Enhanced Generation of Non-Oxygen Dependent Free Radicals by Schottky-type Heterostructures of Au–Bi2S3 Nanoparticles via X-ray-Induced Catalytic Reaction for Radiosensitization

Abstract

Despite the development of nanomaterials with high-Z elements for radiosensitizers, most of them suffer from their oxygen-dependent behavior in hypoxic tumor, nonideal selectivity to tumor, or inevasible damages to normal tissue, greatly limiting their further applications. Herein, we develop a Schottky-type heterostructure of Au–Bi2S3 with promising ability of reactive free radicals generation under X-ray irradiation for selectively enhancing radiotherapeutic efficacy by catalyzing intracellular H2O2 in tumor. On the one hand, like many other nanomaterials with rich high-Z elements, Au–Bi2S3 can deposit higher radiation dose within tumors in the form of high energy electrons. On the other hand, Au–Bi2S3 can remarkably improve the utilization of a large number of X-ray-induced low energy electrons during radiotherapy for nonoxygen dependent free radicals generation even in hypoxic condition. This feature of Schottky-type heterostructures Au–Bi2S3 attributes to the generated Schottky barrier between metal Au and semiconductor Bi2S3, which can trap the X-ray-generated electrons and transfer them to Au, resulting in efficient separation of the electron–hole pairs. Then, because of the matched potential between the conduction band of Bi2S3 and overexpressed H2O2 within tumor, the Au–Bi2S3 HNSCs can decompose the intracellular H2O2 into highly toxic •OH for selective radiosensitization in tumor. As a consequence, this kind of nanoparticle provides an idea to develop rational designed Schottky-type heterostructures as efficient radiosensitizers for enhanced radiotherapy of cancer.