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Metallic Nanoparticles (metallic + nanoparticle)

Distribution by Scientific Domains
Chemistry60%

Selected Abstracts

The zeta potential of surface-functionalized metallic nanorod particles in aqueous solution

ELECTROPHORESIS, Issue 5 2008
George M. Dougherty
Abstract Metallic nanoparticles suspended in aqueous solutions and functionalized with chemical and biological surface coatings are important elements in basic and applied nanoscience research. Many applications require an understanding of the electrokinetic or colloidal properties of such particles. We describe the results of experiments to measure the zeta potential of metallic nanorod particles in aqueous saline solutions, including the effects of pH, ionic strength, metallic composition, and surface functionalization state. Particle substrates tested include gold, silver, and palladium monometallic particles as well as gold/silver bimetallic particles. Surface functionalization conditions included 11-mercaptoundecanoic acid (MUA), mercaptoethanol (ME), and mercaptoethanesulfonic acid (MESA) self-assembled monolayers (SAMs), as well as MUA layers subsequently derivatized with proteins. For comparison, we present zeta potential data for typical charge-stabilized polystyrene particles. We compare experimental zeta potential data with theoretically predicted values for SAM-coated and bimetallic particles. The results of these studies are useful in predicting and controlling the aggregation, adhesion, and transport of functionalized metallic nanoparticles within microfluidic devices and other systems. [source]

Sonoelectrochemical Synthesis of Metallic Aluminum Nanoparticles

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2009
Chinnathambi Mahendiran
Abstract In this paper, we report for the first time on the room-temperature preparation of metallic aluminum nanoparticles by the pulsed sonoelectrochemical method. The prepared nanoparticles were characterized by X-ray diffraction (XRD), high-resolution scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy. TEM analysis shows that the prepared aluminum nanoparticles range from 10 to 20 nm in size. The XRD pattern confirms the formation of metallic aluminum nanoparticles. The results show that the sonoelectrochemical technique is a promising method for the fabrication of air-sensitive metallic nanoparticles that have a high, negative reduction potential.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

One-Pot Preparation of Polymer,Enzyme,Metallic Nanoparticle Composite Films for High-Performance Biosensing of Glucose and Galactose

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Yingchun Fu
Abstract New polymer,enzyme,metallic nanoparticle composite films with a high-load and a high-activity of immobilized enzymes and obvious electrocatalysis/nano-enhancement effects for biosensing of glucose and galactose are designed and prepared by a one-pot chemical pre-synthesis/electropolymerization (CPSE) protocol. Dopamine (DA) as a reductant and a monomer, glucose oxidase (GOx) or galactose oxidase (GaOx) as the enzyme, and HAuCl4 or H2PtCl6 as an oxidant to trigger DA polymerization and the source of metallic nanoparticles, are mixed to yield polymeric bionanocomposites (PBNCs), which are then anchored on the electrode by electropolymerization of the remaining DA monomer. The prepared PBNC material has good biocompatibility, a highly uniform dispersion of the nanoparticles with a narrow size distribution, and high load/activity of the immobilized enzymes, as verified by transmission/scanning electron microscopy and electrochemical quartz crystal microbalance. The thus-prepared enzyme electrodes show a largely improved amperometric biosensing performance, e.g., a very high detection sensitivity (99 or 129,µA cm,2 mM,1 for glucose for Pt PBNCs on bare or platinized Au), a sub-micromolar limit of detection for glucose, and an excellent durability, in comparison with those based on conventional procedures. Also, the PBNC-based enzyme electrodes work well in the second-generation biosensing mode. The proposed one-pot CPSE protocol may be extended to the preparation of many other functionalized PBNCs for wide applications. [source]

Syzygium cumini leaf and seed extract mediated biosynthesis of silver nanoparticles and their characterization

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2010
Vineet Kumar
Abstract BACKGROUND: Plant mediated synthesis of metallic nanoparticles has been studied and reported, however, to date, the biomolecules involved in the synthesis of metallic nanoparticles have not been characterized. This study was therefore undertaken to characterize the biomolecules of Syzygium cumini involved in the synthesis of silver nanoparticles. RESULTS: Synthesis kinetics and morphological characterization of silver nanoparticles (SNP) synthesized using leaf extract (LE) and seed extract (SE) as well as their polar (water) fractions from Syzygium cumini were compared. The polyphenols content and high performance liquid chromatography (HPLC) profile of different fractions revealed good correlation between size and synthesis rate of SNP. SE contains more polyphenols and biochemical constituents than LE and therefore, showed higher synthesis rate and bigger sized SNP. To analyse the nature of biomolecules involved in the synthesis of SNP, LE and SE were fractionated on a polarity basis by solvent,solvent partitioning. Only the water fractions of LE and SE showed potential for SNP synthesis. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis of SNP indicated that all fractions catalyze the synthesis of spherical nanoparticles. The average size of SNP synthesized by LE, leaf water fraction, SE and seed water fraction were 30, 29, 92, and 73 nm respectively. CONCLUSION: Results suggest that only highly polar soluble constituents are responsible for SNP synthesis. The size of SNP was found to be directly correlated with the amount of polyphenols as well as surfactants present in the reaction solution. Thus, the amount of polyphenols could be one of the crucial parameters determining the size and distribution of SNP. Copyright © 2010 Society of Chemical Industry [source]

Surface-enhanced Raman scattering spectroscopy via gold nanostars

JOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2009
E. Nalbant Esenturk
Abstract Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface-enhanced Raman scattering (SERS) spectroscopy. Star-shaped gold (Au) NPs were prepared in aqueous solutions by the seed-mediated growth method and tested for Raman enhancement using 2-mercaptopyridine (2-MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman enhancement factors (EFs) for 2-MPy on Au nanostars and nanorods are comparable and estimated as greater than 5 orders of magnitude. However, the enhancement for CV on nanostars was significantly higher than for nanorods, in particular at CV concentrations of 100 nM or lower. This article is a US Government work and is in the public domain in the USA. Published in 2008 by John Wiley & Sons, Ltd. [source]

Metallic nanoparticle array on GaN by microsphere lithography

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009
Giuseppe Y. Mak
Abstract The optical characteristics of GaN blue-light (peak wavelength at 440 nm) light-emitting diode (LED) under the effect of localized surface plasmon (LSP) have been studied. Hexagonal arrays of triangular metallic nanoparticles deposited through a self-assembled silica microsphere mask have been fabricated using vertical deposition. By comparing the PL spectra of samples coated with Au, Al and Ag nanoparticles, it is found that Ag nanoparticles offer the most pronounced PL enhancement. The resonance wavelength was determined from optical transmission and verified by theoretical calculations. These results provide a cost-effective solution for improving the efficiency of LEDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Carbon-Supported Ruthenium Nanoparticles Stabilized by Methylated Cyclodextrins: A New Family of Heterogeneous Catalysts for the Gas-Phase Hydrogenation of Arenes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2008
Audrey Denicourt-Nowicki Dr.
Cooperation effects: A novel strategy to obtain heterogeneous catalysts for gas-phase hydrogenation has been developed, based on metallic nanoparticles stabilized by methylated cyclodextrins (CDs) and adsorbed onto charcoal. The CDs appear as multifunctional molecular receptors capable of stabilizing and dispersing the metallic particles on the support and modifying the stereoselectivity through host,guest interactions. [source]

Multivalued and Reversible Logic Gates Implemented with Metallic Nanoparticles and Organic Ligands

CHEMPHYSCHEM, Issue 8 2010
Javier Cervera Dr.
It makes perfect sense: Binary and multivalued XOR gates based on metal nanoparticles linked to electrodes by organic ligands are described. The logic scheme makes use of the Coulomb blockade in the metallic nanoparticles and the electron tunneling in the organic ligands. A reversible logic Feynman gate (see picture) can also be implemented. [source]

Carbohydrate-Derived 1,3-Diphosphite Ligands as Chiral Nanoparticle Stabilizers: Promising Catalytic Systems for Asymmetric Hydrogenation

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2009
Aitor Gual Dr.
Abstract Metallic Ru, Rh, and Ir nanoparticles were prepared by the decomposition of organometallic precursors under H2 pressure in the presence of 1,3-diphosphite ligands, derived from carbohydrates, as stabilizing agents. Structural modifications to the diphosphite backbone were found to influence the nanoparticles, size, dispersion, and catalytic activity. In the hydrogenation of o - and m -methylanisole, the Rh nanoparticles showed higher catalytic activity than the corresponding Ru nanoparticles. The Ir nanoparticles presented the lowest catalytic activity of the series. In all cases, the hydrogenation of o -methylanisole gave total selectivity for the cis -product, however, the ee of the product was always less than 6,%. A maximum of 81,% cis -selectivity was obtained for the hydrogenation of m -methylanisole, however, no asymmetric induction was observed. These results show that the catalytic activity is affected by a combination of influences from the substrate, the diphosphite ligands, and the metallic nanoparticles. [source]