Grafting zwitterionic brushes from the surface of an epoxy-based transparent hydrogel for antifouling performance

Non-specific biofilm formation (biofouling) commonly occurs to the surface of biomedical devices, which causes infection to the human tissues and function loss after implantation. To enhance the antifouling properties on the bioinert hydrogel-based biomaterials, a novel surface grafting approach was developed using surface radical chain-transfer reaction mediated by DL-dithiothreitol (DTT), rather than catalyzed by cytotoxic metal ions. Zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) brushes were grafted on the surface of poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (PHG) to obtain PHG-graft-PMPC (PHG-g-PMPC) hydrogel, which were shown to have tunable surface hydrophilicity while maintaining high water content and transparency. Elemental composition analysis and micromorphology demonstrated the success of surface grafting. Protein adhesion assays were carried out, showing the reduction of bovine serum albumin, lactoferrin, and lysozyme adhesion by ∼90%, 80%, and 70%, respectively, compared to the pristine hydrogels. Significant resistance of bacterial attachment was observed on the surface-modified hydrogels using gram-negative Escherichia. coli and gram-positive Staphylococcus aureus, respectively. The PHG-g-PMPC hydrogel is potentially feasible in various biomedical applications, especially for preventing surface biofouling of ophthalmic implants and devices. Furthermore, this de novo approach provides a universal platform for surface functionalization via thiol-epoxy click chemistry and surface radical chain-transfer reaction.