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Noble Metal Nanoparticles (noble + metal_nanoparticle)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Gold Nanorods: From Synthesis and Properties to Biological and Biomedical Applications

ADVANCED MATERIALS, Issue 48 2009
Xiaohua Huang
Abstract Noble metal nanoparticles are capable of confining resonant photons in such a manner as to induce coherent surface plasmon oscillation of their conduction band electrons, a phenomenon leading to two important properties. Firstly, the confinement of the photon to the nanoparticle's dimensions leads to a large increase in its electromagnetic field and consequently great enhancement of all the nanoparticle's radiative properties, such as absorption and scattering. Moreover, by confining the photon's wavelength to the nanoparticle's small dimensions, there exists enhanced imaging resolving powers, which extend well below the diffraction limit, a property of considerable importance in potential device applications. Secondly, the strongly absorbed light by the nanoparticles is followed by a rapid dephasing of the coherent electron motion in tandem with an equally rapid energy transfer to the lattice, a process integral to the technologically relevant photothermal properties of plasmonic nanoparticles. Of all the possible nanoparticle shapes, gold nanorods are especially intriguing as they offer strong plasmonic fields while exhibiting excellent tunability and biocompatibility. We begin this review of gold nanorods by summarizing their radiative and nonradiative properties. Their various synthetic methods are then outlined with an emphasis on the seed-mediated chemical growth. In particular, we describe nanorod spontaneous self-assembly, chemically driven assembly, and polymer-based alignment. The final section details current studies aimed at applications in the biological and biomedical fields. [source]

Engineering Nanoparticle Cluster Arrays for Bacterial Biosensing: The Role of the Building Block in Multiscale SERS Substrates

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
Linglu Yang
Abstract Noble metal nanoparticle cluster arrays (NCAs) are a novel class of engineered substrates for surface enhanced Raman spectroscopy (SERS), in which the noble metal nanoparticles interact on multiple length scales to create a multiscale E-field cascade enhancement. In this work the role of the building block for the NCA performance is quantified. Periodic NCAs with constant cluster diameter (D = 200 nm) but variable nanoparticle diameter (d) and intercluster separation (,) were assembled on glass and their optical response and SERS enhancement were systematically characterized as a function of D, ,, and d. An increase of d from 40 to 80 nm and simultaneous decrease of , from 200 to 50 nm led to an improvement of the ensemble averaged SERS enhancement factor by a factor of up to ,8. The coefficient of variation (cv) of the enhancement factors (G) is significantly lower for the d = 80 nm NCAs than for the d = 40 nm and d = 60 nm NCAs. Optimized (D = 200 nm, , = 50 nm, d = 80 nm) NCAs show the overall highest signal reproducibility of all investigated NCAs and random nanoparticle substrates and achieve effective single cell detection sensitivity. [source]

Reactive Template Method to Synthesize Gold Nanoparticles with Controllable Size and Morphology Supported on Shells of Polymer Hollow Microspheres and Their Application for Aerobic Alcohol Oxidation in Water

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Jie Han
Abstract A novel method has been developed to synthesize gold nanoparticles with tunable size and morphology supported on both inner and outer surfaces of poly(o -phenylenediamine) (PoPD) hollow microspheres, which act as both reductant and template/stabilizer. The size of gold nanoparticles supported on shells of PoPD hollow microspheres can be tuned from 3 to 15,nm by changing the concentration of the gold source, HAuCl4. Gold nanorods supported on shells of PoPD hollow microspheres can also be fabricated by introducing a well-known seed-growth strategy. In addition, silver nanoparticles supported on shells of PoPD hollow microspheres can also be successfully fabricated using the same strategy, which indicates the diversity of this proposed method for polymer hollow microspheres supporting noble metal nanoparticles. The products are characterized by X-ray diffraction and contact angle analysis. Furthermore, the catalytic activity of the obtained PoPD-microsphere-supported gold nanoparticles for aerobic alcohol oxidation is investigated. The results demonstrate that such polymer-supported gold nanoparticles can be used as reusable catalysts with high catalytic activity for aerobic alcohol oxidation in water. [source]

Nonspherical Noble Metal Nanoparticles: Colloid-Chemical Synthesis and Morphology Control

ADVANCED MATERIALS, Issue 16 2010
Tapan K. Sau
Abstract Metal nanoparticles have been the subject of widespread research over the past two decades. In recent years, noble metals have been the focus of numerous studies involving synthesis, characterization, and applications. Synthesis of an impressive range of noble metal nanoparticles with varied morphologies has been reported. Researchers have made a great progress in learning how to engineer materials on a nanometer length scale that has led to the understanding of the fundamental size- and shape-dependent properties of matter and to devising of new applications. In this article, we review the recent progress in the colloid-chemical synthesis of nonspherical nanoparticles of a few important noble metals (mainly Ag, Au, Pd, and Pt), highlighting the factors that influence the particle morphology and discussing the mechanisms behind the nonspherical shape evolution. The article attempts to present a thorough discussion of the basic principles as well as state-of-the-art morphology control in noble metal nanoparticles. [source]

Palladium Nanostructures: Synthesis and Structural Characterization of Branched Palladium Nanostructures (Adv. Mater.

ADVANCED MATERIALS, Issue 22 2009
22/2009)
The front cover stylizes the formation of a palladium tripod nanoparticle, an unusual morphology for a particle that crystallises in the highly symmetrical face centred cubic crystal structure. Their growth is controlled by introducing both twinning into the nanoparticle nuclei and kinetically controlled growth conditions. Richard Tilley and co-workers provide on p. 2288 insights into the formation of anisotropic noble metal nanoparticles, important for a range of applications. [source]