Diatomite-based ceramic biocoating for magnesium implants

The current paper presents the results of the experimental and analytical investigation of a new protective coating for orthopedic magnesium implants and its various physicochemical properties. The coating was synthesized via the micro-arc oxidation method (MAO) at various applied voltages. The electrolyte solution was doped with the particles of diatomite – a biogenic siliceous material, consisting almost entirely of the fossilized shells of diatoms. The coating was examined using various methods, including scanning electron microscopy, X-ray crystallography, mechanical testing, energy dispersive X-ray spectroscopy, immersion testing and potentiodynamic polarization. The coating has shown excellent physical, electrochemical, and mechanical properties, compared to the initial magnesium alloy. The corrosion resistance of the coated samples was approximately three orders of magnitude higher than that of an initial Mg alloy sample. Additionally, the MAO coating significantly reduced the in vitro cytotoxic effect on NIH/3T3 cells, which makes it a promising biogenic tool for increasing the biocompatibility of Mg implants.