A ratiometric fluorescent probe for hydrogen sulfide in neat aqueous solution and its application in lysosome-targetable cell imaging.

Hydrogen sulfide (H2S) has been recently regarded as one of the most important gasotransmitters in the metabolic system, while abnormal H2S concentration is associated with various diseases. Although numerous fluorescent probes have been developed for the detection of cellular H2S, only a few of them can monitor lysosomal H2S with ratiometric fluorescent output. Here, we developed a water-soluble probe 1 toward H2S by introducing 2,4-dinitrophenyl ether into a novel merocyanine-based dye. As expected, H2S induced an obvious red-shift of the probe from 520 nm to 580 nm in neat aqueous solution, and this fluorescent ratiometric response is highly selective and sensitive (with the detection limit of 0.81 nM), rapid (within 10 s), and effective in a wide pH range (2.0-10.0). In particular, the probe was successfully applied for tracing H2S in the lysosomes of living cells and in zebrafish.