Chitosan based fluorescent interpenetrating network polymeric probes for the sensitive detection and efficient removal of Hg+ ions

Chitosan (CS) based interpenetrating polymer network (IPN) is formed by cross-linking of CS with another polymer. It exhibits the ability of detecting environmental pollutants. In this work, the cross-linked CS was used as the network skeleton, the RAFT agent could produce an interpenetrating network with CS during the polymerization process, thereby forming a fluorescent hydrogel-type IPN (CS-Cy-PMAm and CS-Cy-PHD). The basic properties of CS-based hydrogels were analyzed by NMR, MS, FT-IR, SEM, TEM, AFM, and so on. This hydrogel prepared by in-situ synthesis technology not only has excellent film-forming properties but also EGME and toluene solvent molecules can significantly enhance the fluorescence of the hydrogel by infiltrating or squeezing the CS network. Due to the chelation of C N, C O, and thioester bonds with Hg + to block the PET process, the hydrogel exhibited a highly sensitive 46-fold fluorescence enhancement up the Hg + addition. The detection limit (LOD) of Hg + was 13 nM, and the adsorption capacity was 84.0 mg·g −1 . At the same time, the fluorescent film is made into a colorimetric card, which can realize real-time and portable detection of Hg + . This method expands the application of CS-based IPNs in environmental science and engineering.