Wolff Jonas O, Grawe Ingo, Wirth Marina, Karstedt André, Gorb Stanislav N
Department of Functional Morphology and Biomechanics, University of Kiel, Am Botanischen Garten 1-9, D-24098 Kiel, Germany.
Soft Matter. 2015 Mar 28;11(12):2394-403. doi: 10.1039/c4sm02130d.
Silk is a key innovation in spiders, fascinating both biologists and material scientists. However, to fulfil their biological function silken threads must be strongly fastened to substrates or other threads. The majority of modern spiders produce a unique and rather unexplored bio-adhesive: the two-compound pyriform secretion, which is spun into elaborate patterns (so called attachment discs) and used to anchor silken threads to substrates. Strong adhesion is achieved on a high variety of surfaces with a minimum of material consumption. Pyriform threads polymerize under ambient conditions, become functional within less than a second and can remain stable for years. They are biodegradable, biocompatible and highly versatile - the adhesion and the overall toughness of the attachment disc can be controlled by spinneret movements on a macroscopic level (ref. 1: V. Sahni et al., Nat. Commun., 2012, 3, 1106, DOI: 10.1038/ncomms2099). We found that the pyriform thread is a silk fibre that is coated with glue-like cement consisting of aligned nanofibrils, lipid enclosures and a dense, isotropic boundary layer. The threads are spun in a meshwork pattern that promotes stress distribution and crack arresting. Our results demonstrate, that hierarchical organization and fibre embedding may explain the high adhesive strength and flaw tolerance of a structure made by the same, rather simple type of silk glands.
丝是蜘蛛的一项关键创新，吸引着生物学家和材料科学家。然而，为了实现其生物学功能，丝线必须牢固地固定在基质或其他丝线上。大多数现代蜘蛛会产生一种独特且尚未充分探索的生物粘合剂：由两种化合物组成的梨形分泌物，这种分泌物会纺成精致的图案（即所谓的附着盘），用于将丝线固定在基质上。只需消耗极少的材料就能在多种表面上实现强力粘附。梨形丝线在环境条件下聚合，不到一秒钟即可发挥作用，并且可以保持数年稳定。它们可生物降解、具有生物相容性且用途广泛——附着盘的粘附力和整体韧性可通过喷丝板在宏观层面上的运动来控制（参考文献1：V. 萨尼等人，《自然通讯》，2012年，3卷，第1106页，DOI：10.1038/ncomms2099）。我们发现梨形丝线是一种丝纤维，其表面涂有类似胶水的粘结剂，该粘结剂由排列整齐的纳米纤维、脂质包裹体和致密的各向同性边界层组成。丝线以网状图案纺出，有助于应力分布和阻止裂纹扩展。我们的结果表明，分层结构和纤维嵌入可能解释了由同一类相当简单的丝腺制造的结构为何具有高粘附强度和抗缺陷能力。
