EAPSI: New insights into the effects of chemical composition and surface structure on spider silk adhesion and prey retention

粘结力是施工和维修中的一个重要考虑因素。生物体进化出了不同的粘合剂，以在地球上几乎所有的环境中生存。在化学粘合中，化学键的形成和电子的共享在表面之间产生吸引力。例如，蜘蛛利用一种粘性的聚集胶将猎物困在网中。本项目将测试集合胶的粘合强度如何基于表面粗糙度、亲水性和化学成分而变化。这项研究将与东京大学的宫下忠志博士合作，确定哪些表面特征是进化的压力，从而产生最佳的胶粘附力。宫下忠志是此前唯一研究蜘蛛Cytarachne丝质的研究人员。将对胶滴的化学成分进行鉴定。通过对蜘蛛的研究，可以利用和模仿聚集胶化合物，从而产生特定于底物的合成粘合剂产品。聚集丝由一个糖蛋白核心和一个水滴盐滴组成。盐和糖蛋白的结合在一起，在丝线和猎物之间形成了一个纽带。Cyrtarachne属的蜘蛛是专门捕猎飞蛾的圆球编织蜘蛛，只在亚洲发现，更常见于日本。这些蜘蛛已经进化成利用缩小的球状网和异常大而粘稠的胶滴捕食飞蛾。成功捕获猎物主要依赖于胶水和外骨骼之间的长期粘合。不同的表面结构和化学成分可能会与糖蛋白和吸水盐发生不同的反应，导致Cyrtarachne聚合胶性能不足或过高。附着力测试将采用拉开法进行。将获得关于它们含有哪些化学物质以及何时它们最强的信息。该NSF EAPSI奖是与日本科学促进会合作资助的。

Adhesion is an important consideration in construction and repair. Organisms have evolved different adhesives for survival in nearly every environment on earth. In chemical adhesion the formation of chemical bonds and sharing of electrons create attractive forces between surfaces. For example, spiders utilize a sticky aggregate glue to keep their prey ensnared in their webs. This project will test how adhesion strength of aggregate glue varies based on surface roughness, hydrophilicity, and chemical composition. In collaboration with Dr. Tadashi Miyashita at the Unversity of Tokyo - the only researcher to have previously studied the silk of the spider Cytarachne - the research will be determined which surface characteristics have served as evolutionary pressures, leading to optimal glue adhesion. Identification of the chemical composition of glue droplets will be conducted. By studying spiders, it can lead to the utilization and mimicking of aggregate glue chemical compounds leading to substrate specific synthetic adhesive products.Aggregate silk is composed of a glycoprotein core and an aqueous droplet of salts. The combination of salts and the glycoproteins act together to form a bond between the silk threads and prey. Spiders from the genus Cyrtarachne are specialized moth-hunting orb-weavers, only found within Asia and more commonly in Japan. These spiders have evolved to prey on moths by utilizing reduced orb webs with unusually large, viscous droplets of glue. Successful prey capture relies primarily on the prolonged adhesion between the glue and exoskeleton. Varying surface structures and chemical compositions may react with glycoproteins and hydroscopic salts differently resulting in scenarios in which Cyrtarachne aggregate glue under or over performs. Adhesion tests will be conducted by the pull-off method. Information will be gained on what chemicals they contain, and when they are strongest. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.