Facile functionalized fluorescein derivative as a reversible fluorescence probe for selective monitor of the redox cycle between hypochlorous acid and cysteine

The reasonable cellular redox equilibrium mediated by reactive oxygen species/reactive nitrogen species and antioxidants are pivotal importance for maintaining a variety of physiological processes, and disrupted redox equilibrium may derange the cellular components and eventually may lead to cell death, irreversible tissue destruction, and various diseases. In this paper, we develop a phenylseleno-functionalized reversible fluorescent probe Fluo-Se for monitoring the hypochlorous acid/cysteine redox couple in living cells. The advantages of the probe included: a) the synthetic procedure of the probe is very simple by one step reaction; b) the probe shows high sensitivity for HOCl and cysteine (the detection limit is 1.1 nM and 3.0 nM, respectively); c) the probe exhibits high reversibility to the hypochlorous acid/cysteine redox couple both in solutions and in the living cell by taking advantage of the Se atom-led excellent reversible conversions between Fluo-Se and its oxidized product. We think that Fluo-Se should be very useful for gauging the cellular redox status mediated by the hypochlorous acid/cysteine couple.