A red fluorescence probe for reversible detection of HSO₃^-/H₂O₂ and its application in food samples and bioimaging

Reducing agent SO₂ and oxidant H₂O₂ are two essential substances in cells, and the balance between them is closely related to the survival of cells. SO₂ derivative HSO₃^- is often used as food additive. Therefore, simultaneous detection of SO₂ and H₂O₂ is of great significance in biology and food safety. In this work, we successfully developed a mitochondria-targeted red fluorescent probe (HBTI), which has excellent selectivity, high sensitivity and large Stokes shift (202 nm). HBTI and HSO₃^-/SO₃^2- undergo Michael addition on the unsaturated C=C bond, and the addition product (HBTI-HSO₃^-) can react with H₂O₂ to restore the conjugated structure. Fluorescence changes from red to non-emissive and then restores to red, and can be detected quickly and visually. In addition, HBTI has been successfully targeted mitochondria, and achieved dynamic reversible response to SO₂/H₂O₂ in living cells, and has been successfully applied to detect SO₂ in food samples.