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 ZnCl2-containing supersaturated calcium phosphate solutions. With an increase in concentration of ZnCl2 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.