title: Extreme strength observed in limpet teeth.
abstract: The teeth of limpets exploit distinctive composite nanostructures consisting of high volume fractions of reinforcing goethite nanofibres within a softer protein phase to provide mechanical integrity when rasping over rock surfaces during feeding. The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa and was independent of sample size. These observations highlight an absolute material tensile strength that is the highest recorded for a biological material, outperforming the high strength of spider silk currently considered to be the strongest natural material, and approaching values comparable to those of the strongest man-made fibres. This considerable tensile strength of limpet teeth is attributed to a high mineral volume fraction of reinforcing goethite nanofibres with diameters below a defect-controlled critical size, suggesting that natural design in limpet teeth is optimized towards theoretical strength limits.
authors.affiliation: School of Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK asa.barber@port.ac.uk.
authors.forename: Asa H
authors.initials: AH
authors.lastname: Barber
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors.forename: Dun
authors.initials: D
authors.lastname: Lu
authors.affiliation: Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, via Mesiano, 77, 38123 Trento, Italy Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo (Trento), Italy School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Pugno
mesh_terms: D000825:Animal Structures / Q000033:anatomy & histology* / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D016880:Anisotropy; D001696:Biomechanical Phenomena; D002686:Chitin; D004739:England; D049851:Gastropoda / Q000033:anatomy & histology* / Q000737:chemistry / Q000502:physiology*; D058085:Iron Compounds; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D008903:Minerals; D013718:Tensile Strength
chemical_list: D058085:Iron Compounds; D008903:Minerals; C094886:goethite; D002686:Chitin
keywords: mechanics; mineralized tissue; nanoscale