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Contributions to the understanding of the hierarchical structure and dynamics of spider dragline silk

Abstract : Spider dragline silk is a remarkable material, a biopolymer with outstanding mechanical properties. Spider silk has been in the focus of intense research using a wide variety of experimental techniques and in addition theoretical modelling. However, its macroscopic properties are still not well linked to its microscopic structure and dynamics. Synchrotron radiation small- and wide-angle scattering experiments have in recent years particularly contributed to the development of microscopic structural models.
In this thesis work, neutron scattering techniques have been used for the first time for the study of spider silk. The high scattering contribution of hydrogen and the scattering length difference of hydrogen and deuterium have allowed a fresh look at structural and dynamical properties of spider silks. Thus the results support a hierarchical, three-phase model of nanofibrils composed of crystalline and short-range order domains embedded in an amorphous matrix. Complementary synchrotron scattering experiments suggest that water absorbed by the amorphous matrix forms an amorphous ice at low temperatures. Wide-angle neutron scattering (WANS) experiments showed a meridional superlattice peak -not observed by X-ray (WAXS) experiments-, which is assigned to a smectic beta-sheet structure in the short-range order domains. The exchange of H2O against D2O in small-angle neutron scattering (SANS) experiments allowed changing the neutron scattering length density contrast in the nanofibrils and the contrast of the nanofibrils against the amorphous matrix. The molecular mobility was probed by inelastic and quasielastic neutron scattering techniques. A hierarchy of relaxation processes seems to describe hydrated silk, while native silk behaves like a glass at room temperature.
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https://tel.archives-ouvertes.fr/tel-00011700
Contributor : Daniel Sapede <>
Submitted on : Monday, April 10, 2006 - 3:58:20 PM
Last modification on : Monday, April 10, 2006 - 4:13:35 PM
Long-term archiving on: : Thursday, September 23, 2010 - 3:08:05 PM

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  • HAL Id : tel-00011700, version 3

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Daniel Sapede. Contributions to the understanding of the hierarchical structure and dynamics of spider dragline silk. Biological Physics [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2006. English. ⟨tel-00011700v3⟩

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