Recent studies indicate that there is a great demand to optimize pure Zn with tunable degradation rates and more desirable biocompatibility as orthopedic implants. Metal matrix composite (MMC) can be a promising approach for this purpose. In this study, MMC with pure Zn as a matrix and hydroxyapatite (HA) as reinforcements were prepared by spark plasma sintering (SPS). Feasibility of novel Zn-HA composites to be used as orthopedic implant applications was systematically evaluated. After sintering, HA distributed in the Zn particle boundaries uniformly. Corrosion tests indicated that the degradation rates of Zn-HA composites were adjustable due to the biphasic effects of HA. Zn-HA composites showed significantly improved cell viability of osteoblastic MC3T3-E1 cells compared with pure Zn. Both pure Zn and composites exhibited a low thrombosis risk and hemolysis rates while a Zn ion concentration-dependent effect was found on coagulation time. An effective antibacterial property was observed as well. The volume loss of pure Zn and Zn-5HA composite was 1.7% and 3.2% after 8 weeks’ implantation. Histological analysis found newly formed bone surrounding pure Zn and Zn-5HA composite at week 4 and increased bone mass over time. With prolonged implantation time, Zn-5HA composite was more effective on stimulating new bone formation than pure Zn. In summary, MMC is a feasible way to design Zn based materials with adjustable degradation rates and improved biocompatibility.

Statement of Significance

Biodegradable zinc materials are promising candidates for the new generation of orthopedic implants. However, the slow degradation rates and unsatisfactory cytocompatibility of pure Zn in bone environments limit its future clinical applications. Generally, alloying is a common way to improve the performance of pure Zn. In this study, metal matrix composite was chosen as a novel strategy to solve the problems. Hydroxyapatite, as a bioactive component, was added into Zn matrix via spark plasma sintering. We find that Zn-HA composites exhibited adjustable degradation rates and improved biocompatibility both in vitro and in vivo. This study provides exhaustive and significant information including microstructure, mechanical performance, degradation behavior, biocompatibility, hemocompatibility and antibacterial property for the future Zn based implants design.

中文翻译：

---

锌-羟基磷灰石复合材料作为骨科应用的新型可生物降解金属基质复合材料的体外和体内研究

最近的研究表明，作为骨科植入物，对以可调节的降解速率和更理想的生物相容性优化纯锌的需求很大。金属基复合材料（MMC）可能是一种有前途的方法。在这项研究中，通过火花等离子体烧结（SPS）制备了以纯锌为基体和羟基磷灰石（HA）为增强材料的MMC。系统评价了新型Zn-HA复合材料用作骨科植入物的可行性。烧结后，HA均匀地分布在Zn颗粒的边界内。腐蚀试验表明，由于HA的两相作用，Zn-HA复合材料的降解速率是可调节的。与纯锌相比，Zn-HA复合材料显示出成骨细胞MC3T3-E1细胞的细胞活力显着提高。纯锌和复合材料均显示出较低的血栓形成风险和溶血率，而锌离子浓度对凝血时间具有依赖性。还观察到有效的抗菌性能。植入8周后，纯Zn和Zn-5HA复合材料的体积损失分别为1.7％和3.2％。组织学分析发现在第4周时，纯锌和Zn-5HA复合材料周围形成了新形成的骨骼，并随时间增加了骨量。随着植入时间的延长，Zn-5HA复合材料在刺激新骨形成方面比纯锌更有效。总之，MMC是设计具有可调降解速率和改善生物相容性的锌基材料的可行方法。植入8周后，纯Zn和Zn-5HA复合材料的体积损失分别为1.7％和3.2％。组织学分析发现在第4周时，纯锌和Zn-5HA复合材料周围形成了新形成的骨骼，并随时间增加了骨量。随着植入时间的延长，Zn-5HA复合材料在刺激新骨形成方面比纯锌更有效。总之，MMC是设计具有可调降解速率和改善生物相容性的锌基材料的可行方法。植入8周后，纯Zn和Zn-5HA复合材料的体积损失分别为1.7％和3.2％。组织学分析发现在第4周时，纯锌和Zn-5HA复合材料周围形成了新形成的骨骼，并随时间增加了骨量。随着植入时间的延长，Zn-5HA复合材料在刺激新骨形成方面比纯锌更有效。总之，MMC是设计具有可调降解速率和改善生物相容性的锌基材料的可行方法。

重要声明

可生物降解的锌材料是新一代骨科植入物的有希望的候选者。然而，纯锌在骨骼环境中的缓慢降解速率和不令人满意的细胞相容性限制了其未来的临床应用。通常，合金化是改善纯Zn性能的常用方法。在这项研究中，选择金属基复合材料作为解决该问题的新策略。通过火花等离子体烧结将羟基磷灰石作为生物活性成分添加到Zn基体中。我们发现Zn-HA复合材料在体外和体内均表现出可调节的降解速率和改善的生物相容性。这项研究为将来的锌基植入物设计提供了详尽而重要的信息，包括微观结构，机械性能，降解行为，生物相容性，血液相容性和抗菌性能。