Ultrasensitive mercury ion and biothiol detection based on Dansyl-His-Pro-Gly-Asp-NH2 fluorescent sensor

A novel Dansyl-labeled tetrapeptide sensor (D-P4) was designed for the ultrasensitive detection of mercury ion by spectroscopic analyses. The sensor exhibited an excellent selectivity and sensitivity to Hg2+ with a ‘turn-off’ fluorescence response. In addition, D-P4-Hg system presented a good ‘turn-on’ fluorescence response to biothiols. The research findings provide a strategy for the design of new sensors to detect metalions. [Display omitted] •Ultrasensitive Hg2+ and biothiol detection based on the fluorescent peptidyl sensor were developed.•Spectroscopic analyses were applied to study the biointeraction mechanism of Hg2+ to peptidyl sensor.•The possible binding site of Hg2+ to peptidyl sensor was predicted by molecular docking method.•The fluorescent sensor exhibits an excellent selectivity and sensitivity to Hg2+ with a ‘turn-off’ fluorescence response. Mercury is an environmental contaminant, which is highly toxic even at extremely low concentrations. Long-term accumulation of mercury in human body will damage the central nervous system or digestive tract system. Here, a new fluorescent chemical sensor Dansyl-His-Pro-Gly-Asp-NH2 (D-P4) was synthesized for the determination of Hg2+. The D-P4 sensor exhibits excellent selectivity and sensitivity to Hg2+ in aqueous solution with a ‘turn-off’ fluorescence response. Furthermore, D-P4-Hg system displays a good ‘turn-on’ fluorescence response to biothiols. The calculated binding constant for the 1:1 complex of D-P4 with Hg2 + is 1.07 × 105 M−1, which also confirms the high affinity of D-P4 for Hg2+. Results indicate that the detection limit of D-P4 for Hg2+ is 61.0 nM, and that of D-P4-Hg system for Cys is as low as 80.0 nM.