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.