Formation of bioceramic coatings containing hydroxyapatite on the titanium substrate by micro-arc oxidation coupled...

Bioactive ceramic coatings on titanium substrates were prepared successfully by micro-arc oxidation coupled with electrophoretic deposition (MAO and EPD) in NaOH electrolyte solution containing hydroxyapatite (HA) particles. The HA suspensions with various NaOH concentrations were prepared by ultrasonic dispersion. The microstructure, as well as the elemental and phase composition of the coatings was examined by scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction. X-ray diffraction showed that the coatings were composed mainly of rutile, Na(2)Ti(6)O(13), and HA phases. The composition and surface morphologies are strongly dependent on the NaOH electrolyte concentration. The corrosion behavior of the coating layers in simulated body fluids was evaluated using a potentiodynamic polarization test. The corrosion resistance of the coated sample was increased compared with the untreated titanium sample. The in vitro bioactivity assessment showed that the MAO and EPD-treated titanium substrate possesses higher apatite-forming ability than the only MAO-treated titanium substrate. In addition, the cell behavior was also examined using cell proliferation assay, cell morphology, and alkaline phosphatase activity. They obtained an agreement with the result of apatite-forming ability. The results clearly show that combining the MAO and EPD techniques provides an optimal surface for cell differentiation and osseointegration.