Corrosion behavior and biological activity of micro-arc oxidation coating with puerarin on pure magnesium surface

In order to improve the corrosion resistance and biological activity of micro-arc oxidation (MAO) coating on Mg alloys, a puerarin-loaded (PL) coating was prepared and applied on the MAO coating by the method of dipcoating in physic acid (PA) solution with puerarin. The chemical and morphological characterizations of the coatings were examined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The corrosion properties of the coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid (SBF). Besides, the bioactivity properties of the coatings in SBF were investigated following 3, 7, and 14 days of immersion. The results indicate that the defects of through-pores weaken the corrosion resistance of the MAO and PL coatings with a high cross-link density sealing of the pores of the MAO coating. The higher initial impedance, lower current density, and loss of weight show that PL coatings have higher corrosion resistance than do MAO coatings. Furthermore, PL coatings improve the bioactivity of the MAO coating by accelerating apatite mineralization. The use of such a coating is expected to promote the application of Mg in bone repair materials and improve bone healing rate in the early stages of implantation.