An atomistic model of silk protein network for studying the effect of pre-stretching on the mechanical performances of silks

预拉伸对丝蛋白力学性能影响的全原子网络模型

Silk protein builds one of the strongest natural fibers based on its complex nanocomposite structures.However,the mechanical performance of silk protein,related to its molecular structure and packing is still elusive.In this study,we constructed an atomistic silk protein network model,which reproduces the extensive connection topology of silk protein with structure details of theβ-sheet crystallites and amorphous domains.With the silk protein network model,we investigated the structure evolution and stress distribution of silk protein under external loading.We found a pre-stretching treatment during the spinning process can improve the strength of silk protein.This treatment improves the properties of silk protein network,i.e.,increases the number of nodes and bridges,makes the nodes distributed homogeneously,and induces the bridges in the network well aligned to the loading direction,which is of great benefit to the mechanical performances of silk protein.Our study not only provides a realized atomistic model for silk protein network that well represents the structures and deformations of silk proteins under loading,but also gains deep insights into the mechanism how the pre-loading on silk proteins during spinning improves the mechanical properties of silk fibers.

丝蛋白因其复杂的纳米复合结构成为自然界中最强的纤维之一,但是丝蛋白的纳米结构和其力学性能之间的关系仍不明确.在本研究中,我们构建的丝蛋白全原子网络模型充分描述了β-微晶与无定形域交联的拓扑结构.通过该模型我们研究了在外部载荷作用下,丝蛋白的微观结构演化及其应力分布.我们发现纺丝过程中的预拉伸处理可以提升丝蛋白的拉伸强度.研究发现预拉伸处理增强了丝蛋白的网络结构性能,包括预拉伸使得网络内“节点”和“桥”的数量的增加,“节点”的分布更加均匀,“桥”沿加载方向排列等.我们的工作构建了丝蛋白全原子的网络结构模型,该模型能够描述在外载作用下丝蛋白结构演化和变形之间的关系,同时也揭示了预拉伸增强丝蛋白力学性能的分子机制.