Biodegradable magnesium (Mg) and its alloys exhibit excellent biocompatibility and mechanical compatibility, demonstrating tremendous potential for applications in orthopedics. However, the rapid degradation rate has limited their clinical application. Polycaprolactone (PCL) is commonly employed as a polymer coating to impede the rapid degradation of Mg. Unfortunately, its long-term anti-corrosion capability and bioactivity are inadequate. To address these issues, polydopamine (PDA)-modified zeolitic imidazolate framework-8 (PZIF-8) bioactive nanoparticles are fabricated and incorporated into the PCL coating. The PZIF-8 particles, featuring catechol motifs, can enhance the compactness of the PCL coating, reduce its defects, and possess biomineralization ability, thereby effectively improving its anti-corrosive and bioactive properties. Moreover, the active substances released from the degradation of the PZIF-8 particles such as Zn and PDA are beneficial for osteogenesis. The corrosion tests indicate that the corrosion current density of PCL-treated sample decreases by more than one order of magnitude and the amount of H released decreases from 0.23 ± 0.12 to 0.08 ± 0.08 ml cm after doping with the PZIF-8. Furthermore, the improved corrosion resistance and released PDA and Zn from the coating can promote osteogenic differentiation by up-regulating the expression of alkaline phosphatase activity, related osteogenic genes, and proteins. In addition, implantation experiments in rabbit femur defects further offer strong evidence that the doping of PZIF-8 nanoparticles accelerates bone reconstruction of the PCL coating. In summary, this work implies a new strategy to fabricate a PCL-based coating on Mg-based implants by introducing the PZIF-8 particles for orthopedic applications.

中文翻译：

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聚多巴胺改性金属有机骨架纳米粒子增强高纯镁上聚己内酯涂层的耐腐蚀性和生物活性

可生物降解的镁（Mg）及其合金具有优异的生物相容性和机械相容性，在骨科领域具有巨大的应用潜力。然而，其快速降解速度限制了其临床应用。聚己内酯 (PCL) 通常用作聚合物涂层，以阻止镁的快速降解。不幸的是，其长期防腐能力和生物活性不足。为了解决这些问题，制备了聚多巴胺 (PDA) 改性沸石咪唑酯框架 8 (PZIF-8) 生物活性纳米颗粒并将其掺入 PCL 涂层中。PZIF-8颗粒具有儿茶酚基序，可以增强PCL涂层的致密性，减少其缺陷，并具有生物矿化能力，从而有效提高其防腐和生物活性性能。此外，PZIF-8颗粒降解释放的活性物质如Zn和PDA有利于成骨。腐蚀测试表明，掺杂PZIF-8后，PCL处理的样品的腐蚀电流密度降低了一个数量级以上，H释放量从0.23±0.12 ml cm减少到0.08±0.08 ml cm。此外，耐腐蚀性的提高以及涂层中释放的PDA和Zn可以通过上调碱性磷酸酶活性、相关成骨基因和蛋白质的表达来促进成骨分化。此外，兔股骨缺损的植入实验进一步提供了有力的证据，证明PZIF-8纳米粒子的掺杂加速了PCL涂层的骨重建。总之，这项工作意味着通过引入用于骨科应用的 PZIF-8 颗粒，在镁基植入物上制造 PCL 基涂层的新策略。