Magnesium (Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization (PEO)/polydopamine (PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times (60 s, 120 s) and dopamine concentrations (1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml (120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance. Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.

镁 (Mg) 合金因其接近骨骼的弹性模量、生物相容性和生物降解特性而在生物医学材料中广为人知。然而，较差的耐腐蚀性阻碍了它们的生物医学应用。此外，有必要赋予镁合金生物活性，这对于临时骨植入物至关重要。在这里，使用 PEO 和随后的电沉积工艺将等离子电解氧化 (PEO)/聚多巴胺 (PDA) 的自修复、耐腐蚀和生物活性双相涂层应用于 AZ91 基板。此外，还研究了不同电沉积时间（60 s、120 s）和多巴胺浓度（1和1.5 mg/ml）对提高耐腐蚀性、生物活性、生物相容性和自修复性能的作用及其机制。结果表明，PEO 涂层被 PDA 有效密封，具体取决于电沉积参数。值得注意的是，在浓度为 1 mg/ml (120T-1C) 的多巴胺中电沉积 120 秒会形成均匀且无裂纹的 PDA 涂层。与 PEO 涂层相比，双相 PEO/PDA 涂层显示出更高的生物活性，这是由于 PDA 顶层与钙离子和磷酸根离子之间的静电相互作用以及涂层的高亲水性。此外，双相 PEO/PDA 涂层还显示出比 PEO 和裸合金更好且更稳定的保护性能，具体取决于 PDA 沉积参数。值得注意的是，与 PEO 相比，120T-1C 的腐蚀电流密度降低了一个数量级。此外，阳极极化分支中存在宽阔的钝化区域，通过类似拉链的机制显示出持久的自修复特性，表明双相涂层可以保持良好的耐腐蚀性。此外，双面涂层样品的细胞相容性也通过与 MG63 细胞的相互作用得到证实。综上所述，PEO/PDA 涂层具有良好的腐蚀防护、自愈能力、生物活性和生物相容性，有望成为可降解镁基植入物的候选材料。