Emerging nanozymes for potentiating radiotherapy and radiation protection

While radiotherapy is a mainstay therapeutic modality for malignant tumor, the intrinsic tumor resistance to radiotherapy, as well as the concomitant radiation injury to adjacent healthy tissues, greatly limits the efficacy of cancer radiotherapy. As a result, the development of novel radioenhancers and radioprotectants is highly desired for clinical radiotherapy. In recent years, nanozymes have inspired ever-growing research interest because of their multi-enzyme activities and microenvironment-responsive feature. In view of the significant progress of nanozymes in radiation medicine, we, in this review, systematically illustrate the impressive progress of nanozymes for potentiating radiotherapy and radiation protection. First, the types of nanozymes used in tumor radiotherapy are briefly discussed. Subsequently, the main strategies of nanozymes to enhance the radiotherapy efficiency, including promoting the generation of reactive oxygen species (ROS), relieving hypoxia in tumor microenvironment and combining with other cancer therapeutic regimens, are summarized. Finally, the advances of typical nanozymes for preventing radiation-induced hematopoietic damage and gastrointestinal damage are highlighted.