The Study On Deposition HA/TiO₂ Composite Coatings On The Surface Of Titanium Implant By Micro-acr Oxidation And Sol-gel

With favorable combination property and excellent biocompatibility, pure titanium and titanium alloy have been widely used as implant materials in clinics. However, there are still some drawback in practice that has limited the further use of titanium implant. Because of bio-inertia, titanium implant can't form firm chemical bond with surrounding bones and furthermore, it can release metallic ions into surrounding tissue due to susceptible corrosion under physiological conditions.【Objective】In order to resolve the problem mentioned above, Tio2 ceramic coating was deposited on the surface of titanium implant with micr-oarc oxidation in order to improve its corrosion resistant and abrasion performances. Then the layered HA coating was deposited on the surface of Tio2 ceramic coating by sol-gel technology. Finally, HA/Tio2 composite coating was fabricated. Then a series of studies were carried out including analysis of the deposition process and surface characteristics, and the test of physical and chemical properties and biological properties of Tio2 and HA/Tio2 composite coating, which could be helpful to improve the surface bioactivity and promoting clinical curative effect of titanium implant.【Method and Result】1. Tio2 ceramic coating could be deposited on the surface of titanium implant by micro-arc oxidation. The coating had compact inner layer and porous outer layer and the coating had firm adhesive strength with substance. Ca and P element could be added into Tio2 coating by adjusting electrolyte and electrical parameter, which could improve the bioactivity of the coating.2. The HA coating was deposited on the surface of Tio2 ceramic coating by sol-gel technology. The average adhesive strength of the HA/TiO2 coating was (47士2.5)N and its average of thickness was 15～18um.3. The SBF test indicated that HA/TiO2 coating and Tio2 ceramic coating could both induce the deposition of the apatite. Needle-like and granular crystals were found on the surface of both coating and the surface of porous framework was covered with the crystals coating. HA/TiO2 coating could induce the deposition of the apatite formation better than Tio2 did. The deposition speed was faster and the depositing covering was more compact and steady. The XRD(X-ray diffraction) indicated that the deposition on the surface was mainly composed of crystalline hydroxyapatite and other kinds of calcium phosphate.4. According to the ISO,s and our national standards, the tests of hemolysis and cytotoxicity were carried out to evaluate the biocompatibilities of Tio2 and HA/Tio2 coating. The results indicated that both coatings had good biocompatibilities and no latent toxicities. In order to evaluate the cyto-compatibilities of Tio2 and HA/Tio2 coating, MC-3T3-E1 cells were cultured on the surface of two coatings in vitro and both attachment experiment and proliferation experiment were performed. It was found that Tio2 and HA/Tio2 coating significantly promoted the cell attachment at the primary period . But by prolonging the culture time, the influence of different coatings on the attachment of osteoblast decreased gradually. Both coatings promoted the proliferation of osteoblast, but the stimulation effect performed by HA/Tio2 coating was more obvious.【Conclusion】The results showed that HA/TiO2 composite coating was successfully prepared by the micro-arc oxidation and sol-gel technology. It possessed very good combinations of mechanical properties and biocompatib- ilities. HA/TiO2 composite coating could be helpful to improve the surface bioactivity and promote the clinical curative effect of titanium implant.