Aggregation-induced emission cyclometallated Iridium(III) complex for multi-photon FLIM imaging-guided photodynamic therapy

Cyclometallated iridium(III) complexes have unique photophysical properties that turn them into promising photosensitizers and potential fluorescence lifetime imaging probes. Herein, we developed a novel cyclo-metallated iridium(III) complex (Ir-OH) with aggregation-induced emission (AIE) properties for FLIM imaging -guided photodynamic therapy. Studies on photophysical properties show that Ir-OH exhibits excellent fluo-rescence response to in situ mitochondrial viscosity with varied lifetime. In addition, Ir-OH shows satisfactory multiphoton absorption properties in the near-infrared region (Two-photon: 700-800 nm; Three-photon: 1150-1450 nm). More importantly, changes in mitochondrial viscosity during photodynamic processes can be quantified in real-time by FLIM. Thus, our work illustrates that cyclometallated iridium(III) complexes can simultaneously induce and precisely detect microenvironmental changes at the subcellular level using FLIM, leading to self-reporting PDT outcomes.