ABSTRACT
BACKGROUND:It can be theoretical y speculated that the combination of titanium, micro-arc oxidation coating and arginine-glycin-aspartic acid (RGD) polypeptide wil show better mechanical and biological properties. OBJECTIVE:To observe the microstructure and cellproliferation of the titanium and micro-arc oxidation coatings modified with RGD polypeptide by different modification methods. METHODS:Ninety specimens of pure titanium and micro-arc oxidation coatings were divided into three groups, with 30 specimens in each group. The first 30 specimens were pure titanium physical y decorated with RGD polypeptide only. The other two groups of specimens were physical and chemical coupling adsorption RGD polypeptide micro-arc oxidation samples, respectively. The fluorescence microscope was used to observe the effects and amounts of grafting RGD polypeptide on each sample. Content of the RGD polypeptide on the surface of the specimens were measured by X-ray photoelectron spectroscopy. The mouse bone marrow stromal cells were cultured on the surfaces of three groups samples, and the adhesion and proliferation of the cells cultured for 3 hours, 12 hours, 24 hours and 3 days were observed by optical microscope respectively. RESULTS AND CONCLUSION:There were green fluorescence spots, with varying size and amount, on the surface of specimens in three groups. In the unit field of view, the fluorescence was the strongest in chemical coupling adsorption RGD polypeptide micro-arc oxidation samples, indicating that these specimens were grafted with many polypeptides. In physical coupling adsorption RGD polypeptide micro-arc oxidation samples, smal amount of polypeptides were found on the surface, and the content of the RGD polypeptide was the highest in chemical coupling adsorption RGD polypeptide micro-arc oxidation samples. No apparent cytotoxicity was observed in three groups. The cellproliferation was the best in chemical coupling adsorption RGD polypeptide micro-arc oxidation samples. Experimental findings suggest that, chemical coupling method can wel fix the RGD polypeptides on the surface of pure titanium samples containing micro-arc oxidation, without any cytotoxicity, which contribute to promote the cellgrowth and proliferation.
ABSTRACT
A porous hydroxylapatite-containing titania film was prepared by an electrochemical oxidation method, i.e. micro-arc oxidation (MAO). During the oxidation treatment, the titanium sample was immersed in electrolytic solution containing calcium acetate monohydrate and sodium biphosphate dihydrate by using a pulse power supply. The thickness, phase, composition and morphology of the oxide coating were monitored with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS). The thickness of the MAO film is about 20 microm and the coating where each porous size is no more than 5 microm was porous and uneven, without apparent interface to the titanium substrates. The coating formed in the Ca- and P-containing solution with MAO contained Ca and P along with Ti and O. The Ca/P ratio on the surface is 1.63, while that in the interface is 0.51. XRD showed that the porous coating was made up of anatase, rutile and hydroxyapatite. Such MAO films are expected to have significant medical applications as dental implants and artificial bone joints.