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Anodization of Magnesium for Biomedical Applications – Processing, Characterization, Degradation and Cytocompatibility

posted Sep 28, 2017, 3:35 PM by Huinan Liu   [ updated Sep 28, 2017, 4:06 PM ]

Cipriano AF*, Lin J*, Miller C*, Lin A*, Cortez Alcaraz MC*, Soria P*, Liu H. Anodization of Magnesium for Biomedical Applications – Processing, Characterization, Degradation and Cytocompatibility. Acta Biomaterialia. S1742-7061(17)30516-0. DOI: 10.1016/j.actbio.2017.08.017. (PMID: 28818688)

This article reports anodization of Mg in KOH electrolyte and the associated surface, degradation, and biological properties for bioresorbable implant applications. The preparation procedures for electrodes and anodization setup significantly enhanced reproducibility of samples. The results of anodization performed at the applied potentials of 1.8, 1.9, or 2.0 V showed that the sample anodized at 1.9 V and annealed, referred to as the 1.9 AA sample, had homogenous surface microstructure and elemental composition, and a reduction in corrosion current density in the electrochemical testing. In comparison with Mg control, the 1.9 AA sample showed a distinct mode of degradation, e.g., continuous growth of a passivation layer enriched with Ca and P instead of typical localized pitting and undermining, and a greater release rate of Mg2+ ions when immersed in physiologically relevant media. In the direct culture with bone marrow derived mesenchymal stem cells (BMSCs) in vitro, the 1.9 AA sample did not affect BMSC adhesion and morphology under indirect contact; however, the 1.9 AA sample showed a reduction in cell spreading under direct contact. The change in surface topography/composition at the dynamic interface of the anodized-annealed Mg sample might have contributed to the change in BMSC morphology. In summary, this study demonstrated the potential of anodic oxidation to modulate the degradation behaviors of Mg-based biomaterials and BMSC responses in vitro, and confirmed the value of direct culture method for studying cytocompatibility of Mg-based biomaterials for medical implant applications.