Cancer Cell Membrane-Coated siRNA-Decorated Au/MnO2 Nanosensitizers for Synergistically Enhanced Radio-Immunotherapy of Breast Cancer

ABSTRACT Radiotherapy plays a critical role in the clinical treatment of breast cancer. However, the efficacy of traditional X-ray radiotherapy is greatly limited by its low tumor specificity and treatment tolerance mediated by the tumor microenvironment. Herein, we proposed a novel nano-radiotherapy sensitization strategy to design and construct a cancer cell membrane-coated siRNA-decorated Au/MnO 2 nanosensitizer (R&F@Au/MnO 2 -CM) to synergistically enhance radio-immunotherapy for breast cancer. In the integrated nanosensitizer, the cancer cell membrane (CM) derived from 4T1 breast cancer cells is utilized for targeted functionality, while Au/MnO 2 is designed to improve X-ray absorption and alleviate tumor hypoxia. Additionally, PD-L1 siRNA (R) is used to downregulate PD-L1 expression in tumor cells. In an in situ mouse model of 4T1 breast cancer, R&F@Au/MnO 2 -CM demonstrated accurate tumor identification via CM-mediated homologous targeting after intravenous injection, which was monitored in real-time through NIR-II fluorescence imaging of NIR-935 (F). Subsequently, the radiotherapy sensitivity was achieved due to the strong radiation absorption properties and oxygen generation through catalysis of Au/MnO 2 upon X-ray irradiation. Furthermore, the immunosuppressive microenvironment of the tumor is improved by downregulating PD-L1, enhancing synergistic anti-tumor effect. Our findings demonstrate a promising approach for tumor treatment by combining targeted enhanced radiotherapy with immune activation.