Synthesis and characterization of gold–silica core-shell nanoparticles

In this paper, the preparation of nanoparticles core-shell of gold-silica was carried out by coating of citrated gold particles using the Stöber method and products were investigated by XRD, uv-visible and TEM. In this method, first the nanoparticles were synthesized and then the silica shell was obtained. The results showed that gold nanoparticles have been successfully synthesized and results of transmission electron microscopy showed a particle size of about 20 nm. Preparation of coated gold particles with silica is successfully performed and the results showed a thickness of the shell in order of about 35 nm. The results of the uv-visible spectroscopy of gold nanoparticles and core-shell structure indicate a strong peak at 520 nm, characteristic plasmon peak of the gold particles. However, this peak is more intense for the core-shell structure, which is due to the scattering effect of silica shell having a resonant impact on the peak intensity.