Multimechanism Long-Term Antibacterial Coating with Simultaneous Antifouling, Contact-Active, and Release-Kill Properties

Catheter-related infections are some of the most common acquired infections in hospitals, and designing functional coatings on the surface of medical catheters to limit bacterial colonization and biofilm formation can be effective in avoiding infections. In this study, a composite coating (PU-PDA-Ag-PDA-PHMG) with simultaneous antifouling, contact-active, and release-kill properties was prepared on polyurethane (PU) surfaces using polydopamine, Ag nanoparticles, and polyhexamethylene guanidine. This composite coating was systematically evaluated by studying its long-term hydrophilicity, long-term antibacterial property, antibiofilm property, silver release rate, mechanical property, and biocompatibility. The results of scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectrometry, and X-ray photoelectron spectroscopy showed that the PU-PDA-Ag-PDA-PHMG composite coating with multimechanism antibacterial properties was successfully prepared on the PU surface. Relative to the value of 97.62 degrees for the unmodified PU substrate, the water contact angle of this composite coating increased from 49.73 degrees to 61.68 degrees after 28 days of deionized water immersion, indicating excellent long-term hydrophilic properties. Also, this composite coating reduces protein adhesion by 58.67%. After 28 days of immersion in the PBS solution, the antibacterial rates against Staphylococcus aureus and Escherichia coli still reached 97.67% and 99.5%, respectively, indicating broad-spectrum and long-term antibacterial properties. The antibiofilm property of the composite coating surface was significantly improved compared with that of the single-mechanism coating, and the surface was almost free of any bacteria. The total amount of silver ions released from the composite coating was about 16.95% of that from PU-PDA-Ag within 14 days, which proved that the composite coating could significantly reduce the release rate of silver ions. The coating preparation process also did not change the original excellent mechanical properties and biocompatibility of PU (cytotoxicity level of 1). In conclusion, the composite coating developed in this study has great potential for reducing catheter-associated infections.