title: The effect of ageing on the mechanical properties of the silk of the bridge spider Larinioides cornutus (Clerck, 1757).
abstract: Spider silk is regarded as one of the best natural polymer fibers especially in terms of low density, high tensile strength and high elongation until breaking. Since only a few bio-engineering studies have been focused on spider silk ageing, we conducted nano-tensile tests on the vertical naturally spun silk fibers of the bridge spider Larinioides cornutus (Clerck, 1757) (Arachnida, Araneae) to evaluate changes in the mechanical properties of the silk (ultimate stress and strain, Young's modulus, toughness) over time. We studied the natural process of silk ageing at different time intervals from spinning (20 seconds up to one month), comparing silk fibers spun from adult spiders collected in the field. Data were analyzed using Linear Mixed Models. We detected a positive trend versus time for the Young's modulus, indicating that aged silks are stiffer and possibly less effective in catching prey. Moreover, we observed a negative trend for the ultimate strain versus time, attesting a general decrement of the resistance force. These trends are interpreted as being due to the drying of the silk protein chains and the reorientation among the fibers.
authors.affiliation: Laboratory of Bio-inspired &Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Lepore
authors.affiliation: Laboratory of Ecology and Terrestrial Ecosystems, Department of Life Science and Systems Biology, University of Torino, Via Accademia Albertina, 13, 10123 Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Isaia
authors.affiliation: Laboratory of Ecology and Terrestrial Ecosystems, Department of Life Science and Systems Biology, University of Torino, Via Accademia Albertina, 13, 10123 Torino, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mammola
authors.affiliation: Laboratory of Bio-inspired &Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.|Centre of Materials and Microsystems, Bruno Kessler Foundation, via Santa Croce 77, 38122 Trento, Italy.|School of Engineering and Materials Science, Queen Mary University, Mile End Rd, London E1 4NS, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Pugno
mesh_terms: D000818:Animals; D055119:Elastic Modulus; D016014:Linear Models; D008855:Microscopy, Electron, Scanning; D047011:Silk / Q000737:chemistry* / Q000378:metabolism; D013112:Spiders / Q000378:metabolism; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D047011:Silk