Double-network gels and the toughness of terrestrial slug glue
Double-network gels and the toughness of terrestrial slug glue
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DOI：
10.1242/jeb.128991
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发表时间：
2015-10-01
影响因子：
2.8
通讯作者：
Smith, Andrew M.
中科院分区：
文献类型：
--
作者：
Wilks, Alex M.;Rabice, Sarah R.;Smith, Andrew M.
陆地蛞蝓阿里翁subfuscus产生防御分泌物是粘性和坚韧的，尽管是一个稀释的凝胶。凝胶具有高硬度，但仍保留粘液典型的高伸展性，这是不寻常的。在拉伸试验中，它承受的平均峰值应力为101 kPa，并在平均应变为9.5时失效。这赋予了凝胶韧性;它需要比大多数凝胶大得多的应变能来断裂。这种韧性可能来自于双网络型机制。在这种机制中，两个独立的、互穿的具有不同性质的聚合物网络联合收割机结合起来，使韧性比任何一个单独的网络大几个数量级。天然凝胶电泳表明，A.暗褐色细胞胶由两个网络组成：一个是M-r为40 × 10（3）到220 × 10（3）的带负电荷的蛋白质网络，它可以被羟胺解离，另一个是硫酸乙酰肝素样蛋白聚糖网络。这两个网络没有紧密联系，尽管M-r 40 x10（3）和165 x10（3）的蛋白质可能与碳水化合物结合。使用酶水解、二硫键断裂或亚胺键断裂分别靶向破坏任一网络完全破坏胶，导致不可测量的韧性。因此，这两种网络单独提供的韧性很小，但它们一起协同工作，创造一个坚韧的材料，在双网络机制预测。
The terrestrial slug Arion subfuscus produces a defensive secretion that is sticky and tough, despite being a dilute gel. It is unusual in having high stiffness for a gel, yet retaining the high extensibility typical of mucus. In tensile tests, it sustains an average peak stress of 101 kPa, and fails at an average strain of 9.5. This gives the gel toughness; it requires much greater strain energy to fracture than most gels. This toughness may arise from a double-network type mechanism. In this mechanism, two separate, interpenetrating networks of polymers with different properties combine to give toughness that can be several orders of magnitude greater than either network individually. Native gel electrophoresis suggests that A. subfuscus glue consists of two networks: a network of negatively charged proteins ranging in M-r from 40x10(3) to 220x10(3) that can be dissociated by hydroxylamine and a network of heparan sulfate-like proteoglycans. The two networks are not tightly linked, though proteins of M-r 40x10(3) and 165x10(3) may associate with the carbohydrates. Targeted disruption of either network separately, using enzymatic hydrolysis, disulfide bond breakage or imine bond disruption completely disrupted the glue, resulting in no measurable toughness. Thus, the two networks separately provide little toughness, but together they work synergistically to create a tough material, as predicted in the double-network mechanism.