Mitochondria-targeted cyclometalated iridium (III) complex for HS-responsive intracellular redox regulation as potent photo-oxidation anticancer agent.

Owing to the safety and low toxicity, photodynamic therapy (PDT) for cancer treatment has received extensive attention. However, the excess HS in cancer cells reduces the PDT efficiency, because HS indirectly depletes the reactive oxygen species (ROS). To improve anticancer efficiency, a mitochondria-targeted iridium(III) complex Ir-MMB has been developed as HS consumer and photo-oxidation anticancer agent. On the one hand, complex Ir-MMB can consume HS with sensitive phosphorescence turn-on, which has been successfully applied to exogenous and endogenous HS response imaging in living cells. On the other hand, Ir-MMB can enhance its anticancer activity and cause photo-oxidation damage via catalyzing the oxidation of reduced form of nicotinamide-adenine dinucleotide (NADH) to NAD and producing HO under light, and ultimately results in cell apoptosis through mitochondrial depolarization and ROS production.