Smartphone-assisted colorimetric and fluorescent dual-functional peptide-based probe for multianalyte visual detection in 100% aqueous media, living cells and test strips

Abstract

In this study, a novel colorimetric and fluorescent dual-functional peptide-based probe FAHF was rationally designed and successfully prepared using solid phase peptide synthesis (SPPS) technology. As designed, FAHF exhibited high selectivity and rapid response towards Cu2+ and Hg2+ with colorimetric and fluorescent dual-signal sensing mode in 100% aqueous media, and the recognizable color change was clearly observed with naked eye under daylight lamp and 365 nm UV light. In addition, the low concentrations of Cu2+ and Hg2+ could be accurately detected with the limit of detection (LODs) for 61.02 nM and 40.27 nM, respectively. At the same time, due to the strong coordination of Cu2+/Hg2+ with S2−, the FAHF-Cu2+ ensemble and FAHF-Hg2+ ensemble formed in situ were successfully used as two new promising cascade probes for rapidly and sequentially detecting S2− based on colorimetric method and fluorescence “off-on” response, and the corresponding limit of detection (LODs) were calculated to be 45.12 nM and 102.38 nM, respectively. Moreover, FAHF was successfully applied for fluorescence imaging of Cu2+, Hg2+ and S2− in two living cells due to good cell permeability and low cytotoxicity. Finally, FAHF was successfully made into test strips for visual detection and rapid analysis under 365 nm UV lamp, and smartphone-assisted visual assays were successfully used to evaluate and monitor the Cu2+ levels with a limit of detection (LOD) for 0.62 µM.