Wechat: https://mp.weixin.qq.com/s/xjjapWvL4Hv9TxL-dK1SCQ

Saranshu Singla, Gaurav Amarpuri, Nishad Dhopatkar, Todd A. Blackledge & Ali Dhinojwala

doi:10.1038/s41467-018-04263-z

生物物理学；生物力学；材料科学中的有机分子

Published:

Adhesion in humid environments is fundamentally challenging because of the presence of interfacial bound water. Spiders often hunt in wet habitats and overcome this challenge using sticky aggregate glue droplets whose adhesion is resistant to interfacial failure under humid conditions. The mechanism by which spider aggregate glue avoids interfacial failure in humid environments is still unknown. Here, we investigate the mechanism of aggregate glue adhesion by using interface-sensitive spectroscopy in conjunction with infrared spectroscopy. We demonstrate that glycoproteins act as primary binding agents at the interface. As humidity increases, we observe reversible changes in the interfacial secondary structure of glycoproteins. Surprisingly, we do not observe liquid-like water at the interface, even though liquid-like water increases inside the bulk with increasing humidity. We hypothesize that the hygroscopic compounds in aggregate glue sequester interfacial water. Using hygroscopic compounds to sequester interfacial water provides a novel design principle for developing water-resistant synthetic adhesives.

本周《自然-通讯》发表的一篇论文Hygroscopic compounds in spider aggregate glue remove interfacial water to maintain adhesion in humid conditions发现了蛛丝聚合胶能够在潮湿条件下保持粘性的机制，或有助于开发可以在这种环境下使用的新型粘附系统。

固定蛛丝聚合胶。

Singla et al.

在生物界，能够在潮湿环境下保持可靠粘性的粘附系统非常常见。以蜘蛛为例，蜘蛛在潮湿的栖息环境下，可以使用胶水型材料捕捉猎物。以下方法可以有效保证潮湿环境下的粘性：利用可以根据湿度改变自身形式或结构的特殊分子。但是，在此之前，令蛛丝胶液能够在潮湿条件下持续保持粘性的准确机制仍不为人知。

为了解开这个谜题，美国阿克伦大学的Ali Dhinojwala及同事研究了圆蛛聚合胶如何粘附在蓝宝石表面。他们利用和频光谱技术发现糖蛋白是蛛丝聚合胶的主要成分，并且它们可以在潮湿条件下改变自身结构，通过折叠使得在有水的情况下也有利于保持粘性。此外，能够吸引水的小分子在蛛丝聚合胶中也普遍存在。这些复合物可以隔绝游离水，游离水通常会覆盖底物和聚合胶的界面，从而阻止粘附。

湿度在接触界面的影响。

Singla et al.

作者认为搞清楚这种机制或有助于增强相关材料在潮湿环境中的粘附效果，减少失效情况。