| The medical magnesium alloy has good biocompatibility,and its elastic modulus and mechanical properties are closer to the human dense bone than other medical metal materials.In addition,medical magnesium alloys are biodegradable,and their degradation products can be excreted by human metabolism.However,the corrosion resistance of medical magnesium alloys is poor,which cannot meet the requirements of degradable implant materials.Too fast corrosion rate of magnesium alloys will lead to higher hydrogen evolution rate.Therefore,the modification of medical magnesium alloys has become a hot spot.Objective:The aim of this study was to evaluate the corrosion resistance and cytocompatibility of AZ31 magnesium alloy coated with zirconia by plasma electrolytic oxidation,so as to provide basic evidence for the biological application of AZ31magnesium alloy.Methods:The experiment is divided into three groups,surface treatment of magnesium Alloy by plasma electrolytic oxidation.The morphology and phase composition of the coating were characterized by SEM and X-ray diffraction.The corrosion resistance of the coating was characterized by electrochemical experiment,hydrogen evolution test and immersion test.The Cytocompatibility of L-929 fibroblasts was evaluated by MTT assay and morphological observation.Results:The microarc oxide film containing zirconia was successfully prepared on the surface of AZ31 magnesium alloy by one step plasma electrolytic oxidation.The zirconia film is much more homogeneous than the control group.Potentiodynamic polarization and hydrogen evolution tests demonstrated that the Ecorr value?-1.3911V vs.AgCl?of ZrO2 coated AZ31 magnesium alloy was the highest and its Icorr value(1.5072×10-7A·cm-2)was the lowest.Compared with other groups,the amount of hydrogen produced by ZrO2 coated AZ31 magnesium alloy was the least?8.5ml?.The corrosion resistance of the AZ31 magnesium alloy was better than that of the control group.And it can be seen in the long-term immersion test and the bode plot,the ZrO2coated AZ31 magnesium alloy showed much more stable long-term corrosion resistance.The cytotoxicity and the morphology of the cells showed that the viabilities of L-929 cells cultured with the extract media of ZrO2-coated AZ31 for 1?4 and 7 days were much higher than other groups.Cell morphologies in the extracts of ZrO2-coated AZ31 magnesium alloy were normal and healthy,which indicated that the ZrO2-coated AZ31 magnesium alloy was non-toxic to L-929 cells.Conclusion:The corrosion resistance of zirconia coated AZ31 magnesium alloy is much better and more stable,and the toxicity of L-929 cells is not induced. |
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