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.