Peptide-based AIE fluorescent probe for sequential detection of Hg2+ and S2− and its multi-functional applications

It is urgent to develop highly sensitive detection technologies to achieve precise detection of mercury ions (Hg 2+ ) and sulfur ions (S 2− ) as they pose a serious threat to human health and the ecological environment. In this work, a novel peptide-based fluorescent probe TPE-DAH with tetrastyrene (TPE) derivative and tripeptide backbone (Asp-Ala-His-NH 2 ) was precisely designed and successfully synthesized, which exhibited the highly emitting characteristic of aggregation-induced emission (AIE) effect. As design, TPE-DAH exhibited excellent selectivity and high sensitivity for Hg 2+ with the limit of detection (LOD) as low as 8.4 nM. Importantly, the complex TPE-DAH -Hg 2+ was investigated by fluorescence technique which clearly established the high selectivity towards S 2− based on fluorescence “off-on” response, and the LOD of S 2− was 98.9 nM. Notably, TPE-DAH not only successfully achieved fluorescence imaging in living cells and zebrafish larvae with low toxicity and excellent permeability, but also successfully applied to detection of Hg 2+ and S 2− in real water samples with good recovery and accuracy. Advantageously, TPE-DAH was fabricated into a portable fluorescence test strips and was used for visual detection of Hg 2+ and S 2− , demonstrating that its potential for multi-functional applications. Remarkably, an ultrasensitive logic gate with TPE-DAH was constructed by using sequential detection strategy. Furthermore, we ingeniously combined the smartphone App analysis device with the colour change of TPE-DAH solutions to construct a visual analysis device, thereby achieving semi-quantitative determination.