Emerging Bismuth Chalcogenides Based Nanodrugs for Cancer Radiotherapy

Radiotherapy (RT), as one of the main methods of clinical tumor treatment, has been applied to the treatment of most solid tumors. However, the effect of RT is compromised by the radiation resistance of tumor hypoxic environment and non-specific damage caused by high-dose radiation. Bismuth chalcogenides (Bi₂X₃, X = S, Se) based nanodrugs have attracted widespread attention as highly efficient radiosensitizers due to their high photoelectric effect and excellent biocompatibility. More importantly, specially designed nanocomposites can effectively alleviate the radiation resistance of tumor tissues. Here, for the first time, we systematically summarize the latest progresses of Bi₂X₃ nanodrugs to enhance RT by alleviating the hypoxic tumor microenvironment. These emerging Bi₂X₃ nanodrugs mainly include three aspects, which are Bi₂X₃ nanocomposites with high-efficient O₂ supply, non-O₂-dependent Bi₂X₃ nanocomposites RT enhancers, and Bi₂X₃ nanocomposites-based photothermal-enhanced radiosensitizers. These Bi₂X₃ nanodrugs can effectively overcome the RT resistance of tumor hypoxic microenvironment, and have extremely high therapeutic effects and clinical application prospects. Finally, we put forward the challenges and prospects of Bi₂X₃ nanomaterials in the field of RT.