Insufficient reactive oxygen species (ROS) generation and radioresistance resulting from the intrinsic features of tumors consistently give rise to unsatisfactory therapeutic outcomes of radiotherapy (RT). Developing a multifunctional radiosensitizer capable of activating ROS-induced apoptosis and achieving multimodal therapy is highly imperative yet remains a challenge so far. Herein, a multifunctional therapeutic nanoplatform based on Bi2WO6-BP heterojunctions for multimodal synergistic tumor treatment with glutathione depletion and amplifying ROS generation is rationally designed. Rich in high-Z elements, Bi2WO6-BP heterojunctions are able to deposit higher radiation doses into cancer cells, enhancing the radiotherapy effect. The Z-scheme heterojunction structure facilitates the X-ray-triggered catalytic process that catalyzes intracellular overproduced H2O2 into highly toxic ˙OH, which thus enhances ROS generation in a hypoxic environment. The unique sub-band structures of BP NSs and the synergistic effect between Bi2WO6 and BP significantly boosted 1O2 generation. Meanwhile, the acidic TME can trigger the cycle conversion of W from W5+ to W6+, and the redox reaction between W6+ and GSH consumes the high level of GSH in tumor cells and increases the production of ROS. The mild photothermal effect produced by the Bi2WO6-BP heterojunction could further enhance the ROS generation. Both in vitro and in vivo experiments showed that the as-prepared Bi2WO6-BP heterojunction possesses high synergistic therapeutic efficacy. This work offers a viable approach to build a multifunctional radiosensitizer with TME-triggered multiple synergistic therapies for deep tumors.
Read full abstract