Electrichemical Deposition And Morphology Control Of Strontium- Substituted Hydroxyapatite Coatings On Titanium Surface

By adopting an electrodeposition method, hydroxyapatite (HA) coatings were deposited on the surface of titanium substrate in electrolytes of different concentrations. The changing tendency of deposition current over time was monitored and recorded during the deposition process. The morphology or microstructure and compositon of coatings prepared under various conditions were generally analyzed by scanning electronic microscope (SEM) and X-ray diffractor (XRD), respectively. The tendency was studied and summarized that the microstructures and phases of coatings varied as the concentration of electrolytes changed, and the change of deposition potential and temperature would also affect the final compositon of coatings, which contributed to a controllable scope of HA preparation.Strontium-substituted HA (SrHA) coatings with different crystallinity were successfully electrodeposited in electrolytes of high or low concentration by adding corresponding amount of SrCl2 and appropriately adjusting the deposition potential and temperature, in which the Ca2+ was substituted for Sr2+ in the range of 0 to 100%. This also verified that Sr2+ and Ca2+ had an equavilent behavior in the crystallization of SrHA.The electrodepositions in electrolytes of high or low concentration were combined. And under the absorption effect of sodium citrate (Na3Cit), a composite morphology of thorn-like SrHA crystals were fabricated with small thorns assembling and growing on the side face of larger rod-like SrHA crystals. The release amount of Sr2+ of coatings in physiological solution and their contact angles were compared and showed that the thorn-like SrHA coatings with strontium substitution in both electrodepostions have the greatest release rate of Sr2+ and the most favorable wettability. Finally, a preliminary in vitro osteoblast proliferation test was conducted. Owing to their various degradation tendencies and microstructures, SrHA coatings in different groups had different behaviors in promoting the osteoblast proliferation. The results provide a new direction toward the preparation of biomedical materials with similar compositons and microstructures to human natural apatite.