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.