Replacement and regeneration of damaged bone, particularly for those defects with critical size, are still major challenges in orthopaedic surgery. The conventional bone implants, normally with poor internal architecture design, may cause significant issues owing to the mechanical and structural mismatches between target bone and the implants. In this work, as inspired by hierarchical natural bone, for the first time, we developed hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) scaffolds with three-level hierarchical structures across macro to nano scale using combined 3D printing (3DP) and freeze casting routines. It is clear these hierarchical porous scaffolds significantly enhance cell penetration (over 7 times) while maintaining cell proliferation ability. With three levels of hierarchies, the overall mechanical behaviour of the scaffolds can be tailored to be comparable to general cancellous bone (ranging from 1 to 6 MPa), demonstrating great potential for practical applications. Additionally, the combination of nanoindentation and mechanics model makes it possible to predict the mechanical behaviour of scaffolds at micro and macro scales.

中文翻译：

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具有层次结构的仿生支架，用于定制机械行为和细胞迁移

受损骨的置换和再生，特别是对于那些尺寸临界的缺损，仍然是骨科手术中的主要挑战。由于目标骨和植入物之间的机械和结构不匹配，传统的骨植入物通常具有较差的内部结构设计，可能会导致严重的问题。在这项工作中，受分层天然骨骼的启发，我们首次使用组合 3D 打印 (3DP) 开发了具有从宏观到纳米尺度的三级分层结构的羟基磷灰石 (HA) 和 β-磷酸三钙 (β-TCP) 支架。 ) 并冻结铸造程序。很明显，这些分级多孔支架在保持细胞增殖能力的同时显着增强了细胞渗透（超过 7 倍）。通过三个层次的层次结构，支架的整体力学行为可以定制为与一般松质骨（1 至 6 兆帕）相当，显示出实际应用的巨大潜力。此外，纳米压痕和力学模型的结合使得在微观和宏观尺度上预测支架的力学行为成为可能。