Preparations and properties of a tunable void with shell thickness SiO2@SiO2 core–shell structures via activators generated by electron transfer for atom transfer radical polymerization.

Core–shell structure nanoparticles are attracting considerable attention because of their applications in drug delivery, catalysis carrier, and nanomedicine. In this study, SiO 2 @SiO 2 core–shell structure with tunable void and shell thickness was successfully prepared for the first time using SiO 2 -poly(buty acrylate) (PBA)-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) (SiO 2 -PBA- b -PDMAEMA) as the template and tetraethoxysilane (TEOS) as the silica source. An amphiphilic copolymer PBA- b -PDMAEMA was first grafted onto the SiO 2 nanosphere surface through activators regenerated by electron transfer for atom transfer radical polymerization. TEOS was hydrolyzed along with the PDMAEMA chain through hydrogen bonding, and the core–shell structure of SiO 2 @SiO 2 was obtained through calcination to remove the copolymer. The gradient hydrophilicity of the PBA- b -PDMAEMA copolymer template facilitated the hydrolysis of TEOS molecules along the PDMAEMA to PBA segments, thereby tuning the voids between the SiO 2 core and SiO 2 shell, as well as the SiO 2 shell thickness. The voids were about 10–15 nm and the shell thicknesses were about 4–11 nm when adding different amounts of DMAEMA monomer. SiO 2 @SiO 2 core–shell structures with tunable void and shell thickness were employed as supports for the loading and release of doxorubicin hydrochloride (DOX) in PBS (pH 4.0). The samples demonstrated good loading capacity and controlled release rate of DOX. [ABSTRACT FROM AUTHOR]