Pure Mg-Al Layered Double Hydroxide Film on Magnesium Alloys for Orthopedic Applications

Mg alloys are promising biodegradable orthopedic implants in the future. However, poor corrosion resistance and biocompatibility limit their wide applications. In this study, a pure Mg-Al layered double hydroxide (Mg-Al LDH) film on AZ31 was prepared through combining hydrofluoric acid pretreatment and hydrothermal treatment. Electrochemical analysis and the immersion test suggested that the as-prepared Mg-Al LDH-coated sample exhibited significantly enhanced corrosion resistance. The in vitro cell culture revealed that the Mg-Al LDH film was favorable for the alkaline phosphatase activity, collagen secretion, and osteogenesis-related gene expression of MC3T3-E1. Furthermore, the LDH-coated sample was beneficial for the migration, vascular endothelial growth factor secretion, and angiogenesis-related gene expression of human umbilical vein endothelial cells. The subcutaneous implantation test demonstrated that the Mg-Al LDH film could protect the substrate from corrosion and induce milder inflammation. The femur implantation demonstrated that the Mg-Al LDH sample showed better bone regeneration and osseointegration than bare AZ31. In summary, the as-prepared pure Mg-Al LDH film is able to enhance the in vitro and in vivo performances of AZ31, indicating a promising application in the orthopedic field.