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Sonavane S, Westermark P, Rising A, Holm L. Regionalization of cell types in silk glands of Larinioides sclopetarius suggest that spider silk fibers are complex layered structures. Sci Rep 2023; 13:22273. [PMID: 38097700 PMCID: PMC10721825 DOI: 10.1038/s41598-023-49587-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 12/09/2023] [Indexed: 12/17/2023] Open
Abstract
In order to produce artificial silk fibers with properties that match the native spider silk we likely need to closely mimic the spinning process as well as fiber architecture and composition. To increase our understanding of the structure and function of the different silk glands of the orb weaver Larinioides sclopetarius, we used resin sections for detailed morphology, paraffin embedded sections for a variety of different histological stainings, and a histochemical method for localization of carbonic anhydrase activity. Our results show that all silk glands, except the tubuliform glands, are composed of two or more columnar epithelial cell types, some of which have not been described previously. We observed distinct regionalization of the cell types indicating sequential addition of secretory products during silk formation. This means that the major ampullate, minor ampullate, aciniform type II, and piriform silk fibers most likely are layered and that each layer has a specific composition. Furthermore, a substance that stains positive for polysaccharides may be added to the silk in all glands except in the type I aciniform glands. Active carbonic anhydrase was found in all silk glands and/or ducts except in the type I aciniform and tubuliform glands, with the strongest staining in aggregate glands and their ductal nodules. Carbonic anhydrase plays an important role in the generation of a pH gradient in the major ampullate glands, and our results suggest that some other glands may also harbor pH gradients.
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Affiliation(s)
- Sumalata Sonavane
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Per Westermark
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Anna Rising
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, Huddinge, Sweden
| | - Lena Holm
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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2
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Shatrov AB, Soldatenko EV, Benken KA, Petrov AA. The structural analysis of secretion in the freshwater mite Limnesia maculata (Acariformes, Limnesiidae) supports the idea of a new form of arthropod silk. Exp Appl Acarol 2023:10.1007/s10493-023-00826-y. [PMID: 37480394 DOI: 10.1007/s10493-023-00826-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
The structural characteristics of silk secretion of the freshwater mite Limnesia maculata (O.F. Müller) (Acariformes, Limnesiidae) are described and analyzed for the first time based on light, atomic force and electron-microscopical approaches. The common dermal glands (14 pairs scattered over the body) produce silk mostly during the warm summer season. The process of silk secretion lasts from several hours to several days. The silk may appear like barely recognized clouds of a fine whitish substance. An individual silk thread is an indefinitely long uniform unbranched and non-stretchable tube, hollow or with a vesicular electron-dense residual content. In the silk bundle, threads may be freely interlaced, bent, curved or occasionally broken. The diameter of the tubes is in the range of 0.9-1.5 µm. The width of the tube walls varies greatly from 60 to 300 nm. Chaotically interlaced fine fibrils build the tube walls. On the external surface of the tube wall, these fibrils are loosely organized and frequently rising vertically, whereas on the internal side they are packed more tightly sometimes showing a mesh. The walls may reveal a layered structure or, contrary, are quite thin with through foramens. The revealed organization of silk in the freshwater mites is found to be the simplest among that of other arthropods. We propose a role of the silk in the capture of potential prey in the summer season. Silk in water mites significantly widens the wholesome area for the mites' life and gives them better chances in competition for potential resources.
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Affiliation(s)
- Andrey B Shatrov
- Zoological Institute of the Russian Academy of Science, Universitetskaya nab. 1, St. Petersburg, Russia, 199034.
| | - Elena V Soldatenko
- Zoological Institute of the Russian Academy of Science, Universitetskaya nab. 1, St. Petersburg, Russia, 199034
| | - Konstantin A Benken
- Centre for Microscopy and Microanalysis, St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, Russia, 199034
| | - Anatoly A Petrov
- Zoological Institute of the Russian Academy of Science, Universitetskaya nab. 1, St. Petersburg, Russia, 199034
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3
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Iachina I, Brewer JR, Rubahn HG, Fiutowski J. Helium Ion Microscopy and Sectioning of Spider Silk. Scanning 2023; 2023:2936788. [PMID: 37260614 PMCID: PMC10228223 DOI: 10.1155/2023/2936788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 06/02/2023]
Abstract
Focused ion beams have recently emerged as a powerful tool for ultrastructural imaging of biological samples. In this article, we show that helium ion microscopy (HIM), in combination with ion milling, can be used to visualize the inner structure of both major and minor ampullate silk fibers of the orb-web weaving spider Nephila madagascariensis. The internal nanofibrils were imaged in pristine silk fibers, with little or no damage to the sample structure observed. Furthermore, a method to cut/rupture the fibers using He+ ions combined with internal sample tension is presented. This showed that the stretching and rupturing of spider silk is a highly dynamic process with considerable material reorganization.
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Affiliation(s)
- Irina Iachina
- NanoSYD, Mads Clausen Institute, University of Southern Denmark, Denmark
- Department of Biochemisty and Molecular Biology, University of Southern Denmark, Denmark
| | - Jonathan R. Brewer
- Department of Biochemisty and Molecular Biology, University of Southern Denmark, Denmark
| | | | - Jacek Fiutowski
- NanoSYD, Mads Clausen Institute, University of Southern Denmark, Denmark
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4
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Iachina I, Fiutowski J, Rubahn HG, Vollrath F, Brewer JR. Nanoscale imaging of major and minor ampullate silk from the orb-web spider Nephila Madagascariensis. Sci Rep 2023; 13:6695. [PMID: 37095261 PMCID: PMC10125981 DOI: 10.1038/s41598-023-33839-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 04/19/2023] [Indexed: 04/26/2023] Open
Abstract
Spider silk fibres have unique mechanical properties due to their hierarchical structure and the nanoscale organization of their proteins. Novel imaging techniques reveal new insights into the macro- and nanoscopic structure of Major (MAS) and Minor (MiS) Ampullate silk fibres from pristine samples of the orb-web spider Nephila Madagascariensis. Untreated threads were imaged using Coherent Anti-Stokes Raman Scattering and Confocal Microscopy, which revealed an outer lipid layer surrounding an autofluorescent protein core, that is divided into two layers in both fibre types. Helium ion imaging shows the inner fibrils without chemical or mechanical modifications. The fibrils are arranged parallel to the long axis of the fibres with typical spacing between fibrils of 230 nm ± 22 nm in the MAS fibres and 99 nm ± 24 nm in the MiS fibres. Confocal Reflection Fluorescence Depletion (CRFD) microscopy imaged these nano-fibrils through the whole fibre and showed diameters of 145 nm ± 18 nm and 116 nm ± 12 nm for MAS and MiS, respectively. The combined data from HIM and CRFD suggests that the silk fibres consist of multiple nanoscale parallel protein fibrils with crystalline cores oriented along the fibre axes, surrounded by areas with less scattering and more amorphous protein structures.
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Affiliation(s)
- Irina Iachina
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Mads Clausen Institute, SDU NanoSYD, University of Southern Denmark, Sønderborg, Denmark
| | - Jacek Fiutowski
- Mads Clausen Institute, SDU NanoSYD, University of Southern Denmark, Sønderborg, Denmark
| | - Horst-Günter Rubahn
- Mads Clausen Institute, SDU NanoSYD, University of Southern Denmark, Sønderborg, Denmark
| | - Fritz Vollrath
- Department of Biology, University of Oxford, South Parks Rd., Oxford, UK
| | - Jonathan R Brewer
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
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5
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Abstract
There is an urgent need to improve the sustainability of the materials we produce and use. Here, we explore what humans can learn from nature about how to sustainably fabricate polymeric fibers with excellent material properties by reviewing the physical and chemical aspects of materials processing distilled from diverse model systems, including spider silk, mussel byssus, velvet worm slime, hagfish slime, and mistletoe viscin. We identify common and divergent strategies, highlighting the potential for bioinspired design and technology transfer. Despite the diversity of the biopolymeric fibers surveyed, we identify several common strategies across multiple systems, including: (1) use of stimuli-responsive biomolecular building blocks, (2) use of concentrated fluid precursor phases (e.g., coacervates and liquid crystals) stored under controlled chemical conditions, and (3) use of chemical (pH, salt concentration, redox chemistry) and physical (mechanical shear, extensional flow) stimuli to trigger the transition from fluid precursor to solid material. Importantly, because these materials largely form and function outside of the body of the organisms, these principles can more easily be transferred for bioinspired design in synthetic systems. We end the review by discussing ongoing efforts and challenges to mimic biological model systems, with a particular focus on artificial spider silks and mussel-inspired materials.
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Affiliation(s)
- Anna Rising
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge 141 52, Sweden.,Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala 750 07, Sweden
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6
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Blamires SJ, Rawal A, Edwards AD, Yarger JL, Oberst S, Allardyce BJ, Rajkhowa R. Methods for Silk Property Analyses across Structural Hierarchies and Scales. Molecules 2023; 28:molecules28052120. [PMID: 36903366 PMCID: PMC10003856 DOI: 10.3390/molecules28052120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/13/2023] [Accepted: 02/20/2023] [Indexed: 03/02/2023] Open
Abstract
Silk from silkworms and spiders is an exceptionally important natural material, inspiring a range of new products and applications due to its high strength, elasticity, and toughness at low density, as well as its unique conductive and optical properties. Transgenic and recombinant technologies offer great promise for the scaled-up production of new silkworm- and spider-silk-inspired fibres. However, despite considerable effort, producing an artificial silk that recaptures the physico-chemical properties of naturally spun silk has thus far proven elusive. The mechanical, biochemical, and other properties of pre-and post-development fibres accordingly should be determined across scales and structural hierarchies whenever feasible. We have herein reviewed and made recommendations on some of those practices for measuring the bulk fibre properties; skin-core structures; and the primary, secondary, and tertiary structures of silk proteins and the properties of dopes and their proteins. We thereupon examine emerging methodologies and make assessments on how they might be utilized to realize the goal of developing high quality bio-inspired fibres.
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Affiliation(s)
- Sean J. Blamires
- School of Biological, Earth and Environmental Science, University of New South Wales, Sydney, NSW 2052, Australia
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW 2052, Australia
- School of Mechanical and Mechatronic Engineering, University of Technology, Sydney, NSW 2007, Australia
- Correspondence:
| | - Aditya Rawal
- Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW 2052, Australia
| | - Angela D. Edwards
- School of Molecular Science, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Jeffrey L. Yarger
- School of Molecular Science, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Sebastian Oberst
- School of Mechanical and Mechatronic Engineering, University of Technology, Sydney, NSW 2007, Australia
| | | | - Rangam Rajkhowa
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
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7
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Wang Y, Wu Z, Zhou L, Chen X, Guan J, Shao Z. Peculiar Tensile and Fracture Behaviors of Natural Silk Fiber in the Presence of an Artificial Notch. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Yu Wang
- State Key Laboratory of Molecular Engineering of Polymers, Laboratory of Advanced Materials and Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Zihong Wu
- School of Materials Science and Engineering, Beijing Innovation Center of Biomedical Engineering, Beihang University, Beijing 100191, People’s Republic of China
| | - Liang Zhou
- Department of Material Science and Engineering, Anhui Agricultural University, Hefei 230036, People’s Republic of China
| | - Xin Chen
- State Key Laboratory of Molecular Engineering of Polymers, Laboratory of Advanced Materials and Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of China
| | - Juan Guan
- School of Materials Science and Engineering, Beijing Innovation Center of Biomedical Engineering, Beihang University, Beijing 100191, People’s Republic of China
| | - Zhengzhong Shao
- State Key Laboratory of Molecular Engineering of Polymers, Laboratory of Advanced Materials and Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of China
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8
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Cohen N, Eisenbach CD. Humidity-Driven Supercontraction and Twist in Spider Silk. Phys Rev Lett 2022; 128:098101. [PMID: 35302814 DOI: 10.1103/physrevlett.128.098101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 01/05/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Spider silk is a protein material that exhibits extraordinary and nontrivial properties such as the ability to soften, decrease in length (i.e., supercontract), and twist upon exposure to high humidity. These behaviors stem from a unique microstructure in combination with a transition from glassy to rubbery as a result of humidity-driven diffusion of water. In this Letter we propose four length scales that govern the mechanical response of the silk during this transition. In addition, we develop a model that describes the microstructural evolution of the spider silk thread and explains the response due to the diffusion of water molecules. The merit of the model is demonstrated through an excellent agreement to experimental findings. The insights from this Letter can be used as a microstructural design guide to enable the development of new materials with unique spiderlike properties.
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Affiliation(s)
- Noy Cohen
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Claus D Eisenbach
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA and Institute for Polymer Chemistry, University of Stuttgart, D-70569 Stuttgart, Germany
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9
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Li J, Li S, Huang J, Khan AQ, An B, Zhou X, Liu Z, Zhu M. Spider Silk-Inspired Artificial Fibers. Adv Sci (Weinh) 2022; 9:e2103965. [PMID: 34927397 PMCID: PMC8844500 DOI: 10.1002/advs.202103965] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/19/2021] [Indexed: 05/14/2023]
Abstract
Spider silk is a natural polymeric fiber with high tensile strength, toughness, and has distinct thermal, optical, and biocompatible properties. The mechanical properties of spider silk are ascribed to its hierarchical structure, including primary and secondary structures of the spidroins (spider silk proteins), the nanofibril, the "core-shell", and the "nano-fishnet" structures. In addition, spider silk also exhibits remarkable properties regarding humidity/water response, water collection, light transmission, thermal conductance, and shape-memory effect. This motivates researchers to prepare artificial functional fibers mimicking spider silk. In this review, the authors summarize the study of the structure and properties of natural spider silk, and the biomimetic preparation of artificial fibers from different types of molecules and polymers by taking some examples of artificial fibers exhibiting these interesting properties. In conclusion, biomimetic studies have yielded several noteworthy findings in artificial fibers with different functions, and this review aims to provide indications for biomimetic studies of functional fibers that approach and exceed the properties of natural spider silk.
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Affiliation(s)
- Jiatian Li
- State Key Laboratory of Medicinal Chemical BiologyCollege of Pharmacy and College of ChemistryKey Laboratory of Functional Polymer MaterialsFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China
| | - Sitong Li
- State Key Laboratory of Medicinal Chemical BiologyCollege of Pharmacy and College of ChemistryKey Laboratory of Functional Polymer MaterialsFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China
| | - Jiayi Huang
- State Key Laboratory of Medicinal Chemical BiologyCollege of Pharmacy and College of ChemistryKey Laboratory of Functional Polymer MaterialsFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China
| | - Abdul Qadeer Khan
- State Key Laboratory of Medicinal Chemical BiologyCollege of Pharmacy and College of ChemistryKey Laboratory of Functional Polymer MaterialsFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China
| | - Baigang An
- School of Chemical EngineeringUniversity of Science and Technology LiaoningAnshan114051China
| | - Xiang Zhou
- Department of ScienceChina Pharmaceutical UniversityNanjing211198China
| | - Zunfeng Liu
- State Key Laboratory of Medicinal Chemical BiologyCollege of Pharmacy and College of ChemistryKey Laboratory of Functional Polymer MaterialsFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China
- School of Chemical EngineeringUniversity of Science and Technology LiaoningAnshan114051China
| | - Meifang Zhu
- State Key Laboratory for Modification of Chemical Fibers and Polymer MaterialsCollege of Materials Science and EngineeringDonghua UniversityShanghai201620China
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10
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Zhang W, Fan Y. Structure of Animal Silks. Methods Mol Biol 2021; 2347:3-15. [PMID: 34472050 DOI: 10.1007/978-1-0716-1574-4_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
As an abundant fibrous protein, animal silks have received a variety of interests in both traditional and high-tech industries, such as textiles, decoration, and biomedicine, due to their unique advantages in mechanical performance, sustainability, biocompatibility, and biodegradability. While developing applications of animal silks, the structure of animal silks has also received more and more attention in these decades. Briefly, most animal silks can be considered as semicrystalline fibers, which are composed of β-sheet nanocrystals and amorphous regions. However, different animal silks have similarities and also have obvious differences at different structural levels. In this chapter, we will introduce the structures of the three most representative animal silks, that is, spider dragline silk, tussah silk, and mulberry silk. The similarities and differences in their structures will be highlighted, so as to provide fundamental guidance for the research and use of these animal silks.
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11
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Kiseleva A, Nestor G, Östman JR, Kriuchkova A, Savin A, Krivoshapkin P, Krivoshapkina E, Seisenbaeva GA, Kessler VG. Modulating Surface Properties of the Linothele fallax Spider Web by Solvent Treatment. Biomacromolecules 2021; 22:4945-4955. [PMID: 34644050 PMCID: PMC8672351 DOI: 10.1021/acs.biomac.1c00787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 09/23/2021] [Indexed: 11/29/2022]
Abstract
Linothele fallax (Mello-Leitão) (L. fallax) spider web, a potentially attractive tissue engineering material, was investigated using quantitative peak force measurement atomic force microscopy and scanning electron microscopy with energy dispersive spectroscopy both in its natural state and after treatment with solvents of different protein affinities, namely, water, ethanol, and dimethyl sulfoxide (DMSO). Native L. fallax silk threads are densely covered by globular objects, which constitute their inseparable parts. Depending on the solvent, treating L. fallax modifies its appearance. In the case of water and ethanol, the changes are minor. In contrast, DMSO practically removes the globules and fuses the threads into dense bands. Moreover, the solvent treatment influences the chemistry of the threads' surface, changing their adhesive and, therefore, biocompatibility and cell adhesion properties. On the other hand, the solvent-treated web materials' contact effect on different types of biological matter differs considerably. Protein-rich matter controls humidity better when wrapped in spider silk treated with more hydrophobic solvents. However, carbohydrate plant materials retain more moisture when wrapped in native spider silk. The extracts produced with the solvents were analyzed using nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry techniques, revealing unsaturated fatty acids as representative adsorbed species, which may explain the mild antibacterial effect of the spider silk. The extracted metabolites were similar for the different solvents, meaning that the globules were not "dissolved" but "fused into" the threads themselves, being supposedly rolled-in knots of the protein chain.
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Affiliation(s)
- Aleksandra Kiseleva
- Institute
of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 197101, Russia
| | - Gustav Nestor
- Department
of Molecular Sciences, Biocenter, SLU, Box 7015, Uppsala 75007, Sweden
| | - Johnny R. Östman
- Department
of Molecular Sciences, Biocenter, SLU, Box 7015, Uppsala 75007, Sweden
| | - Anastasiia Kriuchkova
- Institute
of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 197101, Russia
| | - Artemii Savin
- Institute
of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 197101, Russia
| | - Pavel Krivoshapkin
- Institute
of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 197101, Russia
| | - Elena Krivoshapkina
- Institute
of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg 197101, Russia
| | | | - Vadim G. Kessler
- Department
of Molecular Sciences, Biocenter, SLU, Box 7015, Uppsala 75007, Sweden
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Blamires SJ, Nobbs M, Wolff JO, Heu C. Nutritionally induced nanoscale variations in spider silk structural and mechanical properties. J Mech Behav Biomed Mater 2021; 125:104873. [PMID: 34653899 DOI: 10.1016/j.jmbbm.2021.104873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 09/24/2021] [Accepted: 09/30/2021] [Indexed: 10/20/2022]
Abstract
Spider major ampullate (MA) silk is characterized by high strength and toughness and is adaptable across environments. Experiments depriving spiders of protein have enabled researchers to examine nutritionally induced changes in gene expression, protein structures, and bulk properties of MA silk. However, it has not been elucidated if it varies in a similar way at a nanoscale. Here we used Atomic Force Microscopy (AFM) to simultaneously examine the topographic, structural, and mechanical properties of silks spun by two species of spider, Argiope keyserlingi and Latrodectus hasselti, at a nanoscale when protein fed or deprived. We found height, a measure of localized width, to substantially vary across species and treatments. We also found that Young's modulus, which may be used as an estimate of localized stiffness, decreased with protein deprivation in both species' silk. Our results suggest that nanoscale skin-core structures of A. keyserlingi's MA silk varied significantly across treatments, whereas only slight structural and functional variability was found for L. hasselti's silk. These results largely agreed with examinations of the bulk properties of each species' silk. However, we could not directly attribute the decoupling between protein structures and bulk mechanics in L. hasselti's silk to nanoscale features. Our results advance the understanding of processes inducing skin and core structural variations in spider silks at a nanoscale, which serves to enhance the prospect of developing biomimetic engineering programs.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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14
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Kiseleva AP, Krivoshapkin PV, Krivoshapkina EF. Recent Advances in Development of Functional Spider Silk-Based Hybrid Materials. Front Chem 2020; 8:554. [PMID: 32695749 PMCID: PMC7338834 DOI: 10.3389/fchem.2020.00554] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/29/2020] [Indexed: 01/10/2023] Open
Abstract
Silkworm silk is mainly known as a luxurious textile. Spider silk is an alternative to silkworm silk fibers and has much more outstanding properties. Silk diversity ensures variation in its application in nature and industry. This review aims to provide a critical summary of up-to-date fabrication methods of spider silk-based organic-inorganic hybrid materials. This paper focuses on the relationship between the molecular structure of spider silk and its mechanical properties. Such knowledge is essential for understanding the innate properties of spider silk as it provides insight into the sophisticated assembly processes of silk proteins into the distinct polymers as a basis for novel products. In this context, we describe the development of spider silk-based hybrids using both natural and bioengineered spider silk proteins blended with inorganic nanoparticles. The following topics are also covered: the diversity of spider silk, its composition and architecture, the differences between silkworm silk and spider silk, and the biosynthesis of natural silk. Referencing biochemical data and processes, this paper outlines the existing challenges and future outcomes.
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Affiliation(s)
| | | | - Elena F. Krivoshapkina
- Laboratory of Solution Chemistry of Advanced Materials and Technologies, ITMO University, St. Petersburg, Russia
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15
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Sogawa H, Nakano K, Tateishi A, Tajima K, Numata K. Surface Analysis of Native Spider Draglines by FE-SEM and XPS. Front Bioeng Biotechnol 2020; 8:231. [PMID: 32266250 PMCID: PMC7099578 DOI: 10.3389/fbioe.2020.00231] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 03/05/2020] [Indexed: 11/13/2022] Open
Abstract
Although the physical and biological functions of the skin layer of spider dragline have been studied and partially clarified, the morphology and elemental contents of the skin layer of silk fibers have not been investigated in detail to date. Here, the surface of Nephila clavata spider dragline was evaluated by field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) to obtain clear surface morphological and molecular information. The FE-SEM images of the spider dragline indicate that the spider dragline forms a bundle of microfibrils. This hierarchical structure might induce faint fibrilar and network-like patterns on the surface of the dragline. XPS analysis revealed the presence of Na, P, and S, which are reasonably explained by considering the biological components of the major ampullate gland of spiders. The results obtained here are preliminary but will be important to consider the molecular transition of silk proteins to form excellent hierarchical structures during the spider dragline spinning process.
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Affiliation(s)
- Hiromitsu Sogawa
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, Saitama, Japan
| | - Kyohei Nakano
- Emergent Functional Polymers Research Team, RIKEN Center for Emergent Matter Science, Saitama, Japan
| | - Ayaka Tateishi
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, Saitama, Japan
| | - Keisuke Tajima
- Emergent Functional Polymers Research Team, RIKEN Center for Emergent Matter Science, Saitama, Japan
| | - Keiji Numata
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, Saitama, Japan
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16
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Abstract
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Spider silks are
remarkable materials designed by nature to have
extraordinary elasticity. Their elasticity, however, remains poorly
understood, as typical stress–strain experiments only allow
access to the axial Young’s modulus. In this work, micro-Brillouin
light spectroscopy (micro-BLS), a noncontact, nondestructive technique,
is utilized to probe the direction-dependent phonon propagation in
the Nephila pilipes spider silk and
hence solve its full elasticity. To the best of our knowledge, this
is the first demonstration on the determination of the anisotropic
Young’s moduli, shear moduli, and Poisson’s ratios of
a single spider fiber. The axial and lateral Young’s moduli
are found to be 20.9 ± 0.8 and 9.2 ± 0.3 GPa, respectively,
and the anisotropy of the Young’s moduli further increases
upon stretching. In contrast, the shear moduli and Poisson’s
ratios exhibit very weak anisotropy and are robust to stretching.
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Affiliation(s)
- Zuyuan Wang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yu Cang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Friedrich Kremer
- Institute of Experimental Physics I, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
| | - Edwin L Thomas
- Department of Materials Science and Nano-Engineering, Rice University, Houston, Texas 77030, United States
| | - George Fytas
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.,Institute of Electronic Structure and Laser, F.O.R.T.H, 70013 Heraklion, Greece
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17
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Blamires SJ, Cerexhe G, White TE, Herberstein ME, Kasumovic MM. Spider silk colour covaries with thermal properties but not protein structure. J R Soc Interface 2019; 16:20190199. [PMID: 31362622 DOI: 10.1098/rsif.2019.0199] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Understanding how and why animal secretions vary in property has important biomimetic implications as desirable properties might covary. Spider major ampullate (MA) silk, for instance, is a secretion earmarked for biomimetic applications, but many of its properties vary among and between species across environments. Here, we tested the hypothesis that MA silk colour, protein structure and thermal properties covary when protein uptake is manipulated in the spider Trichonephila plumipes. We collected silk from adult female spiders maintained on a protein-fed or protein-deprived diet. Based on spectrophotometric quantifications, we classified half the silks as 'bee visible' and the other half 'bee invisible'. Wide angle X-ray diffraction and differential scanning calorimetry were then used to assess the silk's protein structure and thermal properties, respectively. We found that although protein structures and thermal properties varied across our treatments only the thermal properties covaried with colour. This ultimately suggests that protein structure alone is not responsible for MA silk thermal properties, nor does it affect silk colours. We speculate that similar ecological factors act on silk colour and thermal properties, which should be uncovered to inform biomimetic programmes.
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Affiliation(s)
- Sean J Blamires
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences E26, The University of New South Wales, Sydney 2052, Australia.,Department of Biological Science, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Georgia Cerexhe
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences E26, The University of New South Wales, Sydney 2052, Australia
| | - Thomas E White
- Department of Biological Science, Macquarie University, Sydney, New South Wales 2109, Australia.,School of Life and Environmental Sciences, Macleay (A12), Room 208, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Marie E Herberstein
- Department of Biological Science, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Michael M Kasumovic
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences E26, The University of New South Wales, Sydney 2052, Australia
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18
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Liu D, Tarakanova A, Hsu CC, Yu M, Zheng S, Yu L, Liu J, He Y, Dunstan DJ, Buehler MJ. Spider dragline silk as torsional actuator driven by humidity. Sci Adv 2019; 5:eaau9183. [PMID: 30838327 PMCID: PMC6397028 DOI: 10.1126/sciadv.aau9183] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 01/14/2019] [Indexed: 05/25/2023]
Abstract
Self-powered actuation driven by ambient humidity is of practical interest for applications such as hygroscopic artificial muscles. We demonstrate that spider dragline silk exhibits a humidity-induced torsional deformation of more than 300°/mm. When the relative humidity reaches a threshold of about 70%, the dragline silk starts to generate a large twist deformation independent of spider species. The torsional actuation can be precisely controlled by regulating the relative humidity. The behavior of humidity-induced twist is related to the supercontraction behavior of spider dragline silk. Specifically, molecular simulations of MaSp1 and MaSp2 proteins in dragline silk reveal that the unique torsional property originates from the presence of proline in MaSp2. The large proline rings also contribute to steric exclusion and disruption of hydrogen bonding in the molecule. This property of dragline silk and its structural origin can inspire novel design of torsional actuators or artificial muscles and enable the development of designer biomaterials.
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Affiliation(s)
- Dabiao Liu
- Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Wuhan 430074, China
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
| | - Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Claire C. Hsu
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Miao Yu
- Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Shimin Zheng
- Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Longteng Yu
- Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Jie Liu
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan 430062, China
| | - Yuming He
- Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Wuhan 430074, China
| | - D. J. Dunstan
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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19
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Zhang S, Piorkowski D, Lin WR, Lee YR, Liao CP, Wang PH, Tso IM. Nitrogen unavailability helps to protect spider silk from bacterial growth. J Exp Biol 2019; 222:jeb.214981. [DOI: 10.1242/jeb.214981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 09/23/2019] [Indexed: 12/15/2022]
Abstract
Spider silks are protein-based fibers that are incorporated into webs with the unique combination of high mechanical toughness and resistance to microbial degradation. While spiders are undoubtedly exposed to saprophytic microorganisms in their native habitats, such as the forest understory and bush, their silks have rarely been observed to decompose in either field or laboratory studies. We performed cross-streaking assays using silk from three spider species and four bacterial strains and found no inhibition zones, indicating the absence of antibacterial properties. We also cultured all bacteria directly upon silk in Luria-Bertani broth (full nutrients), Phosphate-buffered saline (no nutrients) and nitrogen-free glucose broth (full nutrients, no nitrogen), and found bacteria grew readily on LB broth but not in PBS or NFG buffer. Our results indicated that spider silk's resistance to bacterial degradation is likely due to bacteriostatic, rather than antibacterial, mechanisms, as nitrogen is made unavailable.
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Affiliation(s)
- Shichang Zhang
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Dakota Piorkowski
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Wan-Rou Lin
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
- Bioresource Collection and Research Center (BCRC), Food Industry Research and Development Institute, Hsinchu 30062, Taiwan
| | - Yi-Ru Lee
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Chen-Pan Liao
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Pi-Han Wang
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - I-Min Tso
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
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20
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Yazawa K, Malay AD, Masunaga H, Numata K. Role of Skin Layers on Mechanical Properties and Supercontraction of Spider Dragline Silk Fiber. Macromol Biosci 2018; 19:e1800220. [PMID: 30230228 DOI: 10.1002/mabi.201800220] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/30/2018] [Indexed: 11/07/2022]
Abstract
Spider dragline silk is a composite biopolymer that harbors extraordinary mechanical characteristics, and consists of a hierarchically arranged protein core surrounded by outer "skin" layers. However, the contribution of the successive fiber layers on material properties has not been well defined. Here, the influence of the different components on the physicochemical and mechanical properties of dragline is investigated. The crystal structure and the mechanical properties are not changed significantly after the removal of skin constituents, indicating that the core region of dragline silk fibers determines the structural and mechanical properties. Furthermore, the outer layers have little influence on supercontraction, suggesting they do not function as protection against the penetration of water molecules. On the other hand, the outer layers offer some protection against protease digestion. The present study provides insight into how the function and structure of silk fibers are modulated and facilitates the design of silk-inspired functional materials.
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Affiliation(s)
- Kenjiro Yazawa
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Ali D Malay
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Hiroyasu Masunaga
- Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan
| | - Keiji Numata
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
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21
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Malay AD, Arakawa K, Numata K. Analysis of repetitive amino acid motifs reveals the essential features of spider dragline silk proteins. PLoS One 2017; 12:e0183397. [PMID: 28832627 PMCID: PMC5568437 DOI: 10.1371/journal.pone.0183397] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 08/03/2017] [Indexed: 12/19/2022] Open
Abstract
The extraordinary mechanical properties of spider dragline silk are dependent on the highly repetitive sequences of the component proteins, major ampullate spidroin 1 and 2 (MaSp2 and MaSp2). MaSp sequences are dominated by repetitive modules composed of short amino acid motifs; however, the patterns of motif conservation through evolution and their relevance to silk characteristics are not well understood. We performed a systematic analysis of MaSp sequences encompassing infraorder Araneomorphae based on the conservation of explicitly defined motifs, with the aim of elucidating the essential elements of MaSp1 and MaSp2. The results show that the GGY motif is nearly ubiquitous in the two types of MaSp, while MaSp2 is invariably associated with GP and di-glutamine (QQ) motifs. Further analysis revealed an extended MaSp2 consensus sequence in family Araneidae, with implications for the classification of the archetypal spidroins ADF3 and ADF4. Additionally, the analysis of RNA-seq data showed the expression of a set of distinct MaSp-like variants in genus Tetragnatha. Finally, an apparent association was uncovered between web architecture and the abundance of GP, QQ, and GGY motifs in MaSp2, which suggests a co-expansion of these motifs in response to the evolution of spiders' prey capture strategy.
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Affiliation(s)
- Ali D. Malay
- Enzyme Research Team, Center for Sustainable Resource Science, RIKEN, Wako-shi, Saitama, Japan
- * E-mail: (ADM); (KN)
| | - Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Kakuganji, Tsuruoka, Yamagata, Japan
| | - Keiji Numata
- Enzyme Research Team, Center for Sustainable Resource Science, RIKEN, Wako-shi, Saitama, Japan
- * E-mail: (ADM); (KN)
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22
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Park J, Kim D, Lee SM, Choi JU, You M, So HM, Han J, Nah J, Seol JH. Effects of β-sheet crystals and a glycine-rich matrix on the thermal conductivity of spider dragline silk. Int J Biol Macromol 2017; 96:384-391. [PMID: 28013005 DOI: 10.1016/j.ijbiomac.2016.12.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 12/13/2016] [Accepted: 12/16/2016] [Indexed: 11/25/2022]
Abstract
We measured the thermal conductivity of Araneus ventricosus' spider dragline silk using a suspended microdevice. The thermal conductivity of the silk fiber was approximately 0.4Wm-1K-1 at room temperature and gradually increased with an increasing temperature in a manner similar to that of other disordered crystals or proteins. In order to elucidate the effect of β-sheet crystals in the silk, thermal denaturation was used to reduce the quantity of the β-sheet crystals. A calculation with an effective medium approximation supported this measurement result showing that the thermal conductivity of β-sheet crystals had an insignificant effect on the thermal conductivity of SDS. Additionally, the enhancement of bonding strength in a glycine-rich matrix by atomic layer deposition did not increase the thermal conductivity. Thus, this study suggests that the disordered part of the glycine-rich matrix prevented the peptide chains from being coaxially extended via the cross-linking covalent bonds.
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Affiliation(s)
- Jinju Park
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Republic of Korea
| | - Duckjong Kim
- Department of Nano Mechanics, Korea Institute of Machinery & Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, Republic of Korea
| | - Seung-Mo Lee
- Department of Nano Mechanics, Korea Institute of Machinery & Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, Republic of Korea; Department of Nano Mechatronics, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Ji-Ung Choi
- Jeong Woo Industrial Machine Co. Ltd., 253 5sandan-ro, Susin-myeon, Dongnam-gu, Cheonan-si, Chungcheongnam-do 31251, Republic of Korea
| | - Myungil You
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Republic of Korea
| | - Hye-Mi So
- Department of Nano Mechanics, Korea Institute of Machinery & Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, Republic of Korea
| | - Junkyu Han
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Republic of Korea
| | - Junghyo Nah
- Department of Electrical Engineering, Chungnam University, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Jae Hun Seol
- School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Republic of Korea.
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23
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Abstract
Spider major ampullate silk is often schematically represented as a two-phase material composed of crystalline nanodomains in an amorphous matrix. Here we are interested in revealing its more complex nanoscale organization by probing Argiope bruennichi dragline-type fibers using scanning X-ray nanodiffraction. This allows resolving transversal structural features such as an about 1 μm skin layer composed of around 100 nm diameter nanofibrils serving presumably as an elastic sheath. The core consists of a composite of several nm size crystalline nanodomains with poly(l-alanine) microstructure, embedded in a polypeptide network with short-range order. Stacks of nanodomains separated by less ordered nanosegments form nanofibrils with a periodic axial density modulation which is particularly sensitive to radiation damage. The precipitation of larger β-type nanocrystallites in the outer core-shell is attributed to MaSp1 protein molecules.
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Affiliation(s)
- Christian Riekel
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Manfred Burghammer
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France.,Department of Analytical Chemistry, Ghent University , Krijgslaan 281, S12B-9000 Ghent, Belgium
| | - Thomas G Dane
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Claudio Ferrero
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Martin Rosenthal
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
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24
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Andersson M, Johansson J, Rising A. Silk Spinning in Silkworms and Spiders. Int J Mol Sci 2016; 17:E1290. [PMID: 27517908 DOI: 10.3390/ijms17081290] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/31/2016] [Accepted: 08/02/2016] [Indexed: 01/08/2023] Open
Abstract
Spiders and silkworms spin silks that outcompete the toughness of all natural and manmade fibers. Herein, we compare and contrast the spinning of silk in silkworms and spiders, with the aim of identifying features that are important for fiber formation. Although spiders and silkworms are very distantly related, some features of spinning silk seem to be universal. Both spiders and silkworms produce large silk proteins that are highly repetitive and extremely soluble at high pH, likely due to the globular terminal domains that flank an intermediate repetitive region. The silk proteins are produced and stored at a very high concentration in glands, and then transported along a narrowing tube in which they change conformation in response primarily to a pH gradient generated by carbonic anhydrase and proton pumps, as well as to ions and shear forces. The silk proteins thereby convert from random coil and alpha helical soluble conformations to beta sheet fibers. We suggest that factors that need to be optimized for successful production of artificial silk proteins capable of forming tough fibers include protein solubility, pH sensitivity, and preservation of natively folded proteins throughout the purification and initial spinning processes.
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25
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Lai WL, Goh KL. Consequences of Ultra-Violet Irradiation on the Mechanical Properties of Spider Silk. J Funct Biomater 2015; 6:901-16. [PMID: 26378587 PMCID: PMC4598684 DOI: 10.3390/jfb6030901] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 08/23/2015] [Accepted: 09/02/2015] [Indexed: 11/26/2022] Open
Abstract
The outstanding combination of high tensile strength and extensibility of spider silk is believed to contribute to the material’s toughness. Thus, there is great interest in engineering silk for biomedical products such as suture or implants. Additionally, over the years, many studies have also sought to enhance the mechanical properties of spider silk for wider applicability, e.g., by irradiating the material using ultra-violet radiation. However, the limitations surrounding the use of ultra-violet radiation for enhancing the mechanical properties of spider silk are not well-understood. Here, we have analyzed the mechanical properties of spider silk at short ultra-violet irradiation duration. Specimens of spider silk were subjected to ultra-violet irradiation (254-nm wavelength, i.e. UVC) for 10, 20, and 30 min, respectively, followed by tensile test to rupture to determine the strength (maximum stress), extensibility (rupture strain), and toughness (strain energy density to rupture). Controls, i.e., specimens that did not received UVC, were also subjected to tensile test to rupture to determine the respective mechanical properties. One-way analysis of variance reveals that these properties decrease significantly (p < 0.05) with increasing irradiation duration. Among the three mechanical parameters, the strength of the spider silk degrades most rapidly; the extensibility of the spider silk degrades the slowest. Overall, these changes correspond to the observed surface modifications as well as the bond rupture between the peptide chains of the treated silk. Altogether, this simple but comprehensive study provides some key insights into the dependence of the mechanical properties on ultra-violet irradiation duration.
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Affiliation(s)
- Wee Loong Lai
- School of Engineering, Monash University Malaysia, Bandar Sunway 46150, Malaysia.
| | - Kheng Lim Goh
- School of Engineering, Monash University Malaysia, Bandar Sunway 46150, Malaysia.
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26
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27
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Rising A. Controlled assembly: a prerequisite for the use of recombinant spider silk in regenerative medicine? Acta Biomater 2014; 10:1627-31. [PMID: 24090990 DOI: 10.1016/j.actbio.2013.09.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/13/2013] [Accepted: 09/24/2013] [Indexed: 11/29/2022]
Abstract
Recent biotechnological progress has enabled the production of spider silk proteins, spidroins, in heterologous hosts. Matrices based on recombinant spidroins support stem cell growth and are well tolerated when implanted in living tissue, thus the material is highly attractive for use in regenerative medicine. However, the matrices made are far from natural silk in terms of mechanical properties and are either spontaneously assembled, which results in heterogeneous products, or spun from harsh solvents with the concomitant risk of harmful remnants in the final products. If we could mimic the spider's aqueous silk spinning process we would likely obtain a material that had reproducible and better characteristics and that more easily could be transferred to clinical practice. Herein, the knowledge of the spiders' silk production system and the prerequisites for artificial spinning and assembly of recombinant proteins are reviewed and discussed in a biomedical context.
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Affiliation(s)
- Anna Rising
- KI-Alzheimer Disease Research Center, NVS (Neurobiology, Care Sciences, and Society) Department, Karolinska Institutet, 141 86 Stockholm, Sweden; Department of Anatomy Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, Box 575, 751 23 Uppsala, Sweden.
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28
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Schniepp HC, Koebley SR, Vollrath F. Brown recluse spider's nanometer scale ribbons of stiff extensible silk. Adv Mater 2013; 25:7028-7032. [PMID: 24352987 DOI: 10.1002/adma.201302740] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/12/2013] [Indexed: 06/03/2023]
Abstract
The silk of the recluse spider features a ribbon-like morphology unlike any other spider silk or synthetically spun polymer fiber. These protein ribbons represent free-standing polymer films with a thickness of about 50 nm. Stress-strain characterization of individual fibers via atomic force microscopy reveals that these ribbons, only a few molecular layers of protein thin, rival the mechanical performance of the best silks.
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Affiliation(s)
- Hannes C Schniepp
- Department of Applied Science, The College of William & Mary, PO Box 8795, Williamsburg, VA, 23187, USA
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Cranford SW, Pugno NM, Buehler MJ. Silk and Web Synergy: The Merging of Material and Structural Performance. In: Asakura T, Miller T, editors. Biotechnology of Silk. Dordrecht: Springer Netherlands; 2014. pp. 219-68. [DOI: 10.1007/978-94-007-7119-2_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Andersson M, Holm L, Ridderstråle Y, Johansson J, Rising A. Morphology and composition of the spider major ampullate gland and dragline silk. Biomacromolecules 2013; 14:2945-52. [PMID: 23837699 DOI: 10.1021/bm400898t] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Spider silk is made of unique proteins-spidroins-secreted and stored as a protein solution (dope) in specialized glands. The major ampullate gland, source of the dragline silk, is composed of a tail, a sac and an elongated duct. For this gland, several different types of epithelial cells and granules have been described, but it is largely unknown how they correlate with spidroin production. It is also not settled what parts of the large spidroins end up in the final silk, and it has been suggested that the N-terminal domain (NT) is lacking. Here we show that NT is present in the dope and throughout dragline silk fibers, including the skin layer, and that the major ampullate tail and sac consist of three different and sharply demarcated zones (A-C), each with a distinct epithelial cell type. Finally, we show that spidroins are produced in the A and B zone epithelia, while the C zone granules lack spidroins.
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Affiliation(s)
- Marlene Andersson
- Department of Anatomy, Physiology, and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, Uppsala, Sweden
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31
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Abstract
Can naturally arising disorder in biological materials be beneficial? Materials scientists are continuously attempting to replicate the exemplary performance of materials such as spider silk, with detailed techniques and assembly procedures. At the same time, a spider does not precisely machine silk-imaging indicates that its fibrils are heterogeneous and irregular in cross section. While past investigations either focused on the building material (e.g. the molecular scale protein sequence and behaviour) or on the ultimate structural component (e.g. silk threads and spider webs), the bundled structure of fibrils that compose spider threads has been frequently overlooked. Herein, I exploit a molecular dynamics-based coarse-grain model to construct a fully three-dimensional fibril bundle, with a length on the order of micrometres. I probe the mechanical behaviour of bundled silk fibrils with variable density of heterogenic protrusions or globules, ranging from ideally homogeneous to a saturated distribution. Subject to stretching, the model indicates that cooperativity is enhanced by contact through low-force deformation and shear 'locking' between globules, increasing shear stress transfer by up to 200 per cent. In effect, introduction of a random and disordered structure can serve to improve mechanical performance. Moreover, addition of globules allows a tuning of free volume, and thus the wettability of silk (with implications for supercontraction). These findings support the ability of silk to maintain near-molecular-level strength at the scale of silk threads, and the mechanism could be easily adopted as a strategy for synthetic fibres.
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Affiliation(s)
- Steven W Cranford
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.
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Brown CP, Harnagea C, Gill HS, Price AJ, Traversa E, Licoccia S, Rosei F. Rough fibrils provide a toughening mechanism in biological fibers. ACS Nano 2012; 6:1961-1969. [PMID: 22324287 DOI: 10.1021/nn300130q] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Spider silk is a fascinating natural composite material. Its combination of strength and toughness is unrivalled in nature, and as a result, it has gained considerable interest from the medical, physics, and materials communities. Most of this attention has focused on the one to tens of nanometer scale: predominantly the primary (peptide sequences) and secondary (β sheets, helices, and amorphous domains) structure, with some insights into tertiary structure (the arrangement of these secondary structures) to describe the origins of the mechanical and biological performance. Starting with spider silk, and relating our findings to collagen fibrils, we describe toughening mechanisms at the hundreds of nanometer scale, namely, the fibril morphology and its consequences for mechanical behavior and the dissipation of energy. Under normal conditions, this morphology creates a nonslip fibril kinematics, restricting shearing between fibrils, yet allowing controlled local slipping under high shear stress, dissipating energy without bulk fracturing. This mechanism provides a relatively simple target for biomimicry and, thus, can potentially be used to increase fracture resistance in synthetic materials.
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Affiliation(s)
- Cameron P Brown
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
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Huang X, Liu G, Wang X. New secrets of spider silk: exceptionally high thermal conductivity and its abnormal change under stretching. Adv Mater 2012; 24:1482-6. [PMID: 22388863 DOI: 10.1002/adma.201104668] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Indexed: 05/05/2023]
Abstract
Two new significant discoveries are reported: i) the dragline silk of N. clavipes spider has an exceptionally high thermal conductivity: up to 416 W/m·K that beats most materials; ii) contrary to normal materials, its thermal conductivity increases with strain (19% increase under ∼20% strain). These new findings will revolutionize the design of polymer fibers to increase their thermal conductivity by orders of magnitude.
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Affiliation(s)
- Xiaopeng Huang
- Department of Mechanical Engineering, Iowa State University, Ames, 50011, USA
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34
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Giesa T, Arslan M, Pugno NM, Buehler MJ. Nanoconfinement of spider silk fibrils begets superior strength, extensibility, and toughness. Nano Lett 2011; 11:5038-5046. [PMID: 21967633 DOI: 10.1021/nl203108t] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Silk is an exceptionally strong, extensible, and tough material made from simple protein building blocks. The molecular structure of dragline spider silk repeat units consists of semiamorphous and nanocrystalline β-sheet protein domains. Here we show by a series of computational experiments how the nanoscale properties of silk repeat units are scaled up to create macroscopic silk fibers with outstanding mechanical properties despite the presence of cavities, tears, and cracks. We demonstrate that the geometric confinement of silk fibrils to diameters of 50 ± 30 nm is critical to facilitate a powerful mechanism by which hundreds of thousands of protein domains synergistically resist deformation and failure to provide enhanced strength, extensibility, and toughness at the macroscale, closely matching experimentally measured mechanical properties. Through this mechanism silk fibers exploit the full potential of the nanoscale building blocks, regardless of the details of microscopic loading conditions and despite the presence of large defects. Experimental results confirm that silk fibers are composed of silk fibril bundles with diameters in the range of 20-150 nm, in agreement with our predicted length scale. Our study reveals a general mechanism to map nanoscale properties to the macroscale and provides a potent design strategy toward novel fiber and bulk nanomaterials through hierarchical structures.
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Affiliation(s)
- Tristan Giesa
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-235A&B, Cambridge, Massachusetts 02139, United States
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35
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Abstract
Cocoons of Theridiosoma gemmosum consist of two main parts, the egg sac case and the stalk. The inner space of the egg sac case is filled with nonsticky flocculent silk. Measuring 600-800 nm in diameter, the flocculent threads are never made up of bundles of longitudinally oriented nanofibrils. The egg case wall consists of a lower layer of highly ordered threads and an upper layer of cover silk. The lower, permanently white layer consists of threads in a mesh-like arrangement, the thicker threads being 4-6 microm and the thinner threads being 2-3 microm in diameter. Each thread is a bundle of parallel nanofibrils, with a diameter between 150 and 300 nm. The silk secretions of these fibers, emitted from spigots, are processed by legs. The upper layer of the egg case is applied to the threads of the lower layer by direct rubbing against its surface, i.e. without the use of legs. In the lower and middle part of the egg case, the accumulated secretion forms a virtually compact encrustation, whereas in the upper, conically shaped, part of the egg case where it becomes the stalk, this secretion becomes substantially scarcer. The stalk is a continuation of the egg case, its proximal part made of fibers similar to those forming the inner layer of the egg case wall. The distal part of the stalk continues towards the suspension area either as a compact bundle of parallel fibers, or the stalk forks into two bundles of roughly the same thickness, which continue towards the suspension area separately. On the surface of objects onto which cocoons are attached, the secretion of the piriform glands acts as an adhesive sheet.
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Affiliation(s)
- Jaromír Hajer
- Department of Biology, J.E. Purkinje University in Ustí nad Labem, Czech Republic.
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Affiliation(s)
- Zhongbing Huang
- College of Material Sciences and Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China
| | - Xiaoming Liao
- College of Material Sciences and Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China
| | - Guangfu Yin
- College of Material Sciences and Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China
| | - Yunqing Kang
- College of Material Sciences and Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China
| | - Yadong Yao
- College of Material Sciences and Engineering, Sichuan University, Chengdu, 610065, People’s Republic of China
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Pérez-rigueiro J, Biancotto L, Corsini P, Marsano E, Elices M, Plaza G, Guinea G. Supramolecular organization of regenerated silkworm silk fibers. Int J Biol Macromol 2009; 44:195-202. [DOI: 10.1016/j.ijbiomac.2008.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 10/13/2008] [Accepted: 12/09/2008] [Indexed: 11/21/2022]
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Sponner A, Vater W, Monajembashi S, Unger E, Grosse F, Weisshart K. Composition and hierarchical organisation of a spider silk. PLoS One 2007; 2:e998. [PMID: 17912375 PMCID: PMC1994588 DOI: 10.1371/journal.pone.0000998] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 09/11/2007] [Indexed: 11/19/2022] Open
Abstract
Albeit silks are fairly well understood on a molecular level, their hierarchical organisation and the full complexity of constituents in the spun fibre remain poorly defined. Here we link morphological defined structural elements in dragline silk of Nephila clavipes to their biochemical composition and physicochemical properties. Five layers of different make-ups could be distinguished. Of these only the two core layers contained the known silk proteins, but all can vitally contribute to the mechanical performance or properties of the silk fibre. Understanding the composite nature of silk and its supra-molecular organisation will open avenues in the production of high performance fibres based on artificially spun silk material.
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Affiliation(s)
- Alexander Sponner
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
| | - Wolfram Vater
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
| | | | - Eberhard Unger
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
| | - Frank Grosse
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
| | - Klaus Weisshart
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
- * To whom correspondence should be addressed. E-mail:
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39
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Abstract
It appears that fiber-forming proteins are not an exclusive group but that, with appropriate conditions, many proteins can potentially aggregate and form fibrils; though only certain proteins, for example, amyloids and silks, do so under normal physiological conditions. Even so, this suggests a ubiquitous aggregation mechanism in which the protein environment is at least as important as the sequence. An ideal model system in which forced and natural aggregation has been observed is silk. Silks have evolved specifically to readily form insoluble ordered structures with a wide range of structural functionality. The animal, be it silkworm or spider, will produce, store, and transport high molecular weight proteins in a complex environment to eventually allow formation of silk fibers with a variety of mechanical properties. Here we review fiber formation and its prerequisites, and discuss the mechanism by which the animal facilitates and modulates silk assembly to achieve controlled protein aggregation.
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Affiliation(s)
- Cedric Dicko
- Zoology Department, Oxford University, OX1 3PS, United Kingdom
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40
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Sponner A, Unger E, Grosse F, Weisshart K. Differential polymerization of the two main protein components of dragline silk during fibre spinning. Nat Mater 2005; 4:772-5. [PMID: 16184170 DOI: 10.1038/nmat1493] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Accepted: 08/10/2005] [Indexed: 05/04/2023]
Abstract
Spider silks are some of the strongest materials found in nature. Achieving the high tensile strength and elasticity of the dragline of orb-weaving spiders, such as Nephila clavipes, is a principal goal in biomimetics research. The dragline has a composite nature and is predominantly made up by two proteins, the major ampullate spidroins 1 and 2 (refs 3, 6, 7), which can be considered natural block copolymers. On the basis of their molecular structures both spidroins are thought to contribute, in different ways, to the mechanical properties of dragline silk. The spinning process itself is also considered important for determining the observed features by shaping the hierarchical structure of the fibre. Here we study the heterogeneous distribution of proteins along the radial axis of the fibre. This heterogeneity is generated during the conversion of the liquid spinning dope into solid fibre. Whereas spidroin 1 is distributed almost uniformly within the fibre core, spidroin 2 is missing in the periphery and is tightly packed in certain core areas. Our findings suggest that the role of spidroin 2 in the spinning process could be to facilitate the formation of fibrils and contribute directly to the elasticity of the silk.
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Affiliation(s)
- Alexander Sponner
- Institute for Molecular Biotechnology, Jena, Federal Republic of Germany
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41
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Chang JC, Fletcher MJ, Gurr GM, Kent DS, Gilbert RG. A new silk: Mechanical, compositional, and morphological characterization of leafhopper (Kahaono montana) silk. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.06.077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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42
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Becker N, Oroudjev E, Mutz S, Cleveland JP, Hansma PK, Hayashi CY, Makarov DE, Hansma HG. Molecular nanosprings in spider capture-silk threads. Nat Mater 2003; 2:278-283. [PMID: 12690403 DOI: 10.1038/nmat858] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2002] [Accepted: 02/18/2003] [Indexed: 05/24/2023]
Abstract
Spider capture silk is a natural material that outperforms almost any synthetic material in its combination of strength and elasticity. The structure of this remarkable material is still largely unknown, because spider-silk proteins have not been crystallized. Capture silk is the sticky spiral in the webs of orb-weaving spiders. Here we are investigating specifically the capture spiral threads from Araneus, an ecribellate orb-weaving spider. The major protein of these threads is flagelliform protein, a variety of silk fibroin. We present models for molecular and supramolecular structures of flagelliform protein, derived from amino acid sequences, force spectroscopy (molecular pulling) and stretching of bulk capture web. Pulling on molecules in capture-silk fibres from Araneus has revealed rupture peaks due to sacrificial bonds, characteristic of other self-healing biomaterials. The overall force changes are exponential for both capture-silk molecules and intact strands of capture silk.
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Affiliation(s)
- Nathan Becker
- Department of Physics, University of California, Santa Barbara, California 93106, USA
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43
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Abstract
Liquid crystal spinning appears to be widespread in the animal kingdom, utilizing protein dopes to give materials with a range of different secondary structures including beta-pleat, alpha-helix and collagen-fold. Here we seek to identify the essential design features used in natural liquid crystal spinning by comparing the spinning of two very different materials: the egg case wall of Selachians (dogfish, rays, and their allies) and the dragline silk of orb web spiders. The fish extrudes a "sea and island" composite in which the islands consist of flat ribbons of carefully orientated collagen and the sea, small quantities of an amorphous matrix. Dragline silk filaments are largely constructed from spidroin, a beta protein and have a skin and core structure together with two to three coats. The essential design features common to both systems appear to be the following: (i) intracellular co-storage of a hexagonal columnar liquid crystalline component and a peroxidase within the same secretory vesicles; (ii) luminal storage of a highly concentrated liquid crystalline dope; (iii) use of a dope containing immiscible droplets; (iv) hyperbolic extrusion dies; (v) control of pH and water content of the dope; (vi) preorientation of dope molecules before assembly into fibrils; (vii) combination of extrusion die, treatment/coating bath, and solvent recovery plant within a single microminiaturized device; (viii) slow natural spinning rates. The most important difference is that spiders produce a tough material by unfolding and hydrogen-bonding their silk dope molecules while Selachian fish do it by covalently cross-linking the molecules without unfolding them.
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Affiliation(s)
- D P Knight
- Department of Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, UK
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44
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Abstract
Silk production in the spider occurs within specialized glands that are capable of the synthesis of large fibrous proteins and the post-translational processing of those proteins to form an insoluble fiber. The major ampullate gland of Latrodectus hesperus (black widow) is similar in morphology to those found in the Araneid spiders. The tail domain of this gland is highly protein synthetic, giving rise to a core, fibrous protein product. In addition to a storage function, the ampulla region also synthesizes and exports an electron dense material that appears to form a 'coat' surrounding the silk generated within the tail. The duct of the gland consists of at least two distinct cell types: one type contains 'honeycomb' vesicles of unknown function, while the other possesses elaborate apical microvilli that may be involved in the reabsorption of water and subsequent dehydration of the silk. As the silk product transits through these various stages of assembly, it can been seen to undergo a condensation or concentration, possibly reflecting the influence of both the shear forces induced by movement into the duct and the dehydration that is thought to occur there.
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Affiliation(s)
- Merri Lynn Casem
- Department of Biological Science, California State University, 92834-6850, Fullerton, CA, USA.
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Affiliation(s)
- Frische
- Department of Zoology, Institute of Biology,
| | - Maunsbach
- Department of Cell Biology, Institute of Anatomy, University of Aarhus, DK‐8000 Aarhus C, Denmark
| | - Vollrath
- Department of Zoology, Institute of Biology,
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46
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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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48
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Abstract
Silks are protein fibers with remarkable mechanical properties. The discovery of the structural features that govern these properties is a challenge for biochemistry and structural biology. This review summarizes the results of the biochemistry of silk proteins as well as the knowledge of the molecular biology of the respective genes. In addition, an overview is presented on the efforts to produce recombinant silk proteins by biotechnological techniques.
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Affiliation(s)
- K H Gührs
- Abteilung Biochemie, Institut für Molekulare Biotechnologie e. V., PF 100 813, D-07708 Jena, Germany.
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Abstract
Spider silks are composite materials with often complex microstructures. They are spun from liquid crystalline dope using a complicated spinning mechanism which gives the animal considerable control. The material properties of finished silk are modified by the effects of water and other solvents, and spiders make use of this to produce fibres with specific qualities. The surprising sophistication of spider silks and spinning technologies makes it imperative for us to understand both material and manufacturing in nature before embarking on the commercialization of biotechnologically modified silk dope.
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50
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