A new lysosome-targetable fluorescent probe for detection of endogenous hydrogen polysulfides in living cells and inflamed mouse model.

Hydrogen polysulfides (H2Sn, n > 1) belong to sulfane sulfur in the reactive sulfur species (RSS) family and play significant roles in maintaining biological homeostasis in organisms. The detection of H2Sn in living systems is essential, but further understanding of its "intact" function in living cells has been limited, owing to the lack of appropriate analytical tools. In this work, a new fluorescent probe PP-PS was designed for the detection of endogenous H2Sn. The probe has a large Stokes shift (178 nm), low detection limit (1 nM), and short response time (1 minute). Besides, PP-PS was successfully applied in the imaging of endogenous H2Sn in lysosomes of living cancer cells, xenograft mouse tumor tissues, and LPS-induced mouse inflammation tissues. These results revealed that the probe PP-PS could act as a new fluorescence imaging tool to study the function of intracellular hydropolysulfides.