Phosphorescence Lifetime Imaging of Labile Zn2+ in Mitochondria via a Phosphorescent Iridium(III) Complex

Phosphorescence lifetime Zn 2+ imaging possesses the advantage over normal fluorescence imaging in offering the more accurate temporal-spatial Zn 2+ information. Herein, we report a new phosphorescent cyclometalated Ir(III) complex with a Zn 2+ -chelator bearing 1,10-phenanthrolin acting as ancillary ligand, Zin-IrDPA, which displays the specific Zn 2+ -induced enhancement of phosphorescence and phosphorescence lifetime, and the mitochondria-targeting ability. Moreover, its Zn 2+ -induced phosphorescence lifetime enhancement factor is not affected by medium lipophilicity, viscosity, polarity, and especially ambient oxygen. The reversible tracking of introduced exogenous labile Zn 2+ in MCF-7 and HeLa cells via phosphorescence imaging and phosphorescence lifetime imaging (PLIM) have been realized with Zin-IrDPA . Moreover, PLIM with Zin-IrDPA is able to track the SNOC-stimulated endogenous Zn 2+ release in mitochondria.