Magnesium substituted hydroxyapatite coating on titanium with nanotublar TiO2 intermediate layer via electrochemical deposition

Hydroxyapatite (HAp) coatings doped with magnesium ion is an attractive method to improve the biocompatibility and biodegradability of HAp coatings. In this paper, we used electrochemical deposition to study the production of magnesium-doped HAp (MgHAp) coatings onto pure titanium with anodized titanium oxide (TiO2) nanotubes as intermediate layer. The morphology and composition of coatings were studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Results indicated that Mg was uniformly distributed in the coatings, and each coating was found to be 21 μm thick. With Mg2+ incorporation, Ca2+ was substituted by Mg2+ in the MgHAp coating, thereby reducing apatite crystallinity and weekly increasing bond strength. The bioactivity and corrosion resistance of the coatings were improved in simulated body fluid and polarization tests, respectively. Cell culture tests indicated that the magnesium-substituted coatings had good biocompatibility and no adverse effect.