A super sensitive fluorescent probe for imaging endogenous hydrogen sulfide in living cells

Hydrogen sulfide (H₂S) that typically performs biphasic biological functions in organisms plays an opposite role at the concentrations above or below normal level of the organism. Therefore, it is significant to develop a fluorescent probe with high sensitivity and selectivity and rapid response for the detection of hydrogen sulfide in vivo. The work describes the design and biological applications of a novel turn-on fluorescence probe SS-N₃ in which the quinoline quaternary ammonium salt derivative is introduced as the fluorescent skeleton and azide is employed as the detection group of H₂S. The probe SS-N₃ shows strong fluorescence at 610 nm, as the azide group is reduced to an amino group by H₂S. The probe SS-N₃ shows high selectivity to H₂S than other anions and some biological mercaptans, and strong anti-interference capacity. In addition, the probe SS-N₃ exhibits little cytotoxicity, improved photostability and large Stokes shift (135 nm), as well as can be effectively used as an indicator of H₂S level in living cells.