Session Overview |
Thursday, May 23 |
15:45 |
TBC - Clinical Translation of Biodegradable and Bioactive Materials
TBC |
16:15 |
Biodegradable Zn-Cu-Li-Sc alloys for biomedical applications
* Yuncang Li, Yuncang Li, Associate Professor, RMIT University, Australia Zinc (Zn)-based alloys have emerged as promising new biodegradable materials owing to their moderate corrosion rates and potential biological functionalities. However, as-cast pure Zn and its alloys possess low mechanical strength, poor ductility, and low hardness, which hinder their biomedical application. In this study, biodegradable Zn-3Cu-0.4Li (ZCL) and ZCL-xSc (x=0.20, 0.35, and 0.55 wt.%) alloys were fabricated by casting and further hot rolling, and their mechanical, corrosion and biocompatibility properties were comprehensively investigated for orthopedic implant applications. Results indicated that the mechanical properties of HR ZCL and ZCL-xSc alloys were significantly improved compared to the as-cast alloys. The HR ZCL-0.20Sc alloy displayed the best combination of mechanical properties, including microhardness of 113 HV, elongation of 40%, yield strength of 277 MPa, and ultimate tensile strength of 337 MPa. The nanohardness of HR ZCL–xSc alloys increased from 1.64 to 2.43 GPa with increasing Sc content from 0-0.55 wt.%. Degradation rates of HR ZCL-xSc alloys gradually increased with increasing Sc content, with the HR ZCL-0.55Sc alloy showing the lowest corrosion resistance and the highest degradation rate of 50.1 μm/y after immersion in Hanks’ balanced salt solution for 30 days. In vitro cytocompatibility assessment using human osteoblast-like SaOS2 cells showed high cell viability after 1 day of exposure to undiluted extracts of HR ZCL and ZCL-xSc alloys and after 5 days with 50 % diluted extracts. Overall, due to its excellent mechanical, satisfactory corrosion, and good biocompatibility properties, the HR ZCL-0.20Sc alloy has great potential as a biodegradable bone-implant material. |
16:30 |
Construction of Cell Sheet In Vitro Evaluation Model for Magnesium Alloy
* Liangwei Chen, Peking University School and Hospital of Stomatology, China (People's Republic of) Jianhua Zhu, Peking University School and Hospital of Stomatology Jianmin Han, Peking University School and Hospital of Stomatology Chuanbin Guo, Peking University School and Hospital of Stomatology Biodegradable metals have shown great pro-osteogenic effects but lack an effective in vitro evaluation model, which impedes the clinical transition. Traditional in vitro evaluation models usually use an indirect way by employing metal extract. However, this can not fully reflect the in-vivo situation of biodegradable metals. So, it is urgent to explore a more effective in-vitro method. The cell sheet technique is an effective way to evaluate the toxicity and osteogenesis effect of biomaterials in vitro. Therefore, we aim to explore the feasibility of using the CS model to evaluate magnesium alloy in vitro. In this study, the cell-sheet model shows better osteogenesis ability than the monolayer cell model by ARS staining and RT-qPCR. Then we successfully constructed the cell sheet-magnesium model (CS-Mg). In CCK-8 assays, CS-Mg exhibited enhanced proliferation abilities, and flow cytometry showed lower apoptosis levels compared to the control group. Then we constructed a defect in the cell sheet to mimic the in vivo bone defect. The immunofluorescent staining showed more osteogenesis-related proteins in the CS-Mg group than others. The RNA-sequencing results also showed that the osteogenesis-related genes including those in the CS-Mg group were higher than those in the NC-Mg group. Furthermore, we constructed the in vivo mouse bone defect model and evaluated the gene expression difference. A large number of osteogenesis-related genes were upgraded in the Mg group, and we found the similarity of the differential gene expression of Mg alloy vs. control between the in vivo and the in vitro model. In conclusion, the cell sheet model can effectively evaluate the osteogenesis effect of magnesium alloy and shorten the time of in vitro evaluation. The cell sheet model shows great potential in the evaluation of biodegradable metals, and it may be used as a useful tool for exploring the osteogenesis mechanism in vitro. |
16:45 |
Discussion on afternoon presentations
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