Introduction: Researching ways to regulate the biocorrosion rate of biodegradable magnesium implants is one of the most urgent tasks in the field of biomedical materials science. The most important objective is to maintain the corrosion resistance of the material during the initial stages after implantation, when this resistance subsequently decreases. Nanocoatings are the most effective means of achieving this. The present study investigates the potential of oxide nanocoatings to reduce the biocorrosion rate of AZ31 magnesium alloy in physiological Ringer's solution.

Methods: Atomic layer deposition (ALD) was used to create defect-free, uniform coatings based on titanium, aluminium and zinc oxides on AZ31 magnesium alloy surfaces. The thickness, composition, morphology, and structure of the coatings were analysed using ellipsometry, scanning electron microscopy, X-ray photoelectron microscopy, and X-ray diffraction. The biocorrosion rate was assessed by measuring potentiodynamic polarization curves and the mass loss of the samples.

Results: Al₂O₃ nanocoatings with a thickness ranging from 20 to 80 nm, as well as composite Al₂O₃-TiO₂ nanocoatings, are effective in reducing the rate of biocorrosion in AZ31 alloy. Conversely, TiO₂ coatings demonstrate reduced effectiveness and, in some cases, have been observed to slightly accelerate biocorrosion. The effectiveness of TiO₂ coatings was found to depend significantly on the precursor used: titanium tetrachloride or tetraisopropoxide. AZ31 biocorrosion rates were reduced by 18-54 times with Al₂O₃ and 40 nm thick Al₂O₃-TiO₂ composite coatings.

Conclusions: Among the ALD aluminium, zinc, titanium oxides and their composite nanocoatings, the Al₂O₃ and Al₂O₃-TiO₂ nanocoatings are the most effective in reducing the biocorrosion rate of the AZ31 alloy in the initial stages, while ensuring the material's biodegradability in subsequent stages.

This research was carried out under the financial support the Russian Science Foundation grant (project No. 24-73-00115).