A rapid “on-off-on” peptide-based fluorescent probe for selective and consecutive detection of mercury and sulfide ions in aqueous systems and live cells

Abstract

A simple and rapid responsive peptide-based fluorescent probe DM was designed, synthesized and found that the fluorescent of DM was quenched in the presence of Hg2+ ions with high selectivity, and no interference with other common metal ions. Notably, the detection limit on fluorescent response of DM to Hg2+ was as low as 21.56 nM. The fluorescent titration, Job’s plot and HR-MS data suggested that the formation of a new ensemble system between DM and Hg2+ in 1:1 binding stoichiometry. Additionally, the DFT theoretical investigation was carried out to understand the behavior of the sensing DM toward Hg2+. Once binding with Hg2+, DM-Hg2+ ensemble system showed characteristic fluorescent “off-on” behavior for S2−, and the limit of detection was determined to be 32.92 nM. DM displayed fluorescent “on-off-on” change with alternately added Hg2+ and S2−, and was continuously circulated for more than 10 times. More importantly, DM exhibited the potential for the detection of Hg2+ and S2− in HK2 living cells based on excellent water-solubility and low biological toxicity.