In vitro cytocompatibility, hemocompatibility and antibacterial properties of biodegradable Zn-Cu-Fe alloys for cardiovascular stents applications.

In the present study, the effects of Zn-3Cu-xFe (x = 0, 0.2, 0.5 wt%) alloys on endothelial cells (EA.hy926) and smooth muscle cells (A7r5), the hemocompatibility and antibacterial properties were also evaluated. The cell viability of EA.hy926 cells and A7r5 cells decreased with the increasing of extract concentration. At the same Zn2+ concentration (over 6 ppm), the cell viability of EA.hy926 cells increased with the addition of Cu or Cu and Fe content, but no significant effect on A7r5 cells was observed. The hemolysis rate of Zn-3Cu-xFe alloys samples was about 1%, and there was no adversely affected on platelets adhering to the surface of the Zn alloys. As Fe content increases in the Zn-Cu-Fe alloys, the antibacterial lower concentrations against Staphylococcus aureus and Escherichia coli was improved due to the higher degradation rate and more Zn2+ and Cu2+ released. Our previous study already showed that the Zn-Cu-Fe alloy exhibited excellent mechanical properties and moderate degradation rate. Based on the above results, the in vitro biocompatibilities and antibacterial properties of Zn-3Cu alloy are significantly improved by the alloying of trace Fe, and the hemocompatibility is not adversely affected, which indicated that Zn-Cu-Fe alloy is a promising vascular stents candidate material.

Effects of extrusion temperature on microstructure, mechanical properties and in vitro degradation behavior of biodegradable Zn-3Cu-0.5Fe alloy.

Zn-based alloys as biodegradable materials for cardiovascular stents have drawn more and more attention in recent years. However, the hot plastic deformation of Zn-based alloys does not get enough attention. In this study, Zn-3Cu-0.5Fe alloy was prepared and then hot extruded at 140, 180, 220 and 260 °C. Effects of extrusion temperature on the microstructure, mechanical properties and degradation behavior were investigated. Nano-scaled particles precipitated during extrusion and the quantity decreased with the increasing of extrusion temperature. As the extrusion temperature increased from 140 to 260 °C, the grain size increased from 1.15 to 4.38 µm, the yield strength and ultimate tensile strength increased from 203 ±â€¯3.23 and 221 ±â€¯1.56 MPa to 269 ±â€¯2.65 and 302 ±â€¯8.01 MPa, increased by 32.5% and 45%, while the degradation rate was decreased gradually from 62.8 ±â€¯0.72 µm/year to 49.9 ±â€¯3.35 µm/year, decreased by 20.5%. In addition, the degradation behavior changes from a relatively uniform degradation mode to a localized degradation mode with the increase of the grain size. Dislocation gliding is replaced by grain-boundary movement and dynamic recrystallization (DRX) in the room temperature tensile deformation process. Lower extrusion temperature is beneficial for higher elongation and degradation rate as well as relatively uniform degradation mode, which is better suitable for the clinical application of cardiovascular stents.