Photosynthetic Cyanobacteria-Hybridized Black Phosphorus Nanosheets for Enhanced Tumor Photodynamic Therapy

Photodynamic therapy (PDT) has attracted tremendous attention due to its advantages such as high safety and effectiveness compared to traditional radiotherapy and chemotherapy. However, the intratumoral hypoxic microenvironment will inevitably compromise the PDT effect of the highly oxygen-dependent type II photosensitizers, implicating the urgent demand for continuous intratumoral oxygenation. Herein, biocompatible photosynthetic cyanobacteria have been modified with inorganic two-dimensional black phosphorus nanosheets (BPNSs) to be a novel bioreactor termed as Cyan@BPNSs. Upon 660 nm laser irradiation, the photosynthetic cyanobacteria generate oxygen continuously in situ through photosynthesis, followed by the photosensitization of BPNSs for activating oxygen into singlet oxygen (¹O₂), resulting in a large amount of ¹O₂ accumulation at the tumor site and the consequent strong tumor cell killing effect both in vitro and in vivo. This work provides an attractive strategy for efficient and biocompatible PDT, meanwhile extends the scope of microbiotic nanomedicine by hybridizing microorganisms with inorganic nanophotosensitizer.