniques confirm the location of Au nanoparticles. These promising results indicate that these hybrid nanomaterials could be used in theranostic applications or as contrast agents in dark-field imaging and computed tomography.A new strategy to nanoengineer multi-functional polymer-metal hybrid nanostructures is reported. By using this protocol the hurdles of most of the current developments concerning covalent and non-covalent attachment of polymers to preformed inorganic nanoparticles (NPs) are overcome. The strategy is based on the in situ reduction of metal precursors using the polymeric nanoparticle as a nanoreactor. Gold nanoparticles and poly(dl-lactic-co-glycolic acid), PLGA, are located in the core and shell, respectively. This novel technique enables the production of PLGA NPs smaller than 200 nm that bear either a single encapsulated Au NP or several smaller NPs with tunable sizes and a 100% loading

  5. Zeolitic BIF Crystal Directly Producing Noble-Metal Nanoparticles in Its Pores for Catalysis

    PubMed Central

    Zhang, Hai-Xia; Liu, Meng; Bu, Xianhui; Zhang, Jian

    2014-01-01

    As an integral part of a porous framework and uniformly distributed throughout the internal pore space, the high density of the exposed B–H bond in zeolite-like porous BIF-20 (BIF = Boron Imidazolate Framework) is shown here to effectively produce nanoparticles within its confined pore space. Small noble-metal nanoparticles (Ag or Au) are directly synthesized into its pores without the need for any external reducing agent or photochemical reactions, and the resulting Ag@BIF-20 (or Au@BIF-20) samples show high catalytic activities for the reduction of 4-nitrophenol. PMID:24473155

  6. NiO as a peculiar support for metal nanoparticles in polyols oxidation

    SciTech Connect

    Villa, Alberto; Veith, Gabriel M; Ferri, Davide; Weidenkaff, Anke; Perry, Kelly A; Campisi, Sebastiano; Prati, Laura

    2013-01-01

    The peculiar influence of a NiO support was studied by preparing gold catalysts supported on NiO(1-x) TiO2(x) mixed oxides. PVA protected Au nanoparticles showed high activity when supported on NiO for the selective oxidation of glycerol and ethan-1,2-diol. A detailed characterization of the resulting Au catalysts revealed a preferential deposition of the metal nanoparticles on the NiO phase. However, the activity of Au on NiO(1-x)-TiO2(x) decreased with respect to pure NiO and the selectivity evolved with changes to the support.

  7. Passive mass transport for direct and quantitative SERS detection using purified silica encapsulated metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shrestha, Binaya Kumar

    This thesis focuses on understanding implications of nanomaterial quality control and mass transport through internally etched silica coated nanoparticles for direct and quantitative molecular detection using surface enhanced Raman scattering (SERS). Prior to use, bare nanoparticles (partially or uncoated with silica) are removal using column chromatography to improve the quality of these nanomaterials and their SERS reproducibility. Separation of silica coated nanoparticles with two different diameters is achieved using Surfactant-free size exclusion chromatography with modest fractionation. Next, selective molecular transport is modeled and monitored using SERS and evaluated as a function of solution ionic strength, pH, and polarity. Molecular detection is achieved when the analytes first partition through the silica membrane then interact with the metal surface at short distances (i.e., less than 2 nm). The SERS intensities of unique molecular vibrational modes for a given molecule increases as the number of molecules that bind to the metal surface increases and are enhanced via both chemical and electromagnetic enhancement mechanisms as long as the vibrational mode has a component of polarizability tensor along the surface normal. SERS signals increase linearly with molecular concentration until the three-dimensional SERS-active volume is saturated with molecules. Implications of molecular orientation as well as surface selection rules on SERS intensities of molecular vibrational modes are studied to improve quantitative and reproducible SERS detection using internally etched Ag Au SiO2 nanoparticles. Using the unique vibrational modes, SERS intensities for p-aminothiophenol as a function of metal core compositions and plasmonics are studied. By understanding molecular transport mechanisms through internally etched silica matrices coated on metal nanoparticles, important experimental and materials design parameters are learned, which can be subsequently applied

  8. USING ZERO-VALENT METAL NANOPARTICLES TO REMEDIATE ORGANIC CONTAMINANTS

    EPA Science Inventory

    The transport of organic contaminants down the soil profile constitutes a serious threat to the quality of ground water. Zero-valent metals are considered innocuous abiotic agents capable of mediating decontamination processes in terrestrial systems. In this investigation, ze...

  9. Individual and collective modes of surface magnetoplasmon in thiolate-protected silver nanoparticles studied by MCD spectroscopy.

    PubMed

    Yao, Hiroshi; Shiratsu, Taisuke

    2016-06-01

    Large magneto-optical (MO) responses at the energy of localized surface plasmon resonance (LSPR), namely, surface magnetoplasmons, are demonstrated for the first time in thiolate-protected silver nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiol (DT)-, azobenzenethiol (ABT)-, and ABT/DT mixed-monolayer-protected Ag nanoparticles. ABT-protected Ag nanoparticles are somewhat aggregated and thus exhibit a broad, collective mode of plasmonic absorption, whereas other samples with highly-dispersed nanoparticles show an individual mode of LSPR absorption. In all Ag nanoparticles, a derivative-like MCD signal is observed under an applied magnetic field of 1.6 T, which can be explained in terms of two circular modes of magnetoplasmon caused by the increase (or decrease) in the Lorentz force imparted on the free electrons that oscillate in the left (or right) circular orbits in the nanosphere. For the Ag nanoparticles exhibiting an individual LSPR mode, in particular, simultaneous deconvolution analysis of UV-vis absorption and MCD spectra reveal that (i) the amplitude of the magnetoplasmonic component with lower frequency (ω-), resulting from the reduction in the confinement strength of collective electrons by the Lorentz force, is stronger than that with a higher frequency (ω+); (ii) the accurate shift or cyclotron frequency between two magnetoplasmonic modes (ωc = ω+-ω-) is size-dependent, and presents a very large value with implications for the apparent enhancement of the local magnetic-field in the Ag nanoparticles. These results strongly suggest that the Ag-thiolate layer or Ag-S bonding on the nanoparticle surface plays a significant role in the MO enhancement. PMID:27188783

  10. Synthesis and characterisation of metal nanoparticles and their effects on seed germination and seedling growth in commercially important Eruca sativa.

    PubMed

    Zaka, Mehreen; Abbasi, Bilal Haider; Rahman, Latif-Ur; Shah, Afzal; Zia, Muhammad

    2016-06-01

    The synthesis, characterisation and application of metal nanoparticles have become an important and attractive branch of nanotechnology. In current study, metallic nanoparticles of silver, copper, and gold were synthesised using environment friendly method (polyols process), and applied on medicinally important plant: Eruca sativa. Effects of application of these nanoparticles were evaluated on seed germination frequency and biochemical parameters of plant tissues. Seeds of E. sativa were germinated on Murashige and Skoog (MS) medium incorporated with various combinations of nanoparticles suspension (30 µg/ml). Phytotoxicity study showed that nanoparticles could induce stress in plants by manipulating the endogenous mechanisms. In response to these stresses, plants release various defensive compounds; known as antioxidant secondary metabolites. These plants derived secondary metabolites having a great potential in treating the common human ailments. In the authors study, small-sized nanoparticles showed higher toxicity levels and enhanced secondary metabolites production, total protein content, total flavonoids content and total phenolics content.

  11. Synthesis and characterisation of metal nanoparticles and their effects on seed germination and seedling growth in commercially important Eruca sativa.

    PubMed

    Zaka, Mehreen; Abbasi, Bilal Haider; Rahman, Latif-Ur; Shah, Afzal; Zia, Muhammad

    2016-06-01

    The synthesis, characterisation and application of metal nanoparticles have become an important and attractive branch of nanotechnology. In current study, metallic nanoparticles of silver, copper, and gold were synthesised using environment friendly method (polyols process), and applied on medicinally important plant: Eruca sativa. Effects of application of these nanoparticles were evaluated on seed germination frequency and biochemical parameters of plant tissues. Seeds of E. sativa were germinated on Murashige and Skoog (MS) medium incorporated with various combinations of nanoparticles suspension (30 µg/ml). Phytotoxicity study showed that nanoparticles could induce stress in plants by manipulating the endogenous mechanisms. In response to these stresses, plants release various defensive compounds; known as antioxidant secondary metabolites. These plants derived secondary metabolites having a great potential in treating the common human ailments. In the authors study, small-sized nanoparticles showed higher toxicity levels and enhanced secondary metabolites production, total protein content, total flavonoids content and total phenolics content. PMID:27256893

  12. Synthesis of early transition metal and non-equilibrium intermetallic nanoparticles using n-butyllithium

    NASA Astrophysics Data System (ADS)

    Bondi, James F.

    Over the past decade, the role of inorganic nanomaterials has become an essential cornerstone for modern research applications. Despite these applications becoming progressively more advanced, the field of nanoscience is dependent on a material's physical and chemical properties which are affected by factors such as size, shape, composition, and crystal structure. One synthetic approach to yield inorganic nanomaterials with great control is solution-based methods, particularly the reduction of metal salt precursors. Non-equilibrium phases and early transition metals represent one class of materials that may result in new and enhanced properties at the nanoscale but are challenging to synthesize. In this dissertation, I present my studies on synthesizing non-equilibrium intermetallics and early transition metal nanoparticles using n-butyllithium and solution-based methods. By utilizing a template-driven approach, I first report an optimized synthesis for the non-equilibrium L12-type Au 3M1-x ( M = Fe, Co, or Ni) intermetallics with morphological, compositional, and structural control. Modifying a previous n-butyllithium procedure, it was possible to identify key variables (solvent, order of reagent addition, stabilizer, and heating rate) which led to the generation of high phase purity and increased sample sizes. Aliquot studies showed that the intermetallic nanoparticles were formed through the initial nucleation of Au nanoparticles, followed by subsequent incorporation of the 3d transition metal. Property studies of the non-equilibrium phases found that Au3Fe1- x and Au3Co1-x nanoparticles are superparamagnetic with TB = 7.9 K and 2.4 K, respectively, while Au3Ni 1-x is weakly paramagnetic down to 1.8 K. Elemental analysis by energy dispersive X-ray spectroscopy and refinement of electron diffraction patterns confirmed Au3Fe1- x with a composition of approximately Au3Fe 0.7. The 3d transition metal deficiency in the non-equilibrium Au3 M1-x phases was studied by

  13. Metal nanoparticles enhanced optical absorption in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Xie, Wanlu; Liu, Fang; Qu, Di; Xu, Qi; Huang, Yidong

    2011-12-01

    The plasmonic enhanced absorption for thin film solar cells with silver nanoparticles (NPs) deposited on top of the amorphous silicon film (a-Si:H) solar cells and embedded inside the active layer of organic solar cells (OSCs) has been simulated and analyzed. Obvious optical absorption enhancement is obtained not only at vertical incidence but also at oblique incidence. By properly adjusting the period and size of NPs, an increased absorption enhancement of about 120% and 140% is obtained for a-Si:H solar cells and OSCs, respectively.

  14. Supported metal nanoparticles for the remediation of chlorinated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Schrick, Bettina

    Zero valent iron filings are currently being used in pilot scale field studies to dehalogenate toxic chlorinated hydrocarbons from contaminated surface- and groundwater. Iron filings reduce trichloroethylene (TCE), a model contaminant, via two interconnected degradation pathways: (a) reductive beta-elimination and (b) sequential hydrogenolysis, in which each chlorine atom is sequentially replaced by hydrogen. For the latter pathway, problems arise because the dehalogenation rate decreases as the number of chlorine atoms in the molecule decreases. Therefore, some of the products formed, such as vinyl chloride (VC), are more toxic than the parent compound (TCE), and are only slowly reduced by iron. To improve the rate, cost and technique of remediation for chlorinated hydrocarbons, zero valent nickel-iron (Ni-Fe) nanoparticles have been developed. To elucidate the dehalogenation reaction and particularly the product distributions from a mechanistic standpoint, the roles that nickel and iron play in the dehalogenation of TCE were studied. On the bimetallic particles, the reaction occurs by nickel-catalyzed hydrodechlorination. As the iron actively corrodes, the cathodically protected nickel surface chemisorbs hydrogen ions, and TCE adsorbed to the Ni surface is thus hydrogenated. This reaction competes kinetically with the evolution of molecular hydrogen. Hydrogenolysis of the C-Cl bond results in the formation of linear, as well as branched saturated and unsaturated hydrocarbons. Dispersing the nanometals onto high surface area supports, such as hydrophilic carbon or polyacrylic acid (PAA), provides a delivery vehicle for the reactive nanoparticles. The support acts as a nanometal carrier, and may also help preconcentrate the toxins, and provide a conductive pathway for electron transfer. In general, supports are expected to stabilize the nanoparticles and give an increased surface to volume ratio. The carbon- and PAA-supported nanometals form a permanent suspension

  15. Micro Continuous-Flow Synthesis of Metal Nanoparticles Using Micro Fluid Segment Technology

    NASA Astrophysics Data System (ADS)

    Knauer, Andrea; Köhler, J. Michael

    The micro segmented flow technique is very promising for the synthesis of metal nanoparticles, in particular for plasmonic nanoparticles and is very useful for combinatorial syntheses and screenings of new types of nanomaterials. In this chapter, the specific properties and technical as well as scientific challenges related to metal nanoparticles, the advantages of micro segmented flow and draw-backs of conventional synthesis for metal nanoparticles as well as the general applicability and the potential for the application of micro segmented flow for the preparation of metal and semiconductor nanoparticles are discussed. The specific conditions of micro segmented flow are described relating to the critical steps of reactant mixing, nucleation, and particle growth. It is shown that the intensification of local transport in the microfluidic system causes a significant improvement in particle homogeneity. In the formation and handling of metal particles, aspects of redox reactions, electrochemical parameters, and aspects of coordination chemistry have to be reconsidered. Ligands, which are able to interact with the metal ions in solution or with the forming nanoparticles, have a strong effect on the particle formation, their transport behavior, and interaction. The effect of fast reactant mixing supported by intensive segment-internal convection due to high flow rates is used in order to obtain uniform conditions for nucleation as well as for the particle growth. It is explained why non-spherical particles are of particular interest for different applications and how their quality can be improved by the application of microfluidic synthesis techniques, too. The formation of silver prisms by a micro continuous-flow synthesis in micro fluid segments will be given as a typical example allowing the tuning of the optical properties of the colloidal solutions. Finally, it is demonstrated that the micro segmented flow technique is well suited for an automated variation of

  16. The formation of silver metal nanoparticles by ion implantation in silicate glasses

    NASA Astrophysics Data System (ADS)

    Vytykacova, S.; Svecova, B.; Nekvindova, P.; Spirkova, J.; Mackova, A.; Miksova, R.; Böttger, R.

    2016-03-01

    It has been shown that glasses containing silver metal nanoparticles are promising photonics materials for the fabrication of all-optical components. The resulting optical properties of the nanocomposite glasses depend on the composition and structure of the glass, as well as on the type of metal ion implanted and the experimental procedures involved. The main aim of this article was to study the influence of the conditions of the ion implantation and the composition of the glass on the formation of metal nanoparticles in such glasses. Four various types of silicate glasses were implanted with Ag+ ions with different energy (330 keV, 1.2 MeV and 1.7 MeV), with the fluence being kept constant (1 × 1016 ions cm-2). The as-implanted samples were annealed at 600 °C for 1 h. The samples were characterised in terms of: the nucleation of metal nanoparticles (linear optical absorption), the migration of silver through the glass matrix during the implantation and post-implantation annealing (Rutherford backscattering spectroscopy), and the oxidation state of silver (photoluminescence in the visible region).

  17. Preparation of Magnesium, Cobalt and Nickel Ferrite Nanoparticles from Metal Oxides using Deep Eutectic Solvents.

    PubMed

    Söldner, Anika; Zach, Julia; Iwanow, Melanie; Gärtner, Tobias; Schlosser, Marc; Pfitzner, Arno; König, Burkhard

    2016-09-01

    Natural deep eutectic solvents (DESs) dissolve simple metal oxides and are used as a reaction medium to synthesize spinel-type ferrite nanoparticles MFe2 O4 (M=Mg, Zn, Co, Ni). The best results for phase-pure spinel ferrites are obtained with the DES consisting of choline chloride (ChCl) and maleic acid. By employing DESs, the reactions proceed at much lower temperatures than usual for the respective solid-phase reactions of the metal oxides and at the same temperatures as synthesis with comparable calcination processes using metal salts. The method therefore reduces the overall required energy for the nanoparticle synthesis. Thermogravimetric analysis shows that the thermolysis process of the eutectic melts in air occurs in one major step. The phase-pure spinel-type ferrite particles are thoroughly characterized by X-ray diffraction, diffuse-reflectance UV/Vis spectroscopy, and scanning electron microscopy. The properties of the obtained nanoparticles are shown to be comparable to those obtained by other methods, illustrating the potential of natural DESs for processing metal oxides. PMID:27514793

  18. Preparation of Magnesium, Cobalt and Nickel Ferrite Nanoparticles from Metal Oxides using Deep Eutectic Solvents.

    PubMed

    Söldner, Anika; Zach, Julia; Iwanow, Melanie; Gärtner, Tobias; Schlosser, Marc; Pfitzner, Arno; König, Burkhard

    2016-09-01

    Natural deep eutectic solvents (DESs) dissolve simple metal oxides and are used as a reaction medium to synthesize spinel-type ferrite nanoparticles MFe2 O4 (M=Mg, Zn, Co, Ni). The best results for phase-pure spinel ferrites are obtained with the DES consisting of choline chloride (ChCl) and maleic acid. By employing DESs, the reactions proceed at much lower temperatures than usual for the respective solid-phase reactions of the metal oxides and at the same temperatures as synthesis with comparable calcination processes using metal salts. The method therefore reduces the overall required energy for the nanoparticle synthesis. Thermogravimetric analysis shows that the thermolysis process of the eutectic melts in air occurs in one major step. The phase-pure spinel-type ferrite particles are thoroughly characterized by X-ray diffraction, diffuse-reflectance UV/Vis spectroscopy, and scanning electron microscopy. The properties of the obtained nanoparticles are shown to be comparable to those obtained by other methods, illustrating the potential of natural DESs for processing metal oxides.

  19. Two distinctive energy migration pathways of monolayer molecules on metal nanoparticle surfaces

    PubMed Central

    Li, Jiebo; Qian, Huifeng; Chen, Hailong; Zhao, Zhun; Yuan, Kaijun; Chen, Guangxu; Miranda, Andrea; Guo, Xunmin; Chen, Yajing; Zheng, Nanfeng; Wong, Michael S.; Zheng, Junrong

    2016-01-01

    Energy migrations at metal nanomaterial surfaces are fundamentally important to heterogeneous reactions. Here we report two distinctive energy migration pathways of monolayer adsorbate molecules on differently sized metal nanoparticle surfaces investigated with ultrafast vibrational spectroscopy. On a 5 nm platinum particle, within a few picoseconds the vibrational energy of a carbon monoxide adsorbate rapidly dissipates into the particle through electron/hole pair excitations, generating heat that quickly migrates on surface. In contrast, the lack of vibration-electron coupling on approximately 1 nm particles results in vibrational energy migration among adsorbates that occurs on a twenty times slower timescale. Further investigations reveal that the rapid carbon monoxide energy relaxation is also affected by the adsorption sites and the nature of the metal but to a lesser extent. These findings reflect the dependence of electron/vibration coupling on the metallic nature, size and surface site of nanoparticles and its significance in mediating energy relaxations and migrations on nanoparticle surfaces. PMID:26883665

  20. Metal and nanoparticle occurrence in biosolid-amended soils.

    PubMed

    Yang, Yu; Wang, Yifei; Westerhoff, Paul; Hristovski, Kiril; Jin, Virginia L; Johnson, Mari-Vaughn V; Arnold, Jeffrey G

    2014-07-01

    Metals can accumulate in soils amended with biosolids in which metals have been concentrated during wastewater treatment. The goal of this study is to inspect agricultural sites with long-term biosolid application for a suite of regulated and unregulated metals, including some potentially present as commonly used engineered nanomaterials (ENMs). Sampling occurred in fields at a municipal and a privately operated biosolid recycling facilities in Texas. Depth profiles of various metals were developed for control soils without biosolid amendment and soils with different rates of biosolid application (6.6 to 74 dry tons per hectare per year) over 5 to 25 years. Regulated metals of known toxicity, including chromium, copper, cadmium, lead, and zinc, had higher concentrations in the upper layer of biosolid-amended soils (top 0-30 cm or 0-15 cm) than in control soils. The depth profiles of unregulated metals (antimony, hafnium, molybdenum, niobium, gold, silver, tantalum, tin, tungsten, and zirconium) indicate higher concentrations in the 0-30 cm soil increment than in the 70-100 cm soil increment, indicating low vertical mobility after entering the soils. Titanium-containing particles between 50 nm and 250 nm in diameter were identified in soil by transmission electron microscopy (TEM) coupled with energy dispersive x-ray spectroscopy (EDX) analysis. In conjunction with other studies, this research shows the potential for nanomaterials used in society that enter the sewer system to be removed at municipal biological wastewater treatment plants and accumulate in agricultural fields. The metal concentrations observed herein could be used as representative exposure levels for eco-toxicological studies in these soils. PMID:24742554

  1. Enhancement of light absorption in polyazomethines due to plasmon excitation on randomly distributed metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Wróbel, P.; Antosiewicz, T. J.; Stefaniuk, T.; Ciesielski, A.; Iwan, A.; Wronkowska, A. A.; Wronkowski, A.; Szoplik, T.

    2015-05-01

    In photovoltaic devices, metal nanoparticles embedded in a semiconductor layer allow the enhancement of solar-toelectric energy conversion efficiency due to enhanced light absorption via a prolonged optical path, enhanced electric fields near the metallic inclusions, direct injection of hot electrons, or local heating. Here we pursue the first two avenues. In the first, light scattered at an angle beyond the critical angle for reflection is coupled into the semiconductor layer and confined within such planar waveguide up to possible exciton generation. In the second, light is trapped by the excitation of localized surface plasmons on metal nanoparticles leading to enhanced near-field plasmon-exciton coupling at the peak of the plasmon resonance. We report on results of a numerical experiment on light absorption in polymer- (fullerene derivative) blends, using the 3D FDTD method, where exact optical parameters of the materials involved are taken from our recent measurements. In simulations we investigate light absorption in randomly distributed metal nanoparticles dispersed in polyazomethine-(fullerene derivative) blends, which serve as active layers in bulkheterojunction polymer solar cells. In the study Ag and Al nanoparticles of different diameters and fill factors are diffused in two air-stable aromatic polyazomethines with different chemical structures (abbreviated S9POF and S15POF) mixed with phenyl-C61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The mixtures are spin coated on a 100 nm thick Al layer deposited on a fused silica substrate. Optical constants of the active layers are taken from spectroscopic ellipsometry and reflectance measurements using a rotating analyzer type ellipsometer with auto-retarder performed in the wavelength range from 225 nm to 2200 nm. The permittivities of Ag and Al particles of diameters from 20 to 60 nm are assumed to be equal to those measured on 100 to 200 nm thick metal films.

  2. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications

    NASA Astrophysics Data System (ADS)

    He, Jie; Liu, Yijing; Hood, Taylor C.; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-05-01

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  3. Asymmetric organic/metal(oxide) hybrid nanoparticles: synthesis and applications.

    PubMed

    He, Jie; Liu, Yijing; Hood, Taylor C; Zhang, Peng; Gong, Jinlong; Nie, Zhihong

    2013-06-21

    Asymmetric particles (APs) with broken centrosymmetry are of great interest, due to the asymmetric surface properties and diverse functionalities. In particular, organic/metal(oxide) APs naturally combine the significantly different and complementary properties of organic and inorganic species, leading to their unique applications in various fields. In this review article, we highlighted recent advances in the synthesis and applications of organic/metal(oxide) APs. This type of APs is grounded on chemical or physical interactions between metal(oxide) NPs and organic small molecular or polymeric ligands. The synthetic methodologies were summarized in three categories, including the selective surface modifications, phase separation of mixed ligands on the surface of metal(oxide) NPs, and direct synthesis of APs. We further discussed the unique applications of organic/metal(oxide) APs in self-assembly, sensors, catalysis, and biomedicine, as a result of the distinctions between asymmetrically distributed organic and inorganic components. Finally, challenges and future directions are discussed in an outlook section.

  4. Preparation of Chitosan/Polystyrene Sulfonate Multilayered Composite Metal Nanoparticles and Its Application.

    PubMed

    Xiong, Fangxin; Chen, Chunxiao; Liu, Shantang

    2016-06-01

    Metal-Chitosan (CTS) composite was first synthesized through the metal composition of chitosan (CTS) and metal ions. The formed composite was alternately deposited on the base with sodium polystyrene sulfonate (PSS) through a layer-by-layer self-assembling technique, followed by an in situ reduction by sodium borohydride to produce a polyelectrolyte nanocomposite thin film containing metal nanoparticles. Assembly, surface morphology and electrochemical properties of the composite membrane were analyzed by UV-visible absorption spectroscopy (UV-vis), atomic force microscopy (AFM) and cyclic voltammetry (CV). The UV-Vis results indicated that the absorbance of the multilayer film at the characteristic absorption peak increased as the membrane bilayers increased, in a good linear relationship, which demonstrated that the multilayer film was uniformly assembled on the base. AFM images showed that the surface of the multilayer thin-film composite had some degree of roughness and metal nanoparticles of 10-20 nm in size were generated on the membrane. The CV results indicated that the metal nanocomposite film had excellent electrocatalytic activity to glucose and had a potential for applications in electrochemical sensors.

  5. Preparation of Chitosan/Polystyrene Sulfonate Multilayered Composite Metal Nanoparticles and Its Application.

    PubMed

    Xiong, Fangxin; Chen, Chunxiao; Liu, Shantang

    2016-06-01

    Metal-Chitosan (CTS) composite was first synthesized through the metal composition of chitosan (CTS) and metal ions. The formed composite was alternately deposited on the base with sodium polystyrene sulfonate (PSS) through a layer-by-layer self-assembling technique, followed by an in situ reduction by sodium borohydride to produce a polyelectrolyte nanocomposite thin film containing metal nanoparticles. Assembly, surface morphology and electrochemical properties of the composite membrane were analyzed by UV-visible absorption spectroscopy (UV-vis), atomic force microscopy (AFM) and cyclic voltammetry (CV). The UV-Vis results indicated that the absorbance of the multilayer film at the characteristic absorption peak increased as the membrane bilayers increased, in a good linear relationship, which demonstrated that the multilayer film was uniformly assembled on the base. AFM images showed that the surface of the multilayer thin-film composite had some degree of roughness and metal nanoparticles of 10-20 nm in size were generated on the membrane. The CV results indicated that the metal nanocomposite film had excellent electrocatalytic activity to glucose and had a potential for applications in electrochemical sensors. PMID:27427666

  6. Metallic nickel nanoparticles and their effect on the embryonic development of the sea urchin Paracentrotus lividus.

    PubMed

    Kanold, Julia Maxi; Wang, Jiabin; Brümmer, Franz; Šiller, Lidija

    2016-05-01

    The presence of nanoparticles in many industrial applications and daily products is making it nowadays crucial to assess their impact when exposed to the environment. Metallic nickel nanoparticles (Ni NPs) are of high industrial interest due to their ability to catalyze the reversible hydration of CO2 to carbonic acid at ambient conditions. We characterized metallic Ni NPs by XRD, HRTEM and EDS and determined the solubility of free nickel ions from 3 mg/L metallic Ni NPs in seawater by ICP-MS over 96 h, which was below 3%. Further, embryonic development of the sea urchin Paracentrotus lividus was investigated for 48 h in the presence of metallic Ni NPs (0.03 mg/L to 3 mg/L), but no lethal effects were observed. However, 3 mg/L metallic Ni NPs caused a size reduction similar to 1.2 mg/L NiCl2*6 H2O. The obtained results contribute to current studies on metallic Ni NPs and point to their consequences for the marine ecosystem. PMID:26849528

  7. Beet juice utilization: Expeditious green synthesis of nobel metal nanoparticles (Ag, Au, Pt, and Pd) using microwaves

    EPA Science Inventory

    Metal nanoparticles of Ag, Au, Pt, and Pd were prepared in aqueous solutions via a rapid microwave-assisted green method using beet juice, an abundant sugar-rich agricultural produce, served as both a reducing and a capping reagent. The Ag nanoparticles with capping prepared by b...

  8. Engineering photonic-plasmonic coupling in metal nanoparticle necklaces.

    PubMed

    Pasquale, Alyssa J; Reinhard, Björn M; Dal Negro, Luca

    2011-08-23

    In this paper, by combining three-dimensional finite-difference time-domain simulations, dark-field scattering analysis, and surface-enhanced Raman spectroscopy (SERS) we systematically investigate the light-scattering and field localization properties of circular loops of closely spaced gold nanoparticles, or "nanoplasmonic necklaces", fabricated by electron-beam lithography on quartz substrates. In particular, we show that nanoplasmonic necklaces support two hybridized dipolar scattering resonances with polarization-controlled subwavelength localized fields (i.e., electromagnetic hot-spots), whose intensities are optimized by varying the necklace particle diameter and the particle number. Moreover, we show that strong field intensity enhancement is obtained for the particular necklace diameters where loop-localized photonic resonances efficiently couple to the broadband plasmonic modes, enabling a simple design strategy for the optimization of electromagnetic near-fields. Following the proposed approach, we design nanoplasmonic necklaces supporting stronger field intensity enhancement than traditional nanoparticle monomer and dimer arrays. Finally, by performing SERS experiments on nanoplasmonic necklaces coated with a pMA molecular monolayer, we validate the optimization of their near-field properties and demonstrate their potential for plasmon-enhanced spectroscopy and sensing. PMID:21739951

  9. Chemical sensitivity of graphene edges decorated with metal nanoparticles.

    PubMed

    Vedala, Harindra; Sorescu, Dan C; Kotchey, Gregg P; Star, Alexander

    2011-06-01

    Graphene is a novel two-dimensional nanomaterial that holds great potential in electronic and sensor applications. By etching the edges to form nanoribbons or introducing defects on the basal plane, it has been demonstrated that the physical and chemical properties of graphene can be drastically altered. However, the lithographic or chemical techniques required to reliably produce such nanoribbons remain challenging. Here, we report the fabrication of nanosensors based on holey reduced graphene oxide (hRGO), which can be visualized as interconnected graphene nanoribbons. In our method, enzymatic oxidation generated holes within the basal plane of graphene oxide, and after reduction with hydrazine, hRGO was formed. When decorated with Pt nanoparticles, hRGO exhibited a large and selective electronic response toward hydrogen gas. By combining experimental results and theoretical modeling, we propose that the increased edge-to-plane ratio, oxygen moieties, and Pt nanoparticle decoration were responsible for the observed gas sensing with hRGO nanostructures. PMID:21591652

  10. Homogenous metallic nanoparticle monolayer inside a microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Schröder, Kerstin; Csáki, Andrea; Schwuchow, Anka; Latka, Ines; Strehlau, Katharina; Henkel, Thomas; Malsch, Daniell; Schuster, Kay; Weber, Karina; Möller, Robert; Fritzsche, Wolfgang; Bartelt, Hartmut

    2011-05-01

    Microstructured optical fibers (MOFs) represent a promising platform technology for new biosensing devices. Using MOFs with adapted cavity diameters of about 20 to 30 μm, they can be used to carry the biofluids of analytical interest. Such cavities with their walls coated by transducer material form in combination with adequate microfluidic chips a platform for fully integrated next generation plasmonic devices. This paper describes the use of a dynamic chemical nanoparticle layer deposition (NLD) technique to demonstrate the wet chemical deposition of gold and silver nanoparticles (NP) within MOFs with longitudinal, homogenously-distributed particle densities. The plasmonic structures were realized on the internal capillary walls of a three-hole suspended core fiber. Electron micrographs, taken of the inside of the fiber holes, confirm the even distribution of the NP. With the proposed procedure fiber lengths of several meters can be coated and afterwards cut up into small pieces of desired lengths. Accordingly, this procedure is highly productive and makes the resulting MOF-based sensors potentially cost efficient. In proof-of-principle experiments with liquids of different refractive indices, the dependence of the localized surface plasmon resonance (LSPR) on the surroundings was confirmed. Comparing Raman spectra of NP coated and uncoated MOFs, each filled with crystal violet, a significant signal enhancement demonstrates the usability of such functionalized MOFs for surfaceenhanced Raman spectroscopy (SERS) experiments.

  11. Plasmonic channel waveguides in random arrays of metallic nanoparticles.

    PubMed

    Pisano, Eduardo; Coello, Victor; Garcia-Ortiz, Cesar E; Chen, Yiting; Beermann, Jonas; Bozhevolnyi, Sergey I

    2016-07-25

    We report detailed characterization of surface plasmon-polariton guiding along 1-, 1.5- and 2-μm-wide channels in high-density (~75 μm-2) random arrays of gold 70-nm-high and 50-nm-wide nanoparticles fabricated on a 70-nm-thin gold film supported by a 170-μm-thick silica substrate. The mode propagation losses, effective index dispersion, and scattering parameters are characterized using leakage-radiation microscopy, in direct and Fourier planes, in the wavelength range of 740-840 nm. It is found that the mode supported by 2-μm-wide channels propagates over > 10 μm in straight waveguides, with the corresponding S-bends and Y-splitters functioning reasonably well. The results show that the SPP waves can efficiently be guided by narrow scattering-free channels cut through randomly corrugated surface regions. The potential of this waveguiding mechanism is yet to be fully explored by tuning the scattering mean-free path and localization length via the density and size of random nanoparticles. Nevertheless, the results obtained are encouraging and promising diverse applications of these waveguide components in plasmonic circuitry. PMID:27464159

  12. Photochemical Fixation of Individual Polymer Nanoparticles on Glass Substrates in Solution at Room Temperature

    NASA Astrophysics Data System (ADS)

    Ito, Syoji; Yoshikawa, Hiroyuki; Masuhara, Hiroshi

    2004-07-01

    A new method for fixing single polymer nanoparticles onto a substrate was developed by local photopolymerization. A nanoparticle, dispersed in ethylene glycol containing monomer, crosslinker, and radical photoinitiator, was moved to the surface of a glass substrate using a focused near-infrared laser beam. Local photopolymerization around the nanoparticle was induced by additional irradiation of an ultraviolet pulsed laser beam, resulting in the generation of an acrylamide gel containing the nanoparticle on the substrate. The nanoparticles become fixed and remained after washing. The morphology of the formed polymerized gel was evaluated by atomic force microscope (AFM) observation.

  13. Resistive Switching of Individual, Chemically Synthesized TiO2 Nanoparticles.

    PubMed

    Schmidt, Dirk Oliver; Hoffmann-Eifert, Susanne; Zhang, Hehe; La Torre, Camilla; Besmehn, Astrid; Noyong, Michael; Waser, Rainer; Simon, Ulrich

    2015-12-22

    Resistively switching devices are considered promising for next-generation nonvolatile random-access memories. Today, such memories are fabricated by means of "top-down approaches" applying thin films sandwiched between nanoscaled electrodes. In contrast, this work presents a "bottom-up approach" disclosing for the first time the resistive switching (RS) of individual TiO2 nanoparticles (NPs). The NPs, which have sizes of 80 and 350 nm, respectively, are obtained by wet chemical synthesis and thermally treated under oxidizing or vacuum conditions for crystallization, respectively. These NPs are deposited on a Pt/Ir bottom electrode and individual NPs are electrically characterized by means of a nanomanipulator system in situ, in a scanning electron microscope. While amorphous NPs and calcined NPs reveal no switching hysteresis, a very interesting behavior is found for the vacuum-annealed, crystalline TiO(2-x) NPs. These NPs reveal forming-free RS behavior, dominantly complementary switching (CS) and, to a small degree, bipolar switching (BS) characteristics. In contrast, similarly vacuum-annealed TiO2 thin films grown by atomic layer deposition show standard BS behavior under the same conditions. The interesting CS behavior of the TiO(2-x) NPs is attributed to the formation of a core-shell-like structure by re-oxidation of the reduced NPs as a unique feature.

  14. A review of toxicity and mechanisms of individual and mixtures of heavy metals in the environment.

    PubMed

    Wu, Xiangyang; Cobbina, Samuel J; Mao, Guanghua; Xu, Hai; Zhang, Zhen; Yang, Liuqing

    2016-05-01

    The rational for the study was to review the literature on the toxicity and corresponding mechanisms associated with lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As), individually and as mixtures, in the environment. Heavy metals are ubiquitous and generally persist in the environment, enabling them to biomagnify in the food chain. Living systems most often interact with a cocktail of heavy metals in the environment. Heavy metal exposure to biological systems may lead to oxidation stress which may induce DNA damage, protein modification, lipid peroxidation, and others. In this review, the major mechanism associated with toxicities of individual metals was the generation of reactive oxygen species (ROS). Additionally, toxicities were expressed through depletion of glutathione and bonding to sulfhydryl groups of proteins. Interestingly, a metal like Pb becomes toxic to organisms through the depletion of antioxidants while Cd indirectly generates ROS by its ability to replace iron and copper. ROS generated through exposure to arsenic were associated with many modes of action, and heavy metal mixtures were found to have varied effects on organisms. Many models based on concentration addition (CA) and independent action (IA) have been introduced to help predict toxicities and mechanisms associated with metal mixtures. An integrated model which combines CA and IA was further proposed for evaluating toxicities of non-interactive mixtures. In cases where there are molecular interactions, the toxicogenomic approach was used to predict toxicities. The high-throughput toxicogenomics combines studies in genetics, genome-scale expression, cell and tissue expression, metabolite profiling, and bioinformatics.

  15. Upconverting nanoparticles for the near infrared photoactivation of transition metal complexes: new opportunities and challenges in medicinal inorganic photochemistry.

    PubMed

    Ruggiero, Emmanuel; Alonso-de Castro, Silvia; Habtemariam, Abraha; Salassa, Luca

    2016-08-16

    The article highlights the emergent use of upconverting nanoparticles as tools for the near infrared photoactivation of transition metal complexes, identifying opportunities and challenges of this approach in the context of medicinal inorganic chemistry. PMID:27482656

  16. Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure.

    SciTech Connect

    Somorjai, Gabor A.; Park, Jeong Y.

    2008-04-05

    Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O{double_bond}O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

  17. Probing elasticity at the nanoscale: Terahertz acoustic vibration of small metal nanoparticles.

    PubMed

    Juvé, Vincent; Crut, Aurélien; Maioli, Paolo; Pellarin, Michel; Broyer, Michel; Del Fatti, Natalia; Vallée, Fabrice

    2010-05-12

    The acoustic response of surface-controlled metal (Pt) nanoparticles is investigated in the small size range, between 1.3 and 3 nm (i.e., 75-950 atoms), using time-resolved spectroscopy. Acoustic vibration of the nanoparticles is demonstrated, with frequencies ranging from 1.1 to 2.6 THz, opening the way to the development of THz acoustic resonators. The frequencies, measured with a noncontact optical method, are in excellent agreement with the prediction of a macroscopic approach based on the continuous elastic model, together with the bulk material elastic constants. This demonstrates the validity of this model at the nanoscale and the weak impact of size reduction on the elastic properties of a material, even for nanoparticles formed by less than 100 atoms.

  18. Antimicrobial precious-metal nanoparticles and their use in novel materials.

    PubMed

    Senior, Katharina; Müller, Stefanie; Schacht, Veronika J; Bunge, Michael

    2012-12-01

    Nanotechnology offers powerful new approaches to controlling unwanted microorganisms and other potential biohazards. Engineered nanoparticles with antifungal, antimicrobial, and antiviral properties are now being developed for a variety of applications, including manufacture and maintenance of sterile surfaces, prevention and control of biological contamination, food and water safety, and treatment of infectious diseases and cancer. The great potential of antimicrobial precious-metal nanoparticles is reflected by the high number of recent publications and patent applications, which is summarized, at least in part, in this paper. This review should provide an overview and offer guidance to the scientific community interested in nano(bio)technology, nanomedicine, and nanotoxicology, and may also be of interest to a broader scientific audience. Furthermore, this review covers specific topics in research and development addressing the effects of nanoparticles on microorganisms as well as novel nanotechnology-based approaches for controlling potentially pathogenic microorganisms.

  19. A study of shape optimization on the metallic nanoparticles for thin-film solar cells

    PubMed Central

    2013-01-01

    The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm2. Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions. PMID:24168131

  20. Prediction of Surface and pH-Specific Binding of Peptides to Metal and Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Heinz, Hendrik; Lin, Tzu-Jen; Emami, Fateme Sadat; Ramezani-Dakhel, Hadi; Naik, Rajesh; Knecht, Marc; Perry, Carole C.; Huang, Yu

    2015-03-01

    The mechanism of specific peptide adsorption onto metallic and oxidic nanostructures has been elucidated in atomic resolution using novel force fields and surface models in comparison to measurements. As an example, variations in peptide adsorption on Pd and Pt nanoparticles depending on shape, size, and location of peptides on specific bounding facets are explained. Accurate computational predictions of reaction rates in C-C coupling reactions using particle models derived from HE-XRD and PDF data illustrate the utility of computational methods for the rational design of new catalysts. On oxidic nanoparticles such as silica and apatites, it is revealed how changes in pH lead to similarity scores of attracted peptides lower than 20%, supported by appropriate model surfaces and data from adsorption isotherms. The results demonstrate how new computational methods can support the design of nanoparticle carriers for drug release and the understanding of calcification mechanisms in the human body.