1
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Agostinacchio F, Fitzpatrick V, Dirè S, Kaplan DL, Motta A. Silk fibroin-based inks for in situ 3D printing using a double crosslinking process. Bioact Mater 2024; 35:122-134. [PMID: 38312518 PMCID: PMC10837071 DOI: 10.1016/j.bioactmat.2024.01.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 01/16/2024] [Accepted: 01/16/2024] [Indexed: 02/06/2024] Open
Abstract
The shortage of tissues and organs for transplantation is an urgent clinical concern. In situ 3D printing is an advanced 3D printing technique aimed at printing the new tissue or organ directly in the patient. The ink for this process is central to the outcomes, and must meet specific requirements such as rapid gelation, shape integrity, stability over time, and adhesion to surrounding healthy tissues. Among natural materials, silk fibroin exhibits fascinating properties that have made it widely studied in tissue engineering and regenerative medicine. However, further improvements in silk fibroin inks are needed to match the requirements for in situ 3D printing. In the present study, silk fibroin-based inks were developed for in situ applications by exploiting covalent crosslinking process consisting of a pre-photo-crosslinking prior to printing and in situ enzymatic crosslinking. Two different silk fibroin molecular weights were characterized and the synergistic effect of the covalent bonds with shear forces enhanced the shift in silk secondary structure toward β-sheets, thus, rapid stabilization. These hydrogels exhibited good mechanical properties, stability over time, and resistance to enzymatic degradation over 14 days, with no significant changes over time in their secondary structure and swelling behavior. Additionally, adhesion to tissues in vitro was demonstrated.
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Affiliation(s)
- Francesca Agostinacchio
- National Interuniversity Consortium of Material Science and Technology, Florence, Italy
- BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Department of Industrial Engineering, University of Trento, Trento, Italy
| | - Vincent Fitzpatrick
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Sandra Dirè
- Materials Chemistry Group & “Klaus Müller” Magnetic Resonance Laboratory, Department of Industrial Engineering, University of Trento, Trento, Italy
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Antonella Motta
- BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Department of Industrial Engineering, University of Trento, Trento, Italy
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2
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Suzuki Y, Morie S, Okamura H, Asakura T, Naito A. Real-Time Monitoring of the Structural Transition of Bombyx mori Liquid Silk under Pressure by Solid-State NMR. J Am Chem Soc 2023; 145:22925-22933. [PMID: 37828719 DOI: 10.1021/jacs.3c04361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Silk fibroin is stored in the silk glands of Bombyx mori silkworms as a condensed aqueous solution called liquid silk. It is converted into silk fibers at the silkworm's spinnerets under mechanical forces including shear stress and pressure. However, the detailed mechanism of the structural transition of liquid silk to silk fibers under pressure is not well understood. Magic angle spinning (MAS) in solid-state nuclear magnetic resonance (NMR) can exert pressure on liquid samples in a quantitative manner. In this study, solid-state NMR was used to quantitatively analyze the impact of pressure on the structural transition of liquid silk. A combination of 13C DD-MAS and CP-MAS NMR measurements enabled the conformation and dynamics of the crystalline region of the silk fibroin (both before (Silk Ip) and after (Silk IIp) the structural transition) to be detected in real time with atomic resolution. Spectral analyses proposed that the pressure-induced structural transition from Silk Ip to Silk IIp proceeds by a two-step autocatalytic reaction mechanism. The first reaction step is a nucleation step in which Silk Ip transforms to single lamellar Silk IIp, and the second is a growth step in which the single lamellar Silk IIp acts as a catalyst that reacts with Silk Ip molecules to further form Silk IIp molecules, resulting in stacked lamellar Silk IIp. Furthermore, the rate constant in the second step shows a significant pressure dependence, with an increase in pressure accelerating the formation of large stacked lamellar Silk IIp.
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Affiliation(s)
- Yu Suzuki
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1, Bunkyo, Fukui-shi, Fukui 9108507, Japan
| | - Shota Morie
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1, Bunkyo, Fukui-shi, Fukui 9108507, Japan
| | - Hideyasu Okamura
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui, 3-9-1, Bunkyo, Fukui-shi, Fukui 9108507, Japan
| | - Tetsuo Asakura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei, Tokyo 184-8588, Japan
| | - Akira Naito
- Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16, Nakacho, Koganei, Tokyo 184-8588, Japan
- Graduate School of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501, Japan
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3
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Perera D, Li L, Walsh C, Silliman J, Xiong Y, Wang Q, Schniepp HC. Natural spider silk nanofibrils produced by assembling molecules or disassembling fibers. Acta Biomater 2023; 168:323-332. [PMID: 37414111 DOI: 10.1016/j.actbio.2023.06.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 06/25/2023] [Accepted: 06/28/2023] [Indexed: 07/08/2023]
Abstract
Spider silk is biocompatible, biodegradable, and rivals some of the best synthetic materials in terms of strength and toughness. Despite extensive research, comprehensive experimental evidence of the formation and morphology of its internal structure is still limited and controversially discussed. Here, we report the complete mechanical decomposition of natural silk fibers from the golden silk orb-weaver Trichonephila clavipes into ≈10 nm-diameter nanofibrils, the material's apparent fundamental building blocks. Furthermore, we produced nanofibrils of virtually identical morphology by triggering an intrinsic self-assembly mechanism of the silk proteins. Independent physico-chemical fibrillation triggers were revealed, enabling fiber assembly from stored precursors "at-will". This knowledge furthers the understanding of this exceptional material's fundamentals, and ultimately, leads toward the realization of silk-based high-performance materials. STATEMENT OF SIGNIFICANCE: Spider silk is one of the strongest and toughest biomaterials, rivaling the best man-made materials. The origins of these traits are still under debate but are mostly attributed to the material's intriguing hierarchical structure. Here we fully disassembled spider silk into 10 nm-diameter nanofibrils for the first time and showed that nanofibrils of the same appearance can be produced via molecular self-assembly of spider silk proteins under certain conditions. This shows that nanofibrils are the key structural elements in silk and leads toward the production of high-performance future materials inspired by spider silk.
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Affiliation(s)
- Dinidu Perera
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Linxuan Li
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Chloe Walsh
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Jacob Silliman
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Yawei Xiong
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Qijue Wang
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA
| | - Hannes C Schniepp
- Applied Science Department, William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA.
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4
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Yang S, Zhao C, Yang Y, Ren J, Ling S. The Fractal Network Structure of Silk Fibroin Molecules and Its Effect on Spinning of Silkworm Silk. ACS NANO 2023; 17:7662-7673. [PMID: 37042465 DOI: 10.1021/acsnano.3c00105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Animal silk is usually considered to exist as a solid fiber with a highly ordered structure, formed by the hierarchical assembly starting from a single silk fibroin (SF) chain. However, this study showed that silk protein molecules existed in the form of a fractal network structure in aqueous solution, rather than as a single chain. This type of network was relatively rigid with low fractal dimension. Finite element analysis revealed that this network structure significantly helped in the stable storage of SF prior to the spinning process and in the rapid formation of a β-sheeted nanocrystalline and nematic texture during spinning. Further, the strong but brittle mechanical properties of Bombyx mori silk could also be well-explained through the fractal network model of silk fibroin. The strength was mainly derived from the dual network structure, consisting of nodes and β-sheet cross-links, whereas the brittleness could be attributed to the rigidity of the SF chains between these nodes and cross-links. In summary, this study presents insights from network topology for understanding the spinning process of natural silk and the structure-property relationship in silk materials.
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Affiliation(s)
- Shuo Yang
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Chenxi Zhao
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Yunhao Yang
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Jing Ren
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Shengjie Ling
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
- Shanghai Clinical Research and Trial Center, Shanghai 201210, People's Republic of China
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5
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Kamada A, Toprakcioglu Z, Knowles TPJ. Kinetic Analysis Reveals the Role of Secondary Nucleation in Regenerated Silk Fibroin Self-Assembly. Biomacromolecules 2023; 24:1709-1716. [PMID: 36926854 PMCID: PMC10091410 DOI: 10.1021/acs.biomac.2c01479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Silk proteins obtained from the Bombyx mori silkworm have been extensively studied due to their remarkable mechanical properties. One of the major structural components of this complex material is silk fibroin, which can be isolated and processed further in vitro to form artificial functional materials. Due to the excellent biocompatibility and rich self-assembly behavior, there has been sustained interest in such materials formed through the assembly of regenerated silk fibroin feedstocks. The molecular mechanisms by which the soluble regenerated fibroin molecules self-assemble into protein nanofibrils remain, however, largely unknown. Here, we use the framework of chemical kinetics to connect macroscopic measurements of regenerated silk fibroin self-assembly to the underlying microscopic mechanisms. Our results reveal that the aggregation of regenerated silk fibroin is dominated by a nonclassical secondary nucleation processes, where the formation of new fibrils is catalyzed by the existing aggregates in an autocatalytic manner. Such secondary nucleation pathways were originally discovered in the context of polymerization of disease-associated proteins, but the present results demonstrate that this pathway can also occur in functional assembly. Furthermore, our results show that shear flow induces the formation of nuclei, which subsequently accelerate the process of aggregation through an autocatalytic amplification driven by the secondary nucleation pathway. Taken together, these results allow us to identify the parameters governing the kinetics of regenerated silk fibroin self-assembly and expand our current understanding of the spinning of bioinspired protein-based fibers, which have a wide range of applications in materials science.
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Affiliation(s)
- Ayaka Kamada
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Zenon Toprakcioglu
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.,Cavendish Laboratory, University of Cambridge, Cambridge CB3 0FE, U.K
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6
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Chatterley AS, Laity P, Holland C, Weidner T, Woutersen S, Giubertoni G. Broadband Multidimensional Spectroscopy Identifies the Amide II Vibrations in Silkworm Films. Molecules 2022; 27:molecules27196275. [PMID: 36234809 PMCID: PMC9571984 DOI: 10.3390/molecules27196275] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/19/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
We used two-dimensional infrared spectroscopy to disentangle the broad infrared band in the amide II vibrational regions of Bombyx mori native silk films, identifying the single amide II modes and correlating them to specific secondary structure. Amide I and amide II modes have a strong vibrational coupling, which manifests as cross-peaks in 2D infrared spectra with frequencies determined by both the amide I and amide II frequencies of the same secondary structure. By cross referencing with well-known amide I assignments, we determined that the amide II (N-H) absorbs at around 1552 and at 1530 cm–1 for helical and β-sheet structures, respectively. We also observed a peak at 1517 cm−1 that could not be easily assigned to an amide II mode, and instead we tentatively assigned it to a Tyrosine sidechain. These results stand in contrast with previous findings from linear infrared spectroscopy, highlighting the ability of multidimensional spectroscopy for untangling convoluted spectra, and suggesting the need for caution when assigning silk amide II spectra.
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Affiliation(s)
| | - Peter Laity
- Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK
| | - Chris Holland
- Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
| | - Sander Woutersen
- Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Giulia Giubertoni
- Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
- Correspondence:
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7
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Qu J, Feng P, Zhu Q, Ren Y, Li B. Study on the Effect of Stretching on the Strength of Natural Silk Based on Different Feeding Methods. ACS Biomater Sci Eng 2021; 8:100-108. [PMID: 34918508 DOI: 10.1021/acsbiomaterials.1c01256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Silk is an important biological protein fiber, which has been widely developed and used in textile and biomedical fields due to its excellent mechanical properties and good biocompatibility. Strength is an important indicator that determines the value and use of silk. Although investigations have been made on the mechanical properties of silkworm silks and their dependence relationship with the microstructures, the variation of silk strength formed in the process of silkworm spinning has not been reported. By feeding the same strain of silkworms with mulberry leaves, mulberry leaves + artificial feed, and artificial feed, silks with three filament sizes were obtained, respectively. The tensile test results showed that the strength and filament size of silk are inversely proportional. The structure and fibrosis process of different-strength silks were analyzed. The results showed that, compared with ordinary silk, the β-sheet and crystallinity content of high-strength silk is higher, indicating that its fibrosis process is more sufficient. We proposed that the stretched degree of silk protein determines its structure and properties. During the spinning process of individual silkworms, the secretion of silk protein is not stable, which will cause changes in the stretched degree. The measurement results of the intraindividual stretched degree and strength verified that the degree of stretch determines the strength of the silk. This study not only provides a deeper understanding of the properties of silk protein but also is of interest for the design and development of advanced biomimetic silk materials.
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Affiliation(s)
- Jianwei Qu
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Piao Feng
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Qingyu Zhu
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Yuying Ren
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, Jiangsu 215123, P. R. China
| | - Bing Li
- School of Basic Medicine and Biological Sciences, Soochow University, Suzhou, Jiangsu 215123, P. R. China.,Sericulture Institute of Soochow University, Suzhou, Jiangsu 215123, P. R. China
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8
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Schaefer C, Laity PR, Holland C, McLeish TCB. Stretching of Bombyx mori Silk Protein in Flow. Molecules 2021; 26:molecules26061663. [PMID: 33809814 PMCID: PMC8002474 DOI: 10.3390/molecules26061663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/05/2021] [Accepted: 03/11/2021] [Indexed: 12/31/2022] Open
Abstract
The flow-induced self-assembly of entangled Bombyx mori silk proteins is hypothesised to be aided by the ‘registration’ of aligned protein chains using intermolecularly interacting ‘sticky’ patches. This suggests that upon chain alignment, a hierarchical network forms that collectively stretches and induces nucleation in a precisely controlled way. Through the lens of polymer physics, we argue that if all chains would stretch to a similar extent, a clear correlation length of the stickers in the direction of the flow emerges, which may indeed favour such a registration effect. Through simulations in both extensional flow and shear, we show that there is, on the other hand, a very broad distribution of protein–chain stretch, which suggests the registration of proteins is not directly coupled to the applied strain, but may be a slow statistical process. This qualitative prediction seems to be consistent with the large strains (i.e., at long time scales) required to induce gelation in our rheological measurements under constant shear. We discuss our perspective of how the flow-induced self-assembly of silk may be addressed by new experiments and model development.
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Affiliation(s)
- Charley Schaefer
- Department of Physics, University of York, Heslington, York YO10 5DD, UK;
- Correspondence:
| | - Peter R. Laity
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK; (P.R.L.); (C.H.)
| | - Chris Holland
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK; (P.R.L.); (C.H.)
| | - Tom C. B. McLeish
- Department of Physics, University of York, Heslington, York YO10 5DD, UK;
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9
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Lassenberger A, Martel A, Porcar L, Baccile N. Interpenetrated biosurfactant-silk fibroin networks - a SANS study. SOFT MATTER 2021; 17:2302-2314. [PMID: 33480918 DOI: 10.1039/d0sm01869d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Silk fibroin (SF) based hydrogels have been exploited for years for their inherent biocompatibility and favorable mechanical properties which makes them interesting for biotechnology applications. In this study we investigate silk based composite hydrogels where pH-sensitive, anionic biosurfactant assemblies (sophorolipids SL-C18 : 1 and SL-C18 : 0), are employed to improve the present properties of SF. Results suggest that the presence of SL surfactant assemblies leads to faster gelling of SF by accelerating the refolding from random coil to β-sheet as shown by infrared and UV-visible spectroscopy. Small angle neutron scattering (SANS) including contrast matching studies show that SF and SL assemblies coexist in a fibrillary network that is, in the case of SL-C18 : 0, interpenetrating. The resulting overall network structure in composite gels is slightly more affected by SL-C18 : 1 than by SL-C18 : 0, whereas the structure of both SF and surfactant assemblies remains unchanged. No disassembly of SL surfactant structures is observed, which gives a new perspective on SF-surfactant interactions. The hydrophobic effect within SF is favored in the presence of SL, leading to faster refolding of SF into β-sheet conformation. The presented composite gels, being an interpenetrating network of which one compound (SL-C18 : 0) can be tweaked by pH, open an interesting option towards improved workability and stimuli responsive mechanical properties of SF based hydrogels with possible applications in controlled cell culture and tissue engineering or drug delivery. The presented SANS analysis approach has the potential to be expanded to other protein-surfactant systems and composite hydrogels.
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Affiliation(s)
- Andrea Lassenberger
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France.
| | - Anne Martel
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France.
| | - Lionel Porcar
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France.
| | - Niki Baccile
- Centre National de la Recherche Scientifique, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, Sorbonne Université, Paris F-75005, France.
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10
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Koeppel A, Laity PR, Holland C. The influence of metal ions on native silk rheology. Acta Biomater 2020; 117:204-212. [PMID: 33007482 DOI: 10.1016/j.actbio.2020.09.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 02/06/2023]
Abstract
Whilst flow is the basis for silk fibre formation, subtle changes in a silk feedstocks' chemical environment may serve to increase both energetic efficiency and control hierarchical structure development during spinning. Despite the role of pH being largely understood, the influence of metal ions is not, only being inferred by correlative work and observations. Through a combination of rheology and microscopy, we provide a causative study of how the most abundant metal ions in the silk feedstock, Ca2+ and K+, affect its flow properties and structure. Our results show that Ca2+ ions increase viscosity and prevent molecular alignment and aggregation, providing ideal storage conditions for unspun silk. In contrast, the addition of K+ ions promotes molecular alignment and aggregation and therefore seems to transfer the silk feedstock into a spinning state which confirms recent 'sticky reptation' modelling hypotheses. Additionally, we characterised the influence of the ubiquitous kosmotropic agent Li+, used to prepare regenerated silk solutions, and find that it promotes molecular alignment and prevents aggregation which may permit a range of interesting artificial silk processing techniques to be developed. In summary, our results provide a clearer picture of how metal ions co-ordinate, control and thus contribute towards silk protein self-assembly which in turn can inspire structuring approaches in other biopolymer systems.
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11
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Dunderdale GJ, Davidson SJ, Ryan AJ, Mykhaylyk OO. Flow-induced crystallisation of polymers from aqueous solution. Nat Commun 2020; 11:3372. [PMID: 32632091 PMCID: PMC7338548 DOI: 10.1038/s41467-020-17167-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 06/16/2020] [Indexed: 11/21/2022] Open
Abstract
Synthetic polymers are thoroughly embedded in the modern society and their consumption grows annually. Efficient routes to their production and processing have never been more important. In this respect, silk protein fibrillation is superior to conventional polymer processing, not only by achieving outstanding physical properties of materials, such as high tensile strength and toughness, but also improved process energy efficiency. Natural silk solidifies in response to flow of the liquid using conformation-dependent intermolecular interactions to desolvate (denature) protein chains. This mechanism is reproduced here by an aqueous poly(ethylene oxide) (PEO) solution, which solidifies at ambient conditions when subjected to flow. The transition requires that an energy threshold is exceeded by the flow conditions, which disrupts a protective hydration shell around polymer molecules, releasing them from a metastable state into the thermodynamically favoured crystalline state. This mechanism requires vastly lower energy inputs and demonstrates an alternative route for polymer processing.
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Affiliation(s)
- Gary J Dunderdale
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK
| | - Sarah J Davidson
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK
- Croda International Plc, Snaith, Goole, DN14 9AA, UK
| | - Anthony J Ryan
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK
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12
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Hu L, Han Y, Ling S, Huang Y, Yao J, Shao Z, Chen X. Direct Observation of Native Silk Fibroin Conformation in Silk Gland of Bombyx mori Silkworm. ACS Biomater Sci Eng 2020; 6:1874-1879. [PMID: 33455357 DOI: 10.1021/acsbiomaterials.9b01586] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To understand the natural silk spinning mechanism, synchrotron Fourier transform infrared (S-FTIR) microspectroscopy was employed in this study to monitor the conformation changes of silk protein in the silk gland of Bombyx mori silkworm. The ultrahigh brightness of S-FTIR microspectroscopy allowed the imaging of the silk gland with micrometer-scale spatial resolution. Herein, tissue sections of a silk gland, including cross-section slices and longitudinal-section slices, were characterized. The results obtained clearly confirm that the conformation of the silk fibroin changes gradually along the silk gland from the tail to the spinneret. In the middle silk gland, silk fibroin mainly contains random coil/helix conformation. When it comes to the spinneret through the anterior silk gland, the content of β-sheet increases, but the content of random coil/helix instead reduces gradually. Further, the β-sheet distribution in the cross-section of the anterior silk gland was imaged using S-FTIR mapping technique. The results show that the structural distribution of the silk fibroin in cross-section is uniform without significant shell-core structure, which implies that the primary driving force to induce the conformation transition of silk fibroin from random coil/helix to β-sheet during the spinning process is elongational flow of silk fibroin in the silk gland and not the shear force between the silk fibroin and the lumen wall of silk gland. These direct pieces of evidence of silk fibroin structure in the silk gland would definitely promote a deeper understanding of the natural spinning process.
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Affiliation(s)
- Linli Hu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Yanchen Han
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Shengjie Ling
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Yufang Huang
- Department of Material Science, Fudan University, Shanghai 200433, People's Republic of China
| | - Jinrong Yao
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, 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, 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, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China
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13
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Umuhoza D, Yang F, Long D, Hao Z, Dai J, Zhao A. Strategies for Tuning the Biodegradation of Silk Fibroin-Based Materials for Tissue Engineering Applications. ACS Biomater Sci Eng 2020; 6:1290-1310. [DOI: 10.1021/acsbiomaterials.9b01781] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Diane Umuhoza
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, People’s Republic of China
- Commercial Insect Program, Sericulture, Rwanda Agricultural Board, 5016 Kigali, Rwanda
| | - Fang Yang
- Department of Biomaterials, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Dingpei Long
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, People’s Republic of China
| | - Zhanzhang Hao
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, People’s Republic of China
| | - Jing Dai
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, People’s Republic of China
| | - Aichun Zhao
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, People’s Republic of China
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14
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Brif A, Laity P, Claeyssens F, Holland C. Dynamic Photo-cross-linking of Native Silk Enables Macroscale Patterning at a Microscale Resolution. ACS Biomater Sci Eng 2019; 6:705-714. [DOI: 10.1021/acsbiomaterials.9b00993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Anastasia Brif
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, U.K
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ, U.K
| | - Peter Laity
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, U.K
| | - Frederik Claeyssens
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, Broad Lane, Sheffield S3 7HQ, U.K
| | - Chris Holland
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, U.K
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15
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Zhong J, Liu Y, Ren J, Tang Y, Qi Z, Zhou X, Chen X, Shao Z, Chen M, Kaplan DL, Ling S. Understanding Secondary Structures of Silk Materials via Micro- and Nano-Infrared Spectroscopies. ACS Biomater Sci Eng 2019; 5:3161-3183. [PMID: 33405510 DOI: 10.1021/acsbiomaterials.9b00305] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The secondary structures (also termed conformations) of silk fibroin (SF) in animal silk fibers and regenerated SF materials are critical in determining mechanical performance and function of the materials. In order to understand the structure-mechanics-function relationships of silk materials, a variety of advanced infrared spectroscopic techniques, such as micro-infrared spectroscopies (micro-IR spectroscopies for short), synchrotron micro-IR spectroscopy, and nano-infrared spectroscopies (nano-IR spectroscopies for short), have been used to determine the conformations of SF in silk materials. These IR spectroscopic methods provide a useful toolkit to understand conformations and conformational transitions of SF in various silk materials with spatial resolution from the nano-scale to the micro-scale. In this Review, we first summarize progress in understanding the structure and structure-mechanics relationships of silk materials. We then discuss the state-of-the-art micro- and nano-IR spectroscopic techniques used for silk materials characterization. We also provide a systematic discussion of the strategies to collect high-quality spectra and the methods to analyze these spectra. Finally, we demonstrate the challenges and directions for future exploration of silk-based materials with IR spectroscopies.
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Affiliation(s)
- Jiajia Zhong
- National Facility for Protein Science in Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Yawen Liu
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Jing Ren
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
| | - Yuzhao Tang
- National Facility for Protein Science in Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Zeming Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Xiaojie Zhou
- National Facility for Protein Science in Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Xin Chen
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
| | - Zhengzhong Shao
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
| | - Min Chen
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Shengjie Ling
- School of Physical Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Shanghai 201210, China
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16
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Ng PF, Lee KI, Meng S, Zhang J, Wang Y, Fei B. Wet Spinning of Silk Fibroin-Based Core–Sheath Fibers. ACS Biomater Sci Eng 2019; 5:3119-3130. [DOI: 10.1021/acsbiomaterials.9b00275] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Pui Fai Ng
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, 11 Yuk Choi Road, Kowloon, Hong Kong, China
| | - Ka I Lee
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, 11 Yuk Choi Road, Kowloon, Hong Kong, China
| | - Shengfei Meng
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, No. 5625, Ren Min Street, Changchun 130022, China
| | - Jidong Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, No. 5625, Ren Min Street, Changchun 130022, China
| | - Yuhong Wang
- Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, 11 Yuk Choi Road, Kowloon, Hong Kong, China
| | - Bin Fei
- Institute of Textiles and Clothing, Hong Kong Polytechnic University, 11 Yuk Choi Road, Kowloon, Hong Kong, China
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17
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Koeppel A, Laity PR, Holland C. Extensional flow behaviour and spinnability of native silk. SOFT MATTER 2018; 14:8838-8845. [PMID: 30349916 DOI: 10.1039/c8sm01199k] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Silk fibres are assembled via flow. While changes in the physiological environment of the gland as well as the shear rheology of silk are largely understood, the effect of extensional flow fields on native silk proteins is almost completely unknown. Here we demonstrate that filament stretching on a conventional tensile tester is a suitable technique to assess silk's extensional flow properties and its ability to form fibres under extensional conditions characteristic of natural spinning. We report that native Bombyx mori silk responds differently to extensional flow fields when compared to synthetic linear polymers, as evidenced by a higher Trouton ratio which we attribute to silk's increased interchain interactions. Finally, we show that native silk proteins can only be spun into stable fibres at low extension rates as a result of dehydration, suggesting that extensional fields alone are unable to induce natural fibre formation.
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Affiliation(s)
- Andreas Koeppel
- Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.
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18
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Sparkes J, Holland C. The Energy Requirements for Flow‐Induced Solidification of Silk. Macromol Biosci 2018; 19:e1800229. [DOI: 10.1002/mabi.201800229] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/01/2018] [Indexed: 01/07/2023]
Affiliation(s)
- James Sparkes
- Natural Materials GroupDepartment of Materials Science and Engineering Sir Robert Hadfield Building, Mappin Street Sheffield S1 3JD UK
| | - Chris Holland
- Natural Materials GroupDepartment of Materials Science and Engineering Sir Robert Hadfield Building, Mappin Street Sheffield S1 3JD UK
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19
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Shen T, Wang T, Cheng G, Huang L, Chen L, Wu D. Dissolution behavior of silk fibroin in a low concentration CaCl2-methanol solvent: From morphology to nanostructure. Int J Biol Macromol 2018; 113:458-463. [DOI: 10.1016/j.ijbiomac.2018.02.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/01/2018] [Accepted: 02/04/2018] [Indexed: 02/03/2023]
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20
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Shimanovich U, Pinotsi D, Shimanovich K, Yu N, Bolisetty S, Adamcik J, Mezzenga R, Charmet J, Vollrath F, Gazit E, Dobson CM, Schierle GK, Holland C, Kaminski CF, Knowles TPJ. Biophotonics of Native Silk Fibrils. Macromol Biosci 2018; 18:e1700295. [PMID: 29377575 DOI: 10.1002/mabi.201700295] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/18/2017] [Indexed: 02/02/2023]
Abstract
Native silk fibroin (NSF) is a unique biomaterial with extraordinary mechanical and biochemical properties. These key characteristics are directly associated with the physical transformation of unstructured, soluble NSF into highly organized nano- and microscale fibrils rich in β-sheet content. Here, it is shown that this NSF fibrillation process is accompanied by the development of intrinsic fluorescence in the visible range, upon near-UV excitation, a phenomenon that has not been investigated in detail to date. Here, the optical and fluorescence characteristics of NSF fibrils are probed and a route for potential applications in the field of self-assembled optically active biomaterials and systems is explored. In particular, it is demonstrated that NSF can be structured into autofluorescent microcapsules with a controllable level of β-sheet content and fluorescence properties. Furthermore, a facile and efficient fabrication route that permits arbitrary patterns of NSF microcapsules to be deposited on substrates under ambient conditions is shown. The resulting fluorescent NSF patterns display a high level of photostability. These results demonstrate the potential of using native silk as a new class of biocompatible photonic material.
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Affiliation(s)
- Ulyana Shimanovich
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7600, Israel
| | - Dorothea Pinotsi
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Klimentiy Shimanovich
- The School of Electrical Engineering, University of Tel-Aviv, Tel-Aviv, 69978, Israel
| | - Na Yu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Sreenath Bolisetty
- Department of Health Science and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Jozef Adamcik
- Department of Health Science and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Raffaele Mezzenga
- Department of Health Science and Technology, ETH Zurich, 8092, Zurich, Switzerland
| | - Jerome Charmet
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Fritz Vollrath
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Ehud Gazit
- Department of Molecular Biology and Biotechnology, University of Tel-Aviv, Tel-Aviv, 69978, Israel.,Department of Materials Science and Engineering, University of Tel Aviv, Tel Aviv, 69978, Israel
| | - Christopher M Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Gabriele Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Chris Holland
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK
| | - Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.,Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
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21
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Sparkes J, Holland C. The rheological properties of native sericin. Acta Biomater 2018; 69:234-242. [PMID: 29408618 DOI: 10.1016/j.actbio.2018.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 12/13/2017] [Accepted: 01/16/2018] [Indexed: 11/29/2022]
Abstract
Unlike spider silk, spinning silkworm silk has the added intricacy of being both fibre and micron-thick glue-like coating. Whilst the natural flow properties of the fibre feedstock fibroin are now becoming more established, our understanding of the coating sericin is extremely limited and thus presents both a gap in our knowledge and a hindrance to successful exploitation of these materials. In this study we characterise sericin feedstock from the silkworm Bombyx mori in its native state and by employing both biochemical, rheological and spectroscopic tools, define a natural gold standard. Our results demonstrate that native sericin behaves as a viscoelastic shear thinning fluid, but that it does so at a considerably lower viscosity than its partner fibroin, and that its upper critical shear rate (onset of gelation) lies above that of fibroin. Together these findings provide the first evidence that in addition to acting as a binder in the construction of the cocoon, sericin is capable of lubricating the flow of fibroin within the silk gland, which has implications for future processing, modelling and biomimetic use of these materials. STATEMENT OF SIGNIFICANCE This study addresses one of the major gaps in our knowledge regarding natural silk spinning by providing rigorous rheological characterisation of the other major protein involved - sericin. This allows progress in silk flow modelling, biomimetic system design, and in assessing the quality of bioinspired and waste sericin materials by providing a better understanding of the native, undegraded system.
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Affiliation(s)
- James Sparkes
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S. Yorks S1 3JD, UK
| | - Chris Holland
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S. Yorks S1 3JD, UK.
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22
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Fink TD, Zha RH. Silk and Silk-Like Supramolecular Materials. Macromol Rapid Commun 2018; 39:e1700834. [DOI: 10.1002/marc.201700834] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/16/2018] [Indexed: 01/12/2023]
Affiliation(s)
- Tanner D. Fink
- Department of Chemical and Biological Engineering; Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; 110 8th St. Troy NY 12180 USA
| | - R. Helen Zha
- Department of Chemical and Biological Engineering; Center for Biotechnology and Interdisciplinary Studies; Rensselaer Polytechnic Institute; 110 8th St. Troy NY 12180 USA
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23
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Humenik M, Lang G, Scheibel T. Silk nanofibril self-assembly versus electrospinning. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2018; 10:e1509. [PMID: 29393590 DOI: 10.1002/wnan.1509] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 10/18/2017] [Accepted: 12/19/2017] [Indexed: 01/16/2023]
Abstract
Natural silk fibers represent one of the most advanced blueprints for (bio)polymer scientists, displaying highly optimized mechanical properties due to their hierarchical structures. Biotechnological production of silk proteins and implementation of advanced processing methods enabled harnessing the potential of these biopolymer not just based on the mechanical properties. In addition to fibers, diverse morphologies can be produced, such as nonwoven meshes, films, hydrogels, foams, capsules and particles. Among them, nanoscale fibrils and fibers are particularly interesting concerning medical and technical applications due to their biocompatibility, environmental and mechanical robustness as well as high surface-to-volume ratio. Therefore, we introduce here self-assembly of silk proteins into hierarchically organized structures such as supramolecular nanofibrils and fabricated materials based thereon. As an alternative to self-assembly, we also present electrospinning a technique to produce nanofibers and nanofibrous mats. Accordingly, we introduce a broad range of silk-based dopes, used in self-assembly and electrospinning: natural silk proteins originating from natural spinning glands, natural silk protein solutions reconstituted from fibers, engineered recombinant silk proteins designed from natural blueprints, genetic fusions of recombinant silk proteins with other structural or functional peptides and moieties, as well as hybrids of recombinant silk proteins chemically conjugated with nonproteinaceous biotic or abiotic molecules. We highlight the advantages but also point out drawbacks of each particular production route. The scope includes studies of the natural self-assembly mechanism during natural silk spinning, production of silk fibrils as new nanostructured non-native scaffolds allowing dynamic morphological switches, as well as studying potential applications. This article is categorized under: Biology-Inspired Nanomaterials > Peptide-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.
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Affiliation(s)
- Martin Humenik
- Biomaterials, Faculty of Engineering Science, University of Bayreuth, Bayreuth, Germany
| | - Gregor Lang
- Biomaterials, Faculty of Engineering Science, University of Bayreuth, Bayreuth, Germany
| | - Thomas Scheibel
- Biomaterials, Faculty of Engineering Science, University of Bayreuth, Bayreuth, Germany.,Bayreuth Center for Colloids and Interfaces (BZKG), Research Center Bio-Macromolecules (BIOmac), Bayreuth Center for Molecular Biosciences (BZMB), Bayreuth Center for Material Science (BayMAT), Bavarian Polymer Institute (BPI), Universität Bayreuth, Bayreuth, Germany
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24
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Zhang C, Shao H, Luo J, Hu X, Zhang Y. Structure and interaction of silk fibroin and graphene oxide in concentrated solution under shear. Int J Biol Macromol 2018; 107:2590-2597. [DOI: 10.1016/j.ijbiomac.2017.10.142] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/05/2017] [Accepted: 10/23/2017] [Indexed: 02/06/2023]
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25
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Wan Q, Abrams KJ, Masters RC, Talari ACS, Rehman IU, Claeyssens F, Holland C, Rodenburg C. Mapping Nanostructural Variations in Silk by Secondary Electron Hyperspectral Imaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703510. [PMID: 29116662 DOI: 10.1002/adma.201703510] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/29/2017] [Indexed: 06/07/2023]
Abstract
Nanostructures underpin the excellent properties of silk. Although the bulk nanocomposition of silks is well studied, direct evidence of the spatial variation of nanocrystalline (ordered) and amorphous (disordered) structures remains elusive. Here, secondary electron hyperspectral imaging can be exploited for direct imaging of hierarchical structures in carbon-based materials, which cannot be revealed by any other standard characterization methods. Through applying this technique to silks from domesticated (Bombyx mori) and wild (Antheraea mylitta) silkworms, a variety of previously unseen features are reported, highlighting the local interplay between ordered and disordered structures. This technique is able to differentiate composition on the nanoscale and enables in-depth studies into the relationship between morphology and performance of these complex biopolymer systems.
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Affiliation(s)
- Quan Wan
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Kerry J Abrams
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Robert C Masters
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Abdullah C S Talari
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Ihtesham U Rehman
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Frederik Claeyssens
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Chris Holland
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
| | - Cornelia Rodenburg
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
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26
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Sparkes J, Holland C. Analysis of the pressure requirements for silk spinning reveals a pultrusion dominated process. Nat Commun 2017; 8:594. [PMID: 28928362 PMCID: PMC5605702 DOI: 10.1038/s41467-017-00409-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 06/27/2017] [Indexed: 11/12/2022] Open
Abstract
Silks are remarkable materials with desirable mechanical properties, yet the fine details of natural production remain elusive and subsequently inaccessible to biomimetic strategies. Improved knowledge of the natural processes could therefore unlock development of a host of bio inspired fibre spinning systems. Here, we use the Chinese silkworm Bombyx mori to review the pressure requirements for natural spinning and discuss the limits of a biological extrusion domain. This provides a target for finite element analysis of the flow of silk proteins, with the aim of bringing the simulated and natural domains into closer alignment. Supported by two parallel routes of experimental validation, our results indicate that natural spinning is achieved, not by extruding the feedstock, but by the pulling of nascent silk fibres. This helps unravel the oft-debated question of whether silk is pushed or pulled from the animal, and provides impetus to the development of pultrusion-based biomimetic spinning devices.The natural production of silks remains elusive and subsequently inaccessible to biomimetic strategies. Here the authors show that silks cannot be spun by pushing alone, and that natural spinning is dominated by pultrusion, which provides design guidelines for future biomimetic spinning systems.
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Affiliation(s)
- James Sparkes
- The Natural Materials Group, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, South Yorkshire, UK
| | - Chris Holland
- The Natural Materials Group, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, South Yorkshire, UK.
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27
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Wu X, Wu X, Yang B, Shao M, Feng G. Methanol-Water-Dependent Structural Changes of Regenerated Silk Fibroin Probed Using Terahertz Spectroscopy. APPLIED SPECTROSCOPY 2017; 71:1785-1794. [PMID: 28537487 DOI: 10.1177/0003702817706368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The mechanism of β-sheet crystallization in silk fibroin remains unclear, due to the incomplete information of protein assembly and structural state. The emerging terahertz (THz) spectroscopy (<10 THz) has been taken as an important tool to detect new aspects of biomolecular structure and is used for the first time to analyze the methanol-water (MeOH) induced structural changes of Bombyx mori silk fibroin. Mid-infrared spectroscopy (IR) and X-ray diffraction (XRD) results show that silk fibroin initially exists in a typical silk I form and reassemble into a predominant silk II (antiparallel β-sheet crystal) structure after MeOH treatment. The samples treated with MeOH-H2O mixed solutions show a predominant silk I structure without any silk-II-related peaks. As the MeOH concentration approaches 40 vol%, the absorbance of the β-sheet-related IR bands and the XRD peaks gradually increase, indicating a formation of β-sheet crystal during this process. THz spectrum shows the absorption capacity below 3 THz as well as the absorbance at 5.1 THz and 7.9 THz is indeed affected by the MeOH-H2O treatment, implying a MeOH-H2O-dependent change of intermolecular H-bonds in silk fibroin. The THz spectrum for silk fibroin gives additional information to the existing studies on the MeOH-H2O induced β-sheet crystallization of silk fibroin, which may help us understanding the structural changes of natural silk.
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Affiliation(s)
- Xu Wu
- 1 College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou, China
| | - Xiaodong Wu
- 1 College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou, China
| | - Bin Yang
- 1 College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou, China
- 2 Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, China
| | - Min Shao
- 2 Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou, China
| | - Guojin Feng
- 3 Material Optics and Spectrum Lab, Division of Metrology in Optics and Laser, National Institute of Metrology, Beijing, China
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28
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Silk micrococoons for protein stabilisation and molecular encapsulation. Nat Commun 2017; 8:15902. [PMID: 28722016 PMCID: PMC5524934 DOI: 10.1038/ncomms15902] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 05/12/2017] [Indexed: 12/21/2022] Open
Abstract
Naturally spun silks generate fibres with unique properties, including strength, elasticity and biocompatibility. Here we describe a microfluidics-based strategy to spin liquid native silk, obtained directly from the silk gland of Bombyx mori silkworms, into micron-scale capsules with controllable geometry and variable levels of intermolecular β-sheet content in their protein shells. We demonstrate that such micrococoons can store internally the otherwise highly unstable liquid native silk for several months and without apparent effect on its functionality. We further demonstrate that these native silk micrococoons enable the effective encapsulation, storage and release of other aggregation-prone proteins, such as functional antibodies. These results show that native silk micrococoons are capable of preserving the full activity of sensitive cargo proteins that can aggregate and lose function under conditions of bulk storage, and thus represent an attractive class of materials for the storage and release of active biomolecules. Silk fibres currently used in biotechnology are chemically reconstituted silk fibroins (RSF), which are more stable than native silk fibroin (NSF) but possess different biophysical properties. Here, the authors use microfluidic droplets to encapsulate and store NSF, preserving their native structure.
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29
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Kasoju N, Hawkins N, Pop-Georgievski O, Kubies D, Vollrath F. Silk fibroin gelation via non-solvent induced phase separation. Biomater Sci 2017; 4:460-73. [PMID: 26730413 DOI: 10.1039/c5bm00471c] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tissue engineering benefits from novel materials with precisely tunable physical, chemical and mechanical properties over a broad range. Here we report a practical approach to prepare Bombyx mori silk fibroin hydrogels using the principle of non-solvent induced phase separation (NIPS). A combination of reconstituted silk fibroin (RSF) and methanol (non-solvent), with a final concentration of 2.5% w/v and 12.5% v/v respectively, maintained at 22 °C temperature turned into a hydrogel within 10 hours. Freeze-drying of this gel gave a foam with a porosity of 88%, a water uptake capacity of 89% and a swelling index of 8.6. The gelation kinetics and the loss tangent of the gels were investigated by rheometry. The changes in the morphology of the porous foams were visualized by SEM. The changes in RSF chemical composition and the relative fraction of its secondary structural elements were analyzed by ATR-FTIR along with Fourier self-deconvolution. And, the changes in the glass transition temperature, specific heat capacity and the relative fraction of crystallinity of RSF were determined by TM-DSC. Data suggested that RSF-water-methanol behaved as a polymer-solvent-non-solvent ternary phase system, wherein the demixing of the water-methanol phases altered the thermodynamic equilibrium of RSF-water phases and resulted in the desolvation and eventual separation of the RSF phase. Systematic analysis revealed that both gelation time and the properties of hydrogels and porous foams could be controlled by the ratios of RSF and non-solvent concentration as well as by the type of non-solvent and incubation temperature. Due to the unique properties we envisage that the herein prepared NIPS induced RSF hydrogels and porous foams can possibly be used for the encapsulation of cells and/or for the controlled release of both hydrophilic and hydrophobic drugs.
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Affiliation(s)
- Naresh Kasoju
- Department of Biomaterials and Bioanalogous Polymer Systems, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic. and Department of Zoology, University of Oxford, Oxford, UK.
| | | | - Ognen Pop-Georgievski
- Department of Chemistry and Physics of Surfaces and Biointerfaces, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic
| | - Dana Kubies
- Department of Biomaterials and Bioanalogous Polymer Systems, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic.
| | - Fritz Vollrath
- Department of Zoology, University of Oxford, Oxford, UK.
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Laity PR, Holland C. The Rheology behind Stress-Induced Solidification in Native Silk Feedstocks. Int J Mol Sci 2016; 17:E1812. [PMID: 27801879 PMCID: PMC5133813 DOI: 10.3390/ijms17111812] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/21/2016] [Accepted: 10/25/2016] [Indexed: 01/24/2023] Open
Abstract
The mechanism by which native silk feedstocks are converted to solid fibres in nature has attracted much interest. To address this question, the present work used rheology to investigate the gelation of Bombyx mori native silk feedstock. Exceeding a critical shear stress appeared to be more important than shear rate, during flow-induced initiation. Compositional changes (salts, pH etc.,) were not required, although their possible role in vivo is not excluded. Moreover, after successful initiation, gel strength continued to increase over a considerable time under effectively quiescent conditions, without requiring further application of the initial stimulus. Gelation by elevated temperature or freezing was also observed. Prior to gelation, literature suggests that silk protein adopts a random coil configuration, which argued against the conventional explanation of gelation, based on hydrophilic and hydrophobic interactions. Instead, a new hypothesis is presented, based on entropically-driven loss of hydration, which appears to explain the apparently diverse methods by which silk feedstocks can be gelled.
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Affiliation(s)
- Peter R Laity
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK.
| | - Chris Holland
- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK.
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Boulet-Audet M, Holland C, Gheysens T, Vollrath F. Dry-Spun Silk Produces Native-Like Fibroin Solutions. Biomacromolecules 2016; 17:3198-3204. [PMID: 27526078 PMCID: PMC5059755 DOI: 10.1021/acs.biomac.6b00887] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
![]()
Silk’s
outstanding mechanical properties and energy efficient
solidification mechanisms provide inspiration for biomaterial self-assembly
as well as offering a diverse platform of materials suitable for many
biotechnology applications. Experiments now reveal that the mulberry
silkworm Bombyx mori secretes its silk
in a practically “unspun” state that retains much of
the solvent water and exhibits a surprisingly low degree of molecular
order (β-sheet crystallinity) compared to the state found in
a fully formed and matured fiber. These new observations challenge
the general understanding of silk spinning and in particular the role
of the spinning duct for structure development. Building on this discovery
we report that silk spun in low humidity appears to arrest a molecular
annealing process crucial for β-sheet formation. This, in turn,
has significant positive implications, enabling the production of
a high fidelity reconstituted silk fibroin with properties akin to
the gold standard of unspun native silk.
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Affiliation(s)
- Maxime Boulet-Audet
- Department of Zoology, Oxford University , Oxford, United Kingdom.,Department of Life Sciences, Imperial College London , London, United Kingdom
| | - Chris Holland
- Department of Zoology, Oxford University , Oxford, United Kingdom.,Department of Materials Science and Engineering, The University of Sheffield , Sheffield, United Kingdom
| | - Tom Gheysens
- Department of Zoology, Oxford University , Oxford, United Kingdom.,Department of Organic and Macromolecular Chemistry, University of Ghent , Ghent, Belgium
| | - Fritz Vollrath
- Department of Zoology, Oxford University , Oxford, United Kingdom
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Vulpe R, Le Cerf D, Dulong V, Popa M, Peptu C, Verestiuc L, Picton L. Rheological study of in-situ crosslinkable hydrogels based on hyaluronanic acid, collagen and sericin. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 69:388-97. [PMID: 27612727 DOI: 10.1016/j.msec.2016.07.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/06/2016] [Accepted: 07/04/2016] [Indexed: 01/10/2023]
Abstract
The elaboration of chemically crosslinked hydrogels based on collagen (C), hyaluronanic acid (HA) and sericin (S) with different polymer ratios was investigated by in-situ rheology. This reaction was performed via amide or ester bond reaction activated by carbodiimide, in pure water. Prior to molecule crosslinking, the rheological behaviour of the biopolymers (alone or in mixture) was characterized in a semi-dilute concentration regime. Both flow and dynamic measurements showed that uncrosslinked collagen alone appears to be rather elastic with yield stress properties, whereas uncrosslinked HA alone appears to be rather shear thinning and viscoelastic in agreement with entangled polymer behaviour. Sericin exhibited Newtonian low viscosity behaviour according to its very low molar mass. Before crosslinking, HA exhibited viscoelastic behaviour at concentrations above the critical entangled concentration (C*) in the mixtures, thus HA shows promise as a matrix for future crosslinked networks, whereas sericin did not significantly modify the rheology. During the reaction, followed by rheology, the kinetics were slower for pure HA systems compared with the mixtures (i.e., with added collagen and/or to a lesser extent sericin). At the same time, the final network of hydrogels (i.e., the elastic modulus) was more structured in the mixture based systems. This result is explained by ester bonds (the only possibility for pure HA systems), which are less favourable and reactive than amide bonds (possible with sericin and collagen). The presence of collagen in the HA matrix reinforced the hydrogel network. SEM studies confirmed the structure of the hydrogels, and in vitro degradability was globally consistent with the effect of the selected enzyme according to the hydrogel composition. All the elaborated hydrogels were non-cytotoxic in vitro.
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Affiliation(s)
- Raluca Vulpe
- "Gheorghe Asachi" Technical University, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, 73 Prof. Dr. docent Dimitrie Mangeron Street, 700050 Iasi, Romania; Université de Rouen, Laboratoire Polymères Biopolymères Surfaces, F-76821 Mont Saint Aignan, France
| | - Didier Le Cerf
- Normandie Université, France; Université de Rouen, Laboratoire Polymères Biopolymères Surfaces, F-76821 Mont Saint Aignan, France; CNRS UMR 6270 & FR3038, F-76821 Mont Saint Aignan, France
| | - Virginie Dulong
- Normandie Université, France; Université de Rouen, Laboratoire Polymères Biopolymères Surfaces, F-76821 Mont Saint Aignan, France; CNRS UMR 6270 & FR3038, F-76821 Mont Saint Aignan, France
| | - Marcel Popa
- "Gheorghe Asachi" Technical University, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, 73 Prof. Dr. docent Dimitrie Mangeron Street, 700050 Iasi, Romania; Academy of Romanian Scientists, Splaiul Independentei, 54, Sector 5, 050094, Bucuresti, Romania; "Apollonia" University of Iași, Faculty of Dental Medicine, Muzicii Avenue, 2, 700399, Iasi, Romania
| | - Catalina Peptu
- "Gheorghe Asachi" Technical University, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, 73 Prof. Dr. docent Dimitrie Mangeron Street, 700050 Iasi, Romania
| | - Liliana Verestiuc
- "Grigore T. Popa" University of Medicine and Pharmacy, Faculty of Medical Bioengineering, Department of Biological Sciences, 9-13 Kogalniceanu Street, 700454 Iasi, Romania
| | - Luc Picton
- Normandie Université, France; Université de Rouen, Laboratoire Polymères Biopolymères Surfaces, F-76821 Mont Saint Aignan, France; CNRS UMR 6270 & FR3038, F-76821 Mont Saint Aignan, France.
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Laity PR, Holland C. Native Silk Feedstock as a Model Biopolymer: A Rheological Perspective. Biomacromolecules 2016; 17:2662-71. [PMID: 27315508 DOI: 10.1021/acs.biomac.6b00709] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Variability in silk's rheology is often regarded as an impediment to understanding or successfully copying the natural spinning process. We have previously reported such variability in unspun native silk extracted straight from the gland of the domesticated silkworm Bombyx mori and discounted classical explanations such as differences in molecular weight and concentration. We now report that variability in oscillatory measurements can be reduced onto a simple master-curve through normalizing with respect to the crossover. This remarkable result suggests that differences between silk feedstocks are rheologically simple and not as complex as originally thought. By comparison, solutions of poly(ethylene-oxide) and hydroxypropyl-methyl-cellulose showed similar normalization behavior; however, the resulting curves were broader than for silk, suggesting greater polydispersity in the (semi)synthetic materials. Thus, we conclude Nature may in fact produce polymer feedstocks that are more consistent than typical man-made counterparts as a model for future rheological investigations.
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Affiliation(s)
- Peter R Laity
- Department of Materials Science and Engineering, The University of Sheffield , Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, United Kingdom
| | - Chris Holland
- Department of Materials Science and Engineering, The University of Sheffield , Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, United Kingdom
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Mykhaylyk OO, Warren NJ, Parnell AJ, Pfeifer G, Laeuger J. Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24111] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | - Nicholas J. Warren
- Department of Chemistry; The University of Sheffield; Sheffield S3 7HF United Kingdom
| | - Andrew J. Parnell
- Department of Physics and Astronomy; The University of Sheffield; Sheffield S3 7RH United Kingdom
| | | | - Joerg Laeuger
- Anton Paar Germany GmbH; Helmuth-Hirth-Strasse 6 D-73760 Ostfildern Germany
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Dicko C, Kasoju N, Hawkins N, Vollrath F. Differential scanning fluorimetry illuminates silk feedstock stability and processability. SOFT MATTER 2016; 12:255-262. [PMID: 26457973 DOI: 10.1039/c5sm02036k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The ability to design and implement silk feedstock formulations for tailored spinning has so far eluded the bioengineers. Recently, the high throughput screening technique of differential scanning fluorimetry (DSF) demonstrated the link between the instability transition temperature (Ti) and the processability of the silk feedstock. Using DSF we screened a large set of chemicals known to affect solvent quality. A multivariate analysis of the results shows that, regardless of the diversity of chemicals, three groupings are significantly distinguishable: G1 = similar to native silk; G2 = largely dominated by electrostatic interactions; and G3 = dominated by chelating interactions. We propose a thermodynamic analysis based on a pre- and post-transition fit to estimate the van't Hoff enthalpies (ΔHv) and the instability temperature (Ti). Our analysis shows that the ΔTi and ΔHv values were distinct: G1 (ΔTi = 0.23 ± 0.2; ΔHv = -159.1 ± 5.6 kcal mol(-1)), G2 (ΔTi = -7.3 ± 0.7; ΔHv = -191.4 ± 5.5 kcal mol(-1)), and G3 (ΔTi = -19.9 ± 3.3; ΔHv = -68.8 ± 6.0 kcal mol(-1)). Our analysis further combined the ΔTi value and the ΔHv value using stability ΔΔG to find that G1 only marginally stabilizes native silks (ΔΔG = -0.15 ± 0.04 kcal mol(-1)), whereas G2 and G3 destabilize native silk (ΔΔG = 3.8 ± 0.11 and ΔΔG = 3.8 ± 0.3 kcal mol(-1), respectively). Here our analysis shows that native silk has a complex multistep transition that is possibly non-cooperative. However, all three groupings also show a direct and cooperative transition with varied stabilization effects. This analysis suggests that native silks are able to sample multiple substates prior to undergoing (or to delay) the final transition. We conclude by hypothesizing that the observed energetic plasticity may be mediated by a fragile packaging of the silk tertiary structure that is readily lost when the solvent quality changes.
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Affiliation(s)
- C Dicko
- Department of Chemistry, Division for Pure and Applied Biochemistry, Lund University, Getigevägen 60, 2241, Lund, Sweden.
| | - N Kasoju
- Department of Zoology, University of Oxford, South Parks Road, OX1 3PS, Oxford, UK and Department of Biomaterials and Bioanalogous Polymer Systems, Institute of Macromolecular Chemistry, Academy of Sciences of Czech Republic, Heyrovského Square 2, 162 06, Prague, Czech Republic
| | - N Hawkins
- Department of Zoology, University of Oxford, South Parks Road, OX1 3PS, Oxford, UK
| | - F Vollrath
- Department of Zoology, University of Oxford, South Parks Road, OX1 3PS, Oxford, UK
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Boulet-Audet M, Vollrath F, Holland C. Identification and classification of silks using infrared spectroscopy. J Exp Biol 2015; 218:3138-49. [PMID: 26347557 PMCID: PMC4631776 DOI: 10.1242/jeb.128306] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 08/06/2015] [Indexed: 11/20/2022]
Abstract
Lepidopteran silks number in the thousands and display a vast diversity of structures, properties and industrial potential. To map this remarkable biochemical diversity, we present an identification and screening method based on the infrared spectra of native silk feedstock and cocoons. Multivariate analysis of over 1214 infrared spectra obtained from 35 species allowed us to group silks into distinct hierarchies and a classification that agrees well with current phylogenetic data and taxonomies. This approach also provides information on the relative content of sericin, calcium oxalate, phenolic compounds, poly-alanine and poly(alanine-glycine) β-sheets. It emerged that the domesticated mulberry silkmoth Bombyx mori represents an outlier compared with other silkmoth taxa in terms of spectral properties. Interestingly, Epiphora bauhiniae was found to contain the highest amount of β-sheets reported to date for any wild silkmoth. We conclude that our approach provides a new route to determine cocoon chemical composition and in turn a novel, biological as well as material, classification of silks.
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Affiliation(s)
- Maxime Boulet-Audet
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Fritz Vollrath
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Chris Holland
- Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK
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Boulet-Audet M, Byrne B, Kazarian SG. Cleaning-in-place of immunoaffinity resins monitored by in situ ATR-FTIR spectroscopy. Anal Bioanal Chem 2015; 407:7111-22. [PMID: 26159572 PMCID: PMC4551555 DOI: 10.1007/s00216-015-8871-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 06/10/2015] [Accepted: 06/18/2015] [Indexed: 12/04/2022]
Abstract
In the next 10 years, the pharmaceutical industry anticipates that revenue from biotherapeutics will overtake those generated from small drug molecules. Despite effectively treating a range of chronic and life-threatening diseases, the high cost of biotherapeutics limits their use. For biotherapeutic monoclonal antibodies (mAbs), an important production cost is the affinity resin used for protein capture. Cleaning-in-place (CIP) protocols aim to optimise the lifespan of the resin by slowing binding capacity decay. Binding assays can determine resin capacity from the mobile phase, but do not reveal the underlying causes of Protein A ligand degradation. The focus needs to be on the stationary phase to examine the effect of CIP on the resin. To directly determine both the local Protein A ligand concentration and conformation on two Protein A resins, we developed a method based on attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. ATR-FTIR spectroscopic imaging revealed that applying a carefully controlled load to agarose beads produces an even and reproducible contact with the internal reflection element. This allowed detection and quantification of the binding capacity of the stationary phase. ATR-FTIR spectroscopy also showed that Protein A proteolysis does not seem to occur under typical CIP conditions (below 1 M NaOH). However, our data revealed that concentrations of NaOH above 0.1 M cause significant changes in Protein A conformation. The addition of >0.4 M trehalose during CIP significantly reduced NaOH-induced ligand unfolding observed for one of the two Protein A resins tested. Such insights could help to optimise CIP protocols in order to extend resin lifetime and reduce mAb production costs.
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Affiliation(s)
- Maxime Boulet-Audet
- />Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ UK
- />Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Bernadette Byrne
- />Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Sergei G. Kazarian
- />Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ UK
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Koebley SR, Thorpe D, Pang P, Chrisochoides P, Greving I, Vollrath F, Schniepp HC. Silk Reconstitution Disrupts Fibroin Self-Assembly. Biomacromolecules 2015; 16:2796-804. [DOI: 10.1021/acs.biomac.5b00732] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sean R. Koebley
- The College of William & Mary, Department of Applied Science, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Daniel Thorpe
- The College of William & Mary, Department of Applied Science, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Pei Pang
- The College of William & Mary, Department of Applied Science, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Panos Chrisochoides
- The College of William & Mary, Department of Applied Science, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
| | - Imke Greving
- Oxford Silk Group, Department of Zoology, Oxford University, Tinbergen
Building, South Parks Road, Oxford, Oxfordshire OX1 3PS, United Kingdom
| | - Fritz Vollrath
- Oxford Silk Group, Department of Zoology, Oxford University, Tinbergen
Building, South Parks Road, Oxford, Oxfordshire OX1 3PS, United Kingdom
| | - Hannes C. Schniepp
- The College of William & Mary, Department of Applied Science, P.O. Box 8795, Williamsburg, Virginia 23187-8795, United States
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Walker AA, Holland C, Sutherland TD. More than one way to spin a crystallite: multiple trajectories through liquid crystallinity to solid silk. Proc Biol Sci 2015; 282:20150259. [PMID: 26041350 PMCID: PMC4590440 DOI: 10.1098/rspb.2015.0259] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 05/11/2015] [Indexed: 12/13/2022] Open
Abstract
Arthropods face several key challenges in processing concentrated feedstocks of proteins (silk dope) into solid, semi-crystalline silk fibres. Strikingly, independently evolved lineages of silk-producing organisms have converged on the use of liquid crystal intermediates (mesophases) to reduce the viscosity of silk dope and assist the formation of supramolecular structure. However, the exact nature of the liquid-crystal-forming-units (mesogens) in silk dope, and the relationship between liquid crystallinity, protein structure and silk processing is yet to be fully elucidated. In this review, we focus on emerging differences in this area between the canonical silks containing extended-β-sheets made by silkworms and spiders, and 'non-canonical' silks made by other insect taxa in which the final crystallites are coiled-coils, collagen helices or cross-β-sheets. We compared the amino acid sequences and processing of natural, regenerated and recombinant silk proteins, finding that canonical and non-canonical silk proteins show marked differences in length, architecture, amino acid content and protein folding. Canonical silk proteins are long, flexible in solution and amphipathic; these features allow them both to form large, micelle-like mesogens in solution, and to transition to a crystallite-containing form due to mechanical deformation near the liquid-solid transition. By contrast, non-canonical silk proteins are short and have rod or lath-like structures that are well suited to act both as mesogens and as crystallites without a major intervening phase transition. Given many non-canonical silk proteins can be produced at high yield in E. coli, and that mesophase formation is a versatile way to direct numerous kinds of supramolecular structure, further elucidation of the natural processing of non-canonical silk proteins may to lead to new developments in the production of advanced protein materials.
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Affiliation(s)
- Andrew A Walker
- Research School of Biology, Australian National University, Canberra 0200, Australia Food and Nutrition, CSIRO, Canberra 2600, Australia
| | - Chris Holland
- Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD, UK
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Xu D, Guo C, Holland GP. Probing the Impact of Acidification on Spider Silk Assembly Kinetics. Biomacromolecules 2015; 16:2072-9. [PMID: 26030517 DOI: 10.1021/acs.biomac.5b00487] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spiders utilize fine adjustment of the physicochemical conditions within its silk spinning system to regulate spidroin assembly into solid silk fibers with outstanding mechanical properties. However, the exact mechanism about which this occurs remains elusive and is still hotly debated. In this study, the effect of acidification on spider silk assembly was investigated on native spidroins from the major ampullate (MA) gland fluid excised from Latrodectus hesperus (Black Widow) spiders. Incubating the protein-rich MA silk gland fluid at acidic pH conditions results in the formation of silk fibers that are 10-100 μm in length and ∼2 μm in diameter as judged by optical and electron microscope methods. The in vitro spider silk assembly kinetics were monitored as a function of pH with a (13)C solid-state MAS NMR approach. The results confirm the importance of acidic pH in the spider silk self-assembly process with observation of a sigmoidal nucleation-elongation kinetic profile. The rates of nucleation and elongation as well as the percentage of β-sheet structure in the grown fibers depend on the pH. These results confirm the importance of an acidic pH gradient along the spinning duct for spider silk formation and provide a powerful spectroscopic approach to probe the kinetics of spider silk formation under various biochemical conditions.
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Affiliation(s)
- Dian Xu
- †Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Chengchen Guo
- †Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gregory P Holland
- ‡Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1030, United States
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Huot A, Lefèvre T, Rioux-Dubé JF, Paquet-Mercier F, Nault AP, Auger M, Pézolet M. Effect of mechanical deformation on the structure of regenerated Bombyx mori silk fibroin films as revealed using Raman and infrared spectroscopy. APPLIED SPECTROSCOPY 2015; 69:689-698. [PMID: 25954973 DOI: 10.1366/14-07776] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To better understand the effect of mechanical stress during the spinning of silk, the protein orientation and conformation of Bombyx mori regenerated silk fibroin (RSF) films have been studied as a function of deformation in a static mode or in real time by tensile-Raman experiments and polarization modulation infrared linear dichroism (PM-IRLD), respectively. The data show that either for step-by-step or continuous stretching, elongation induces the progressive formation of β-sheets that align along the drawing axis, in particular above a draw ratio of ~2. The formation of β-sheets begins before their alignment during a continuous drawing. Unordered chains were, however, never found to be oriented, which explains the very low level of orientation of the amorphous phase of the natural fiber. Stress-perturbed unordered chains readily convert into β-sheets, the strain-induced transformation following a two-state process. The final level of orientation and β-sheet content are lower than those found in the native fiber, indicating that various parameters have to be optimized in order to implement a spinning process as efficient as the natural one. Finally, during the stress relaxation period in a step-by-step drawing, there is essentially no change of the content and orientation of the β-sheets, suggesting that only unordered structures tend to reorganize.
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Affiliation(s)
- Alexandrine Huot
- Department of Chemistry, Centre de recherche sur les matériaux avancés, Centre québécois sur les matériaux fonctionnels, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines, Université Laval, Québec, QC, Canada G1V 0A6
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Zhang S, Li J, Yin Z, Zhang X, Kundu SC, Lu S. Silk fibroin composite membranes for application in corneal regeneration. J Appl Polym Sci 2015. [DOI: 10.1002/app.42407] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Shanshan Zhang
- National Engineering Laboratory for Modern Silk, Soochow University; Suzhou China
| | - Jiaojiao Li
- National Engineering Laboratory for Modern Silk, Soochow University; Suzhou China
| | - Zhuping Yin
- National Engineering Laboratory for Modern Silk, Soochow University; Suzhou China
| | - Xiaofeng Zhang
- Department of Ophthalmology; Affiliated First Hospital of Soochow University; Suzhou China
| | - Subhas C. Kundu
- Department of Biotechnology; Indian Institute of Technology Kharagpur; West Bengal India
| | - Shenzhou Lu
- National Engineering Laboratory for Modern Silk, Soochow University; Suzhou China
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Asakura T, Ohata T, Kametani S, Okushita K, Yazawa K, Nishiyama Y, Nishimura K, Aoki A, Suzuki F, Kaji H, Ulrich AS, Williamson MP. Intermolecular Packing in B. mori Silk Fibroin: Multinuclear NMR Study of the Model Peptide (Ala-Gly)15 Defines a Heterogeneous Antiparallel Antipolar Mode of Assembly in the Silk II Form. Macromolecules 2014. [DOI: 10.1021/ma502191g] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tetsuo Asakura
- Department
of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
- Institute for
Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Takuya Ohata
- Department
of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Shunsuke Kametani
- Mitsui Chemical Analysis & Consulting Service, Inc., 580-32, Nagaura, Sodegaura, Chiba 299-0265, Japan
| | - Keiko Okushita
- Department
of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Koji Yazawa
- JEOL RESONANCE
Inc., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Yusuke Nishiyama
- JEOL RESONANCE
Inc., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Katsuyuki Nishimura
- Institute for
Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Akihiro Aoki
- Department
of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Furitsu Suzuki
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Hironori Kaji
- Institute
for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Anne S. Ulrich
- Karlsruhe Institute of
Technology, IBG-2 and IOC, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Mike P. Williamson
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Firth Court,
Western Bank, Sheffield S10 2TN, U.K
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46
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Boulet-Audet M, Byrne B, Kazarian SG. High-throughput thermal stability analysis of a monoclonal antibody by attenuated total reflection FT-IR spectroscopic imaging. Anal Chem 2014; 86:9786-93. [PMID: 25221926 PMCID: PMC4218712 DOI: 10.1021/ac502529q] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/15/2014] [Indexed: 01/03/2023]
Abstract
The use of biotherapeutics, such as monoclonal antibodies, has markedly increased in recent years. It is thus essential that biotherapeutic production pipelines are as efficient as possible. For the production process, one of the major concerns is the propensity of a biotherapeutic antibody to aggregate. In addition to reducing bioactive material recovery, protein aggregation can have major effects on drug potency and cause highly undesirable immunological effects. It is thus essential to identify processing conditions which maximize recovery while avoiding aggregation. Heat resistance is a proxy for long-term aggregation propensity. Thermal stability assays are routinely performed using various spectroscopic and scattering detection methods. Here, we evaluated the potential of macro attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopic imaging as a novel method for the high-throughput thermal stability assay of a monoclonal antibody. This chemically specific visualization method has the distinct advantage of being able to discriminate between monomeric and aggregated protein. Attenuated total reflection is particularly suitable for selectively probing the bottom of vessels, where precipitated aggregates accumulate. With focal plane array detection, we tested 12 different buffer conditions simultaneously to assess the effect of pH and ionic strength on protein thermal stability. Applying the Finke model to our imaging kinetics allowed us to determine the rate constants of nucleation and autocatalytic growth. This analysis demonstrated the greater stability of our immunoglobulin at higher pH and moderate ionic strength, revealing the key role of electrostatic interactions. The high-throughput approach presented here has significant potential for analyzing the stability of biotherapeutics as well as any other biological molecules prone to aggregation.
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Affiliation(s)
- Maxime Boulet-Audet
- Department
of Chemical Engineering, Imperial College
London, South Kensington Campus, London, SW7 2AZ, United
Kingdom
- Department
of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
| | - Bernadette Byrne
- Department
of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
| | - Sergei G. Kazarian
- Department
of Chemical Engineering, Imperial College
London, South Kensington Campus, London, SW7 2AZ, United
Kingdom
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47
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Differential Scanning Fluorimetry provides high throughput data on silk protein transitions. Sci Rep 2014; 4:5625. [PMID: 25004800 PMCID: PMC4088128 DOI: 10.1038/srep05625] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/16/2014] [Indexed: 11/08/2022] Open
Abstract
Here we present a set of measurements using Differential Scanning Fluorimetry (DSF) as an inexpensive, high throughput screening method to investigate the folding of silk protein molecules as they abandon their first native melt conformation, dehydrate and denature into their final solid filament conformation. Our first data and analyses comparing silks from spiders, mulberry and wild silkworms as well as reconstituted ‘silk' fibroin show that DSF can provide valuable insights into details of silk denaturation processes that might be active during spinning. We conclude that this technique and technology offers a powerful and novel tool to analyse silk protein transitions in detail by allowing many changes to the silk solutions to be tested rapidly with microliter scale sample sizes. Such transition mechanisms will lead to important generic insights into the folding patterns not only of silks but also of other fibrous protein (bio)polymers.
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