Schottky heterojunction CeO@MXene nanosheets with synergistic type I and type II PDT for anti-osteosarcoma.

Photodynamic therapy (PDT) has shown great potential for tumor treatment as the method is noninvasive, highly selective, and causes minimal side effects. However, conventional type II PDT, which relies on O, presents poor therapeutic efficacy for hypoxic tumors due to its reliance on oxygen. Here, CeO/TiC-MXene (CeO@MXene) hybrids were successfully designed by growing CeO using TiC-MXene (MXene) nanosheets. CeO@MXene serves as a reduction-oxidation (REDOX) center due to the presence of Ce in the lattice of CeO nanoparticles. This REDOX center reacts with HO to generate oxygen and weakens the hypoxic tumor cell environment, achieving type II PDT. At the same time, many other ROS (such as ⋅O and ⋅OH) can be produced a type I photodynamic mechanism (electron transfer process). The CeO@MXene heterojunction performs nanoenzymatic functions for synergistic type I and type II PDT, which improves cancer treatment.