Humidity mediated performance and material properties of orb weaving spider adhesive droplets
Humidity mediated performance and material properties of orb weaving spider adhesive droplets
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DOI：
10.1016/j.actbio.2021.06.017
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发表时间：
2021-08-14
影响因子：
9.7
通讯作者：
Hendricks, Mary L.
中科院分区：
文献类型：
--
作者：
Opell, Brent D.;Elmore, Hannah Mae;Hendricks, Mary L.
捕捉线胶液滴可以留住撞击圆网的昆虫，是4,600多种蜘蛛物种成功的关键。每个液滴都是一个自组装的粘合剂系统，其新兴的生物力学特性集中在其粘弹性蛋白质核心上。这种生物粘附剂依赖于其周围的吸湿水层进行水合和化学调节。因此，液滴的含水量和粘合性能跟踪环境湿度。我们测试了这样一个假设，即自然选择已经调整了水滴的粘附性能和材料特性，以适应物种的觅食湿度。在55%的相对湿度（RH）下，12种材料的粘合性能范围从PEG基水凝胶到硅橡胶，表现出1088倍的种间刚度差异（0.02-21.76 MPa）和147倍的韧性差异（0.14-20.51 MJ/m3）。当测试超过70%的相对湿度范围内，液滴延伸长度每蛋白质核心体积达到峰值，在较低的湿度在物种暴露，低湿度的栖息地，并在较高的湿度在夜间活动的物种和潮湿的栖息地。然而，在观察到这些物种的最大延伸/蛋白质体积指数的RH下，大多数物种的粘合剂的刚度没有差异，证明选择通过调节液滴吸湿性来调节弹性模量。液滴吸湿性和物种觅食湿度之间的这种反比关系确保了最佳的粘合剂刚度。通过表征圆蛛胶滴的湿度响应性和特性，我们的研究还描绘了其仿生潜力的范围。重要性声明超过4，600种描述的圆蛛依靠网中的微小胶滴来保留网拦截的昆虫。覆盖在每个液滴核心的水层使这种粘合剂保持柔韧，并在昆虫挣扎逃跑时伸展。水溶液还从空气中吸收水分，导致胶滴的性能随湿度变化。通过表征12个物种在相对湿度为20%至90%之间的液滴扩展和粘合剂材料特性，本研究研究了这种独特的粘合剂系统如何对其环境做出响应，以及它如何适应物种栖息地的湿度。(C)2021 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Capture thread glue droplets retain insects that strike an orb web and are key to the success of over 4,600 described spider species. Each droplet is a self-assembling adhesive system whose emergent biomechanical properties are centered on its viscoelastic, protein core. This bioadhesive is dependent on its surrounding hygroscopic aqueous layer for hydration and chemical conditioning. Consequently, a droplet's water content and adhesive performance track environmental humidity. We tested the hypothesis that natural selection has tuned a droplet's adhesive performance and material properties to a species' foraging humidity. At 55% relative humidity (RH) the adhesive properties of 12 species ranged from that of PEG-based hydrogels to that of silicone rubber, exhibiting a 1088-fold inter-specific difference in stiffness (0.02-21.76 MPa) and a 147-fold difference in toughness (0.14-20.51 MJ/m(3)). When tested over a 70% RH range, droplet extension lengths per protein core volume peaked at lower humidities in species from exposed, low humidity habitats, and at higher humidities in nocturnal species and those found in humid habitats. However, at the RH's where these species' maximum extension per protein volume indices were observed, the stiffness of most species' adhesive did not differ, documenting that selection has tuned elastic modulus by adjusting droplet hygroscopicity. This inverse relationship between droplet hygroscopicity and a species' foraging humidity ensures optimal adhesive stiffness. By characterizing the humidity responsiveness and properties of orb spider glue droplets, our study also profiles the range of its biomimetic potential.Statement of significanceOver 4,600 described species of orb weaving spider rely on tiny glue droplets in their webs to retain insect that the web intercepts. The aqueous layer that covers each droplet's core allows this adhesive to remain pliable and to stretch as an insect struggles to escape. The aqueous solution also attracts water from the air, causing the glue droplet's performance to change with humidity. By characterizing the droplet extensions and adhesive material properties of twelve species at relative humidities between of 20 and 90%, this study examined how this unique adhesive system responds to its environment and how it is tuned to the humidity of a species' habitat. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.