Dual-functional AIE-active Ir(III) complexes for trypsin detection and organelle-targeted photodynamic therapy

Cyclometallated Ir(III) complex is a potential photosensitizer for photodynamic therapy (PDT) due to its unique photophysical properties. As an emerging anti-tumor therapy, PDT kills tumor cells by leveraging the toxic reactive oxygen species (ROS) generated by light-activated photosensitizers. In this work, two Ir(III) complexes with aggregation-induced emission (AIE) properties were designed and synthesized. A biosensor based on bovine serum albumin (BSA)-enhanced AIE of Ir(III) complexes for selective sensing of trypsin was constructed and explored. The therapeutic potential of the probes for PDT was evaluated by measuring their ROS generation efficiency, along with their phototoxicity and dark cytotoxicity in HeLa cells. In addition, localization of the two probes on organelles was investigated and the mechanism of apoptosis induced by the probe Ir-2 as a photosensitizer was studied using flow cytometry. The results demonstrated that these AIE-active complexes exhibited high ROS efficiency and good mitochondrial/lysosome dual-organelle targeting capability, which can enhance the efficacy of PDT in cancer treatment. This Ir(III)-AIE theragnostic probe merges enzymatic sensing with organelle-specific PDT, offering dual biomedical applications.