Simultaneous Discrimination of Cysteine, Homocysteine, Glutathione, and H 2 S in Living Cells through a Multisignal Combination Strategy

Biothiols are essential reactive sulfur species (RSS), which play crucial roles in various critical physiological activities. To clarify their complex correlations in signal transduction and metabolism pathways, methods to distinguish H 2 S, cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) at the same time are highly needed. Herein, we deliberately integrate 7-diethylcoumarin and resorufin through an ether bond to develop RC for simultaneous differentiation of Cys, Hcy, GSH, and H 2 S for the first time. RC displays distinct fluorescence colors in response to H 2 S, Cys, Hcy, and GSH as red, blue-red, blue-green-red, and green-red, respectively, both in aqueous media and living cells. This work not only reported a robust molecule, RC, to disentangle the intricate interplay networks among different biothiols in biosystems but also demonstrated a strategy for the design of multisignal fluorescent probes for the simultaneous sensing of diverse RSS species as well as other biological species.