An ESIPT-based reversible ratiometric fluorescent sensor for detecting HClO/H2S redox cycle in living cells.

HClO and H2S, as two kinds of crucial small biomolecules, are endowed various roles in biological organisms. The redox balance between HClO and H2S is closely related to the physiological and pathological processes. Thus, it is significant to monitor the redox process between HClO and H2S. Inspired by the advantages of ratiometric fluorescent probes, we firstly developed a reversible ratiometric fluorescent probe (BT-Se) for HClO and H2S via combination of phenyl selenide as the response group and 2-(2'-hydroxyphenyl)benzothiazole dye as the fluorophore. The proposed probe BT-Se could detect HClO with well-separated dual emission (110 nm), fast response, good selectivity and sensitivity owing to the oxidation reaction of the Se atom induced by HClO. Moreover, only H2S could effectively recover the fluorescence of the detection system to the original state via H2S induced-reduction of selenoxide. Cell imaging studies demonstrated that the probe BT-Se was capable of ratiometric monitoring the changes of intracellular HClO/H2S, which suggested that it has great potential for researching the biological functions of HClO and H2S.