Waterborne Polyurethane-Stabilized Hydrogel Coating with Lubrication and Antibacterial Properties on Medical Catheters

Medical catheters require lubrication and antimicrobial properties to reduce complications, such as tissue trauma and bacterial infections. Coating hydrogel on the catheter surface is a promising strategy; however, it usually faces the challenge of weak interfacial adhesion, thus leading to coating delamination or fracture and failure. Here, a waterborne polyurethane (WPU)-triggered surface bonding strategy was presented to construct hydrogel coatings, which involved two key steps: (i) coating a sticky WPU layer on the catheter surface and (ii) dip-coating the WPU-coated catheter with a monomer solution consisting of quaternary ammonium chitosan (QCS), sulfobetaine methacrylate (SBMA), <i>N</i>-vinylpyrrolidone (NVP), and zinc sulfate heptahydrate (ZnSO₄·7H₂O) for growing the hydrogel layer by ultraviolet initiation. The hydrogel coating demonstrated tough adhesion performance to the catheter, and the interfacial bonding strength achieved 536 N/m. Meanwhile, the hydrogel coating had a variable thickness adjusted by QCS and possessed excellent hydrophilicity (WCA = 24.6°) and low surface friction properties (COF = 0.0357) based on the formation of the hydration layer. Furthermore, the introduction of ZnSO₄·7H₂O endowed the hydrogel coating with prominent antimicrobial properties against <i>Escherichia coli</i> (Gram-negative bacteria) and <i>Bacillus subtilis</i> (Gram-positive bacteria). This approach paves an avenue for fabricating hydrogel coatings with strong interface stability, controllable thickness, lubrication, and antibacterial properties.