An Aggregation‐Induced Emission Active Peptide‐Based Fluorescent Probe for Highly Selective and Sensitive Detection of Hg(II) Ions and Its Multifield Applications

In this study, a novel aggregation‐induced emission (AIE) active peptide‐based fluorescent probe ( L ) was rationally designed and successfully synthesized with a tetraphenylethene (TPE) derivative modified tetrapeptide (Pro–Gly–Asp–His–NH 2 ). L has many advantages of good water solubility, a large Stokes shift, and a high fluorescence quantum yield. According to the design, L was utilized to selectively recognize Hg 2+ against other competitive metal ions in the HEPES buffer solution (pH = 7.4, 10.0 mM, containing 5% DMSO), and the limit of detection (LOD) for Hg 2+ was obtained to be as low as 25.4 nM. In addition, L not only was successfully applied to monitor Hg 2+ in living cells and zebrafish larvae, but also was used to measure Hg 2+ in three different real water samples. Moreover, the test strips were successfully made using L solution, and qualitatively identified Hg 2+ through using the naked eye under UV light at 365 nm. Furthermore, the reversible switching characteristics of L were used to mimic the INHIBIT molecular logic gate. More interestingly, the integrated smartphone color recognition App converts the color of L solution into digital values through the RGB channel and was successfully applied to the semiquantitative detection of Hg 2+ without relying on expensive instruments.