Carbon dot sensitized hollow Co9S8−x for enhanced sonodynamic cancer therapy

Sonodynamic therapy activates sonosensitizers through US to generate a large amount of reactive oxygen species (ROS), which causes apoptosis of tumor cells and achieves a therapeutic effect against tumors. However, the excessively wide bandgap of inorganic sonosensitizers and the easy recombination of electron–hole pairs limit the yield of ROS of sonosensitizers. Herein, for the first time, we report carbon dot (CD)-sensitized hollow Co₉S_8−x as a novel inorganic sonosensitizer for enhanced sonodynamic tumor therapy. The presence of sulfur vacancies endows Co₉S₈ with excellent sonodynamic and chemodynamic activities. Furthermore, CDs with good sonodynamic activity are utilized to form CD@Co₉S_8−x heterojunctions with hollow Co₉S_8−x, realizing the cascaded amplification of the ROS yield. The significantly increased ROS level induces a powerful effect of cell apoptosis, thus completely eradicating tumors. Overall, this work delivers useful insights for utilizing vacancy engineering and heterojunction engineering to achieve enhanced sonodynamic tumor therapy.