Drynda Andreas, Hassel Thomas, Bach Friedrich Wilhelm, Peuster Matthias
Department of Orthopaedics, Otto-von-Guericke University of Magdeburg, Magdeburg, Germany.
J Biomed Mater Res B Appl Biomater. 2015 Apr;103(3):649-60. doi: 10.1002/jbm.b.33234. Epub 2014 Jun 28.
The principle of biodegradation for the production of temporary implant materials (e.g. stents) plays an important role in the treatment of congenital heart defects. In the last decade several attempts have been made with different alloy materials-mainly based on iron and magnesium. None of the currently available materials in this field have demonstrated satisfying results and have therefore not found entry into broad clinical practice. While magnesium or magnesium alloy systems corrode too fast, the corrosion rate of pure iron-stents is too slow for cardiovascular applications. In the last years FeMn alloy systems were developed with the idea that galvanic effects, caused by different electrochemical properties of Fe and Mn, would increase the corrosion rate. In vitro tests with alloys containing up to 30% Mn showed promising results in terms of biocompatibility. This study deals with the development of new FeMn alloy systems with lower Mn concentrations (FeMn 0.5 wt %, FeMn 2.7 wt %, FeMn 6.9 wt %) to avoid Mn toxicity. Our results show, that these alloys exhibit good mechanical features as well as suitable in vitro biocompatibility and corrosion properties. In contrast, the evaluation of these alloys in a mouse model led to unexpected results-even after 9 months no significant corrosion was detectable. Preliminary SEM investigations showed that passivation layers (FeMn phosphates) might be the reason for corrosion resistance. If this can be proved in further experiments, strategies to prevent or dissolve those layers need to be developed to expedite the in vivo corrosion of FeMn alloys.
用于生产临时植入材料（如支架）的生物降解原理在先天性心脏病治疗中起着重要作用。在过去十年中，人们尝试了几种不同的合金材料，主要基于铁和镁。该领域目前可用的材料均未取得令人满意的结果，因此尚未广泛应用于临床实践。虽然镁或镁合金系统腐蚀太快，但纯铁支架的腐蚀速率对于心血管应用来说又太慢。近年来，开发了铁锰合金系统，其理念是铁和锰不同的电化学性质所引起的电化效应会提高腐蚀速率。对含锰量高达30%的合金进行的体外测试在生物相容性方面显示出有前景的结果。本研究致力于开发锰浓度较低的新型铁锰合金系统（铁锰0.5 wt%、铁锰2.7 wt%、铁锰6.9 wt%）以避免锰毒性。我们的结果表明，这些合金具有良好的机械性能以及合适的体外生物相容性和腐蚀性能。相比之下，在小鼠模型中对这些合金的评估却得出了意想不到的结果——即使在9个月后也未检测到明显的腐蚀。初步的扫描电子显微镜研究表明，钝化层（铁锰磷酸盐）可能是耐腐蚀的原因。如果能在进一步实验中得到证实，就需要制定防止或溶解这些层的策略，以加快铁锰合金在体内的腐蚀。
