Surface modification of biodegradable AZ91 magnesium alloy by electrospun polymer nanocomposite: Evaluation of in vitro degradation and cytocompatibility

Abstract

Magnesium alloys have recently attracted significant attention for the fabrication of biodegradable orthopedic implants and cardiovascular stents. Nevertheless, the high degradation rate of magnesium alloys under physiological conditions is still challenging. We present a surface modification strategy to tailor the degradation rate and in vitro cell behavior of AZ91 alloy through electrospinning of continuous poly (ε-caprolactone) fibers containing bioactive glass nanoparticles (~30 nm). The average thickness of the nanocomposite film and the fibers are 30 μm ± 5 and 300 ± 31 nm, respectively. Electrochemical studies in simulated body fluid and standard immersion corrosion tests have determined that the degradation rate of the magnesium alloy is reduced by two orders of magnitude. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses have shown the formation and precipitation of hydroxyapatite and magnesium hydroxides on the surface of fibrous film after 7 days of incubation. In addition to enhancing the in vitro bioactivity, osteosarcoma and fibroblast cell assays have revealed better cell adhesion and viability on the coated surface. The mechanisms of improved properties are ascribed to the effect of nanocomposite film on the hydrophilicity of the surface and mass transport through the fibrous structure as well as the presence of bioactive nanoparticles.