Gomes Pedro S, Zomorodian Amir, Kwiatkowski Lech, Lutze Rafal, Balkowiec Alicja, Colaço Bruno, Pinheiro Vitor, Fernandes João C S, Montemor Maria F, Fernandes Maria H
Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, U. Porto, R. Dr Manuel Pereira da Silva, 4200-393 Porto, Portugal.
Biomed Mater. 2016 Aug 10;11(4):045007. doi: 10.1088/1748-6041/11/4/045007.
Magnesium alloys are regarded as potential biodegradable load-bearing biomaterials for orthopedic applications due to their physico-chemical and biomechanical properties. However, their clinical applicability is restricted by their high degradation rate, which limits the physiological reconstruction of the neighbouring tissues. In this work, a multifunctional coating architecture was developed on an AZ31 alloy by conjoining an anodization process with the deposition of a polymeric-based layer consisting of polyether imine reinforced with hydroxyapatite nanoparticles, aiming at improved control of the corrosion activity and biological performance of the Mg substrate. Anodization and coating protocols were evaluated either independently or combined for corrosion resistance and biological behaviour, i.e. the irritation potential and angiogenic capability within a chicken chorioallantoic membrane assay, and bone tissue response following tibia implantation within a rabbit model. Electrochemical impedance spectroscopy (EIS) analysis showed that coated Mg constructs, particularly anodized plus coated with AZ31, exhibited excellent stability compared to the anodized alloy and, particularly, to the bare AZ31. Microtomographic evaluation of the implanted samples correlated with these degradation results. Mg constructs displayed a non-irritating behaviour, and were associated with high levels of vascular ingrowth. Bone ingrowth neighbouring the implanted constructs was observed for all samples, with coated and anodized plus coated samples presenting the highest bone formation. Gene expression analysis suggested that the enhanced bone tissue formation was associated with the boost in osteogenic activity through Runx2 upregulation, following the activation of PGC-1α/ERRα signaling. Overall, the developed multifunctional coatings appear to be a promising strategy to obtain safe and bioactive biodegradable Mg-based implants with potential applications within bone tissue.
镁合金因其物理化学和生物力学性能，被视为用于骨科应用的潜在可生物降解承重生物材料。然而，其临床适用性受到高降解速率的限制，这限制了邻近组织的生理重建。在这项工作中，通过将阳极氧化工艺与由羟基磷灰石纳米颗粒增强的聚醚酰亚胺组成的聚合物基层的沉积相结合，在AZ31合金上开发了一种多功能涂层结构，旨在更好地控制镁基体的腐蚀活性和生物学性能。对阳极氧化和涂层方案进行了单独或组合评估，以考察其耐腐蚀性和生物学行为，即在鸡胚绒毛尿囊膜试验中的刺激潜力和血管生成能力，以及在兔模型中胫骨植入后的骨组织反应。电化学阻抗谱（EIS）分析表明，与阳极氧化合金相比，特别是与裸AZ31相比，涂覆的镁构建体，尤其是阳极氧化后再涂覆AZ31的构建体，表现出优异的稳定性。植入样品的显微断层扫描评估与这些降解结果相关。镁构建体表现出无刺激行为，并与高水平的血管向内生长有关。在所有样品中均观察到植入构建体附近的骨向内生长，涂覆和阳极氧化后再涂覆的样品骨形成最高。基因表达分析表明，在PGC-1α/ERRα信号激活后，通过Runx2上调，成骨活性增强，从而促进了骨组织形成。总体而言，所开发的多功能涂层似乎是一种有前景的策略，可用于获得安全且具有生物活性的可生物降解镁基植入物，并在骨组织中具有潜在应用。
