The common house spider, Parasteatoda tepidariorum, maintains silk gene expression on sub-optimal diet

Mechanical Properties of Dragline Silk Fiber Using a Bottom-Up Approach

We propose a molecular-based three-dimensional (3D) continuum model of dragline silk of Araneus diadematus, which takes into account the plasticity of the β-sheet crystals, the rate-dependent behavior of the amorphous matrix, and the viscous interface friction between them. For the proposed model, we computed the tensile properties, the effects of velocity on the mechanical properties, and hysteresis values, which are in good agreement with available experimental data. The silk fiber model’s yield point, breaking strength, post-yield stiffness, and toughness increased with increasing pulling velocity, while extensibility and the diameter of the silk fiber decreased. Our bottom-up approach has shed light on silk fiber mechanics, which can be used as an essential tool to design artificial composite materials.

Basic Principles in the Design of Spider Silk Fibers

The prominence of spider silk as a hallmark in biomimetics relies not only on its unrivalled mechanical properties, but also on how these properties are the result of a set of original design principles. In this sense, the study of spider silk summarizes most of the main topics relevant to the field and, consequently, offers a nice example on how these topics could be considered in other biomimetic systems. This review is intended to present a selection of some of the essential design principles that underlie the singular microstructure of major ampullate gland silk, as well as to show how the interplay between them leads to the outstanding tensile behavior of spider silk. Following this rationale, the mechanical behavior of the material is analyzed in detail and connected with its main microstructural features, specifically with those derived from the semicrystalline organization of the fibers. Establishing the relationship between mechanical properties and microstructure in spider silk not only offers a vivid image of the paths explored by nature in the search for high performance materials, but is also a valuable guide for the development of new artificial fibers inspired in their natural counterparts.