| Autor: |
Balog, Martin, Marques de Castro, Moara, Čapek, Jaroslav, Švec Jr, Peter, Takáčová, Martina, Csáderová, Lucia, Sedláčková, Eva, Švastová, Eliška, Školáková, Andrea, Dvorský, Drahomír, Pinc, Jan, Hybášek, Vojtěch, Kubásek, Jiří, Krížik, Peter, Skiba, Jacek, Bajana, Oto, Hassan Ibrahim, Ahmed Mohamed |
| Zdroj: |
Journal of Materials Research and Technology; July-August 2023, Vol. 25 Issue: 1 p4510-4527, 18p |
| Abstrakt: |
The issue of intrinsic microstructural and mechanical instability of Zn-based metals limits their expansion in potential applications of bioresorbable stents and orthopedic fixators. A new concept of stabilization of Zn microstructure by a small fraction of nontoxic nanometric ZnO dispersoids is proposed for the first time and demonstrated on the particular bioabsorbable model material. The effect of the ZnO dispersoids on post-processing microstructural stability, deformation and strengthening mechanisms, corrosion, and in-vitrobiological behavior are pursued. The ZnO dispersoids arise in situwithin deformed Zn structure during the consolidation of fine atomized Zn 99.99wt.% powder by hydro-extrusion. ZnO nanodispersoids (4.75 vol.%; ∼136 nm) form from passivating films present on Zn. They allow formation of ultrafine-grained Zn structure with an average grain size of ∼750 nm and its retention by Zener pinning action during annealing held at 100 °C. The model Zn + ZnO composite shows the superior mechanical properties than those reported for pure Zn materials. The utilized stabilization concept doesn't compromise corrosion and biological responses. Immersion of the Zn + ZnO in DMEM results in a corrosion rate, which complies with the desirable standard rate for biodegradable materials. Electrochemical tests suggest that the Zn + ZnO reaches a similar degradation rate after the first week of immersion and a more uniform corrosion behavior compared to the cast Zn reference. In-vitrocyto/genotoxicity assays performed using DMEM diluted extracts of the Zn + ZnO and cast Zn incubated with L929 cells yield in comparable and non-toxic responses. The presence of ZnO dispersoids induces a small but still significant bacteriostatic activity. |
| Databáze: |
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