This study introduces a nanostructured MgO coating fabricated via anodization in a non-aqueous electrolyte, offering a novel approach to addressing the challenges of corrosion resistance and biofunctionality. The surface was characterized before and after immersion testing using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests demonstrated a 2-fold reduction in the corrosion resistance compared to untreated magnesium. Biomineralization studies demonstrated the uniform formation of apatite with a Ca/P ratio of 1.35 on the nanostructured surface after 14 days in simulated body fluid (SBF), surpassing that of microstructured MgO. Hydrogen evolution decreased from 912±38 µL cm^-2 for untreated Mg to 615±32 µL cm^-2 for the Mg/MgO nanostructure and 545±29 µL cm^-2 for the Mg/MgO/HA sample. These findings highlight the potential of nanostructured MgO coatings to advance Mg-based implants by providing enhanced corrosion protection, improved biomineralization, reduced hemolysis and increased cell viability, and reduced H₂ generation.

This study investigated the effects of multi-walled carbon nanotubes (MWCNTs) and polycaprolactone (PCL) on the quasi-in vivo corrosion behavior of AZ31B Mg alloy treated by plasma electrolytic oxidation (PEO). Thin (~2 µm, PCTPCL4) and thick (~60 µm, PCTPCL6) PCL layers were applied only onto the MWCNTs-PEO coating (PCT) as it showed better corrosion performance. Findings reveal that incorporation of MWCNTs induced several structural and functional modifications in the PEO coating, such as increased roughness, a thicker inner barrier layer, and reduced hydrophilicity.

Quasi-in vivo corrosion testing was carried out under controlled temperature, pH, and fluid flow in simulated body fluid (SBF) by electrochemical impedance spectroscopy (EIS) and hydrogen evolution experiments. EIS results revealed that, after 48 h immersion, a diffusion process controlled hydration of the ceramic coatings. Comparison of the collected hydrogen after 15 days of immersion in the quasi-in vivo environment revealed that the PEO and PCT ceramic coatings decreased hydrogen generation by up to 74% and 91%, respectively, compared to non-coated alloy.

PCTPCL6 coating exhibited the lowest amount of collected hydrogen (0.2 mL/cm²). The thick PCL layer delayed the onset of substrate corrosion for at least 120 h, reducing the corrosion rate by 85% compared with the PCT.