Corrosion behavior and cytocompatibility of nanostructured hydroxyapatite hydrothermally grown on porous MgO coatings with different P contents on magnesium

Abstract Clinical application of magnesium (Mg) in bone reconstruction has been hindered owing to its high degradation rate in physiological environment. Surface modification by the strategy combining micro-arc oxidation (MAO) and hydrothermal treatment (HT) to prepare a composite coating (MAO-HT) and improve its corrosion resistance has been proved an effective method. In this work, Mg was micro-arc oxidized in electrolyte with different Na3PO4 contents, and subsequently hydrothermally treated in Ca(NO3)2 solution. The results show that hydroxyapatite (HA) can be fabricated on MAO coating after HT for 4 h. The HA shows nano-flake morphology when P content in the MAO coating is low (12.1 at%), while nano-particle morphology is observed when the P content is high (20.0 at %). Electrochemical tests reveal an improved corrosion resistance of MAO-HT coatings than corresponding MAO coatings. In vitro biological tests indicate that MAO-HT coatings are more favorable for MG63 cells proliferation than MAO coatings. Especially, Nano-flake HA/MAO composite coating shows the highest corrosion resistance and cytocomatibility thus is promising as biomedical coatings of Mg.