Zinc-containing apatite layers on external fixation rods promoting cell activity

Zinc-containing apatite layers were successfully formed on commercially available anodically oxidized Ti external fixation rods using ZnCl 2-containing supersaturated calcium phosphate solutions. With an increase in concentration of ZnCl 2 in the supersaturated calcium phosphate solutions, the amounts of zinc that precipitated on the Ti external fixation rods increased (from 0 to 0.195 ± 0.020 μg cm −2); meanwhile, the amounts of calcium and phosphorus that precipitated on the Ti external fixation rods decreased (from 11.2 ± 1.5 and 4.8 ± 0.5 μg cm −2 to 2.9 ± 1.6 and 1.3 ± 0.9 μg cm −2, respectively). The zinc-containing apatite layers precipitated on the Ti external fixation rods caused a significant increase in fibroblastic proliferation, osteoblastic proliferation and differentiation in vitro. The Ti external fixation rods coated with zinc-containing apatite layers are expected to be more effective in accelerating the tissue regeneration around the surgical site than those coated with an apatite layer.