Au (III) cross-linked hollow organosilica capsules from 3-aminopropyltriethoxysilane

Hollow organosilica capsules have received extensive interest due to their application potentials in catalyst, sensor, drug delivery etc. In this work, we demonstrate a novel strategy to fabricate hollow organosilica capsules based on coordination interaction, by using 3-aminopropyltriethoxysilane (APTES) as precursor and Au (III) as cross-linker. In this approach, stable APTES droplets are first formed in water with the presence of Au (III) due to the coordination effect between Au (III) and the amino groups of APTES located on the surface of the droplets. Subsequently, the self-catalyzed hydrolysis/condensation of APTES allows for the formation of hollow organosilica capsules, in which the droplets of APTES themselves act as soft template and the Au (III) as cross-linker. The formation mechanism of the capsules was investigated, and potential of the as-prepared Au (III) cross-linked hollow organosilica capsules as glutathione (GSH) sensitive drug carriers was evaluated. In addition, Au particle embedded hollow capsules are further obtained by in-situ reduction of the Au (III) in the shell, which showed excellent stability towards the cyclic catalytic reductions of p-nitroaniline.