Magnesium (Mg) alloys have recently attracted attention in biomedicine as biodegradable materials with non-toxic degradable products. Such compounds have become a frontier in the study of biodegradable materials because of their remarkable biomechanical compatibility and superior biocompatibility. The use of Mg-based implants reduces the negative consequences of permanent biological implants by eliminating the necessity for biomaterial surgery following the healing process. However, the quick deterioration, formation of considerable gas of hydrogen volumes and a rise in the body environment pH are obstacles in the application of Mg as an implant material. Hence, compelling advances for erosion resistance and biocompatibility of magnesium and its alloys are noteworthy. Surface modification may be a practical approach because it improves the erosion resistance compared with extensive preparation of a treated surface for progressed bone recovery and cell attachment. Coating produced by plasma electrolytic oxidation (PEO) seems a compelling method in order to enhance magnesium and the properties of its alloys. PEO-formed coatings cannot provide long-term protection in the physiological environment due to their porous nature. Thus, a polymer coating is applied on the porous PEO-formed coating, which is steadily applied on the surface. Polymer coatings improve the biocompatibility properties of Mg and its alloys and increase corrosion resistance. In this article, the most recent advancements in PEO/polymer composite coatings are reviewed, and the biocompatibility of such coatings is examined.
Keywords: Mg alloy; PEO; biocompatibility; corrosion; polymer coating.