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

•A near-infrared (NIR) emitted fluorescent probe for HSO3− has been developed.•SZY has the advantages of large Stokes shift, high water solubility, reliability in broad pH range, fast response time and low cytotoxicity.•The fluorescent imaging function of SZY for HSO3− tracking in live adult zebrafish and nude mouse has been successfully realized.•Semi-quantitative analysis of HSO3− levels in four food samples has been realized by “naked-eye” using SZY. Bisulfite (HSO3–) has been widely used as an important food additive in daily life. Furthermore, a normal amount of HSO3– plays a significant role in biological systems. However, excessive intake of HSO3– 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 HSO3– 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 HSO3– in several food samples and live animals. The proposed nucleophilic addition sensing mechanism of SZY towards HSO3– has been confirmed by 1H NMR titration, high resolution mass spectrometry (HR-MS) and density functional theory (DFT) theoretical computation. The HSO3–-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 HSO3– in live nude mouse and adult zebrafish. Semi-quantitatively analyzing the HSO3− 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.