Nanozymes as Glucose Scavengers and Oxygenerators for Enhancing Tumor Radiotherapy

Insufficient accumulation of reactive oxygen species (ROS) due to tumor hypoxia significantly contributes to increased radiation resistance and the failure of radiotherapy (RT). Therefore, developing methods to alleviate hypoxia and boost ROS levels represents a promising strategy for enhanced radiosensitivity. This study introduced a self-cascade catalytic Pt@Au nanozymes as a radiosensitizer, using glucose oxidase (GOx)-, catalase (CAT)-, and peroxidase (POD)-like activities to improve hypoxia and increase ROS accumulation, thereby affecting glucose metabolism and enhancing the effects of RT. Pt@Au nanozymes exhibit GOx-like activity, which not only depletes glucose to induce starvation therapy, but also generates hydrogen peroxide (H₂O₂) for cascade reactions. Moreover, Pt@Au nanozymes demonstrate CAT-like activity, catalyzing the conversion of H₂O₂ to O₂. This conversion effectively alleviates hypoxia, stabilizes ROS, increases DNA damage, significantly enhancing RT efficacy and sustaining the effects of starvation therapy. As high-Z materials, Pt@Au nanozymes can deposit more X-ray energy. Furthermore, the POD-like activity catalyzes the conversion of H₂O₂ into highly reactive hydroxyl radicals (·OH), which increases ROS levels and enhances RT. Pt@Au nanozymes serve as X-ray computed tomography (CT) imaging agents, allowing for clear differentiation between tumor and normal tissue boundaries and enhancing the precision of RT. In summary, Pt@Au nanozymes serve as effective radiosensitizers by depleting glucose to induce starvation therapy, enhancing cascade reactions, and inhibiting tumor proliferation. Through their self-cascade reactions, these nanozymes dramatically increase oxygen levels within tumors, reduce hypoxia, and enhance ROS levels. This advancement addresses the radioresistance associated with hypoxic tumors, paving the way for innovative strategies in RT.