A pH-Sensitive Glucose Oxidase and Hemin Coordination Micelle for Multi-Enzyme Cascade and Amplified Cancer Chemodynamic Therapy

Chemodynamic therapy (CDT) is an emerging therapeutic paradigm for cancer treatment that utilizes reactive oxygen species (ROS) to induce apoptosis of cancer cells but few biomaterials have been developed to differentiate the cancer cells and normal cells to achieve precise and targeted CDT. Herein, a simple cascade enzyme system is developed, termed hemin-micelles-GOx, based on hemin and glucose oxidase (GOx)-encapsulated Pluronic F127 (F127) micelles with pH-sensitive enzymatic activities. Histidine-tagged GOx can be easily chelated to hemin-F127 micelles via the coordination of histidine and ferrous ions in the center of hemin by simple admixture in an aqueous solution. In tumor microenvironment (TME), hemin-micelles-GOx exhibits enhanced peroxidase (POD)-like activities to generate toxic hydroxyl radicals due to the acidic condition, whereas in normal cells the catalase (CAT)-like, but not POD-like activity is amplified, resulting in the elimination of hydrogen peroxide to generate oxygen. In a murine melanoma model, hemin-micelles-GOx significantly suppresses tumor growth, demonstrating its great potential as a pH-mediated enzymatic switch for tumor management by CDT. A cascade enzyme system with pH-sensitive enzymatic activities is developed using glucose oxidase (GOx) and hemin coordination micelles, termed hemin-micelles-GOx. In the tumor microenvironment, hemin-micelles-GOx shows enhanced POD-like activity for toxic <middle dot>OH generation to kill cancer cells. By contrast, in normal cells hemin-micelles-GOx exhibits enhanced CAT-like activity that converts H2O2 to oxygen. Importantly, hemin-micelles-GOx demonstrates good efficacy for targeted cancer treatment via this chemodynamic cascade strategy. image