Zhang Xiyuan, Niu Jialin, Yeung Kelvin Wai-Kwok, Huang Hua, Gao Zhiqiang, Chen Chun, Guan Qingqing, Zhang Guangjian, Zhang Linlin, Xue Guanhua, Yuan Guangyin
National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Acta Biomater. 2024 Jun 12. doi: 10.1016/j.actbio.2024.06.007.
Biodegradable Zn alloys show great potential for vascular stents due to their moderate degradation rates and acceptable biocompatibility. However, the poor mechanical properties limit their applications. In this study, low alloyed Zn-2Cu-xLi (x = 0.004, 0.01, 0.07 wt %) alloys with favorable mechanical properties were developed. The microstructure consists of fine equiaxed η-Zn grains, micron, submicron-sized and coherent nano ε-CuZn phases. The introduced Li exists as a solute in the η-Zn matrix and ε-CuZn phase, and results in the increase of ε-CuZn volume fraction, the refinement of grains and more uniform distribution of grain sizes. As Li content increases, the strength of alloys is dramatically improved by grain boundary strengthening, precipitate strengthening of ε-CuZn and solid solution strengthening of Li. Zn-2Cu-0.07Li alloy has the optimal mechanical properties with a tensile yield strength of 321.8 MPa, ultimate tensile strength of 362.3 MPa and fracture elongation of 28.0 %, exceeding the benchmark of stents. It also has favorable mechanical property stability, weak tension compression yield asymmetry and strain rate sensitivity. It exhibits uniform degradation and a little improved degradation rate of 89.5 μm∙year, due to the improved electrochemical activity by increased ε-CuZn volume fraction, and generates LiCO and LiOH. It shows favorable cytocompatibility without adverse influence on endothelial cell viability by trace Li. The fabricated microtubes show favorable mechanical properties, and stents exhibit an average radial strength of 118 kPa. The present study indicates that Zn-2Cu-0.07Li alloy is a potential and promising candidate for vascular stent applications. STATEMENT OF SIGNIFICANCE: Zn alloys are promising candidates for biodegradable vascular stents. However, improving their mechanical properties is challenging. Combining the advantages of Cu and trace Li, Zn-2Cu-xLi (x < 0.1 wt %) alloys were developed for stents. As Li increases, the strength of alloys is dramatically improved by refined grains, increased volume fraction of ε-CuZn and solid solution of Li. Zn-2Cu-0.07Li alloy exhibits a TYS exceeding 320 MPa, UTS exceeding 360 MPa and fracture EL of nearly 30 %. It shows favorable mechanical stability, degradation behaviors and cytocompatibility. The alloy was fabricated into microtubes and stents for mechanical property tests to verify application feasibility for the first time. This indicates that Zn-2Cu-0.07Li alloy has great potential for vascular stent applications.
由于具有适度的降解速率和可接受的生物相容性,可生物降解锌合金在血管支架方面显示出巨大潜力。然而,其较差的力学性能限制了它们的应用。在本研究中,开发了具有良好力学性能的低合金化Zn-2Cu-xLi(x = 0.004、0.01、0.07 wt%)合金。微观结构由细小的等轴η-Zn晶粒、微米级、亚微米级且相干的纳米ε-CuZn相组成。引入的Li以溶质形式存在于η-Zn基体和ε-CuZn相中,导致ε-CuZn体积分数增加、晶粒细化以及晶粒尺寸分布更均匀。随着Li含量增加,合金强度通过晶界强化、ε-CuZn的析出强化和Li的固溶强化而显著提高。Zn-2Cu-0.07Li合金具有最佳力学性能,其拉伸屈服强度为321.8 MPa,极限抗拉强度为362.3 MPa,断裂伸长率为28.0%,超过了支架的基准。它还具有良好的力学性能稳定性、较弱的拉伸压缩屈服不对称性和应变率敏感性。由于ε-CuZn体积分数增加提高了电化学活性,它表现出均匀降解且降解速率略有提高,为89.5 μm∙年,并生成LiCO和LiOH。它显示出良好的细胞相容性,痕量Li对内皮细胞活力无不利影响。制造的微管具有良好的力学性能,支架的平均径向强度为118 kPa。本研究表明,Zn-2Cu-0.07Li合金是血管支架应用的潜在且有前景的候选材料。
锌合金是可生物降解血管支架的有前景候选材料。然而,改善其力学性能具有挑战性。结合Cu和痕量Li的优点,开发了用于支架的Zn-2Cu-xLi(x < 0.1 wt%)合金。随着Li增加,合金强度通过细化晶粒、增加ε-CuZn体积分数和Li的固溶而显著提高。Zn-2Cu-0.07Li合金的拉伸屈服强度超过320 MPa,极限抗拉强度超过360 MPa,断裂伸长率接近30%。它显示出良好的力学稳定性、降解行为和细胞相容性。首次将该合金制成微管和支架进行力学性能测试以验证应用可行性。这表明Zn-2Cu-0.07Li合金在血管支架应用方面具有巨大潜力。