Developing a dual-site fluorescent probe for simultaneously discriminating Cys/Hcy and GSH, and visualizing metabolism of Cys to SO2

Abstract Biothiols as sulfur-containing active substances -play an important physiological and pathological function in organisms, however their specific markers in situ is a big challenging because they have high reactivity, the nature of the short half-life. Among of which due to their similar structure and properties, in particular, the research on their special physiological function is limited. In our study, we designed two biothiol nucleophilic substitution reaction sites in the benzene ring of SBD-Cl. Because of the conjugate effect of Cl, the para-sulfonic acid activated C was inactivated, the nucleophilic substitution of biothiol and Cl occurred, further, the intramolecular rearrangement occurred between the amino and sulfhydryl of Cys/Hcy, and the yellow fluorescence of SBD was released. However, GSH with large structure could not undergo intramolecular rearrangement, so there was no emission of yellow fluorescence, thus, Cys/Hcy and GSH can be detected distingusihly. In the above, adding SO2 can quench the red emission of benzopyrylium. In this way, we visualized the metabolism process from Cys to sulfur dioxide in the mitochondria with the probe. The above metabolic processes were further studied in zebrafish and tissues, and found the probe imaged tissue to a depth of 80 μm.