Methods for improving the properties of zinc for the application of biodegradable vascular stents

Corrosion behavior, antibacterial properties and in vitro and in vivo biocompatibility of biodegradable Zn-5Cu-xMg alloy for bone-implant applications

Reasonable optimization of degradation rate, antibacterial performance and biocompatibility is crucial for the development of biodegradable zinc alloy medical implant devices with antibacterial properties. In this study, various amounts of Mg elements were incorporated into Zn5Cu alloy to modulate the degradation rate, antibacterial properties and biocompatibility. The effects of Mg contents on the microstructure, corrosion behavior, antibacterial properties and biocompatibility of Zn-5Cu-xMg alloy were extensively investigated. The results revealed that with an increase of Mg content, the amount of Mg2Zn11 phase increased and its galvanic effect with the Zn matrix was enhanced, which accelerated the corrosion process and led to higher corrosion rate and high degradation rate of the alloy. Additionally, there was an increased release of Mg2+ and Zn2+ ions from the alloy which imparted excellent resistance against Escherichia coli and Staphylococcus aureus bacteria and improved biocompatibility, subcutaneous antibacterial and immune microenvironment regulation properties. Zn-5Cu-2 Mg exhibited superior antibacterial ability, cell compatibility, proliferation effect, subcutaneous antibacterial and immune microenvironment regulation performances, which can work as a promising candidate of biodegradable antibacterial medical implants.

Fe-Zn alloy, a new biodegradable material capable of reducing ROS and inhibiting oxidative stress

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable biocompatibility. Currently, research on Fe-based materials mainly focuses on regulating the degradation rate. However, excessive release of Fe ions during material degradation will induce the generation of reactive oxygen species (ROS), leading to oxidative stress and ferroptosis. Therefore, the control of ROS release and the improvement of biocompatibility for Fe-based materials are very important. In this study, new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy degradation. Initially, the impact of three potential degradation ions (Fe2+, Fe3+, Zn2+) from the Fe-Zn alloy on human endothelial cell (EC) activity and migration ability was investigated. Subsequently, cell adhesion, cell activity, ROS production and DNA damage were assessed at various locations surrounding the alloy. Finally, the influence of different concentrations of Zn2+ in the medium on cell viability and ROS production was evaluated. High levels of ROS exhibited evident toxic effects on ECs and promoted DNA damage. As an antioxidant, Zn2+ effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/l. These findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation thereby enhancing cytocompatibility.