One-pot one-step synthesis of Au@SiO(2) core–shell nanoparticles and their shell-thickness-dependent fluorescent properties

Herein, we report a one-pot one-step method for the preparation of Au@SiO(2) core–shell nanoparticles (NPs) via a facile heating treatment of an alcoholic-aqueous solution of chloroauric acid (HAuCl(4)), 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 HAuCl(4) and TEOS, respectively, which can hardly be achieved by other approaches. The as-prepared Au@SiO(2) 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@SiO(2) core–shell NPs and promotes their potential applications in ultrasensitive analyte detection, theranostics, catalysts and thin-film solar cells.