title: Ubiquitous distribution of salts and proteins in spider glue enhances spider silk adhesion.
abstract: Modern orb-weaving spiders use micron-sized glue droplets on their viscid silk to retain prey in webs. A combination of low molecular weight salts and proteins makes the glue viscoelastic and humidity responsive in a way not easily achieved by synthetic adhesives. Optically, the glue droplet shows a heterogeneous structure, but the spatial arrangement of its chemical components is poorly understood. Here, we use optical and confocal Raman microscopy to show that salts and proteins are present ubiquitously throughout the droplet. The distribution of adhesive proteins in the peripheral region explains the superior prey capture performance of orb webs as it enables the entire surface area of the glue droplet to act as a site for prey capture. The presence of salts throughout the droplet explains the recent Solid-State NMR results that show salts directly facilitate protein mobility. Understanding the function of individual glue components and the role of the droplet's macro-structure can help in designing better synthetic adhesives for humid environments.
authors.affiliation: Department of Polymer Science, The University of Akron, Akron, OH 44325.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Amarpuri
authors.affiliation: Department of Mechanical Engineering, The University of Akron, Akron, OH 44325, USA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Chaurasia
authors.affiliation: Department of Polymer Science, The University of Akron, Akron, OH 44325.
authors.forename: Dharamdeep
authors.initials: D
authors.lastname: Jain
authors.affiliation: Department of Biology, Integrated Bioscience Program, The University of Akron, Akron, OH 44325, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Blackledge
authors.affiliation: Department of Polymer Science, The University of Akron, Akron, OH 44325.
authors.forename: Ali
authors.initials: A
authors.lastname: Dhinojwala
mesh_terms: D000269:Adhesives / Q000737:chemistry; D000818:Animals; D011506:Proteins / Q000737:chemistry*; D012492:Salts / Q000737:chemistry*; D047011:Silk / Q000737:chemistry; D013112:Spiders
chemical_list: D000269:Adhesives; D011506:Proteins; D012492:Salts; D047011:Silk