Super Hydrophilic Semi-IPN Fluorescent Poly( N -(2-hydroxyethyl)acrylamide) Hydrogel for Ultrafast, Selective, and Long-Term Effective Mercury(II) Detection in a Bacteria-Laden System.

Convenient, low-cost chemosensors for hazardous mercury ion detection have been receiving more and more attention in recent studies. However, most of these practical studies are based on an ideal sterile detecting atmosphere and ignore the role of bacteria in actual Hg(II) analytes. Herein, we demonstrate a new type of hydrophilic semi-IPN fluorescent polyHEAA hydrogel chemosensors fabricated by UV polymerization in situ interpenetrating fluorescent polymer PA-NDBCB with a polyHEAA network. Because of specific intermolecular interaction, i.e., hydrogen bonding between hydrophilic fluorescent polymer and polyHEAA matrix comprising a distinct semi-IPN structure, the mechanical property of bulk fluorescent hydrogels can be greatly improved over that of pure polyHEAA hydrogels. Moreover, the design of the hydrogel chemosensors rely on the highly efficient cyclization reaction between Hg(II) ions and the thiourea moieties that induce a visible "green-to-blue" fluorescence color change. On account of the hydrophilic porous structures, these hydrogel chemosensors achieve ultrafast, sensitive, selective Hg(II) detection (detection limit of 0.067 μM) and enable facile ratiometric actual detection in real-world aqueous system. Notably, they maintain fluorescence emission and detection property even under long-term coculture in a complex E. coli bacteria-laden environment. This novel strategy could inspire future construction of soft interfaces/fluorescent apparatus for hazardous Hg(II) detection in a complex real-world system.