Original article“One-pot” synthesis of fluorescent Au@SiO2 and SiO2@Au nanoparticles

A class of fluorescent Au@SiO2 and SiO2@Au core-shell fluorescent nanoparticles has been synthesized using microemulsion assisted sol-gel method coupled with photoreduction reaction as an easy, rapid and versatile “one-pot” procedure. In the case of Au@SiO2-RhB (gold nanoparticles core coated with silica-Rhodamine B shell) different silica shell sizes were obtained ranging from 3 to 116 nm, while for RhB-SiO2@Au (Rhodamine B-silica core coated with gold nanoparticles shell) the size of gold shell falls within 3-38 nm interval. The synthesized core-shell nanoparticles have been characterized by a variety of techniques including Dynamic Light Scattering (DLS), High-Resolution Transmission Electron Microscopy (HR-TEM) coupled with Energy-Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and UV-VIS-NIR spectroscopy to confirm the size, shape, stability and topographic structure of the both core-shell nanostructures. The fluorescence enhancement of Rhodamine B (RhB) dye in the presence of gold nanoparticles (AuNPs) was demonstrated for the core-shell nanostructures synthesized in the present study, for different silica or gold shells. These interesting fluorescent core-shell nanoparticles provide ideal candidates for a variety of applications in materials science, biology, catalysis and optical fields.