Bacterial Adhesion on Orthopedic Titanium Implants Coated with Silver-Doped Hydroxyapatite and Chitosan

Orthopedic site infections remain a growing concern in implantology, particularly in light of rising antibiotic resistance. Identifying optimal, standardized antimicrobial treatments is increasingly challenging. Beyond the design and functional properties of orthopedic materials, key factors such as bacterial adhesion and genotoxicity must also be considered. To develop implant materials with enhanced antibacterial properties and biocompatibility, this study investigated titanium (Ti) surfaces coated with chitosan (CS) and silver-doped hydroxyapatite (AgHA) at weight ratios of 1:1, 1:2, and 2:1. The incorporation of silver ions into hydroxyapatite demonstrated potent antibacterial activity, achieving a greater than 99% reduction in Staphylococcus aureus (S. aureus) viability in solution after just two hours of incubation, effectively inhibiting further bacterial growth. Furthermore, CS coatings combined with AgHA significantly reduced S. aureus adhesion and proliferation on Ti surfaces, with over 96% reduction in total bacterial viability. Further biological evaluation was performed on the CS:AgHA = 2:1 coating, selected for its favorable surface and antibacterial characteristics. Genotoxicity and cytotoxicity assessments using human peripheral blood lymphocytes showed no significant increase in micronuclei incidence for either uncoated Ti or CS:AgHA = 2:1-coated surfaces. Additionally, cell viability remained above 84%, indicating favorable biocompatibility under the experimental conditions used. Overall, these findings highlight the potential of CS:AgHA = 2:1 composite coatings for further investigation in antibacterial orthopedic implant applications.