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Gold nanoparticles were synthesized by adapting an ecofriendly green method using aloe leaf extract. Aloe leaf extract acts both as stabilizing as well as reducing agent. The microwave method was adopted to prepare gold nanoparticles (GNPs). The formation of GNPs was observed using Ultraviolet surface plasmon resonance (UV-SPR) analysis. Morphology and characterization of GNPs were done by using Field emission scanning electron microscopy (FESEM), High resolution transmission electron microscopy (HRTEM), Fourier transforms infrared spectroscopy (FT-IR), and Energy dispersive x-ray analysis (EDAX) techniques. FESEM and HRTEM analysis showed that the morphology of the obtained GNPs was polygon-shaped. Crystalline nature was studied using X-ray diffraction (XRD) analysis. By applying the Scherrer formula, the average size of the GNPS was estimated to be 6±1nm. The catalytic activity of the prepared nanoparticles was studied by taking methyl red reduction as a model reaction. UV-VIS spectroscopy was used to follow the reaction by observing a change in absorbance with respect to time. The reaction is monitored under pseudo first order kinetics. [ABSTRACT FROM AUTHOR]

In this work, a facile method is proposed to synthesis graphene oxide (GO), reduced graphene oxide (rGO), silver and gold nanoparticles with 1:3 volume ratio decorated onto reduced graphene oxide (Ag1Au3/rGO). A chemical reduction route using sodium citrate as reducing agents have been used to prepared the as-synthesized samples. The produced samples have been characterized using Raman spectroscopy, UV-Visible, X-Ray Diffraction spectroscopy and High Resolution Transmission Electron Microscopy. The removal of oxygen containing groups from the graphene oxide to reduced graphene oxide was confirmed by intensity ratio (ID/IG) between the D and G band appeared at the peak. The change in optical properties of the product authenticated by the shift in the absorption peak and formation of silver and gold nanoparticles was determined by XRD spectroscopy. The morphological results illustrate that silver and gold nanoparticles decorated reduced graphene oxide formed stable dispersions and well distributed on the reduced graphene oxide surface with 10 nm – 40 nm of particle size. [ABSTRACT FROM AUTHOR]

The synthesis of gold nanoparticles using silk sericin (SS) extracted from Bombyx mori silk cocoons is an eco-friendly, low-cost, non-toxic, and facile method. The synthesis of biocompatible gold nanoparticles (AuNPs) by the redox reaction of chloroauric acid (HAuCl4.H2O) with SS is reported here. Synthesized SS-AuNPs were confirmed by the visual recognition of changes in color from pale yellow to pink color, and it was further confirmed by various analytical techniques. UV-visible spectroscopy (UV-vis) confirmed the formation of gold nanoparticles by showing surface plasmon resonance (SPR) strong peak at λ= 520nm. Fourier transmission infrared (FT-IR) spectroscopy reveals the presence of secondary functional groups involved in redox reaction. High resolution transmission electron microscopy (HR-TEM) illustrated the formed AuNPs are spherical in shape with highly crystalline nature. Dynamic light scattering (DLS) study reveals the average particles size and size distribution of the SS-AuNPs present in the solution. [ABSTRACT FROM AUTHOR]

The spatial and spectral characteristics due to localized surface plasmon resonance of individual gold nanorod (NR) have been studied using cathodoluminescence (CL) in a high resolution scanning electron microscope (SEM). Simultaneous determination of morphology and luminescence with spatial resolution down to a few nanometers, from the same area of interest enables us to map different plasmonic modes supported by Au NR. [ABSTRACT FROM AUTHOR]