Role Of Metal Nanoparticles Research Articles

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

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.

Neurological Disorders and Oxidative Toxic Stress: A Role of Metal Nanoparticles

Context: Oxidative stress is a hallmark of many types of neuropathology disorders and underlying mechanism in several neurodegenerative diseases and brain injuries. The CNS is particularly susceptible to oxidative toxic stress (OTS). Reactive oxygen spices are the basic inflammation and neurotoxicity mediators in ischemia/reperfusion injuries. The purpose of the present review is to provide an overview of some nanoparticles (NPs) in developing OTS conditions and neurological disorders. Evidence Acquisition: Here, a nanotechnology approach is evaluated using NPs in human neuronal protection against OTS. It may be wide therapeutic applications in the case of acute and/or chronic neurodegenerative disorders related to OTS. Results: In the brain of mice treated with nanosize TiO 2 , a significant association was found between the ability to induce the production of ROS and metabolic stress in intracellular environments and inflammatory responses in mice brai. The large surface area of AgNPs may efficiently facilitate the radicals generation including ROS in various organs. The production of ROS may cause DNA damage, cellular apoptosis, and activation of the mitogen activated protein kinase (MAPK) pathways which is responsible for regulating many cellular processes. Prolonged and excessive OTS may contribute to the activation of transcription factors and genes responsible for inflammation responses such as NF-κB and AP-1. Furthermore, OTS may contribute to the onset of neurodegenerative diseases. The ability of CuONPs to generate OTS in vitro studies has been demonstrated; however, information on the neurotoxicity of the CuONPs in vivo is low. Conclusions: The NPs-induced OTS may increase the pro-inflammatory responses. On the other hand, administration of antioxidants such as NAC and vitamin C and E prior to exposure to metal NPs significantly decreases OTS conditions.

Surface mediated chiral interactions between cyclodextrins and propranolol enantiomers: a SERS and DFT study.

The nanoparticles mediated enantioselective recognition of propranolol enantiomers through native cyclodextrin complexation has been investigated by using surface-enhanced Raman spectroscopy (SERS). The highly efficient chiral recognition mechanism is based on a synergistic interaction between spherical noble metal nanoparticles, propranolol enantiomers and native cyclodextrins (CDs). Amongst the native cyclodextrins, β-CD has the highest chiral recognition ability for propranolol enantiomers, due to its specific shape and cavity size, thus producing the largest difference between the recorded SERS spectra of the two hosted enantiomers. The molecular interaction mechanism responsible for enantioselectivity was furthermore proven by quantum chemical calculations based on density functional theory (DFT). The theoretical calculations and experimental SER spectra allowed the assignment of functional moieties involved in the chiral recognition mechanism. The most important factors governing the highly efficient chiral probing by SERS are the fundamentally different mechanism of interaction between the R- and S-enantiomers and β-CD and the strength of interaction between the nanoparticle surface and the two propranolol-CD complexes. The role of metallic nanoparticles in the enantioselective recognition process has been experimentally evaluated by using silver and gold nanoparticles as SERS substrates, given their ability to interact differently with the complexes. The viability of this new method for chiral discrimination has been demonstrated for both substrates and could open new avenues for these kinds of applications.

Addition to The Role of Metal Nanoparticles in Influencing Arbuscular Mycorrhizal Fungi Effects on Plant Growth

Addition to The Role of Metal Nanoparticles in Influencing Arbuscular Mycorrhizal Fungi Effects on Plant Growth

Pt and Au/TiO2 photocatalysts for methanol reforming: Role of metal nanoparticles in tuning charge trapping properties and photoefficiency

Metal-loaded TiO2 is, by far, one of the most important class of photocatalysts in hydrogen production through photoreforming of organics and water photosplitting. In this study anatase loaded with Au and Pt nanoparticles (Au/TiO2 and Pt/TiO2) by an impregnation-reduction method was investigated as for morphological, electronic (XPS) and photocatalytic properties in hydrogen production by methanol photoreforming. The electron and hole trapping centers, Ti3+ and O−, respectively, formed under UV–vis irradiation of the photocatalysts, were studied by in situ electron spin resonance (ESR) spectroscopy. The nature of the loaded metal affected both the H2 evolution rate and the distribution of the methanol oxidation products. The better performance of Pt/TiO2 is attributable to the greater ability of Pt with respect to Au to act as electron sink, slowering the recombination of photoproduced electron–hole couples. Direct evidence of this effect was obtained by ESR analysis, showing that the amount of Ti3+ active sites follows the order TiO2>Au/TiO2≫Pt/TiO2, thus confirming easier electron transfer from Ti3+ to Pt, where the H+ reduction to H2 occurs.

The role of metal nanoparticles and nanonetworks in alloy degradation

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.

The Role of Metal Nanoparticles in Remote Release of Encapsulated Materials

Laser mediated remote release of encapsulated fluorescently labeled polymers from nanoengineered polyelectrolyte multilayer capsules containing gold sulfide core/gold shell nanoparticles in their walls is observed in real time on a single capsule level. We have developed a method for measuring the temperature increase and have quantitatively investigated the influence of absorption, size, and surface density of metal nanoparticles using an analytical model. Experimental measurements and numerical simulations agree with the model. The treatment presented in this work is of general nature, and it is applicable to any system where nanoparticles are used as absorbing centers. Potential biomedical applications are highlighted.

The Role of Metal Nanoparticles in the Catalytic Production of Single‐Walled Carbon Nanotubes — A Review

AbstractFor Abstract see ChemInform Abstract in Full Text.