Performance of a Ce-Regulated Cerium–Titanium–Oxygen Solid Solution with a Tunable Bandgap for Sonodynamic–Chemodynamic Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT) employing semiconductor nanomaterials has garnered significant attention in cancer treatment. However, the wide bandgap of acoustic sensitizers limits the effectiveness of SDT, leading to rapid recombination of electron (e-) and hole (h+) pairs under ultrasound irradiation. In this study, we constructed a Ce-Ti-O solid solution system (Ce1-xTixO2, CTO) and innovatively fine-tuned the bandgap structure of TiO2 by adjusting the doping concentration of Ce ions, significantly enhancing the carrier separation efficiency under ultrasound irradiation. This marks a significant advancement in the application of solid solution materials in tumor SDT. Furthermore, the CTO exhibits Fenton-like reactivity, capable of converting endogenous H2O2 into hydroxyl radicals (·OH) for chemical dynamic therapy (CDT). The combination of SDT and CDT significantly enhanced the generation of reactive oxygen species (ROS) and mitochondrial damage in cells. Cumulative in vitro/vivo findings revealed that this system exhibits significant cytotoxicity and tumor suppression effects against refractory breast cancer in mice. This research not only provides a new nanodiagnostic platform for the efficient and precise treatment of malignant tumors but also provides a crucial theoretical foundation for the multifunctional applications of solid solution materials in the biomedical field.