Mussel-inspired citric acid crosslinked antifouling and bactericidal coatings constructed using sulfobetaine zwitterionic/quaternary ammonium cationic copolymers

Inhibiting and reducing bacterial infections associated with biomedical implants and devices remains a significant challenge. In this study, we successfully grafted crosslinked antifouling and bactericidal coatings onto a polyurethane (PU) surface using sulfobetaine (SB) zwitterionic and quaternary ammonium cationic (QAC) copolymers through a combination of PDA-assisted co-deposition and amidation reactions. The successful formation and surface properties of the crosslinked coatings were characterized using Fourier transform infrared spectroscopy (FT-IR), water contact angle (WCA) measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical corrosion tribometry (MFT-EC), and atomic force microscopy (AFM). The antifouling performance was evaluated <i>via</i> protein adsorption, platelet adhesion, whole blood adhesion, and cytotoxicity assays. Additionally, the antibacterial and bactericidal efficacy was evaluated using <i>E. coli</i>, <i>P. aeruginosa</i> and <i>S. aureus</i> as models. Our results indicate that the molar ratio of SB and QAC critically influences the antifouling and bactericidal properties, and a relatively high SB content (60 mol%) combined with a low QAC content (20 mol%) achieves an optimal balance between antifouling and bactericidal properties. This combination of zwitterionic and quaternary ammonium cationic copolymer modifications not only effectively kills bacteria upon contact but also prevents the adhesion of dead bacteria, demonstrating promising potential for applications in biomedical implants and devices.