Reversible fluorescent probe for visually monitoring the concentration-dependent dynamic correlations among HOCl, H2S, and Ca2+ in neurons

Abstract

The redox fluctuations regulated by endogenous reactive oxygen species and reductive sulphur species play vital roles in many biological functions. Simultaneously, it has been discovered that HOCl and H2S are able to interfere with calcium homeostasis via the regulation of calcium channels in neurons. Therefore, a novel fluorescent probe PzSe containing a buit-in selenium atom as reversible responding site has been designed and synthesized. The selenium atom in PzSe can be oxidized to the form of selenoxide by HOCl, and the oxidized form of selenoxide can be reduced rapidly back to its original form of selenide by H2S. The conversion of the probe between its selenoxide and selenide forms lead the fluophore to present electron-withdrawing and electron-rich effects, respectively, which lead to the probe present different optical properties at the oxidized and reduced states. Based on the rapid valence-guided reversible molecular events, PzSe could sensitively and selectively detect the HOCl/H2S redox cycle in the solution and in living cells. Meanwhile, via the reversible three-colour fluorescence changes from the PC-12 cells being co-stained with the probe PzSe and the Ca2+-selective Fluo-4 AM, it can be used for trapping the concentration-dependent dynamic correlations among HOCl, H2S, and Ca2+ in neurons.