The mechanical properties of biologic scaffolds are critical to cellular interactions and hence functional response within the body. In the case of scaffolds for bone tissue regeneration, engineered scaffolds created by combining collagen with inorganic mineral are increasingly being explored, due to their favourable structural and chemical characteristics. Development of a method for controlling the mechanics of these scaffolds could lead to significant additional advantages by harnessing the intrinsic mechnotransduction pathways of stem cells via appropriate control of scaffold mechanical properties. Here we present a method for controlling the macroscale flexural modulus of mineralized collagen sheets, and the radial indentation modulus of the sheets’ constituent collagen fibrils. Scaffolds were created starting with sheets of highly aligned, natively structured collagen fibrils, prepared via cryosectioning of decellularized tendon. Sheets underwent an alternate soaking mineralization procedure, with sequential exposure to citrate-doped calcium and carbonate-containing phosphate solutions, both of which included poly aspartic acid. The extent of scaffold mineralization was controlled via number of repeated mineralization cycles: 0 (unmineralized), 5, 10, and 20 cycles were trialed. Following scaffold preparation, ultrastructure, macroscale flexural modulus, and nanoscale indentation modulus were assessed. Surface architecture studied by SEM, and inspection of individual extracted fibrils by TEM and AFM confirmed that fibrils became increasingly laden with mineral as the number of mineralization cycles increased. Measurements of collagen fibril nanomechanics using AFM showed that the radial modulus of collagen fibrils increased linearly with mineralization cycles completed, from 215 $\pm$ 125 MPa for fibrils from unmineralized (0 cycle) scaffolds to 778 $\pm$ 302 MPa for fibrils from the 20 mineralization cycle scaffolds. Measurements of scaffold macromechanics via flexural testing also showed a linear increase in flexural modulus with increasing number of mineralization cycles completed, from 18 $\pm$ 7 MPa for the 5 cycle scaffolds to 156 $\pm$ 50 MPa for the 20 cycle scaffolds. The process detailed herein provides a way to create mineralized collagen scaffolds with easily controllable mechanical properties.

生物支架的机械性质对于细胞相互作用以及因此在体内的功能反应至关重要。在用于骨组织再生的支架的情况下，由于其良好的结构和化学特性，越来越多地探索通过将胶原蛋白与无机矿物质结合而产生的工程支架。通过适当控制支架的机械性能，利用干细胞的固有机械转导途径，控制这些支架的力学的方法的开发可能会带来其他显着的优势。在这里，我们提出了一种方法，用于控制矿化的胶原片的宏观弯曲模量，以及片的组成胶原纤维的径向压痕模量。脚手架从高度对齐的板材开始，天然结构的胶原蛋白原纤维，通过脱细胞肌腱的冷冻切片制备。片材经历了另一种浸泡矿化程序，依次暴露于柠檬酸盐掺杂的钙和含碳酸盐的磷酸盐溶液，这两种溶液均包括聚天冬氨酸。支架矿化的程度通过重复的矿化循环数来控制：尝试了0（未矿化），5、10和20个循环。制备支架后，评估超微结构，宏观弯曲模量和纳米压痕模量。通过SEM研究的表面结构，以及通过TEM和AFM对单个提取的原纤维的检查证实，随着矿化循环次数的增加，原纤维中的矿物含量越来越高。$\pm$ 未矿化（0循环）支架的原纤维为125 MPa至778 $\pm$20个矿化循环支架的原纤维为302 MPa。通过挠曲测试对支架宏观力学的测量还显示，随着完成的矿化循环次数的增加，挠曲模量呈线性增加，从18开始$\pm$ 5个循环支架为7 MPa至156 $\pm$20个循环脚手架为50 MPa。本文详述的方法提供了一种产生具有易于控制的机械性能的矿化胶原蛋白支架的方法。