Fiber Morphology of Spider Silk:  The Effects of Tensile Deformation

Grubb, D. T.; Jelinski, Lynn W.

doi:10.1021/ma961293c

Cited by 308 publications

(427 citation statements)

References 25 publications

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“…1a) [6][7][8]. Thereby, the anti-parallel beta-sheet nanocrystals [9][10][11][12] play a key role in defining the mechanical properties as they provide stiff orderly cross-linking domains embedded in a semiamorphous matrix that consists of less orderly beta-structures, 3 1 helices and beta-turns [6,13,14].…”

Section: Introductionmentioning

confidence: 99%

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

Keten²,

et al. 2010

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Section: Introductionmentioning

confidence: 99%

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

Keten²,

et al. 2010

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“…The poly-Ala domains have previously been characterized by NMR and x-ray and were found to be predominantly in ␤ sheet conformation (22)(23)(24) and to organize into microcrystals with sizes of at least 2 ϫ 5 ϫ 7 nm (25,26). Considerably larger domains were seen by transmission electron microscopy (27); the size of the ordered domains hints that these must incorporate some glycine.…”

mentioning

confidence: 99%

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

Beek

Heß

Vollrath

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

479

607

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The design principles of spider dragline silk, nature's highperformance fiber, are still largely unknown, in particular for the noncrystalline glycine-rich domains, which form the bulk of the material. Here we apply two-dimensional solid-state NMR to determine the distribution of the backbone torsion angles ( , ) as well as the orientation of the polypeptide backbone toward the fiber at both the glycine and alanine residues. Instead of an ''amorphous matrix,'' suggested earlier for the glycine-rich domains, these new data indicate that all domains in dragline silk have a preferred secondary structure and are strongly oriented, with the chains predominantly parallel to the fiber. As proposed previously, the alanine residues are predominantly found in a ␤ sheet conformation. The glycine residues are partly incorporated into the ␤ sheets and otherwise form helical structures with an approximate 3-fold symmetry.

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“…Both are semicrystalline nanocomposites, with ordered regions (-sheet protein nanocrystals) embedded in a softer matrix of disordered material (spider silk, [3]; silkworm fibroin, [4]). Tensile deformation of silk fibers involves a strong contribution of viscoelastic material, presumably in the disordered regions [5].…”

mentioning

confidence: 99%

“…To this end, we combined high-resolution cyclic stress-strain measurements of single silkworm silk fibers (such as reported in [13][14][15]) with in situ tensile tests during synchrotron radiation x-ray diffraction experiments (see previous work [3,9,16]), the latter probing directly the deformation of the nanocrystals.…”

mentioning

confidence: 99%

Mechanical Properties of Silk: Interplay of Deformation on Macroscopic and Molecular Length Scales

et al. 2008

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Using an in situ combination of tensile tests and x-ray diffraction, we have determined the mechanical properties of both the crystalline and the disordered phase of the biological nanocomposite silk by adapting a model from linear viscoelastic theory to the semicrystalline morphology of silk. We observe a strong interplay between morphology and mechanical properties. Silk's high extensibility results principally from the disordered phase; however, the crystals are also elastically deformed. DOI: 10.1103/PhysRevLett.100.048104 PACS numbers: 87.85.Jÿ, 61.05.cp, 81.70.Bt, 87.15.La Natural silks exhibit extraordinary mechanical properties, combining high tensile strength with a high elongation at failure. Producing man-made fibers with such properties requires a considerable input of energy compared to natural silk fibers spun from aqueous protein solution at ambient temperature. The toughest silk known is spun by spiders. However, it has recently been shown that, chemically and rheologically closely related, silkworm silk [1] could reach comparable parameters in an optimized spinning process [2].The similarity between spider and silkworm silk fibers extends to their morphology. Both are semicrystalline nanocomposites, with ordered regions (-sheet protein nanocrystals) embedded in a softer matrix of disordered material (spider silk, [3]; silkworm fibroin, [4]). Tensile deformation of silk fibers involves a strong contribution of viscoelastic material, presumably in the disordered regions [5]. However, detailed information on the relaxation mechanism is still missing.The mesoscopic structure of polymer nanocomposites is the key to their mechanical properties [6]. Mimicking nature's spinning process to produce artificial fibers with optimized morphology and, thus, optimal mechanical performance either from silkworm or recombinant spider silk spinning dope [7] would be highly desirable. The models of silk available today do not directly connect structure and macroscopic properties. Termonia's model [8] describes silk as a hydrogen-bonded rubberlike matrix with embedded stiff crystals serving as cross-link sites. At their surface, another ordered phase of protein molecules is required in order to explain the static mechanical properties. The assumed high rigidity of the -sheet crystals has been questioned by x-ray diffraction results [9]. While the recent model by Porter et al. [10] and Vollrath and Porter [11] includes morphological parameters such as ordered/ disordered fractions, which are very difficult to obtain experimentally, deformation processes in crystals and matrix are neglected. A molecular model for spider capture silk is available but restricted to this very specialized silk type [12].The aim of this Letter is to establish a model for silk incorporating the macroscopic mechanical behavior, in particular, viscoelasticity, on the basis of its semicrystalline morphology. To this end, we combined high-resolution cyclic stress-strain measurements of single silkworm silk fibers (such as reported in [13][14...

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Fiber Morphology of Spider Silk: The Effects of Tensile Deformation

Cited by 308 publications

References 25 publications

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

Mechanical Properties of Silk: Interplay of Deformation on Macroscopic and Molecular Length Scales

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