Bilayer micro-arc oxidation-poly (glycerol sebacate) coating on AZ91 for improved corrosion resistance and biological activity

Magnesium alloys have recently been used in the biomedical field due to their low stress shielding and density closer to the natural bone. However, the corrosion resistance and biocompatibility of magnesium alloys should be improved for effective applications. In this study, a bilayer coating based on micro-arc oxidation and poly (glycerol sebacate) (PGS) (MAO-PGS) was developed on AZ91 alloy. Moreover, the effects of the electrosprying time (1, 3, 5 and 7 h) to develop PGS coatings on the physical, electrochemical and biological properties of the AZ91 alloy were evaluated. Electrochemical measurements in phosphate buffer solution confirmed that PGS coatings significantly improved the corrosion resistance of MAO coated sample, depending on the electrosprying time. Noticeably, by increasing PGS coating time upon 3 h, the corrosion resistance significantly improved, due to filling the pores formed during MAO process. Consequently, protein adsorption and biocompatibility of MAO-PGS coatings in contact with Human umbilical vein endothelial cells (HUVECs) significantly improved. Moreover, our result revealed the adhesion strength of MAO-PGS coating was directly modulated via PGS coating time. We found that 3 h coating significantly improved the adhesion strength of MAO coating. In summary, the bilayer MAO-PGS coatings on biodegradable AZ91 alloy not only increased corrosion resistance but also improved the biocompatibility of biodegradable AZ91 alloys. In summary, bilayer MAO-PGS coating may have the potential to provide greater protection of magnesium-based implants.