Recently, the problem of infection on implanted devices caused by the formation of biofilms has been recognized. Surface treatment to prevent the initial stages of bacterial adhesion and subsequent bacterial growth is the only possible solution against such infection. In this study, simple electrochemical treatment was used for introducing silver, an antibiotic agent, on the titanium surface. A porous oxide layer containing small amounts of silver was formed on the metal of the substrate. This was done by microarc oxidation using the electrolyte with silver nitrate. The porous oxide layer was almost amorphous with a small fraction of anatase phase. The samples prepared using the electrolyte containing 0.04 mM or a higher concentration of silver nitrate showed an excellent antibacterial effect against both E. coli and S. aureus. However, the proliferation of osteoblast-like cells in the samples was not affected when a concentration of 0.5 mM or lower was used. Moreover, samples containing silver showed no harmful effects on the process of bone differentiation. Furthermore, the calcification process of the cells on the samples treated with and without silver were more promoted than that on untreated Ti. Thus, we found that it is possible to use this optimum concentration of silver to realize the conflicting biofunctions: its antibacterial property and osteogenic cell compatibility.
Keywords: anodic spark deposition; antibacterial property; biofilm; calcification; cytotoxicity; microarc oxidation; osteoblast-like cell; plasma electrolytic oxidation; silver; titanium.