A novel "turn-on" mitochondria-targeting near-infrared fluorescent probe for H2S detection and in living cells imaging.

Hydrogen sulfide (H2S) has been considered to be involved in cytoprotective processes and redox signaling. It is very meaningful to track and analyze it in mitochondria. Herein, we report a novel "turn-on" mitochondria-targeting near-infrared fluorescent probe (Mito-NIR-SH) for detection of H2S in living cells, which was designed and synthesized by introducing 2,4-dinitrophenyl as fluorescence quenching group and H2S response moiety into Changsha near-infrared fluorophore (CS-OH). The structure of the fluorophore and the probe were characterized by 1H NMR, 13C NMR and mass spectrometry. Meanwhile, Mito-NIR-SH could quantitatively detect H2S at concentrations ranging from 0 to 30 μM with a detection limit as low as 89.3 nM, showing good chemical stability, fast "turn-on" response, selectively mitochondrial location, as well as high sensitivity and selectivity toward H2S. Based on this, it was successfully applied to imaging exogenous and endogenous H2S in living HeLa cells via confocal fluorescence microscopy.