Ph-Responsive Dual-Functional Coating For Titanium Implants

This study developed a pH-responsive multilayer coating based on antimicrobial peptides for titanium implants, aiming to simultaneously address the clinical challenges of implant-associated infection control and insufficient soft tissue integration. A cyclic electrostatic self-assembly technique was used to construct the functional coating (Ti-LBL): A chitosan layer was deposited on polished Ti to modulate surface potential; Ten LbL cycles of alternating deposition of [tannic acid/polyacrylic acid (TA/PAA)] complexes and antimicrobial peptide LL-37 were performed. Control groups: Ti (bare) and Ti-LL37 (physically adsorbed). Physicochemical properties were characterized by SEM/XPS/FTIR/contact angle analysis, with assembly kinetics monitored via quartz crystal microbalance. LL-37 release profiles under simulated physiological/infectious conditions were quantified by ELISA, antibacterial efficacy against S. aureus by CFU assays, and fibroblast response through F-actin/CCK-8 assays. A pH-responsive release coating was successfully constructed. Under acidic conditions, the TA/PAA-mediated coating triggered rapid LL-37 release, whereas lower cumulative release was observed at physiological pH. Compared to the Ti and Ti-LL37 groups, the Ti-LBL group exhibited significantly reduced bacterial survival rates and enhanced early adhesion, proliferation, and spreading of gingival fibroblasts. This TA/PAA-mediated intelligent responsive coating provides a dual-functional strategy for implants to improve biocompatibility and anti-infection performance.