Interfacial Assembly of a Zwitterionic-Cationic Terpolymer on Titanium via Mussel-Inspired Chemistry for Antifouling and Antibacterial Coatings

The fabrication of robust multifunctional polymer coatings on titanium remains challenging because of the limited surface reactivity of metallic substrates. Herein, a zwitterionic-cationic random terpolymer, poly(GMA- co -MPC- co -DMC) (PGMD), was designed and synthesized by integrating glycidyl methacrylate (GMA) as a reactive anchoring unit, 2-methacryloyloxyethyl phosphorylcholine (MPC) as an antifouling component, and methacryloxyethyl trimethylammonium chloride (DMC) as an antibacterial component. Using mussel-inspired polydopamine chemistry, PGMD was immobilized onto titanium via two PDA-assisted interfacial assembly routes: one-step codeposition and sequential deposition. The sequential route produced a more defined interfacial architecture, higher deposition efficiency at a lower polymer feed concentration, and improved surface hydrophilicity. These differences in surface structure and physicochemical properties resulted in markedly reduced bovine serum albumin and fibrinogen adsorption and strong inhibition of Streptococcus mutans biofilm formation at both 4 and 24 h. In addition, the coatings exhibited good cytocompatibility toward human gingival fibroblasts and negligible hemolysis. This work identifies the PDA-assisted assembly route as a key factor controlling polymer exposure, deposition efficiency, and the antifouling/antibiofilm performance of zwitterionic-cationic coatings on titanium.