In Vitro Degradation, Hemocompatibility, and Cytocompatibility of Nanostructured Absorbable Fe–Mn–Ag Alloys for Biomedical Application

The addition of noble elements such as Ag was shown as a successful method to accelerate the corrosion rate of absorbable Fe-based alloys. One major concern of Ag addition is its effect on hemocompatibility and biocompatibility. In this study, in vitro degradation and surface analysis of Fe–30Mn–xAg (x = 0, 1, and 3 wt %) alloys as well as their effects on hemocompatibility and cell viability of human umbilical vein endothelial cells (HUVECs) were investigated. The static degradation rate of the alloys was 4.97, 4.69, and 4.49 mg/cm2 for Fe–30Mn, Fe–30Mn–1Ag, and Fe–30Mn–3Ag, respectively. The surface analysis after degradation showed that γ-FeOOH was formed on Fe–30Mn–3Ag, while α-FeOOH was more dominant on Fe–30Mn and Fe–30Mn–1Ag. As γ-FeOOH is more soluble than α-FeOOH, it assists further degradation of Fe–30Mn–3Ag alloy. The high amount of Ag, which induced the hemolysis ratio, however, inhibited coagulation by decreasing the platelet adhesion. Fe–30Mn–1Ag and Fe–30Mn–3Ag alloys show an improved cell viability as compared to that of Fe–Mn alloy. Shear yield strength and shear elastic modulus of the samples after immersion tests were increased, while the ultimate shear strength was not affected. On the basis of the acceptable hemolysis rate, low platelet adhesion, acceptable cell viability, and appropriate mechanical properties after degradation, Fe–30Mn–1Ag can be considered as a suitable blood-contacting Fe-based absorbable alloy.