Effective BiOBr(I)-BP nanocomposite for synergistic photothermal and radiodynamic therapy against hypoxic tumor to complement low dose radiotherapy

Improving radiation effect and reducing radiation resistance is the key issue to boost the effectiveness of radiotherapy. Herein, we have developed a novel BiOBr 0.5 I 0.5 -BP heterojunction nanosheets (BOBI-BP NSs) for synergistic radiodynamic and photothermal therapy to enhance the efficacy of low-dose radiotherapy under hypoxic conditions. On one hand, this BOBI-BP heterojunction is rich in high-Z elements (Bi, I) and able to deposit high radiation doses into cancer cells, enhancing the radiotherapy effect. On the other hand, due to the heterojunction structure, a large number of electron-hole pairs can be generated and separated under X-ray trigger, which significantly improves the catalytic activity of catalyzing the overexpressed H 2 O 2 in cancer cells into highly toxic •OH, overcoming the oxygen dependence. 1 O 2 could be generated because of the unique sub-band structures of BP NSs and the synergistic effect between BOBI and BP, thereby improving the therapeutic utility of low-dose X-ray irradiation. The synergistic utility of BOBI-BP NSs as a combination of radiodynamic therapy, photothermal therapy agent and radiosensitizer was demonstrated both in vitro and in vivo. This work provides the idea to develop rational designed heterostructures as efficient therapeutic nanoplatform for cancer treatment.