Visualizing hydrogen peroxide and hydrogen sulfide fluctuations in living cells via dynamic-reversible fluorescent probes

Visualizing the complex crosstalk between biological signaling molecules, such as H2O2 and H2S, is in an urgent demand. However, reaction with specific biomarkers makes conventional fluorescent probes inactive to further stimuli, thereby annihilating their responsiveness to the alternating existence of various targets. Herein, we engineer dynamic-reversible probes with dually responsive sites for visualizing the fluctuations of H2O2 and H2S. This designed reporter features H2O2-mediated self-immolation and H2S-initiated aromatic nucleophilic reaction to yield sulfhydryl-functionalized intermediate probe for lighting up bright NIR emissions. Importantly, the resultant intermediate probe can repeatedly cycle S-oxidation and reduction processes when successively treated with H2O2 and H2S, thus affording the fluorescence alternation at 800 nm between off and on state to visualize the intracellular coexistence and alternating existence of H2O2 and H2S. It is anticipated that this dynamic-reversible probe will elucidate the interplay between H2O2 and H2S in biological redox processes.