Hydroxyapatite/chitosan-metformin composite coating enhances the biocompatibility and osteogenic activity of AZ31 magnesium alloy

The rapid degradation rate of degradable magnesium alloys limits their application as orthopaedic implants. To improve the osteogenic activity and corrosion resistance of magnesium alloys, a hydroxyapatite/chitosan-metformin (HA/CS-MF) composite coating was prepared on AZ31 magnesium alloy by hydrothermal treatment. The structure and morphology of the composite coating were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Electrochemical tests and hydrogen evolution experiments were carried out to evaluate the corrosion resistance of the HA/CS-MF composite coating. At the same time, the cytocompatibility, osseointegration ability and anti-inflammatory activity of the HA/CS-MF composite coating were studied. The findings revealed that the HA/CS-MF composite coating exhibits excellent corrosion resistance, biocompatibility and osteogenic activity; can upregulate the expression level of bone-related genes; and is conducive to the polarization of M2 macrophages.