Corrosion resistance and surface biocompatibility of a microarc oxidation coating on a Mg–Ca alloy

• Published in: Acta biomaterialia 2011-04, Vol.7 (4), p.1880-1889
• Main Authors: Gu, X.N., Li, N., Zhou, W.R., Zheng, Y.F., Zhao, X., Cai, Q.Z., Ruan, Liquan
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase - metabolism; alloys; Alloys - chemistry; Biocompatibility; Calcium - analysis; Calcium - chemistry; cell adhesion; Cell Count; Cell Line, Tumor; Cell Shape; Cell Survival; Coated Materials, Biocompatible - chemistry; coatings; Corrosion; Corrosion resistance; culture media; electric power; Electrochemical Techniques - methods; Humans; Hydrogen - analysis; hydrogen production; Hydrogen-Ion Concentration; magnesium; Magnesium - analysis; Magnesium - chemistry; Mg–Ca alloy; Microarc oxidation; oxidation; Oxidation-Reduction; Surface modification; Surface Properties; X-Ray Diffraction
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2010.11.034

The Mg–Ca alloy system has been proposed as a potential new kind of degradable biomaterial with possible application within bone. Here microarc oxidation (MAO) coatings were fabricated on top of a Mg–Ca alloy using different applied voltages and the effect of applied voltage on the surface morphology and phase constitution, hydrogen evolution, pH variation in the immersion solution and in vitro biocompatibility of the MAO coating on the Mg–Ca alloy were extensively studied. It was found that the thickness and pore size of the MAO coating increased with the increasing applied voltage, whereas some micro-pores could be seen inside the 400V treated MAO coating. The 360V treated MAO coating gave the best long-term corrosion resistance during a 50days immersion test. All the MAO coatings could promote MG63 cell adhesion, proliferation and differentiation in comparison with the uncoated Mg–Ca alloy sample, due to significantly reduced Mg ion release and pH value variations in the culture medium. After 5days culture well-spread and elongated MG63 cells could be seen on the surface of the 360V and 400V MAO coatings, in contrast to no cells on the uncoated Mg–Ca alloy sample. In summary, MAO showed beneficial effects on the corrosion resistance of, and thus improved cell adhesion to, the Mg–Ca alloy, and should be a good surface modification method for other biomedical magnesium alloys.