Surface-engineered antibacterial and anti-calculus coatings on polyester via chitosan–amino acid grafting and silver–ion coordination

Surface modification strategies play a vital role in preventing calculus formation and bacterial adhesion, which are crucial for improving the performance of degradable implantable medical devices such as ureteral stents. In this study, poly(glycolide-co-caprolactone) (PGACL), a representative biodegradable polyester with excellent elasticity and degradability, was selected as the substrate. Chitosan–amino acid graft copolymers were synthesized via EDC/HOBt mediated acylation and immobilized onto aminated PGACL sheets through a Schiff-base coupling reaction, followed by silver–ion coordination to introduce antibacterial properties. FTIR and 1H NMR analyses confirmed that different types of amino acids were successfully grafted onto the chitosan backbone. The modified PGACL sheets exhibited significantly improved hydrophilicity, enhanced antibacterial activity, and strong resistance to calculus formation, while maintaining favorable cytocompatibility. Among all coatings, the one containing thiol groups showed the best comprehensive performance, attributed to the formation of stable Ag–S coordination structures between thiol (–SH) groups and Ag+ ions. These results demonstrate that chitosan–amino acid–silver coatings provide a biocompatible and efficient surface-engineering strategy with both antibacterial and anti-calculus functions, offering a promising approach for the development of next-generation degradable polymeric materials for urological applications.