Department of Bioengineering, University of California Riverside, Riverside, California, United States of America.
PLoS One. 2013 Jun 14;8(6):e65603. doi: 10.1371/journal.pone.0065603. Print 2013.
Controlling degradation of magnesium or its alloys in physiological saline solutions is essential for their potential applications in clinically viable implants. Rapid degradation of magnesium-based materials reduces the mechanical properties of implants prematurely and severely increases alkalinity of the local environment. Therefore, the objective of this study is to investigate the effects of three interactive factors on magnesium degradation, specifically, the addition of yttrium to form a magnesium-yttrium alloy versus pure magnesium, the metallic versus oxide surfaces, and the presence versus absence of physiological salt ions in the immersion solution. In the immersion solution of phosphate buffered saline (PBS), the magnesium-yttrium alloy with metallic surface degraded the slowest, followed by pure magnesium with metallic or oxide surfaces, and the magnesium-yttrium alloy with oxide surface degraded the fastest. However, in deionized (DI) water, the degradation rate showed a different trend. Specifically, pure magnesium with metallic or oxide surfaces degraded the slowest, followed by the magnesium-yttrium alloy with oxide surface, and the magnesium-yttrium alloy with metallic surface degraded the fastest. Interestingly, only magnesium-yttrium alloy with metallic surface degraded slower in PBS than in DI water, while all the other samples degraded faster in PBS than in DI water. Clearly, the results showed that the alloy composition, presence or absence of surface oxide layer, and presence or absence of physiological salt ions in the immersion solution all influenced the degradation rate and mode. Moreover, these three factors showed statistically significant interactions. This study revealed the complex interrelationships among these factors and their respective contributions to degradation for the first time. The results of this study not only improved our understanding of magnesium degradation in physiological environment, but also presented the key factors to consider in order to satisfy the degradation requirements for next-generation biodegradable implants and devices.
控制镁或其合金在生理盐水溶液中的降解对于它们在临床上可行的植入物中的潜在应用至关重要。镁基材料的快速降解会过早降低植入物的机械性能，并严重增加局部环境的碱性。因此，本研究的目的是研究三个交互因素对镁降解的影响，具体来说，是添加钇形成镁-钇合金与纯镁、金属与氧化物表面以及浸溶液中是否存在生理盐离子的影响。在磷酸盐缓冲盐水（PBS）的浸溶液中，具有金属表面的镁-钇合金降解最慢，其次是具有金属或氧化物表面的纯镁，而具有氧化物表面的镁-钇合金降解最快。然而，在去离子（DI）水中，降解速率呈现出不同的趋势。具体来说，具有金属或氧化物表面的纯镁降解最慢，其次是具有氧化物表面的镁-钇合金，而具有金属表面的镁-钇合金降解最快。有趣的是，只有具有金属表面的镁-钇合金在 PBS 中的降解速度比在 DI 水中慢，而其他所有样品在 PBS 中的降解速度都比在 DI 水中快。显然，结果表明，合金成分、表面氧化层的存在与否以及浸溶液中生理盐离子的存在与否都会影响降解速率和模式。此外，这三个因素表现出统计学上显著的相互作用。本研究首次揭示了这些因素之间的复杂相互关系及其对降解的各自贡献。本研究的结果不仅提高了我们对镁在生理环境中降解的理解，还提出了为满足下一代可生物降解植入物和设备的降解要求而需要考虑的关键因素。
