Construction of a mitochondria-targeted near-infrared fluorescence turn-on fluorescent probe for H₂S detection and imaging in living cells and drug-induced mice inflammatory models

The mechanism of the interaction between the signaling molecule hydrogen sulfide (H₂S) and mitochondria and its related diseases is difficult to elusive. Thus it is urgent to develop effective methods and tools to visualize H₂S in mitochondria and in vivo. In this work, a robust mitochondrial-targeting NIR fluorescence "turn-on" fluorescent probe, NIR1, was reported, by adopting a Changsha-OH near-infrared (NIR) dye as the NIR fluorophore, a 2,4-dinitrophenyl (DNB) moiety as both the responsive site of the H₂S and the fluorescence quenching group of the NIR fluorophore, and an oxygen onium ion site as the mitochondria-targeting group, for the detection and analysis of H₂S in living Raw 264.7 cells and drug-induced inflammatory mice models. NIR1 exhibited a much smaller background fluorescence signal in lack of H₂S, whereas strong enhanced NIR fluorescence "turn-on" was detected in the presence of H₂S, these results showed a low detection limit (30.2 nM) for quantitative detection of H₂S in aqueous solutions with concentrations ranging from 0 to 1 μM H₂S. These characteristics were beneficial to direct detection and imaging analysis of H₂S in complicated biosystems. Therefore, first, NIR1 was applied for the NIR detection of mitochondrial H₂S in living inflammatory cells with satisfactory results. Finally, NIR1 was applied to detect H₂S in drug-induced inflammatory mice models with agreeable results, demonstrating that NIR1 as a molecular tool has an excellent practical application in the study of the interaction between inflammatory and H₂S.