PEO/Polymer hybrid coatings on magnesium alloy to improve biodegradation and biocompatibility properties

There is an increasing tendency towards replacing permanent implants with biodegradable magnesium implants in temporary bone applications like screws and pins. This inclination arises from the close mechanical properties and biocompatibility of magnesium (Mg) to bone. Nonetheless, the high degradation rate of Mg can be a reason for implant loosening even in the early weeks after implantation. This study aims to design a multifunctional multilayered coating based on a combination of inorganic and organic layers for controlling the degradation behaviour. An inorganic layer was created on the substrate of magnesium alloy, AZ31B Mg, via plasma electrolytic oxidation (PEO) process while an organic layer of elastic poly trimethylene carbonate (PTMC) polymer was deposited by dip coating in the vacuum condition to have open pores of the PEO layer sealed. Subsequently, the coating was functionalized with a biomimetic polydopamine layer. The electrochemical corrosion measurements in simulated body fluid (SBF) showed the resistance against corrosion increases after deposition of the polydopamine functionalized PTMC on the PEO layer. In-vitro investigations in SBF evaluated the bioactivity of the multilayered coating. Moreover, MTT assays did not show cytotoxicity in the coating. Cell culture evaluations helped to determine the cell spreading and adhesion on the multilayered coating. Based on our findings, the fabricated layered composite on the biodegradable AZ31B alloy would add privileges to the sector of temporary implants.