Materials Engineering Department, Faculty of Engineering, Malayer University, Malayer, Iran.
Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong.
J Biomed Mater Res A. 2021 Dec;109(12):2657-2672. doi: 10.1002/jbm.a.37258. Epub 2021 Jun 29.
Much effort has made to lessen the cytotoxicity and enhance the corrosion resistance of biodegradable magnesium alloys, for example, by depositing multilayered polymeric coatings containing hydroxyapatite. In this work, a hierarchical structure composed of ciprofloxacin (Cip)-loaded on polyacrylic acid (PAA) and poly (ethyleneimine) (PEI) as biocompatible polymeric multilayers and calcium phosphate coating as the top layer is formed by the sol-gel method on the AZ91 Mg alloy with an intermediate layer formed by nitrogen plasma immersion ion implantation. The thicknesses of the multilayered coating and nitrided layer (Mg N ) are 10 μm and 140 nm, respectively. The corrosion current density decreases by 95.6% and the corrosion potential in the polarization curve shifts to the positive direction by 23%. The passivation process which occurs at defects by deposition of corrosion products mitigates both galvanic and localized corrosion. Slight increase in the contact angle and surface free energy, enhanced corrosion resistance, and reduced cytotoxicity are observed from the multilayered structure. The better corrosion resistance enables better control of release of Cip. Biological assessment indicates that the antibacterial activity against Escherichia coli is improved by 100% after culturing for 24 hr and the cell viability and noncytotoxic behavior of the coated AZ91 are enhanced as well. The corrosion behavior and biological results suggest that the strategy of using a hierarchical structure composed of Cip-loaded polymeric multilayers in conjunction with an intermediate plasma nitrided layer has large potential in the development of biodegradable orthopedic implants made of Mg alloys.
人们付出了大量努力来降低生物可降解镁合金的细胞毒性并提高其耐腐蚀性，例如，通过沉积包含羟基磷灰石的多层聚合涂层。在这项工作中，通过溶胶-凝胶法在 AZ91 镁合金上形成了一种由载有环丙沙星（Cip）的聚丙烯酸（PAA）和聚（乙二胺）（PEI）组成的生物相容聚合物多层和磷酸钙涂层的分层结构，中间层由氮等离子体浸没离子注入形成。多层涂层和氮化层（MgN）的厚度分别为 10μm 和 140nm。腐蚀电流密度降低了 95.6%，极化曲线中的腐蚀电位向正方向移动了 23%。通过沉积腐蚀产物，在缺陷处发生钝化过程，减轻了电偶腐蚀和局部腐蚀。从多层结构中观察到接触角和表面自由能略有增加、耐腐蚀性增强和细胞毒性降低。更好的耐腐蚀性使得更好地控制 Cip 的释放成为可能。生物评估表明，在培养 24 小时后，对大肠杆菌的抗菌活性提高了 100%，并且涂层 AZ91 的细胞活力和非细胞毒性行为也得到了增强。腐蚀行为和生物结果表明，使用载有 Cip 的聚合物多层与中间等离子体氮化层组成的分层结构的策略在开发用于生物可降解骨科植入物的镁合金方面具有很大的潜力。
