A sensitive and ratiometric fluorescent probe for imaging cytosolic H2S generation

Abstract

As a labile molecule with a short half-life, the true concentration of H₂S in biological systems is controversial. H₂S-producing enzymes are mainly in the cytosol. Probes that can image cytosolic H₂S in real-time and accurately are sought after. An indol–coumarin fluorophore is an ideal scaffold for mitochondrial H₂S imaging. By a simple (yet rational) structural modification, CouMa was constructed with the fluorophore for cytosolic H₂S detection. CouMa responded to H₂S within 3 min in a ratiometric way without interference from common bio-relevant species and pH. The probe could image changes in exogenous H₂S level and fluctuations in endogenous H₂S generation in MCF-7 cells. The increment and depression of nitric oxide-related H₂S generation in the cytosol was monitored by CouMa. It could be a powerful tool to reveal crosstalk between these two transmitters, and to image H₂S generation in the cytosol. The structural-modification strategy could be useful to regulate subcellular localization.