Wang Qijue, Schniepp Hannes C
Applied Science Department, The College of William and Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States.
ACS Macro Lett. 2018 Nov 20;7(11):1364-1370. doi: 10.1021/acsmacrolett.8b00678. Epub 2018 Oct 29.
Spider silk exhibits a combination of outstanding tensile strength and extensibility unique among all synthetic and biogenic polymer fibers. It has thus generated great interest to understand protein-based high-toughness materials and inspired the design of similar synthetic materials. The unrivaled properties of silk fibers have been recognized to be intimately related to their hierarchical structure. However, in the absence of unambiguous experimental evidence, competing and incompatible structural models of natural silk fibers have been proposed, some of them including various types of fibrillar components. Here we show that the fibers of the recluse () spider exhibit the typical tensile properties of a very good spider silk and are entirely composed of 20 nm diameter protein fibrils that are more than 1 μm long. Based on these findings, we developed the most detailed structural model for any silk directly supported by experimental evidence. Our work suggests that all the key properties of a spider silk are implemented within a single nanofibril, and we have isolated and imaged such a nanofibril from a native spider silk fiber. The nanofibril breaking force was estimated to be ≈120 nN. Our work underlines the importance of nanofibrils and furthers the understanding of the structure-property relationships of silk, with wide-ranging implications for silk research and the design of silk-inspired high-performance materials.
蜘蛛丝展现出了出色的拉伸强度与延展性的结合，这在所有合成和生物聚合物纤维中是独一无二的。因此，它引发了人们对基于蛋白质的高韧性材料的浓厚兴趣，并启发了类似合成材料的设计。人们已经认识到丝纤维无与伦比的性能与其层次结构密切相关。然而，在缺乏明确实验证据的情况下，人们提出了相互竞争且不相容的天然丝纤维结构模型，其中一些模型包含各种类型的纤维状成分。在这里，我们表明隐居褐蛛的纤维展现出了非常优质的蜘蛛丝典型的拉伸性能，并且完全由直径20纳米、长度超过1微米的蛋白质原纤维组成。基于这些发现，我们构建了首个直接由实验证据支持的、针对任何蛛丝的最详细结构模型。我们的研究表明，蜘蛛丝的所有关键特性都在单个纳米原纤维中得以实现，并且我们已经从天然蜘蛛丝纤维中分离出这种纳米原纤维并对其成像。估计该纳米原纤维的断裂力约为120纳牛。我们的工作强调了纳米原纤维的重要性，并进一步加深了对丝的结构-性能关系的理解，对丝的研究以及受丝启发的高性能材料设计具有广泛的意义。
