Flower-Like MnO₂ Nanoparticle-Based Dual GSH-Depleting Nanosystems for Chemo-/Chemodynamic/Sonodynamic Cancer Therapy

Chemodynamic therapy (CDT) generating hydroxyl radicals (•OH) by utilizing metal ions reacting with hydrogen peroxide (H2O2) is a highly encouraging strategy for cancer treatment. However, highly expressed GSH in tumor cells severely limits the efficacy of CDT, and CDT alone is also not sufficient to produce excellent antitumor efficiency. Herein, a dual GSH depletion nanosystem (MnO2@PDA@PEG@DOX) was designed and synthesized to achieve synergistic cancer treatment under ultrasound (US) irritation. To achieve an acidic response, dopamine (DA) was loaded onto manganese dioxide, and the water solubility and stability were greatly improved after PEG modification; finally, the loading of doxorubicin (DOX) achieved the combinational therapy. When the nanoparticles arrived at the tumor site, the acidic and high expression of GSH in the tumor microenvironment prompted the degrading of the nanosystem, followed by the release of MnO2 and DOX. The released MnO2 can react with intracellular GSH to produce Mn2+, which realizes chemodynamic therapy by catalyzing H2O2 to generate highly toxic hydroxyl radicals (•OH) at the tumor site; also, the depletion of GSH will significantly promote the level of •OH, improving the efficiency of CDT simultaneously. Moreover, the release of DOX could be boosted by US irradiation, thus enhancing the effect of chemotherapy on DOX and achieving sonodynamic therapy (SDT). Therefore, strategies to enhance CDT efficiency by dual GSH depletion and combining chemotherapy and sonodynamic therapy modalities can provide more ideas and approaches for combination therapy in cancer treatment.