Research press release


Nature Communications

Biomechanics: Spider glue: sticky when wet



今回、Ali Dhinojwalaたちの研究グループは、コガネグモ科のクモの聚状腺から分泌される粘着物質がサファイアの表面に粘着する機構を調べて、湿潤条件下の粘着機構を解明した。Dhinojwalaたちは、分光学的手法の1種である和周波発生分光法を用いて、粘着物質の主成分が糖タンパク質(アミノ酸と糖分子からなるタンパク質)であり、その構造が湿潤条件下で変化することを明らかにした。糖タンパク質は、水分の存在下で粘着力が高まるように折りたたまれるのだ。また、クモの粘着物質中には、親水性低分子も至る所に見られる。これらの低分子は、通常は基質と粘着物質の界面を覆って粘着力を損ねている自由水を隔離する。


The mechanism by which spider aggregate glue is able to stick to surfaces in humid and wet conditions is identified in an article, published in Nature Communications this week. This finding could inspire the development of new adhesion systems that can be used in such environments.

In biology, adhesion systems that work reliably under humid conditions are common. Spiders, for example, use a glue-type material to hunt and capture their prey in humid or wet habitats. Effective approaches to guarantee adhesion in humid and wet environments include utilising specialized molecules, which can change their form or structure depending on the humidity. However, the exact mechanism by which spider glue continues to work in humid conditions had not been identified.

Ali Dhinojwala and colleagues investigated how orb-web spider aggregate glue sticks on a sapphire surface, to determine the adhesion mechanism under wet conditions. Using a spectroscopic method called sum frequency generation spectroscopy, they reveal that glycoproteins (proteins which consist of amino acids and sugar molecules) are the main component of spider aggregate glue, and can change their structure in wet conditions. By doing so, these proteins fold in a way that makes adhesion favourable in the presence of water. Additionally, small molecules, which are able to attract water, are also ubiquitous in spider aggregate glue. These compounds sequester free water that normally covers the substrate and glue interface and thus impede adhesion.

The authors suggest that understanding this mechanism could facilitate improved adhesion performance and reduce failure in wet environments.

doi: 10.1038/s41467-018-04263-z


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