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Hu L, Chen Q, Yao J, Shao Z, Chen X. Structural Changes in Spider Dragline Silk after Repeated Supercontraction-Stretching Processes. Biomacromolecules 2020; 21:5306-5314. [PMID: 33206498 DOI: 10.1021/acs.biomac.0c01378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spider dragline silk is well-known for its excellent combination of strength and extensibility as well as another unique property called supercontraction. In our previous work, the changes in conformations of the Nephila edulis spider dragline silk when subjected to different supercontraction processes were extensively investigated. When a native spider dragline silk had free supercontraction, and then restretched to its original length, the content and molecular orientation of different conformations (β-sheet, helix, and random coil) changed but the mechanical properties remained almost the same. Therefore, herein, further supercontraction-stretching treatment was performed up to three cycles, and the corresponding structural changes were investigated. In addition to the synchrotron radiation FTIR (S-FTIR) microspectroscopy employed in our previous study, synchrotron radiation small-angle X-ray scattering (S-SAXS) and atomic force microscopy (AFM) were also used in this work to determine the structural changes of spider dragline silk in different scales. The results show that by repeating the supercontraction-stretching treatment, the β-sheet structure content in spider dragline silk was slightly increased, but its orientation degree remained almost the same. Also, with the increase in cycle of supercontraction-stretching treatments, a 10.5 nm long period perpendicular to the silk fiber axis gradually appeared, endowing the spider dragline silk with periodic structure both along (6.6 nm, already existed in native silk and did not change with the supercontraction-stretching treatment) and perpendicular to the silk fiber axis. After the third supercontraction-stretching cycle, the AFM images displayed a clear 210 nm × 80 nm corn kernel-like structure on the surface of nanofibrils in spider dragline silks, which may be related to the aggregation of 10.5 nm × 6.6 nm periodic structure observed via S-SAXS. Finally, although the structure of spider dragline silk became increasingly regular with the rise in supercontraction-stretching cycles, mechanical properties remained constant after every cycle of the supercontraction-stretching treatment. These findings can aid in further understanding the structural changes that are related to the supercontraction of spider dragline silk and provide useful guidance in fabrication of high-performance regenerated or artificial silk fibers.
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Affiliation(s)
- Linli Hu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Shanghai Stomatological Hospital, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Qianying Chen
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Shanghai Stomatological Hospital, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Jinrong Yao
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Shanghai Stomatological Hospital, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Zhengzhong Shao
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Shanghai Stomatological Hospital, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Xin Chen
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Shanghai Stomatological Hospital, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
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Yoshioka T, Tsubota T, Tashiro K, Jouraku A, Kameda T. A study of the extraordinarily strong and tough silk produced by bagworms. Nat Commun 2019; 10:1469. [PMID: 30931923 PMCID: PMC6443776 DOI: 10.1038/s41467-019-09350-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/27/2019] [Indexed: 01/03/2023] Open
Abstract
Global ecological damage has heightened the demand for silk as 'a structural material made from sustainable resources'. Scientists have earnestly searched for stronger and tougher silks. Bagworm silk might be a promising candidate considering its superior capacity to dangle a heavy weight, summed up by the weights of the larva and its house. However, detailed mechanical and structural studies on bagworm silks have been lacking. Herein, we show the superior potential of the silk produced by Japan's largest bagworm, Eumeta variegata. This bagworm silk is extraordinarily strong and tough, and its tensile deformation behaviour is quite elastic. The outstanding mechanical property is the result of a highly ordered hierarchical structure, which remains unchanged until fracture. Our findings demonstrate how the hierarchical structure of silk proteins plays an important role in the mechanical property of silk fibres.
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Affiliation(s)
- Taiyo Yoshioka
- Silk Materials Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Takuya Tsubota
- Transgenic Silkworm Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Kohji Tashiro
- Department of Future Industry-Oriented Basic Science and Materials, Graduate School of Engineering, Toyota Technological Institute, Tempaku, Nagoya, 468-8511, Japan
| | - Akiya Jouraku
- Insect Genome Research and Engineering Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Tsunenori Kameda
- Silk Materials Research Unit, National Agriculture and Food Research Organization (NARO), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan.
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Sapede D, Seydel T, Forsyth VT, Koza MM, Schweins R, Vollrath F, Riekel C. Nanofibrillar Structure and Molecular Mobility in Spider Dragline Silk. Macromolecules 2005. [DOI: 10.1021/ma0507995] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Sapede
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - T. Seydel
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - V. T. Forsyth
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - M. M. Koza
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - R. Schweins
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - F. Vollrath
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
| | - C. Riekel
- Institut Max von Laue-Paul Langevin, B.P. 156, F-38042 Grenoble, France; European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, France; Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K.; and Institute for Science and Technology in Medicine, Keele University Medical School, ST4 7QB, U.K
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Putthanarat S, Eby R, Naik RR, Juhl SB, Walker MA, Peterman E, Ristich S, Magoshi J, Tanaka T, Stone MO, Farmer B, Brewer C, Ott D. Nonlinear optical transmission of silk/green fluorescent protein (GFP) films. POLYMER 2004. [DOI: 10.1016/j.polymer.2004.10.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
X-ray studies on degummed B. mori silk fibers and on hydrogels prepared under a variety of conditions reveal moderately small angle reflections. These reflections are often highly oriented and are correlated to silk II lattice reflections. A superstructure can explain these features. Silk fibroin hydrogels were monitored as they dried to form the silk II structure. The silk II wide angle and moderately small angle patterns obtained from dried hydrogels and silk fibers are identical. The "superstructure" reflections at moderately small angle (3-7 nm) were first to appear, followed by the "intersheet" spacing, and then the remainder of the silk II wide angle scattering pattern. Thus, any superstructure hypothesized for the hydrogels (and for Silk II in fibers) must be both stable in a highly hydrated environment and must convert to silk II with little large scale diffusion. A folded structure, similar to amyloids and cross-beta-sheets but with much longer beta-strand stems, is proposed for silk II in fibers.
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Affiliation(s)
- Regina Valluzzi
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA.
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Riekel C, Vollrath F. Spider silk fibre extrusion: combined wide- and small-angle X-ray microdiffraction experiments. Int J Biol Macromol 2001; 29:203-10. [PMID: 11589973 DOI: 10.1016/s0141-8130(01)00166-0] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The major and minor ampullate silks from live Nephila senegalensis (Tetragnathidae) and the major ampullate silk from Euprostenops spp. (Pisauridae) spiders were investigated in situ by X-ray diffraction during forced silking. Wide- (WAXS) and small-angle (SAXS) scattering patterns were obtained at the same time. WAXS data show that the thread at the exit of the spigots already contains beta-sheet poly(alanine) crystallites. SAXS data suggest the presence of microfibrils with an axial repeating period of approximately 8 nm for both Nephila and Euprostenops. Minor ampullate (MI) Nephila silk, however, does not show this axial repeat which is probably due to a higher amount of crystal forming poly(alanine). A microfibrillar morphology, connected by a network of random polymer chains, can explain the presence of highly oriented crystallites, an oriented halo and a diffuse background in the WAXS patterns. At high reeling speeds, bound water is co-extruded with the fibre. It can be squeezed out of the fibre by friction at a needle. Under natural conditions it is the spider's tarsal claws which might serve to squeeze out the water to improve the mechanical properties of the thread during dragline production.
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Affiliation(s)
- C Riekel
- European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble Cedex, France.
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