Khan Muhammad Mudasser, Deen Kashif Mairaj, Shabib Ishraq, Asselin Edouard, Haider Waseem
School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI, United States of America.
Department of Materials Engineering, The University of British Columbia, Vancouver, V6T 1Z4 Canada.
Acta Biomater. 2020 Sep 1;113:660-676. doi: 10.1016/j.actbio.2020.06.014. Epub 2020 Jun 14.
In the field of biodegradable metallic materials, rapid and non-uniform biodegradation, caused by uncontrolled corrosion rates, is a potential shortcoming. Among the prominent biodegradable materials, magnesium is an attractive choice, however, it is prone to rapid dissolution. In contrast, iron possesses a slow dissolution rate. To approach the middle ground, instead of making magnesium more corrosion-resistant, the less-explored approach of making iron less corrosion-resistant is employed here. In this study, iron, and magnesium, having contrasting corrosion rates, are combined via magnetron co-sputtering. The idea of combinatorial synthesis is employed to fabricate two model nanostructured Fe-Mg samples, i.e. CSFM-1 (FeMg), and CSFM-2 (FeMg), exhibiting a controlled and uniform degradation in phosphate-buffer saline solution. The structural characterization of the two samples demonstrates a substitutional solid solution of bcc-Fe-Mg in CSFM-1 and an amorphous short-range-ordered structure in the CSFM-2 sample. Electrochemical investigation shows increased corrosion rates for the two Fe-Mg samples in comparison to pure Fe, validated by relatively active corrosion potentials, higher corrosion current densities, faster anodic dissolution, and lower charge transfer resistances, governed by chemical composition and non-equilibrium nanostructures. Finally, nano-indentation testing of the two samples reveals relatively higher hardness and lower elastic moduli, a suitable combination for bio-implants. STATEMENT OF SIGNIFICANCE: The use of Mg as a biodegradable in-vivo implant material is problematic because of its high dissolution rate and potential for hydrogen gas generation. This is the first time that the idea of combinatorial synthesis is employed to fabricate two model nanostructured Fe-Mg systems, i.e. CSFM-1 (FeMg), and CSFM-2 (FeMg), exhibiting a controlled and uniform degradation. The structural characterization of the two systems demonstrates a substitutional solid solution of bcc-Fe-Mg in CSFM-1 and an amorphous short-range-ordered structure in the CSFM-2 system. Electrochemical investigation shows increased biodegradation rates for the two Fe-Mg systems in comparison to pure Fe, validated by relatively active corrosion potentials, higher corrosion current densities, faster anodic dissolution, and lower charge transfer resistances, governed by chemical composition and non-equilibrium nanostructures.
在可生物降解金属材料领域，由不受控制的腐蚀速率导致的快速且不均匀的生物降解是一个潜在的缺点。在著名的可生物降解材料中，镁是一个有吸引力的选择，然而，它易于快速溶解。相比之下，铁具有缓慢的溶解速率。为了达到中间状态，这里采用的不是使镁更耐腐蚀，而是采用较少探索的使铁更不耐腐蚀的方法。在本研究中，具有相反腐蚀速率的铁和镁通过磁控共溅射结合。采用组合合成的理念制备了两个模型纳米结构的铁 - 镁样品，即CSFM - 1（FeMg）和CSFM - 2（FeMg），它们在磷酸盐缓冲盐溶液中表现出可控且均匀的降解。两个样品的结构表征表明，CSFM - 1中为体心立方铁 - 镁置换固溶体，CSFM - 2样品中为非晶短程有序结构。电化学研究表明，与纯铁相比，两个铁 - 镁样品的腐蚀速率增加，这通过相对活跃的腐蚀电位、更高的腐蚀电流密度、更快的阳极溶解以及更低的电荷转移电阻得到验证，这些受化学成分和非平衡纳米结构的控制。最后，对两个样品的纳米压痕测试显示出相对较高的硬度和较低的弹性模量，这是生物植入物的合适组合。重要性声明：将镁用作可生物降解的体内植入材料存在问题，因为其溶解速率高且有产生氢气的可能性。这是首次采用组合合成的理念制备两个模型纳米结构的铁 - 镁体系，即CSFM - 1（FeMg）和CSFM - 2（FeMg），它们表现出可控且均匀的降解。两个体系的结构表征表明，CSFM - 1中为体心立方铁 - 镁置换固溶体，CSFM - 2体系中为非晶短程有序结构。电化学研究表明与纯铁相比，两个铁 - 镁体系的生物降解速率增加，这通过相对活跃的腐蚀电位、更高的腐蚀电流密度、更快的阳极溶解以及更低的电荷转移电阻得到验证，这些受化学成分和非平衡纳米结构的控制。
