Bio-corrosion behaviors of hyaluronic acid and cerium multi-layer films on degradable implant

Initial corrosion resistance and bioactivity of biodegradable magnesium are major success factors for implant applications. Electrodeposition containing Ce prevent material damage and local corrosion resulting from implantation, and Ce penetrates hydrogels and consequently maximizes surface self-healing. Ce(NO₃) was used to form an electrodeposition layer on magnesium, and hyaluronic acid(HA) was coated through hydrothermal treatment, which created a composite layer consisting of a polymer compound with Ce and a thick and stable MgO layer. The morphology, chemical structure, and scratch tests conducted on various surface treatments showed hydrothermally treated Ce to be the most effective self-healing and corrosion-resistance. In the electrodeposition of Ca/Ce, relatively reactive Ce quickly adhered to the surface, and according to the hydrothermal process, Ca and Ce ions diffused inward as water and HA penetrated the irregular layers. The cell viability of osteoblasts showed no toxicity with Ce, and the osteoblasts were showed the highest differentiation especially in treated with the HA hydrothermal group. Implantation into rat tibias resulted in stable bone marrow and osteoblast growth in the hydrothermal treatment group containing Ce. Consequently, Ce(OH)₃/CeO₂ penetrating the natural polymer HA had a self-healing ability and resistance to initial corrosion, local damage, and the biodegradation of the magnesium implant.