Peptide-Based Fluorescent and Colorimetric Dual-Functional Probe for Visual Detection of Cu2+, Hg2+ and S2− in 100% Aqueous Media, Living Cells and Paper Test Strips

Abstract

In this study, a novel peptide-based fluorescent and colorimetric dual-functional probe ( FAHK ) was designed and synthesized by simulating the structure of copper peptide. FAHK exhibited high selectivity and rapid response to Cu 2+ and Hg 2+ with two non-fluorescence ensembles FAHK- Cu 2+ and FAHK- Hg 2+ formation by the 2:1 coordination mode, the detection limits of Cu 2+ and Hg 2+ were 29.8 nM and 20.3 nM, respectively. FAHK showed a naked eye colorimetric response for Cu 2+ and Hg 2+ in an aqueous solutions under visible light. As two new promising cascade probes, FAHK- Cu 2+ and FAHK- Hg 2+ ensemble were used for the sequential selective recognition of S 2− according to the displacement approach with a fluorescence turn-on response and colorimetric change, and the detection limit of 0.28 μM ( FAHK -Cu 2+ ensemble) and 0.13 μM ( FAHK -Hg 2+ ensemble) for S 2− were well below the safety level the H 2 S standard in drinking waters (14.8 µM, WHO guidelines). What’ more, in view of low toxicity and biocompatibility, the potential application of FAHK in biological systems was demonstrated via imaging living cells. More importantly, FAHK could also be made into a paper test strips for visual detection of Cu 2+ , Hg 2+ and S 2− with the naked eye under 365 nm UV light and visible light, which suggested that better portability and operation simplicity that is favourable for on-site analysis.

Keywords: Tripeptide, Dual-functional probe, Visual detection, Cells imaging, Paper test strips