Enhancing biocompatibility of magnesium implants: nanocomposite coating for corrosion resistance and bioactivity

The biodegradability of magnesium (Mg) metal implants necessitates surface modification to mitigate the high corrosion rate in the body’s physiological environment. This study focuses on synthesizing and applying a nanocomposite coating of polydimethylsiloxane-nanosized bioactive glass (PDMS-nBG) on the surface of a plasma electrolytic oxidation (PEO)-modified AZ91 Mg alloy. The PDMS-1 wt% nBG nanocomposite coating was deposited on the PEO-treated substrate using the dip-coating method. Surface and cross-sectional morphologies of the nanocomposite coatings were examined using field emission scanning electron microscopy (FESEM). Corrosion behavior of the AZ91 substrate, PEO coating, and double-layer PEO/PDMS-nBG coating was investigated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests. Results showed that the corrosion resistance and corrosion current density of Mg substrates increased and decreased from 4815 Ω.cm 2 and 8.96 µA.cm − 2 to 18 MΩ.cm 2 and 0.00016 µA.cm − 2 for AZ91 and PEO/PDMS-nBG coating, respectively. Additionally, the morphology and adhesion of cultured human mesenchymal cells on the PEO-modified AZ91 substrates with a single PDMS polymer coating and a PDMS-nBG nanocomposite coating were investigated using fluorescent light microscopy and FESEM. The PEO/PDMS-nBG bilayer coating effectively addressed the limitations of magnesium alloys and holds potential for biomedical applications, particularly in orthopedic implants, due to the enhanced biocompatibility and bioactivity of Mg alloys.