Green synthesis of gold-silver core-shell nanoparticles and its characterizations

Core shell nanoparticles have become an interesting topic of research because of their enhanced optical, catalytic and antibacterial property. Several alloy type nanoparticles have been synthesized like gold-silver, silver-gold, gold–silica, silver–silica, gold-platinum etc. In the present study we have demonstrated a new wet chemical route to synthesize gold-silver core shell nanoparticles using a medicinal plant extract, which act both as reducing agent and stabilizing agent. The method is facile and very fast. In the synthesis process, pre–synthesized spherical gold nano particles of 20-30 nm size served as nucleation sites for silver ions that formed coating over the gold core. The synthesized gold nano particles have been characterized by uv-vis spectroscopy, Transmission Electron Microscope (TEM) and zeta-potential analyser.