Rational design of a GSH silent fluorescent probe for simultaneous detection of H2S and Cys/Hcy from distinct channels

Abstract

In light of elucidating the intricacy relationship of cellular cross-talk for reactive sulfur species in cellular activity, it is an urgent demand for the development of effective assessment methods to detect H2S and Cys/Hcy concurrently. In this work, by introducing thiophene-2-carboxylate and NBD moiety as the reactive sites to the 7-hydroxycoumarin-4-acetic acid, we have designed and synthesized a GSH silent fluorescent probe (COT-NBD) for simultaneous detection of H2S and Cys/Hcy from distinct channels. With the existence of reactive sulfur species (Cys/Hcy and H2S), two kinds of distinct signals could be produced, blue for H2S (λex = 355 nm) and green for Cys/Hcy (λex = 450 nm). Additionally, remarkable fluorescence enhancement (77-fold for Cys, 61-fold for Hcy and 68-fold for H2S), high sensitivity (the limit of detection of probe COT-NBD was calculated to be 0.012 μM, 0.034 μM and 0.06 μM for Cys, Hcy and H2S, the limit of quantification of probe COT-NBD was calculated to be 0.040 μM, 0.113 μM and 0.200 μM for Cys, Hcy and H2S), desirable selectivity, large separation of the emission wavelengths (87 nm) and low cytotoxicity make it a ideal tool to detect H2S and Cys/Hcy concurrently. Furthermore, probe COT-NBD had high cell membrane permeability, enabling H2S and Cys/Hcy in living MCF-7 cells and zebrafish through different emission channels to be imaged. All in all, probe COT-NBD could be served as a promise molecular tool for investigating the function and synergy of H2S and Cys/Hcy in physiological processes.