Effects of Laminate Architecture on Fracture Resistance of Sponge Biosilica: Lessons from Nature

Authors

  • Ali Miserez,

    1. Materials Department University of California, Santa Barbara, CA 93106 (USA)
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  • James C. Weaver,

    1. Department of Molecular, Cellular and Developmental Biology and Institute for Collaborative Biotechnologies University of California, Santa Barbara, CA 93106 (USA)
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  • Philipp J. Thurner,

    1. Bioengineering Science Research Group School of Engineering Science University of Southampton Highfield, Southampton, S017, 1BJ (U.K.)
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  • Joanna Aizenberg,

    1. Harvard School of Engineering and Applied Sciences Cambridge, MA 02138 (USA)
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  • Yannicke Dauphin,

    1. University UMR IDES University of Paris-Sud Orsay, 91405 (France)
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  • Peter Fratzl,

    1. Department of Biomaterials Max Planck Institute of Colloids and Interfaces Potsdam 14424 (Germany)
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  • Daniel E. Morse,

    Corresponding author
    1. Department of Molecular, Cellular and Developmental Biology and Institute for Collaborative Biotechnologies University of California, Santa Barbara, CA 93106 (USA)
    • Daniel E. Morse, Department of Molecular, Cellular and Developmental Biology and Institute for Collaborative Biotechnologies University of California, Santa Barbara, CA 93106 (USA).===

      Frank W. Zok, Materials Department University of California, Santa Barbara, CA 93106 (USA).===

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  • Frank W. Zok

    Corresponding author
    1. Materials Department University of California, Santa Barbara, CA 93106 (USA)
    • Daniel E. Morse, Department of Molecular, Cellular and Developmental Biology and Institute for Collaborative Biotechnologies University of California, Santa Barbara, CA 93106 (USA).===

      Frank W. Zok, Materials Department University of California, Santa Barbara, CA 93106 (USA).===

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  • We thank Michael J. Porter, Garrett W. Milliron and Amy Butros for assistance and helpful discussions and B. Richer de Forges, IRD, Nouméa, New Caledonia, for collecting the giant spicules of Monorhaphis chuni used in this study. AM acknowledges an advanced researcher fellowship from the Swiss National Science Foundation (PA002–113176/1). Additionally, AM and FWZ were supported by a grant from the Bioengineering Research Partnership Program, National Institutes of Health (NIHR01DE014672). JCW and DEM were supported by grants from NASA (NAG1-01-003 and NCC-1-02037); the Institute for Collaborative Biotechnologies, Army Research Office (DAAD19-03D-0004); the NOAA National Sea Grant College Program, U.S. Department of Commerce (NA36RG0537, Project R/MP-92); and the MRSEC Program of the National Science Foundation (DMR-00-8034). AM and JCW contributed equally to this work.

Abstract

Hexactinellid sponges are known for their ability to synthesize unusually long and highly flexible fibrous spicules, which serve as the building blocks of their skeletal systems. The spicules consist of a central core of monolithic hydrated silica, surrounded by alternating layers of hydrated silica and proteinaceous material. The principal objective of the present study is to ascertain the role of the latter laminate architecture in the material's resistance to both crack initiation and subsequent crack growth. This has been accomplished through indentation testing on the giant anchor spicule of Monorhaphis chuni, both in the laminated region and in the monolithic core, along with a theoretical analysis of deformation and cracking at indents. The latter suggests that the threshold load for crack initiation is proportional to Kc4/E2H where Kc is fracture toughness, E is Young's modulus, and H is hardness. Two key experimental results emerge. First, the load required to form well-defined radial cracks from a sharp indent in the laminated region is two orders of magnitude greater than that for the monolithic material. Secondly, its fracture toughness is about 2.5 times that of the monolith, whereas the modulus and hardness are about 20% lower. Combining the latter property values with the theoretical analysis, the predicted increase in the threshold load is a factor of about 80, broadly consistent with the experimental measurements.

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