A Water-soluble Fluorescent Probe for Rapid Detection of Sulfur Dioxide Derivatives

The content of sulfur dioxide derivatives in cells is closely related to life and health. Therefore, it is essential to detect the content of sulfur dioxide derivatives in cells under physiological conditions to ensure life and health. In this paper, a novel sulfur dioxide derivative fluorescent water-soluble probe ((E)-1,1,3-trimethyl-2-(2-(naphthalen-1-yl)vinyl)-1H-3λ⁴-benzo[e]indole, TNB) was synthesized by using naphthalene formaldehyde (1) and 1,1,2,3-tetramethyl-1H-3λ⁴-benzo[e]indole (2) as raw materials. Based on the intramolecular charge transfer (ICT) mechanism of the naphthalene ring to benzoindole, TNB exhibits very weak fluorescence emission in PBS buffer (pH 7.4). The olefin unit of TNB can be combined with HSO₃^-/SO₃^2- with high selectivity to make the π-π conjugate interrupt. ICT is blocked, TNB produces a strong fluorescence emission, and the color visible to the naked eye changes from yellow to colorless. The effect of TNB on HSO₃^-/SO₃^2- can be completed in 40 s, the fluorescence intensity is increased by 91 times, and the detection limit is as low as 0.089 μM. It is expected to be able to rapidly detect low levels of sulfur dioxide derivatives in cells, which has important application prospects in maintaining life and health.