Bioceramics Development and Applications

Next Generation Antibacterial Hydroxyapatite Coating: Antibacterial Activity of Ag Ions in Serum

Abstract

I. Noda, F. Miyaji, Y. Ando, H. Miyamoto, T. Shimazaki, Y. Yonekura, M. Miyazaki, M. Mawatari and T. Hotokebuchi

We developed a novel thermal spraying technology for a silver-containing hydroxyapatite (Ag-HA) coating with antibacterial activity to reduce the incidence of implant-associated infections. In this study, we determined the concentration of Ag ions that show antibacterial activity in fetal bovine serum (FBS) and antibacterial activity of the Ag-HA coating in FBS. The minimum inhibitory concentration (MIC) of Ag ions for several bacteria in FBS was in the range of 4.0–7.9 ppm. When 10 ppm Ag were added (as AgNO3 solution), 0.01 ppm of free Ag ions was detected. As the MIC of Ag ions approached the concentration that enabled formation of free Ag ions in FBS, the antibacterial activity of added Ag can be attributed to the free Ag ions. The Ag-HA coating showed strong antibacterial activity in FBS as well; the Ag concentration in FBS was 26 ppm for the antibacterial test of the Ag-HA coating. Because the Ag-HA coating can release sufficient free Ag ions in FBS, we observed that the Ag-HA coating shows a strong antibacterial effect in the biological medium studied.