Antibacterial Efficiency and Osteoblast Viability of Ag/AgO/Ag₂O Nanoparticles on Microarc-Oxidized TiO₂

Infections associated with titanium-based medical and dental implants present a major clinical challenge, as they can compromise osseointegration and long-term implant stability. Silver-based nanoparticles (NPs) are widely recognized for their strong antimicrobial properties, and when combined with titanium, they hold significant promise for developing infection-resistant and biocompatible implant surfaces. In this study, Ag/AgO/Ag₂O NPs were deposited onto highly porous TiO₂ layers formed on the Ti6Al4V alloy by microarc oxidation (MAO), with the aim of simultaneously enhancing antibacterial performance and supporting osteoblast activity. The NPs exhibited a predominant size of 8.7 ± 0.1 nm, with smaller particles oxidized to AgO and Ag₂O, and larger particles (∼10 nm) composed of metallic Ag. SEM evaluation revealed that the NPs were homogeneously dispersed across the oxide surfaces without altering the rough and porous morphology of TiO₂. The MAO-treated surfaces initially showed hydrophobic behavior (contact angle of 94.1 ± 0.3°), which shifted to hydrophilic after Ag/AgO/Ag₂O NP deposition due to increased hydroxyl group formation. Antibacterial assays against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) revealed a significant enhancement in antibacterial activity, particularly for surfaces with the highest Ag/AgO/Ag₂O NP density. Meanwhile, osteoblast cell viability assays demonstrated no reduction in metabolic activity after 72 h, and SEM images confirmed cell adhesion and proliferation. Overall, these findings highlight the potential of Ag/AgO/Ag₂O NP-modified TiO₂ surfaces as multifunctional coatings that combine infection resistance with osteoblast compatibility, offering promising applications in dental and orthopedic implants.