In vitro degradation and biocompatibility of in-situ fabricated Mg-Al-Ga-LDH/MAO hybrid coating on Mg alloy AZ31

A novel antibacterial Mg-Al-Ga layered double hydroxide (LDH) coating was fabricated on micro-arc oxide (MAO) coated magnesium (Mg) alloy AZ31 via low-temperature water bath treatment. Electrochemical polarization and impedance spectroscopy, hydrogen evolution rates, and pH monitoring tests were used to characterize the degradation behaviors. The morphology, compositions, and microstructures of the samples were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Antibacterial activities of the coatings against Staphylococcus aureus and Escherichia coli were evaluated by plate-counting method. Cell-Counting Kit-8 (CCK-8) was applied to evaluate the cytotoxicity of coatings. The results demonstrate that the Mg-Al-Ga-LDH coating with a nanosheet structure is constructed to blanket the porous MAO coating. Electrochemical and hydrogen evolution tests reveal that the MAO/Mg-Al-Ga-LDH coating exhibits superior corrosion resistance. Furthermore, antibacterial and cytotoxicity tests prove that the MAO/Mg-Al-Ga-LDH coating possesses an obvious antibacterial and osteogenic effect.