A “double-locked” fluorescent probe for HClO/H2S detection

Abstract

This study explores the “double-locked” probe strategy for simultaneous detection of oxidative hypochlorous acid (HClO) and reductive hydrogen sulfide (H₂S). Drawing on our previous work on push–pull electronic structure-based probe Sa1, we designed and synthesized a novel double-locked probe, An1, for the simultaneous sensing of HClO and H₂S. Our results demonstrate that An1 remains fluorescently quenched in the presence of either HClO or H₂S alone, while displaying robust fluorescence turn-on upon their coexistence. This detection mechanism is well-supported by mass spectrometry analysis. Reaction kinetics studies reveal excellent responsiveness, and selectivity experiments confirm the specific recognition of HClO and H₂S. Prior to biological applications, the low cytotoxicity of An1 was validated through MTT assays. Finally, the applicability of An1 in biological systems was successfully demonstrated in tumor cells and zebrafish models. This work not only validates the potent double-locked detection capability of An1 with potential clinical implications but also underscores the versatility of the push–pull electronic structure as a generic platform for double-locked probe design.