Natural bone is a complex composite, consisting predominantly of collagen and hydroxyapatite (HA), which form a highly organized, hierarchical structure from the nano- to the macroscale. Because of its biphasic, anisotropic, ultrafine structural design, bone tissue possesses excellent mechanical properties. Herein, inspired by the composition and microstructure of natural bone, a biphasic composite consisting of highly aligned strontium/copper-doped one-dimensional hydroxyapatite (Sr/Cu-doped 1D HA) and poly(d,l-lactide) (PDLA) was developed. The presence and alignment of Sr/Cu-doped 1D HA crystals resulted in mechanical reinforcement of the polymer matrix, including compressive and tensile strength and modulus, fracture toughness, swelling resistance, and long-term structural stability. The compressive strength, tensile strength, and Young’s modulus of the biomimetic composite were comparable to that of cortical bone. Biologically, the biomimetic composite showed a sustained release of the incorporated Sr and Cu ions, facilitated mineral deposition from simulated body fluid, and supported attachment, proliferation, and alkaline phosphatase activity of human mesenchymal stromal cells (hMSCs). Moreover, the highly aligned Sr/Cu-doped 1D HA crystals in the 3D porous scaffolds induced the alignment of hMSCs and secretion of an anisotropic collagen fiber matrix in 3D. The biomimetic Sr/Cu-doped 1D HA/PDLA composite presented here contributes to the current efforts aiming at the design and development of load-bearing bioactive synthetic bone graft substitutes. Moreover, the biomimetic composite may serve as a 3D platform for studying cell–extracellular matrix interactions in bone tissue.

中文翻译：

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仿生机械强一维羟基磷灰石/聚（d，l-丙交酯）复合诱导各向异性胶原基质的形成

天然骨骼是一种复杂的复合材料，主要由胶原蛋白和羟基磷灰石 (HA) 组成，它们形成了从纳米到宏观尺度的高度组织化的层次结构。由于其双相、各向异性、超精细的结构设计，骨组织具有优异的机械性能。在此，受天然骨的成分和微观结构的启发，一种双相复合材料由高度排列的锶/铜掺杂一维羟基磷灰石（Sr/Cu 掺杂 1D HA）和聚（d，l ）组成-丙交酯）（PDLA）被开发出来。Sr/Cu 掺杂的一维 HA 晶体的存在和排列导致聚合物基体的机械增强，包括压缩和拉伸强度和模量、断裂韧性、抗溶胀性和长期结构稳定性。仿生复合材料的抗压强度、抗拉强度和杨氏模量与皮质骨相当。在生物学上，仿生复合材料显示出掺入的 Sr 和 Cu 离子的持续释放，促进模拟体液中的矿物质沉积，并支持人间充质基质细胞 (hMSC) 的附着、增殖和碱性磷酸酶活性。而且，3D 多孔支架中高度对齐的 Sr/Cu 掺杂 1D HA 晶体在 3D 中诱导了 hMSC 的对齐和各向异性胶原纤维基质的分泌。此处介绍的仿生 Sr/Cu 掺杂一维 HA/PDLA 复合材料有助于当前旨在设计和开发承重生物活性合成骨移植替代品的努力。此外，仿生复合材料可作为研究骨组织中细胞-细胞外基质相互作用的 3D 平台。