One-pot one-step synthesis of Au@SiO2 core-shell nanoparticles and their shell-thickness-dependent fluorescent properties

Abstract

Herein, we report a one-pot one-step method for the preparation of Au@SiO2 core-shell nanoparticles (NPs) via a facile heating treatment of an alcoholic-aqueous solution of chloroauric acid (HAuCl4), 2-methylaminoethanol (2-MAE), cetyltrimethylammonimum bromide (CTAB), and tetraethylorthosilicate (TEOS). The size of the Au core and the thickness of the silica shell can be easily controlled by simply adjusting the volume of HAuCl4 and TEOS, respectively, which can hardly be achieved by other approaches. The as-prepared Au@SiO2 core-shell NPs exhibited shell-thickness-dependent fluorescent properties. The optimum fluorescence enhancement of fluorescein isothiocyanate (FITC) was found to occur at a silica shell thickness of 34 nm with an enhancement factor of 5.0. This work provides a new approach for the preparation of Au@SiO2 core-shell NPs and promotes their potential applications in ultrasensitive analyte detection, theranostics, catalysts and thin-film solar cells.