A novel dual-ratiometric-response fluorescent probe for SO₂/ClO^- detection in cells and in vivo and its application in exploring the dichotomous role of SO₂ under the ClO^- induced oxidative stress.

Abstract

Intracellular reactive sulfur species and reactive oxygen species play vital roles in immunologic mechanism. As an emerging signal transmitter, SO₂ can be generated as the anti-oxidant, while SO₂ is also a potential oxidative stress-inducer in organism. Aiming to elucidate in-depth the dichotomous role of SO₂ under oxidative stress, we designed a dual-response fluorescent probe that enabled the respective or successive detection of SO₂ 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 SO₂ and ClO^-, allowing the highly selective and accurate ratiometric quantification for both SO₂ and ClO^- in cells. Moreover the ultrafast (SO₂: <60 s; ClO^-: within sec) and highly sensitive (detection limits: SO₂: 3.5 nM; ClO^-: 12.5 nM) detection were achieved. With the robust applicability, the developed probe was successfully used to quantify SO₂ and endogenous ClO^- in respectively the HeLa cells and the RAW 264.7 cells, as well as to visualize the dynamic of SO₂/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 SO₂ under the NaClO induced oxidative stress.