A highly selective colorimetric and far-red fluorescent probe for imaging bisulfite in living cells

The development of probes for specific bisulfite (HSO3-) detection is of great importance, due to its toxicity in the environment and important biological functions in living systems. In the present study, we developed a highly selective colorimetric and far-red fluorescent probe (1) for the determination of HSO3- in aqueous solution and living cells. The excellent properties of our proposed probe can be listed as follows. Firstly, probe 1 showed excellent selectivity for HSO3- over various other species including Cys, GSH, S2-, SO32-, and ROS, which might be ascribed to the introduction of a receptor of the electron-poor C] C double bond for HSO3-. Secondly, our proposed probe possesses the higher molar absorption coefficient, and it can serve as a sensitive "naked-eye" probe for HSO3-. So, probe 1 would provide a convenient and promising method for the visual detection of HSO3- and the toxic gaseous SO2 in the environment. Thirdly, probe 1 has a long-wavelength emission spectrum at 643 nm, and thus it possesses many superiorities over short-wavelength ones in bioimaging. Finally, probe 1 exhibited excellent cell permeability and low cytotoxicity for the successful detection of HSO3- in living RAW 264.7 macrophage cells, implying that this probe would be of great benefit to biological researchers for investigating the detailed biological and pharmacological functions of HSO3- in biological systems.