Physiological pH Responsive Integrated Antifouling and Antimicrobial Interface with Long-Term Activity via Amino-Carboxylate Coordination Chemistry

Microbial colonization and infection of biomedical devices remain a persistent clinical challenge. Interfacial coatings with antifouling and antimicrobial functions simultaneously under physiological conditions are highly desired to mitigate the infection risks. Herein, we constructed a durable serine-derived zwitterionic antifouling and antimicrobial interfacial structure via amino-carboxylate coordination with Cu(II) ions in alkaline aqueous solutions. Comprehensive surface characterizations verified the successful incorporation of Cu(II) into serine-based zwitterionic polymeric brushes without changing the valence state. The engineered interfaces maintained favorable hydrophilicity with water contact angles ranging between 16° and 24°, which contributed to their remarkable antifouling activities against bacteria, red blood cells, and platelet adhesion. Crucially, the surface exhibited broad-spectrum antimicrobial efficacy against both Gram-positive and Gram-negative pathogens under physiological pH conditions without extra stimulation, achieving bactericidal rates exceeding 99%. Moreover, owing to the durable control release of Cu(II), the antibacterial rate against E. coli was still over 90% even after 28 days of exposure in PBS. Furthermore, the surface exhibited acceptable cytotoxicity while maintaining superior hemocompatibility, with the hemolysis rate below 1%. Overall, this physiological pH responsive integrated antifouling and antimicrobial interface presented a promising and convenient platform for next-generation biomedical devices requiring antifouling properties and long-term antimicrobial protection simultaneously.