Mineral and cross-linking in collagen fibrils: The mechanical behavior of bone tissue at the nano-scale
Mineral and cross-linking in collagen fibrils: The mechanical behavior of bone tissue at the nano-scale
复制标题
DOI：
10.1016/j.jmbbm.2024.106697
复制
发表时间：
2024-11-01
影响因子：
3.9
通讯作者：
Kammer，David S.
中科院分区：
文献类型：
--
作者：
Kamml，Julia;Acevedo，Claire;Kammer，David S.
矿化的胶原纤维是构成硬组织的主要构件，直接影响骨等生物组织的宏观力学性能。纤维本身的力学行为由其结构决定：胶原分子、矿物质和交联物的含量，以及这些成分的机械相互作用和性质。晚期糖基化终末产物(AGEs)在胶原原纤维内形成原胶原分子之间的交联链，是被认为对组织有重大影响的一个重要因素。例如，已有研究表明，骨骼的脆性与年龄密度的增加有关。然而，矿化的胶原纤维中潜在的纳米级机制仍不清楚。在这里，我们通过使用粗粒分子动力学模拟进行破坏性拉伸测试来研究矿物和AGEs的交联性对纤维变形和断裂行为的影响。我们的结果表明，在超过临界矿物质含量后，它会在高应变水平下诱导胶原纤维僵硬。我们发现矿物的形态和位置影响胶原原纤维的力学：这种硬化发生的矿物含量取决于矿物的位置和形态。此外，年龄密度和矿物含量的增加都会导致硬化和峰值应力的增加。在低矿物含量时，纤维的力学响应由年龄决定，而在高矿物含量时，矿物本身决定纤维的力学性能。
The mineralized collagen fibril is the main building block of hard tissues and it directly affects the macroscopic mechanics of biological tissues such as bone. The mechanical behavior of the fibril itself is determined by its structure: the content of collagen molecules, minerals, and cross-links, and the mechanical interactions and properties of these components. Advanced glycation end products (AGEs) form cross-links between tropocollagen molecules within the collagen fibril and are one important factor that is believed to have a major influence on the tissue. For instance, it has been shown that brittleness in bone correlates with increased AGEs densities. However, the underlying nano-scale mechanisms within the mineralized collagen fibril remain unknown. Here, we study the effect of mineral and AGEs cross-linking on fibril deformation and fracture behavior by performing destructive tensile tests using coarse-grained molecular dynamics simulations. Our results demonstrate that after exceeding a critical content of mineral, it induces stiffening of the collagen fibril at high strain levels. We show that mineral morphology and location affect collagen fibril mechanics: The mineral content at which this stiffening occurs depends on the mineral’s location and morphology. Further, both, increasing AGEs density and mineral content lead to stiffening and increased peak stresses. At low mineral contents, the mechanical response of the fibril is dominated by the AGEs, while at high mineral contents, the mineral itself determines fibril mechanics.