A novel dual-ratiometric-response fluorescent probe for SO/ClO detection in cells and in vivo and its application in exploring the dichotomous role of SO under the ClO induced oxidative stress.

Intracellular reactive sulfur species and reactive oxygen species play vital roles in immunologic mechanism. As an emerging signal transmitter, SO can be generated as the anti-oxidant, while SO is also a potential oxidative stress-inducer in organism. Aiming to elucidate in-depth the dichotomous role of SO under oxidative stress, we designed a dual-response fluorescent probe that enabled the respective or successive detection of SO and ClO. The probe itself emits the red fluorescence (625 nm) which can largely switch to blue (410 nm) and green fluorescence (500 nm) respectively in response to SO and ClO, allowing the highly selective and accurate ratiometric quantification for both SO and ClO in cells. Moreover the ultrafast (SO: <60 s; ClO: within sec) and highly sensitive (detection limits: SO: 3.5 nM; ClO: 12.5 nM) detection were achieved. With the robust applicability, the developed probe was successfully used to quantify SO and endogenous ClO in respectively the HeLa cells and the RAW 264.7 cells, as well as to visualize the dynamic of SO/ClO in zebrafish. The fluorescent imaging studies and flow cytometry analysis confirmed the burst-and-depletion and meanwhile the oxidative-and-antioxidative effects of intracellular SO under the NaClO induced oxidative stress.