Charge-dependent co-deposition of polydopamine with functional polymers for stable and antibacterial surface coatings

The development of effective antibacterial surface coatings is essential for reducing the risk of implant-associated infections. Polymers with different charge characteristics, including nonionic, cationic and anionic polymers, have been widely explored for antibacterial/antifouling surface modification. However, a systematic comparison of their interactions with polydopamine (PDA) during coating formation remains limited. In this work, a series of composite coatings were fabricated via a one-step co -deposition process involving dopamine and polymers with different charge properties. The coating formation behavior, interfacial adhesion, stability, surface morphology, and antibacterial performance were systematically investigated. The results demonstrate that co -deposition with cationic polymers, particularly polyquaternary-2 (PQ), and polyhexamethylene biguanide hydrochloride (PHMB), significantly enhances the adhesion and stability of PDA coatings. Among the evaluated systems, the PDA-PQ coating exhibited pronounced antibacterial activity through contact-mediated and photothermal mechanisms while maintaining good cytocompatibility, as confirmed by both in vitro and in vivo assessments. This study elucidates the role of polymer charge in governing PDA-based coating formation and performance, providing valuable insights for the rational design of PDA-based antibacterial coatings for medical device surfaces.