Mg-Fe LDH sealed PEO coating on magnesium for biodegradation control, antibacteria and osteogenesis

Abstract Attempt of developing bio-safety and functional layered double hydroxides (LDHs) modified plasma electrolytic oxidation (PEO) coatings, has become a hotspot in the protection of magnesium (Mg) based biomedical implants. In the present work, Mg-Fe LDH films with different Fe contents were fabricated on PEO coating via a novel two-step method: firstly, the FeOOH films were prepared by immersing PEO sample in Fe2+-containing solution, and then Mg-Fe LDH films were formed by transforming the FeOOH films via a hydrothermal treatment in water. The highly-oriented LDH nano-sheets could enhance the anti-corrosion performance of PEO coating, which was proved by the results of electrochemical test, hydrogen evolution and corroded morphology. PEO/Mg-Fe LDH coatings showed a low hemolysis rate (less 5%) than PEO coating. In addition, PEO/Mg-Fe LDH coatings were more favorable for cell adhesion and proliferation than PEO coating. Moreover, PEO/Mg-Fe LDH coatings showed good photothermal conversion property, which demonstrated the excellent rapid antibacterial effect under NIR light. In vitro culture of rat bone marrow stem cell (rBMSC) suggested that cells cultured in the extract of PEO/Mg-Fe LDH coatings had a better osteogenic activity. In vivo subcutaneous implantation test revealed that PEO/Mg-Fe LDH coatings exhibited good anti-corrosion and histocompatibility.