Chitosan based fluorescent interpenetrating network polymeric probes for the sensitive detection and efficient...

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 CN, CO, 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.