Hybrid ZnO/chitosan antimicrobial coatings with enhanced mechanical and bioactive properties for titanium implants

A biocomposite coating comprising chitosan and ZnO deposited on a porous Ti oxide is developed to avoid orthopedic and dental implant-related infections. The coating comprised of an inner layer of nanoporous TiO₂ and the outer layer of the chitosan matrix with ZnO nanoparticles. Microbiological tests show that chitosan coating is effective against Escherichia coli (E. coli), however, its ability to inhibit bacterial adhesion is very limited. A 1.2-fold increase in the antibacterial activity of chitosan/ZnO coating against E. coli was detected as compared to the chitosan coating alone, and the chitosan/ZnO efficiently inhibited biofilm formation. In addition, the chitosan/ZnO coating exhibited improved bioactivity compared to the chitosan coating. The improvement in antibacterial properties and bioactivity of the chitosan/ZnO coating is attributed to the release of Zn²⁺ ions. The critical force of scratching the chitosan/ZnO coating was approximately twice that of the chitosan coating. The potentiodynamic polarization results confirmed that the corrosion resistance of the implant with ZnO/chitosan/Ti structure was improved. In addition, cytocompatibility evaluation indicated that the chitosan/ZnO coating has good cytocompatibility in MG-63 cells as compared to pure Ti.