Fluorescence Lifetime Guided Precision Photodynamic Therapy for Treating Tumour Stem Cells by a Cyclometalated Iridium (III) Complex with free rotational pyridine units in Tissue Level

Tumour stem cells has been shown to be highly correlated with tumour occurrence, metastasis, recurrence, and drug resistance. However, current clinical methods for the identification and specific treatment of tumour stem cells are limited, complicated and ineffective. Herein, we rationally developed a novel cyclometalated iridium (III) complex, having free rotational pyridine units, with the capability in generating singlet oxygen in living cells as well as showing sensitive fluorescence lifetime response towards in situ microenvironment. In addition, we have successfully demonstrated that it can be used to distinguish tumour stem cells from tumour tissue and self-report the anti-tumour effect via fluorescence lifetime imaging microscopy (FLIM). • FGP-Ir exhibits microenvironmental responsiveness and excellent ROS generation capacity. • FGP-Ir demonstrated the difference in fluorescence lifetime at different intracellular viscosities. • FGP-Ir enables quantitative detection the fluorescence lifetime of different areas through FLIM. • FGP-Ir can perform precise photodynamic therapy on tumor stem cell regions.