Bismuth selenide nanoflowers for internal irradiation combined with photothermal therapy for tumor sensitization and killing

The radioisotope ¹⁷⁷Lu has shown great potential in the treatment of tumors. However, free radioisotopes may cause toxicity to normal tissues and organs. Therefore, it is crucial for enhanced tumor therapy that ¹⁷⁷Lu can be retained in tumor tissues by the development of novel delivery systems. However, the efficacy of internal radiotherapy (IRT) is limited by the hypoxic microenvironment induced by the insufficient blood supply in solid tumors. Herein, we synthesized novel ¹⁷⁷Lu-labeled bismuth selenide nanoflowers that possess the peculiarity of photothermal conversion and can achieve photothermal therapy (PTT) for tumors under light conditions. Moreover, the amino group of selenocysteine in the outer layer of Bi₂Se₃ can efficiently form covalent bonds with ¹⁷⁷Lu, decreasing the side effects of free radioisotopes on normal tissues. These results demonstrate that selenocysteine-modified Bi₂Se₃ nanoflowers (Bi₂Se₃@Sec NFs) have the potential for application as radionuclide delivery carriers and radionuclide-photothermal therapy drugs.