Enhanced Long-Term Antibacterial and Osteogenic Properties of Silver-Loaded Titanium Dioxide Nanotube Arrays for Implant Applications

Yicun Yao,1,2 Peifen Lin,1 Dongping Ye,1 Haixiong Miao,1 Lin Cao,3 Peng Zhang,3 Jiake Xu,4,5 Libing Dai1,2 1Department of Orthopedics, Guangzhou Red Cross Hospital, Guangzhou Red Cross Hospital of Jinan University, Guangzhou, Guangdong, 510220, People’s Republic of China; 2Guangzhou Institute of Traumatic Surgery, Guangzhou Red Cross Hospital, Guangzhou Red Cross Hospital of Jinan University, Guangzhou, Guangdong, 510220, People’s Republic of China; 3Institute of Advanced Wear & Corrosion Resistant and Functional Materials, National Joint Engineering Research Center of High Performance Metal Wear Resistant Materials Technology, Jinan University, Guangzhou, 510632, People’s Republic of China; 4Faculty of Pharmaceutical Sciences, Shenzhen University of Advanced Technology, ShenZhen, Guangdong, 518107, People’s Republic of China; 5School of Biomedical Sciences, The University of Western Australia, Perth, 6009, AustraliaCorrespondence: Peng Zhang, Email [email protected] Libing Dai, Email [email protected]: This study explored constructing silver-loaded titanium dioxide nanotube (TiO2 NT) arrays on titanium surfaces using anodic oxidation combined with ion implantation. We assessed the cytocompatibility, antibacterial properties, and osteogenic potential of these silver-loaded TiO2 NT arrays, along with the underlying mechanisms.Methods: We utilized anodization to create TiO2 NT arrays and employed ion implantation to load silver ions, categorizing samples into groups NT-Ag-II-L, NT-Ag-II-M, and NT-Ag-II-H based on different Ag ion dosages. Characterization was performed via scanning electron microscopy (SEM). We evaluated cell compatibility and assessed the antimicrobial performance and Ag ion release profiles. The osteogenic ability of the samples was measured, and the effects on ERK5 and osteogenesis-related factors were analyzed. To clarify the role of ERK5 in osteogenesis, we inhibited the ERK5 pathway using BIX02188 and subsequently re-evaluated osteogenic capacity in co-cultured cells.Results: SEM analysis showed that in the NT-Ag-II-M group, Ag ions exhibited a flake-like distribution atop the TiO2 NTs, while NT-Ag-II-L and NT-Ag-II-H groups presented clustered grid structures. Energy-filtered transmission electron microscopy (EFTEM) confirmed orderly Ag ion arrangements within the lumens of the nanotubes. Notably, the silver-loaded TiO2 NT arrays did not inhibit MC3T3-E1 cell proliferation and enhanced early cellular adhesion. All samples displayed significant antimicrobial activity initially, which decreased after seven days; however, Ag ion release decreased gradually over the first 14 days before stabilizing. Additionally, the samples increased alkaline phosphatase activity, collagen secretion, and extracellular matrix mineralization, up-regulating ERK5 and other osteogenic factors. Inhibition of the ERK5 pathway suppressed the osteogenic capabilities of the samples.Conclusion: Anodization and ion implantation successfully produced silver-loaded TiO2 NT arrays on titanium surfaces, demonstrating no cytotoxicity, sustained antimicrobial properties, and enhanced osteogenic potential. The antimicrobial effect relates to silver ion release, whereas osteogenesis is promoted by ERK5 signaling triggered by silver ions. Keywords: titanium, implant associated infection, silver ion, ion implantation, antibacterial properties, osseointegration, ERK5