Silica composite nanoparticles containing fluorescent solid core and mesoporous shell with different thickness as drug carrier.

Nonporous silica transitional approach was employed to create core-shell architectural nanocomposites, which performed particularly well in morphology and controllable synthesis. The silica nanocomposites containing fluorescent solid SiO2 core and mesoporous silica shell (F-nSiO2/mSiO2) presented distinct structures of narrow size distribution, stable and shell thickness independent fluorescence, and high specific surface area. Furthermore, the thickness of mesoporous shell could be precisely tailored by the amount of TEOS and solid SiO2 seeds. Drug delivery study of F-nSiO2/mSiO2 with different mesoporous thicknesses were carried out, and Peppas equation was adopted to demonstrate the controlled releasing mechanism of doxorubicin (DOX). The diffusion rate of DOX from F-nSiO2/mSiO2 nanocomposites depended on the thickness of mesoporous shell and electrostatic interaction between drug and silanol group, which facilitated an enhanced drug releasing activity at pH 5.5 than 7.4. What's more, particles loaded DOX showed similar cytotoxicity compared with pure DOX, while no obvious cytotoxicity of carrier was observed in MTT tests for blank particles. These characteristics mentioned above implied that core/shell structured F-nSiO2/mSiO2 had a great potential for controlled drug delivery system.