Comparison study of Mg(OH)2, Mg-Fe LDH, and FeOOH coatings on PEO-treated Mg alloy in anticorrosion and biocompatibility

Magnesium hydroxide (Mg(OH)2), Mg-Fe layered double hydroxide (Mg-Fe LDH), and ferric hydroxide (FeOOH) coatings were prepared on plasma electrolytic oxidation (PEO)-treated magnesium (Mg) alloy by immersion and hydrothermal treatment. These three kinds of hydroxides coatings exhibited nanosheet like surface structures, which completely sealed the micro-pores formed during PEO treatment. The anti-corrosion and biocompatibility of these three kinds of hydroxides coatings on Mg were systematically investigated. The results of electrochemical test, Mg2+ release behavior, and corrosion morphology indicated that FeOOH coating showed the best corrosion resistance. And, the results of cell adhesion, live/dead staining, and proliferation indicated FeOOH coating showed better biocompatibility than other hydroxides coatings. The study provides a detailed understanding and deep insight for metal hydroxides-based coatings on Mg alloy and indicated that FeOOH coating could as a novel potential coating for modification of Mg-based implants.