Preparation of a new core-shell Ag@SiO2 nanocomposite and its application for fluorescence enhancement

Ag@SiO2 nanoparticles with different shell thicknesses were synthesized via modified Stober method. Rhodamine B isothiocyanate was covalently bound onto the surface of Ag@SiO2 nanoparticles to form fluorescent core-shell Ag@SiO2 nanocomposites. Effects of shell thickness on the fluorescence enhancement were examined using the corresponding nanobubbles prepared by cyanide etching as a control. The result showed that the fluorescence enhanced as the shell thickness increased till the distance between fluorophore and metal core reached about 75 nm with the optimal enhancement factor of similar to 5-folds. Further increasing of fluorophore-metal distance caused a decrease in the enhancement factor. (C) 2010 Elsevier B.V. All rights reserved.