In vitro assessment of corrosion resistance and biocompatibility of tantalum-niobium oxide surface-functionalized Mg alloy

Magnesium alloys have been considered as temporary biomaterials for orthopedic applications. Despite having great mechanical (bone-like) characteristics and osseointegration, magnesium alloys deteriorate quickly in physiological conditions. Modifying the Mg alloy surface with tantalum-based thin films is an effective process to reduce the rate of corrosion and improve biocompatibility. In the present work, tantalum-niobium oxide nanocomposite thin films were successively deposited on Mg–Al6–Zn1.5-Cu2-Ge0.5 Mg alloys via reactive magnetron sputtering to improve anticorrosion and biocompatibility. Crystallographic structure, surface morphology and chemical compositions were characterized using XRD, TEM, FE-SEM, EDS and XPS. Electrochemical and hydrogen evolution experiments were used to evaluate the resistance to corrosion of the samples. The biocompatibility of the samples was evaluated by cell viability using the osteoblast cell line (MC3T3-E1). Results revealed the existence of the composite thin-film in the crystalline form and the cauliflower-like clustered morphology. Enhancement in the corrosion resistance of nanocomposite coatings was confirmed by a decrease in current density (Icorr) during the polarization studies. The wettability studies revealed the hydrophilic character of the coatings and they are bioactive in simulated body fluid (SBF) after 5 days by the mineralization of calcium phosphate. The hemocompatibility assessment proved that the coatings were blood compatible in nature. MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay on MC3T3-E1 cells showed that tantalum-niobium oxide thin films are biocompatible and can stimulate cellular proliferation and differentiation. Overall, the outcome of these studies provided promising tantalum-niobium oxide composite thin films with unique nanocrystalline surface properties and improved the corrosion resistance and biocompatibility of the Mg alloys for orthopedic applications.