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Issue 9, 2015
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Self-recovering caddisfly silk: energy dissipating, Ca2+-dependent, double dynamic network fibers

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Abstract

Single fibers of the sticky underwater larval silk of the casemaker caddisfly (H. occidentalis) are viscoelastic, display large strain cycle hysteresis, and self-recover 99% of their initial stiffness and strength within 120 min. Mechanical response to cyclical strains suggested viscoelasticity is due to two independent, self-recovering Ca2+-crosslinked networks. The networks display distinct pH dependence. The first network is attributed to Ca2+-stabilized phosphoserine motifs in H-fibroin, the second to Ca2+ complexed carboxylate groups in the N-terminus of H-fibroin and a PEVK-like protein. These assignments were corroborated by IR spectroscopy. The results are consolidated into a multi-network model in which reversible rupture of the Ca2+-crosslinked domains at a critical stress results in pseudo-plastic deformation. Slow refolding of the domains results in nearly full recovery of fiber length, stiffness, and strength. The fiber toughening, energy dissipation, and recovery mechanisms, are highly adaptive for the high energy aquatic environment of caddisfly larvae.

Graphical abstract: Self-recovering caddisfly silk: energy dissipating, Ca2+-dependent, double dynamic network fibers

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Publication details

The article was received on 03 Nov 2014, accepted on 11 Dec 2014 and first published on 11 Dec 2014


Article type: Paper
DOI: 10.1039/C4SM02435D
Citation: Soft Matter, 2015,11, 1667-1676
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    Self-recovering caddisfly silk: energy dissipating, Ca2+-dependent, double dynamic network fibers

    N. N. Ashton and R. J. Stewart, Soft Matter, 2015, 11, 1667
    DOI: 10.1039/C4SM02435D

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