Durable heparin/zwitterion composite coatings for enhanced hemocompatibility and antibacterial performance.

The effectiveness of surface coatings for blood-contacting medical devices is often limited by poor stability, increasing the risk of thrombosis and infection. We developed a heparin/zwitterion coating comprising an amine-rich dopamine/polyethyleneimine adhesive layer and a composite top layer of sulfobetaine methacrylate/glyceryl methacrylate copolymer with surface-immobilized heparin. The top layer's carboxyl and epoxy groups reacted with the adhesive layer's amino groups, forming interfacial multipoint amide crosslinking and enhancing stability. This crosslinked coating showed excellent mechanical durability from 25 °C to 100 °C and maintained stability on PVC substrates for 14 days in phosphate-buffered saline after soaking and shearing. Heparin integration endowed natural anticoagulant properties, while zwitterionic components provided strong antimicrobial effects through charge-balanced hydration layers, resolving the electrostatic conflict between anticoagulation and antibacterial needs. In vitro tests showed excellent antibacterial efficacy (93.46% against E. coli, 98.48% against P. aeruginosa, 99.62% against S. aureus, and 99.09% against MRSA) and anticoagulant performance, with a 98.72% reduction in thrombus weight compared to bare PVC after 6 hours of blood exposure. This study presents a solid platform for creating stable, multifunctional coatings with great potential to improve the hemocompatibility and infection resistance of blood-contacting medical devices.