A near-infrared emitted fluorescence probe for the detection of biosulfite in live zebrafish, mouse and real food samples.

Bisulfite (HSO) has been widely used as an important food additive in daily life. Furthermore, a normal amount of HSO plays a significant role in biological systems. However, excessive intake of HSO will lead to a variety of diseases. Therefore, it is of great significance to develop an efficient fluorescent probe that can be used for detection of HSO in biological systems and food samples. In this work, a near-infrared (NIR) emitted fluorescent probe (SZY) based on hemicyanine dye was successfully synthesized and applied to detect HSO in several food samples and live animals. The proposed nucleophilic addition sensing mechanism of SZY towards HSO has been confirmed by H NMR titration, high resolution mass spectrometry (HR-MS) and density functional theory (DFT) theoretical computation. The HSO-induced nucleophilic reaction with α,β-unsaturated CC binding of SZY results in the dramatic decline of the UV-vis absorption and remarkable quenching of the fluorescence emission. SZY features the advantages of near infrared emission (centered at 720 nm), high water solubility (in 98% aqueous solution), fast response time (50 s), large Stokes shift (244 nm) and low cytotoxicity. The probe SZY was successfully applied to image of HSO in live nude mouse and adult zebrafish. Semi-quantitatively analyzing the HSO level by "naked eye" in several food samples including canned fruit, white wine, white sugar and jasmine tea drinks has been realized by the colorimetric method.