Tailoring the corrosion resistance and biological performance of Mg-Zn-Y-Nd bioimplants with multiphasic, pore-sealed cerium-doped ceramic coatings via facile one-pot plasma electrolytic oxidation

Abstract

Magnesium alloys have illustrated great promise for building biodegradable implantable devices due to their unique combination of biocompatibility, mechanical properties, and degradable absorption characteristics. However, the uncontrollably fast degradation in physiological environments remains a humongous challenge restraining their clinical application, requiring engineering strategies such as surface modification for biocorrosion and biofunctionality optimization. Herein, CeO₂ nanoparticle-doped plasma electrolytic oxidation (PEO) coatings were applied to surface modify a novel Mg-Zn-Y-Nd alloy. During the PEO process, nanocrystal CeO₂ nanoparticles, alongside the newly formed secondary corrosion-resistant (CePO₄) phase, sealed the micropores of the PEO coatings under discharge, affording enhanced barrier effects against biocorrosion. Electrochemical tests in Hank's solution showed a remarkable increase in corrosion potential and charge transfer resistance and a decrease in corrosion current density. Further characterization showed that a dense anti-corrosion coating of Mg(OH)₂/CeO₂/Ce(OH)₃ was formed, effectively limiting the attacks of corrosive mediums and ensuring controlled degradation. The coating-functionalized implants, as reveled in vitro and in ovo, were compatible with NIH3T3 fibroblasts, HUVECs, red blood cells, and chick chorioallantoic membranes, with even enhanced pro-healing effects in scratch-based wound models. Overall, this work highlights the potential of CeO₂-doped PEO coatings to fine-tune the corrosion resistance and biocompatibility of Mg-Zn-Y-Nd alloys for biomaterial implants.