Spatiotemporally Synchronous Oxygen Self-Supply and Reactive Oxygen Species Production on Z-Scheme Heterostructures for Hypoxic Tumor Therapy.

Photodynamic therapy (PDT) efficacy has been severely limited by oxygen (O2 ) deficiency in tumors and the electron-hole separation inefficiency in photosensitizers, especially the long-range diffusion of O2 toward photosensitizers during the PDT process. Herein, novel bismuth sulfide (Bi2 S3 )@bismuth (Bi) Z-scheme heterostructured nanorods (NRs) are designed to realize the spatiotemporally synchronous O2 self-supply and production of reactive oxygen species for hypoxic tumor therapy. Both narrow-bandgap Bi2 S3 and Bi components can be excited by a near-infrared laser to generate abundant electrons and holes. The Z-scheme heterostructure endows Bi2 S3 @Bi NRs with an efficient electron-hole separation ability and potent redox potentials, where the hole on the valence band of Bi2 S3 can react with water to supply O2 for the electron on the conduction band of Bi to produce reactive oxygen species. The Bi2 S3 @Bi NRs overcome the major obstacles of conventional photosensitizers during the PDT process and exhibit a promising phototherapeutic effect, supplying a new strategy for hypoxic tumor elimination.