Sensitive Water-Soluble Fluorescent Probe Based on Umpolung and Aggregation-Induced Emission Strategies for Selective Detection of Hg²⁺ in Living Cells and Zebrafish

Using Hg2+-induced umpolung reaction and aggregation induced emission (AIE), we have rationally developed a water-soluble fluorescent probe 2,2′-(((4-(4,5-bis­(4-methoxyphenyl)-1-phenyl-1H-imidazol-2-yl)­phenyl)­methylene)­bis­(sulfanediyl))­diethanol (MPIPBS) for Hg2+ detection. MPIPBS was found to have high selectivity and sensitivity toward Hg2+ detection. The mechanism of MPIPBS response to Hg2+ was verified by 1H NMR titration, HPLC, and HRMS spectroscopy. The detection limit was examined to be 1.45 nM, which is lower than most reported probes for Hg2+. Taking advantage of excellent optical properties of AIEgen, a paper based sensor for Hg2+ detection was fabricated by immobilizing the MPIPBS on Waterman test paper. Meanwhile, MPIPBS showed satisfactory analytical performance in real water and urine samples. Further, thanks to the high water solubility, cell membrane permeability and low cytotoxicity, MPIPBS was further used to detect Hg2+ both in living cells and zebrafish. We anticipate that the prepared probe was available to detect Hg2+ in environment and biosamples