Effects of phosphate/silicate electrolytes and oxidation sequence on the corrosion resistance, cytotoxicity, and osteogenic property of micro-arc oxidation coating on magnesium alloy as GBR membrane

Abstract

In order to further improve the degradation resistance and osteogenic property of the micro arc oxidation (MAO) coating of Mg alloys, the Mg alloy samples were oxidized in phosphate electrolyte, silicate electrolyte, first phosphate electrolyte + second silicate electrolyte, and first silicate electrolyte + second phosphate electrolyte. And the corrosion resistance, cytotoxicity, and osteogenic property of the samples were studied. The results showed that the Na₂SiO₃-MAO coated sample had more micropores than the CaP-MAO coated sample. The composite micro-arc oxidation (MAO) coatings obviously improved the degradation resistance of the alloy. Moreover, the samples fabricated first in silicate electrolyte and then in phosphate electrolyte showed the best corrosion resistance with the corrosion current density of only 0.1 µA/cm², which was two orders of magnitude lower than the single silicate Na₂SiO₃-MAO coated (10.9 µA/cm²). Besides, the cytocompatibility of the MAO coated samples was good, presenting no cell toxicity. The extract from the Na₂SiO₃+CaP coated sample promoted cell proliferation, reaching almost 100% after 5 d. Na₂SiO₃+CaP coated sample showed the best osteogenic property with bone volume/total volume (BV/TV) about 55% after 8 weeks implantation in calvarial region (parietal bone) of the skull. The results indicated that the Na₂SiO₃+CaP coated magnesium alloy exhibited the best corrosion resistance and osteogenic property.

Keywords

micro arc oxidation / oxidation sequence / corrosion resistance / osteogenic property / guided bone regeneration (GBR) membrane

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Central South University