A pH-switched mesoporous nanoreactor for synergetic therapy

Zinc oxide nanoparticles （ZnO NPs）, as a new type of pH-sensitive drug carrier, have received much attention. ZnO NPs are stable at physiological pH, but can dissolve quickly in the acidic tumor environment （pH 〈 6） to generate cytotoxic zinc ions and reactive oxygen species （ROS）. However, the protein corona usually causes the non-specific degradation of ZnO NPs, which has limited their application considerably. Herein, a new type of pH-sensitive nanoreactor （ZnO-DOX@F-mSiO2-FA）, aimed at reducing the non-specific degradation of ZnO NPs, is presented. In the acidic tumor environment （pH 〈 6）, it can release cytotoxic zinc ions, ROS, and anticancer drugs to kill cancer cells effectively. In addition, the fluorescence emitted from fluorescein isothiocyanate （FITC）-labeled mesoporous silica （F-mSiO2） and doxorubicin （DOX） can be used to monitor the release behavior of the anticancer drug. This report provides a new method to avoid the non-specific degradation of ZnO NPs, resulting in synergetic therapy by taking advantage of ZnO NPs-induced oxidative stress and targeted drug release.