Wu Jingyao, Zhao Daoli, Lee Boeun, Roy Abhijit, Yao Raymon, Chen Shauna, Dong Zhongyun, Heineman William R, Kumta Prashant N
Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States.
McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States.
ACS Biomater Sci Eng. 2020 Apr 13;6(4):1950-1964. doi: 10.1021/acsbiomaterials.9b01591. Epub 2020 Mar 26.
Magnesium alloys are the most widely studied biodegradable metals for biodegradable vascular stent application. Two major issues with current magnesium alloy based stents are their low ductility and fast corrosion rates. Several studies have validated that introduction of Li into the magnesium alloys will significantly improve the ductility while alloying with Al will improve the corrosion resistance and strength. In the present study, we studied the effects of alloying different amounts of Li and Al on the Mg-Li-Al-Zn (LAZ) quaternary alloy system. Rods were made from four different LAZ alloys, namely, LAZ611, LAZ631, LAZ911, and LAZ931 following melting, casting, and then extrusion. Systematic assessment of mechanical properties, corrosion, cytotoxicity, and degradation including local and systemic toxicity conducted demonstrated the beneficial effects of Li and Al on the mechanical properties. Our results specifically suggest that alloying with Li significantly improved the ductility while Al enhanced the strength of the LAZ alloys. Four of the LAZ alloys exhibited different corrosion rates in Hank's balanced salt solution depending on the chemical composition. Indirect cytotoxicity tests also showed lower cytotoxicity for the alloys exhibiting higher corrosion resistance. corrosion rates in the mouse subcutaneous model showed different corrosion rates compared to the tests. Nevertheless, all of the four LAZ alloys displayed no local and systemic toxicity based on the histology analysis. This research study, therefore, demonstrated the benefits of using Li and Al as alloying elements in LAZ alloys and the potential use of LAZ alloys for vascular stent application.
镁合金是用于可生物降解血管支架应用研究最为广泛的可生物降解金属。当前基于镁合金的支架存在两个主要问题，即延展性低和腐蚀速率快。多项研究证实，在镁合金中引入锂可显著提高延展性，而与铝合金化则可提高耐腐蚀性和强度。在本研究中，我们研究了不同含量的锂和铝合金化对Mg-Li-Al-Zn（LAZ）四元合金体系的影响。通过熔炼、铸造，然后挤压，由四种不同的LAZ合金，即LAZ611、LAZ631、LAZ911和LAZ931制成棒材。对机械性能、腐蚀、细胞毒性以及包括局部和全身毒性在内的降解进行系统评估，结果表明锂和铝对机械性能具有有益影响。我们的结果具体表明，与锂合金化可显著提高LAZ合金的延展性，而铝则增强了其强度。四种LAZ合金在汉克平衡盐溶液中的腐蚀速率因化学成分而异。间接细胞毒性测试还表明，耐腐蚀性较高的合金细胞毒性较低。与体外测试相比，小鼠皮下模型中的腐蚀速率显示出不同的腐蚀速率。然而，基于组织学分析，所有四种LAZ合金均未显示出局部和全身毒性。因此，本研究证明了在LAZ合金中使用锂和铝作为合金元素的益处以及LAZ合金在血管支架应用中的潜在用途。
