A novel peptide-based fluorescent probe with large Stokes shift for simultaneous detection of zinc (II) and mercury (II): Smartphone, test strips, living cells and real samples applications

A simple and efficient peptide-based fluorescent probe L with large Stokes shift was synthesized, which used dansyl group as fluorophore and tetrapeptide backbone (HisGluPheCys-NH2) as recognition group for the determinations of Zn2+and Hg2+by different fluorescence response modes in 100% aqueous solution. L exhibited a highly efficient and specific selectivity for Zn2+ based on fluorescence enhancement as well as the naked eye recognition of Zn2+ was realized through the solutions color changed. Meanwhile, as a highly selective "turn off" probe, L could rapidly detect Hg2+ based on obvious fluorescence quenching. The limit of detection (LODs) for Zn2+ and Hg2+were 52.6 and 49.7 nM, respectively. Moreover, L has good accuracy, exciting water-solubility and low toxicity, which was successfully applied to determinations of Zn2+ and Hg2+ in real water samples and fluorescence imaging of Zn2+ and Hg2+ in living cells. Test strips of probe L was prepared by immersion and used for visual detection of Zn2+ and Hg2+by naked eye. Finally, the gradient change of fluorescence color of L was captured by smartphone, and then content analysis was carried out by smartphone color recognition APP.