A NIR fluorescent chemodosimeter for imaging endogenous hydrogen polysulfides via the CSE enzymatic pathway

Sodium polysulfides (Na₂S_n, n > 1) as important raw materials in the chemical industry can afford hydrogen polysulfides (H₂S_n, n > 1) under physiological conditions. Hydrogen polysulfides are important reactive sulfide species that play crucial roles in biological systems. The simple detection of H₂S_n in solution and biosystems becomes very important as a consequence of the foregoing applications. Herein, we report a NIR fluorescent chemodosimeter, Cy-S_n, displaying turn-on fluorescence after reaction with H₂S_n, which exhibits good selectivity and sensitivity in solution and biosystems. Moreover, it was applied successfully to monitor endogenous hydrogen polysulfides via the cystathionine γ-lyase (CSE) enzymatic pathway during inflammation and anti-inflammation in living RAW 264.7 cells. Mouse experiments indicated that this chemodosimeter has good potential to be employed in the imaging of living biosystems.