Enzyme initiated in situ gelation as an oxygen-tolerant, high adhesive, and versatile strategy for hydrogel coating preparation

Hydrogel coatings have great potential for applications in antifouling, biomedical, and electronic fields, but the lack of preparation strategies with mild gel-forming conditions, high adhesion, and versatility hinders their widespread use. Herein, a method called glucose oxidase (GOD)-initiated in situ gelation (GOD-IIG) is developed for preparing hydrogel coatings. The procedure includes immobilizing Fe[Gly]2 and GOD on the surface of the substrates by forming an intermediate layer using epoxy resin, and then immersing the pre-treated substrates into a monomer solution to initiate polymerization. In situ gelation on the surface of the substrates is triggered by free radicals generated through the redox reaction between ferrous glycine (Fe[Gly]2) and hydrogen peroxide (H2O2) produced by the GOD-catalyzed glucose oxidation process, which can be carried out in open-air environments. Using the GOD-IIG method, hydrogel coatings constructed from common low-adhesive polymers displayed an adhesive strength of up to 686 kPa and stable underwater adhesion for at least 7 days. Moreover, this method shows controllable hydrogel thickness and recyclable monomer solution for at least 25 times at room temperature. It is also applicable to a variety of hydrogel structures and substrates, such as plastic, metal, and glass, regardless of flatness or geometry. In order to demonstrate the applications of hydrogel coatings prepared by GOD-IIG method, the lubrication and antifouling abilities of the coatings were assessed, and the results indicated that the coatings had good hydration lubrication as well as oil and biofouling resistance. This method holds promise for advancing the preparation of hydrogel coatings and has potential applications in the fields of electrical, biological, and environmental engineering.