Applications Of Metal Nanoparticles Research Articles

Wavelength and Intensity Multiplexing of Metal Nanoparticles for the Fabrication of Multicolored Micro‐ and Nanospheres

AbstractMulticolored micro‐ and nanospheres have been successfully fabricated by a novel method that was developed to broaden the selection of colors available in the application of metal nanoparticles (NPs). The colors of the metal NPs have been systematically tuned over a wide spectral range by wavelength and intensity multiplexing of three‐colored NPs. Multicolor polystyrene micro‐ and nanospheres could be fabricated by combining the systematic color tuning of metal NPs and self‐assembly of metal NPs on the surfaces of the polymer spheres. The agglomeration of metal NPs on the surfaces of polymer spheres could be prevented by optimizing the concentration of the metal NPs and the reaction pH.

金属ナノ粒子の色材への応用

金属ナノ粒子の色材への応用

Anisotropic Metal Nanoparticles: Synthesis, Assembly, and Optical Applications

AbstractFor Abstract see ChemInform Abstract in Full Text.

Anisotropic Metal Nanoparticles: Synthesis, Assembly, and Optical Applications

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.

Environmentally Benign Preparation of Metal Nano‐particles by Using Water‐in‐CO2 Microemulsions Technology

AbstractFor Abstract see ChemInform Abstract in Full Text.

Application of metal nanoparticles in confocal laser scanning microscopy: improved resolution by optical field enhancement

We describe experiments in which the field enhancement by metal nanoparticles that accompanies surface plasmon excitation has been exploited in confocal laser scanning microscopy. The objective was to make use of the rapid decay of the enhanced light field with distance from the nanoparticles to increase the longitudinal resolution, by confining the emission of fluorescence light to the immediate vicinity of the contact area between the substrate and the objects under study. We demonstrate that the increased longitudinal resolution is accompanied by a better lateral resolution if the imaged objects have a curved surface.

Environmentally benign preparation of metal nano-particles by using water-in-CO 2 microemulsions technology

Water-in-CO 2 (W/C) microemulsion technology offers a new environmentally friendly approach for the synthesis of a variety of metal nano-particles in supercritical CO 2 using water-soluble reagents as starting material. W/C microemulsions have unique advantages over conventional water-in-oil (W/O) microemulsions because of the use of environmentally benign, cheap, and recyclable CO 2 as the continuous phase in place of organic solvents. In this review, we will discuss some recent progress on the preparation and applications of metal nano-particles prepared in W/C microemulsions.

Metal-Nanoparticles Based Electroanalysis

A general view of the electroanalytical applications of metal-nanoparticles in the last decade is discussed in this review. The electrocatalytical properties of various metal-nanoparticles, the employment of nanoparticles in electrochemical sensors and the use of colloidal gold as electrochemical label (no other metal nanoparticle was found to act as a label in electrochemistry) are described. Also, a description of the fabrication and electrochemical characterization of metal-nanoparticle modified electrodes is given. Finally, due to its growing importance, semiconductor-nanoparticle modified electrodes are described, although they can not be strictly considered as electroanalytical devices.

Photophysics of Nanometer Sized Metal Particles: Electron−Phonon Coupling and Coherent Excitation of Breathing Vibrational Modes

The wide variety of applications of metal nanoparticles has motivated many studies of their properties. Some important practical issues are how the size, composition and structure of these materials affect their catalytic and optical properties. In this article we review our recent work on the photophysics of metal nanoparticles. The systems that have been investigated include Au particles with sizes ranging from 2 nm diameter (several hundred atoms) to 120 nm diameter, and bimetallic core−shell particles composed of Au, Ag, Pt and/or Pb. These particles, which have a rather narrow size distribution, are prepared by radiolytic techniques. By performing time-resolved laser measurements we have been able to investigate the coupling between the electrons and phonons in the particles, and their low frequency “breathing” modes. These experiments show that for Au the time scale for electron−phonon coupling does not depend on size, in contrast to metals such as Ga and Ag. On the other hand, the frequency of the acoustic breathing modes strongly depends on the size of the particles, as well as their composition. These modes are impulsively excited by the rapid lattice heating that accompanies ultrafast laser excitation. The subsequent coherent nuclear motion modulates the transmitted probe laser intensity, giving a “beat” signal in our experiments. Unlike quantum-beats in molecules or semiconductors, this signal can be completely understood by classical mechanics.

Response inhibition: A stable vulnerability factor in chronic schizophrenia

Modern lifestyle demands high-end commodities, for instance, cosmetics, detergents, shampoos, household cleaning, sanitary items, medicines, and so forth. In recent years, these products' consumption has increased considerably, being antibiotics and some other pharmaceutical and personal care products (PPCPs). Several antibiotics and PPCPs represent a wide range of emerging contaminants with a straight ingress into aquatic systems, given their high persistence in seawater, effluent treatment plants, and even drinking water. Under these considerations, the necessity of developing new and affordable technologies for the treatment and sustainable mitigation of pollutants is highly requisite for a safer and cleaner environment. One possible mitigation solution is an effective deployment of nanotechnological cues as promising matrices that can contribute by attending issues and improving the current strategies to detect, prevent, and mitigate hazardous pollutants in water. Focused on nanoparticles' distinctive physical and chemical properties, such as high surface area, small size, and shape, metallic nanoparticles (MNPs) have been investigated for water remediation. MNPs gained increasing interest among research groups due to their superior efficiency, stability, and high catalyst activity compared with conventional systems. This review summarizes the occurrence of antibiotics and PPCPs and the application of MNPs as pollutant mitigators in the aquatic environment. The work also focuses on transportation fate, toxicity, and current regulations for environmental safety.