A novel iridium(III) complex-based ratiometric luminescence probe for monitoring hydrogen sulfide in living cells and zebrafish

Hydrogen sulfide exhibits crucial functions in many biological and physiological processes. The abnormal levels of H2S have been revealed to be associated with numerous human diseases. The majority of existing fluorescent probes toward H2S may still need to be improved in terms of single output signal, water solubility, biotoxicity and photostability. The construction of a ratiometric fluorescent probe based on metal complex is one effective strategy for avoiding the mentioned problems for precisely detecting H2S. Herein, we report an iridium(III) complex-based ratiometric luminescence probe (Ir-PNBD), which is designed by coupling the 7-nitro-2,1,3-benzoxadiazoles (NBD) to one of the bipyridine ligands of Ir (III) complex luminophore through a piperazition moiety. Ir-PNBD owns high selectivity and sensitivity toward H2S, and an excellent ability to target mitochondria. Moreover, Ir-PNBD was further successfully utilized to visualize exogenous and endogenous H2S in HeLa cells and zebrafish. Our work offers new opportunities to gain deeper insights into the construction of transition metal complex-based ratiometric luminescent probes and expands their applications in biomedical imaging and disease diagnosis. A ratiometric luminescent probe based on Ir(III) complex with excellent photostability, biocompatibility, large Stokes shift, and long-lived phosphorescence for H2S detection was constructed, which was a greatly effective tool for accurately detecting and ratio-imaging both exogenous and endogenous H2S in vivo. [Display omitted] •A ratiometric luminescent probe based on Ir(III) complex for H2S was constructed.•Ir-PNBD owns high sensitivity, selectivity and mitochondrial localization ability.•Ir-PNBD was utilized to ratio imaging H2S in living cells and zebrafish.