Despite their status of being widely used as food additives, bisulfite (HSO3-)/sulfite (SO32-) can pose serious health risks when they are excessively added. Therefore, it is vital to develop a new method for detecting HSO3-/SO32- in foodstuff. In this paper, a benzopyran-benzothiazole derivative (probe DCA-Btl) with near-infrared emission was designed and synthesized by constructing a "push-pull" electronic system. DCA-Btl can selectively recognize HSO3-/SO32- via a colorimetric and fluorescence dual channel in DMF/PBS (1:1, v/v, pH = 8.4), and the emission wavelength of DCA-Btl can reach 710 nm. The fluorescence quenching of DCA-Btl after recognition of HSO3- is attributed to the photoinduced electron transfer (PET) process of the adduct DCA-Btl-HSO3- as evaluated by the DFT/TD-DFT method. In addition, DCA-Btl has many advantages, including a large Stokes shift (95 nm), good anti-interference ability, and little cytotoxicity. What's more, DCA-Btl has been successfully applied for the detection of HSO3-/SO32- in actual water samples and food samples such as sugar, red wine, and biscuits with satisfying results, as well as for fluorescent imaging of HSO3- in living MCF-7 cells.
Keywords: bisulfite/sulfite; colorimetric; fluorescent probe; food sample; near-infrared.