Modification of titanium surface with calcium and phosphorus ions using micro-arc oxidation and its effect on osteoblast attachment

OBJECTIVE: To study the method for modifying titanium surface with calcium and phosphorus ions using micro-arc oxidation technique and observe osteoblast attachment to the modified surface. METHODS: TA(2) titanium discs were treated with micro-arc oxidation in electrolyte solution containing Ca(2+) and PO(4)(3-). The influence of Ca(2+) and PO(4)(3-) concentrations in the solution and the electrical parameters of the micro-arc oxidization on the content of calcium and phosphorus ions incorporated into the surface of titanium was investigated using energy-dispersive X-ray (EDX) analysis. Scanning electron microscopy was employed for morphological observation of the ceramic coating on the metal surface. The binding strength of ceramic coating with titanium was tested by shear bonding experiment. MC-3T3-E1 osteoblast-like cells were then cultured on the treated surface of titanium discs to investigate the influence of the ceramic coating on osteoblast attachment. RESULTS: Micro-arc oxidation treatment produced a layer of porous TiO(2) coating on the surface of titanium discs, with the average pore size of 2 to 10 mum. EDX analysis revealed that the ceramic coating contained Ca and P elements, whose content had close correlation with Ca(2+) and PO(4)(3-) concentrations in the electrolyte solution and voltage, duty cycle and frequency of micro-arc oxidation. The average bonding strength of the ceramic coating with titanium was 22+/-3 MPa, and TiO(2) coating promoted attachment and spread of osteoblast-like cells on the metal surface as demonstrated by cell culture. CONCLUSIONS: Porous TiO(2) coating can be constructed on the surface of titanium using micro-arc oxidation, and Ca(2+) and PO(4)(3-) incorporated into the coating can improve the biocompatibility of titanium. The content of Ca(2+) and PO(4)(3-) in the coating can be modulated by adjusting the concentrations of Ca(2+) and PO(4)(3-) in the electrolyte solution and the electrical parameters of the micro-arc oxidation.