A coumarin-hemicyanine fluorescent probe for simultaneous detection and discrimination of biothiols, HSO3− and S2-

Biomercaptan, bisulfite (HSO₃⁻) and hydrogen sulfide (H₂S) are involved in many physiological and pathological processes in the human body. Therefore, it is of great significance to develop a fluorescent probe that can simultaneously detect and distinguish biological mercaptans from HSO₃⁻ and S²⁻. The probe CDI-1 was synthesized by combining coumarin with hemicyanine. The maximum absorption wavelength of the probe is at 609 nm. After adding Cys/Hcy and GSH, the probe shows varying degrees of blue shift, which can be used to distinguish Cys/Hcy and GSH. After it reacts with Cys/Hcy, the fluorescence intensity of the solution increases about twice, while it increases three times after it reacts with GSH. This phenomenon can also be used to distinguish Cys/Hcy from GSH. The probe CDI-1 can react with Cys completely within 30 min, with Hcy or GSH completely within 80 min, and with HSO₃⁻ and S²⁻ quickly within 20 min. The study on the effect of pH on the fluorescence performance of CDI-1 shows that the probe is suitable for detecting biological mercaptan or HSO₃⁻, S²⁻ in weak acid to weak alkali environments. The selectivity study showed that the probe CDI-1 had high specificity for biological mercaptan, HSO₃⁻ and S²⁻. This provides a new and simple method for simultaneous detection of biological mercaptan, HSO₃⁻ and S²⁻ ions.