Synergistic effects of collagen and silver on the deposition characteristics, antibacterial ability, and cytocompatibility of a collagen/silver coating on titanium

Abstract Implant-associated infections may be prevented by coating silver on a titanium implant; however, the excessive release of Ag+ can induce cytotoxicity. This study fabricated a silver/collagen coating on a porous titanium oxide surface to improve the antibacterial ability of titanium implants without compromising cytocompatibility. Micro-arc oxidation was first applied on titanium to form a porous surface, which was then coated with silver through electrochemical deposition. Collagen was then used to modulate the amount and shape of the silver applied. It was found that high potential induced silver aggregations grow anisotropically into coarse dendritic structures non-uniformly distributed on the surface. The co-deposition of collagen and silver reduces the silver-aggregation size and allows the silver to grow into a spherical shape. The silver/collagen coating can effectively prevent adhesion and proliferation of Escherichia coli. In addition, the silver/collagen coating significantly improves the hydrophilicity (water contact angle of 39.8°) of the porous titanium oxide (109.5°). Based on MTT assay tests, the mean optical densities for the silver/collagen coated surfaces after 72 h of MG63 osteoblast cell adhesion were greater than those obtained from the silver coated surfaces. Therefore, the silver/collagen coating is expected to be useful for the development of new antibacterial dental and orthopedic implants.