A colorimetric fluorescent probe for reversible detection of HSO3-/H2O2 and effective discrimination of HSO3-/ClO- and its application in food and bioimaging.

In view of the significant role of reactive sulfur species (RSS) and reactive oxygen species (ROS) in maintaining the redox homeostasis of organisms, we proposed a colorimetric fluorescent probe (HTN) for reversible detection of HSO₃^-/H₂O₂ and effective discrimination of HSO₃^-/ClO^-. C = C is the active site for the Michael addition of HSO₃^- and the oxidation of ClO^-. When HTN interacts with HSO₃^- and ClO^-, it exhibits fluorescence quenching. The addition of oxidizing H₂O₂ to the system can restore the conjugate structure of the addition product of HSO₃^- (HTN-HSO₃^-) and the fluorescence recovery, but it cannot restore the structure of the oxidation product of ClO^- (HTN-ClO^-). By studying the change of the reversibility/non-reversibility of the probe structure with the addition of H₂O₂, the purpose of reversible detection of HSO₃^-/H₂O₂ and distinguishing HSO₃^-/ClO^- is achieved. In addition, HTN can not only be used as a fluorescent ink to detect HSO₃^- on the test paper, but also has excellent detection effect on HSO₃^- and ClO^- in real food samples and water samples. Meantime, HTN has good biocompatibility and can target mitochondria to achieve reversible detection of HSO₃^-/H₂O₂ and effective discrimination of HSO₃^-/ClO^- in living cells. Therefore, HTN has great potential as a molecular tool for studying redox homeostasis in the interaction network of complex living systems.