Promising corrosion-resistant and pre-osteoblast growth promotion performance in vitro of hydroxyapatite/TiO2 nano-porous composite coatings

The inertness of titanium alloys restricts the high intensity of the biological bonding between artificial implants and human skeletons, and there is residual stress in hydroxyapatite (HA) coatings fabricated by the frequently applied plasma spraying method. With the intention to address the aforementioned two issues, combined utilization of constant current anodization and pulsed laser deposition (PLD) was conducted to fabricate HA/TiO 2 nano-porous composite coatings , and the as-fabricated samples were heat-treated under the selected appropriate conditions. The oxygen bubble mold theory has made a persuasive explanation for the growth mechanism of TiO 2 nano-porous arrays. The morphologies and composition of the composite coatings including the heat-treated ones were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), grazing incidence X-ray diffraction (GI XRD) and X-ray photoelectron spectrometer (XPS). Through comprehensive analysis of the corrosion resistance in modified simulated body fluid (m-SBF) and growth efficiency of cocultured MC3T3-E1 cells in vitro, together with the characterization results, it is concluded that the sample heat-treated at 450 °C shows the most satisfactory performance in general. Therefore, the HA/ TiO 2 nano-porous composite coatings have broad application prospect in the osseointegration and bone repairing abilities of artificial implants.