title: Ancestrally high elastic modulus of gecko setal beta-keratin.
abstract: Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1MPa. Geckos possess subdigital adhesives composed mostly of beta-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of beta-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of beta-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa +/- 0.15s.e.; n=24 setae) and Ptyodactylus hasselquistii (1.4 GPa +/- 0.15s.e.; n=24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.
authors: Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720-3140, USA. apeattie@gmail.com
authors: Anne M
authors: AM
authors: Peattie
authors: Carmel
authors: C
authors: Majidi
authors: Andrew
authors: A
authors: Corder
authors: Robert J
authors: RJ
authors: Full
mesh_terms: D000268:Adhesiveness; D000818:Animals; D005075:Biological Evolution; D001696:Biomechanical Phenomena; D004548:Elasticity; D006813:Humidity; D008116:Lizards; D013696:Temperature; D053800:beta-Keratins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D053800:beta-Keratins