Controlled preparation of OS@au/Ag nanoshells with chitosan polyelectrolyte

This paper discusses the effect of two crucial processing parameters (seed size and amount of ion solution) on the controlled seed-and-grow preparation of polystyrene@gold/silver nanoshells with chitosan (CHI) as a surface modifier. Experiments involved synthesizing PS nanospheres and functionalizing them with CHI. Au seeds were then attached onto the CHI-functionalized PS spheres and metal was subsequently deposited onto the PS spheres from metal ion solutions to form PS@metal nanoshells. It is found that Au seed size can have a profound effect on the seed coverage of PS surface and the quality (morphology and optical properties) of nanoshells. Use of smaller-sized seed sizes gives a better seed coverage and good quality nanoshells. Appropriate volumetric amount of K-gold/silver nitrate solution is required for obtaining a complete nanshell with desired shell thickness. These findings are confirmed by the TEM characterization and the UV-vis spectra of light absorption.