Layer-by-layer assembly of chitosan quaternary ammonium salt/polyacrylic acid-Zn2+ as a titanium dental implant coating with prominent antibacterial and osteogenic activities†

Bacterial resistance and osteogenic activity are crucial requirements for titanium (Ti) dental implants during their practical use in clinical applications. In this work, a layer consisting of positively charged chitosan quaternary ammonium salt (QCS), negatively charged polyacrylic acid (PAA) and zinc gluconate was well constructed via a layer-by-layer (LbL) procedure. After surface modification, the layer exhibited a significant reduction of approximately 46° in the water contact angle, demonstrating enhanced hydrophilicity. The modified surface further demonstrated excellent thermal stability at a sterilization temperature of 115 °C. Owing to the consistent release of Zn²⁺, the structurally optimized QCS/PAA-Zn²⁺ coating achieved a remarkable antimicrobial activity of 97% against S. aureus. Moreover, its antibacterial efficacy remained highly effective, with an inhibition rate of 85%, even after cycling tests. The excellent biocompatibility and osteogenic activity of the layer were further proved by a cellular experiment. Our results may provide guidance for the upgradation of Ti-based implant coatings.