51
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Asakura T, Matsuda H, Kataoka N, Imai A. Changes in the Local Structure of Nephila clavipes Dragline Silk Model Peptides upon Trifluoroacetic Acid, Low pH, Freeze-Drying, and Hydration Treatments Studied by 13C Solid-State NMR. Biomacromolecules 2018; 19:4396-4410. [DOI: 10.1021/acs.biomac.8b01267] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Tetsuo Asakura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Hironori Matsuda
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Naomi Kataoka
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Akiko Imai
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
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52
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Ling S, Chen W, Fan Y, Zheng K, Jin K, Yu H, Buehler MJ, Kaplan DL. Biopolymer nanofibrils: structure, modeling, preparation, and applications. Prog Polym Sci 2018; 85:1-56. [PMID: 31915410 PMCID: PMC6948189 DOI: 10.1016/j.progpolymsci.2018.06.004] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Biopolymer nanofibrils exhibit exceptional mechanical properties with a unique combination of strength and toughness, while also presenting biological functions that interact with the surrounding environment. These features of biopolymer nanofibrils profit from their hierarchical structures that spun angstrom to hundreds of nanometer scales. To maintain these unique structural features and to directly utilize these natural supramolecular assemblies, a variety of new methods have been developed to produce biopolymer nanofibrils. In particular, cellulose nanofibrils (CNFs), chitin nanofibrils (ChNFs), silk nanofibrils (SNFs) and collagen nanofibrils (CoNFs), as the four most abundant biopolymer nanofibrils on earth, have been the focus of research in recent years due to their renewable features, wide availability, low-cost, biocompatibility, and biodegradability. A series of top-down and bottom-up strategies have been accessed to exfoliate and regenerate these nanofibrils for versatile advanced applications. In this review, we first summarize the structures of biopolymer nanofibrils in nature and outline their related computational models with the aim of disclosing fundamental structure-property relationships in biological materials. Then, we discuss the underlying methods used for the preparation of CNFs, ChNFs, SNF and CoNFs, and discuss emerging applications for these biopolymer nanofibrils.
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Affiliation(s)
- Shengjie Ling
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Wenshuai Chen
- Key Laboratory of Bio-based Material Science & Technology, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Yimin Fan
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, China
| | - Ke Zheng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Kai Jin
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Haipeng Yu
- Key Laboratory of Bio-based Material Science & Technology, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Markus J. Buehler
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
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53
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Kim Y, Lee M, Baek I, Yoon T, Na S. Mechanically inferior constituents in spider silk result in mechanically superior fibres by adaptation to harsh hydration conditions: a molecular dynamics study. J R Soc Interface 2018; 15:20180305. [PMID: 30021926 PMCID: PMC6073636 DOI: 10.1098/rsif.2018.0305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/21/2018] [Indexed: 11/12/2022] Open
Abstract
Spider silk exhibits mechanical properties such as high strength and toughness that are superior to those of any man-made fibre (Bourzac 2015 Nature519, S4-S6 (doi:10.1038/519S4a)). This high strength and toughness originates from a combination of the crystalline (exhibiting robust strength) and amorphous (exhibiting superb extensibility) regions present in the silk (Asakura et al 2015 Macromolecules48, 2345-2357 (doi:10.1021/acs.macromol.5b00160)). The crystalline regions comprise a mixture of poly-alanine and poly-glycine-alanine. Poly-alanine is expected to be stronger than poly-glycine-alanine, because alanine exhibits greater interactions between the strands than glycine (Tokareva et al 2014 Acta Biomater.10, 1612-1626 (doi:10.1016/j.actbio.2013.08.020)). We connect this characteristic sequence to the interactions observed upon the hydration of spider silk. Like most proteinaceous materials, spider silks become highly brittle upon dehydration, and thus water collection is crucial to maintaining its toughness (Gosline et al 1986 Endeavour10, 37-43 (doi:10.1016/0160-9327(86)90049-9)). We report on the molecular dynamic simulations of spider silk structures with different sequences for the crystalline region of the silk structures, of wild-type (WT), poly-alanine, and poly-glycine-alanine. We reveal that the characteristic sequence of spider silk results in the β-sheets being maintained as the degree of hydration changes and that the high water collection capabilities of WT spider silk sequence prevent the silk from becoming brittle and weak in dry conditions. The characteristic crystalline sequence of spider dragline silk is therefore relevant not for maximizing the interactions between the strands but for adaption to changing hydration conditions to maintain an optimal performance even in harsh conditions.
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Affiliation(s)
- Yoonjung Kim
- Department of Mechanical Engineering, Korea University, 02841 Seoul, Republic of Korea
| | - Myeongsang Lee
- Institute of Advanced Machinery Design and Technology, Korea University, 02841 Seoul, Republic of Korea
| | - Inchul Baek
- Department of Mechanical Engineering, Korea University, 02841 Seoul, Republic of Korea
| | - Taeyoung Yoon
- Department of Mechanical Engineering, Korea University, 02841 Seoul, Republic of Korea
| | - Sungsoo Na
- Department of Mechanical Engineering, Korea University, 02841 Seoul, Republic of Korea
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54
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Abstract
The formation of ordered nanostructures by molecular self-assembly of proteins and peptides represents one of the principal directions in nanotechnology. Indeed, polyamides provide superior features as materials with diverse physical properties. A reductionist approach allowed the identification of extremely short peptide sequences, as short as dipeptides, which could form well-ordered amyloid-like β-sheet-rich assemblies comparable to supramolecular structures made of much larger proteins. Some of the peptide assemblies show remarkable mechanical, optical, and electrical characteristics. Another direction of reductionism utilized a natural noncoded amino acid, α-aminoisobutryic acid, to form short superhelical assemblies. The use of this exceptional helix inducer motif allowed the fabrication of single heptad repeats used in various biointerfaces, including their use as surfactants and DNA-binding agents. Two additional directions of the reductionist approach include the use of peptide nucleic acids (PNAs) and coassembly techniques. The diversified accomplishments of the reductionist approach, as well as the exciting future advances it bears, are discussed.
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Affiliation(s)
- Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv 6997801, Israel;
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55
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Asakura T, Nishimura A, Tasei Y. Determination of Local Structure of 13C Selectively Labeled 47-mer Peptides as a Model for Gly-Rich Region of Nephila clavipes Dragline Silk Using a Combination of 13C Solid-State NMR and MD Simulation. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00536] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Tetsuo Asakura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Akio Nishimura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Yugo Tasei
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
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56
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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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57
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Soomro A, Alsop RJ, Negishi A, Kreplak L, Fudge D, Kuczmarski ER, Goldman RD, Rheinstädter MC. Giant axonal neuropathy alters the structure of keratin intermediate filaments in human hair. J R Soc Interface 2017; 14:rsif.2017.0123. [PMID: 28424304 DOI: 10.1098/rsif.2017.0123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 03/24/2017] [Indexed: 11/12/2022] Open
Abstract
Giant axonal neuropathy (GAN) follows an autosomal recessive genetic inheritance and impedes the peripheral and central nervous system due to axonal swellings that are packed with neurofilaments. The patients display a number of phenotypes, including hypotonia, muscle weakness, decreased reflexes, ataxia, seizures, intellectual disability, pale skin and often curled hair. We used X-ray diffraction and tensile testing to determine potential changes to the structure of keratin intermediate filaments (IFs) in the hair of patients with GAN. A statistically significant decrease in the 47 and the 27 Å diffraction signals were observed. Tensile tests determined that the hair was slightly stiffer, stronger and more extensible in GAN patients. These results suggest that the structure of keratin IFs in hair is altered in GAN, and the findings are compatible with an increased positional disorder of the keratin tetramers within the hair fibres.
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Affiliation(s)
- Asfia Soomro
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Richard J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Atsuko Negishi
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Douglas Fudge
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Edward R Kuczmarski
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL, USA
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL, USA
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58
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Giesa T, Schuetz R, Fratzl P, Buehler MJ, Masic A. Unraveling the Molecular Requirements for Macroscopic Silk Supercontraction. ACS NANO 2017; 11:9750-9758. [PMID: 28846384 DOI: 10.1021/acsnano.7b01532] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Spider dragline silk is a protein material that has evolved over millions of years to achieve finely tuned mechanical properties. A less known feature of some dragline silk fibers is that they shrink along the main axis by up to 50% when exposed to high humidity, a phenomenon called supercontraction. This contrasts the typical behavior of many other materials that swell when exposed to humidity. Molecular level details and mechanisms of the supercontraction effect are heavily debated. Here we report a molecular dynamics analysis of supercontraction in Nephila clavipes silk combined with in situ mechanical testing and Raman spectroscopy linking the reorganization of the nanostructure to the polar and charged amino acids in the sequence. We further show in our in silico approach that point mutations of these groups not only suppress the supercontraction effect, but even reverse it, while maintaining the exceptional mechanical properties of the silk material. This work has imminent impact on the design of biomimetic equivalents and recombinant silks for which supercontraction may or may not be a desirable feature. The approach applied is appropriate to explore the effect of point mutations on the overall physical properties of protein based materials.
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Affiliation(s)
- Tristan Giesa
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Roman Schuetz
- Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany
| | - Peter Fratzl
- Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany
| | - Markus J Buehler
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Admir Masic
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany
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59
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Anton AM, Heidebrecht A, Mahmood N, Beiner M, Scheibel T, Kremer F. Foundation of the Outstanding Toughness in Biomimetic and Natural Spider Silk. Biomacromolecules 2017; 18:3954-3962. [DOI: 10.1021/acs.biomac.7b00990] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Arthur Markus Anton
- Peter
Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, D-04103 Leipzig, Germany
| | - Aniela Heidebrecht
- Department
for Biomaterials, Faculty of Engineering Science, University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
| | - Nasir Mahmood
- Institute
of Chemistry, Martin Luther University Halle Wittenberg, Heinrich-Damerow-Str.
4, D-06120 Halle
(Saale), Germany
| | - Mario Beiner
- Institute
of Chemistry, Martin Luther University Halle Wittenberg, Heinrich-Damerow-Str.
4, D-06120 Halle
(Saale), Germany
- Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter Hülse Str. 1, D-06120 Halle (Saale), Germany
| | - Thomas Scheibel
- Department
for Biomaterials, Faculty of Engineering Science, University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
- Research
Center for Bio Macromolecules (BIOmac), University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
- Bayreuth
Center for Colloids and Interfaces (BZKG), University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
- Bayreuth
Center for Molecular Biosciences (BZMB), University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
- Bayreuth
Center for Material Science and Engineering (BayMAT), University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
| | - Friedrich Kremer
- Peter
Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, D-04103 Leipzig, Germany
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60
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61
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Kim Y, Lee M, Choi H, Baek I, Kim JI, Na S. Mechanical features of various silkworm crystalline considering hydration effect via molecular dynamics simulations. J Biomol Struct Dyn 2017; 36:1360-1368. [DOI: 10.1080/07391102.2017.1323015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Yoonjung Kim
- Department of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Myeongsang Lee
- Institute of Advanced Machinery Design & Technology, Korea University, Seoul 02841, Republic of Korea
| | - Hyunsung Choi
- Department of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Inchul Baek
- Department of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Jae in Kim
- Department of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Sungsoo Na
- Department of Mechanical Engineering, Korea University, Seoul 02841, Republic of Korea
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62
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Tarakanova A, Huang W, Qin Z, Kaplan DL, Buehler MJ. Modeling and Experiment Reveal Structure and Nanomechanics across the Inverse Temperature Transition in B. mori Silk-Elastin-like Protein Polymers. ACS Biomater Sci Eng 2017; 3:2889-2899. [PMID: 33418710 DOI: 10.1021/acsbiomaterials.6b00688] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Silk and elastin are exemplary protein materials that exhibit exceptional material properties. Silk is uniquely strong, surpassing engineering materials such as Kevlar and steel, while elastin has exquisite flexibility and can reversibly fold into a more structured form at high temperatures when many other proteins would unfold and denature. This phenomenon in elastin is termed the inverse temperature transition. It is a reversible, controllable process that motivates applications in drug delivery, shape change materials, and biomimetic devices. Silk-elastinlike protein polymers (SELPs), which combine repeating B. mori silk and elastin blocks, have been introduced as biologically inspired materials that combine the distinctive properties of the component parts to achieve strong and extensible, tunable biomaterials. Here, we considered a single SELP sequence to examine temperature transition effects at the molecular scale. SELP molecular models were created using Replica Exchange Molecular Dynamics, an accelerated sampling method, and confirmed in experiment by comparing secondary structure distributions. A molecular collapse of the SELP molecule was observed with increased temperature in both molecular simulation and experiment. Temperature-specific differences were observed in the mechanical properties and the unfolding pathways of the polypeptide. Using the Bell-Evans model, we analyzed the free energy landscape associated with molecular unfolding at temperatures below and above the transition temperature range (Tt) of the polypeptide. We found that at physiological pulling rates, the energy barrier to unfold SELPs was counterintuitively higher above Tt. Our findings offer a foundational perspective on the molecular scale mechanisms of temperature-induced phase transition in SELPs, and suggest a novel approach to combine simulation and experiment to study materials for multifunctional biomimetic applications.
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Affiliation(s)
- Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-290, Cambridge, Massachusetts 02139, United States
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, Science & Technology Center, Room 251, Medford, Massachusetts 02155, United States
| | - Zhao Qin
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-290, Cambridge, Massachusetts 02139, United States
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Science & Technology Center, Room 251, Medford, Massachusetts 02155, United States
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-290, Cambridge, Massachusetts 02139, United States
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63
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Lin TY, Masunaga H, Sato R, Malay AD, Toyooka K, Hikima T, Numata K. Liquid Crystalline Granules Align in a Hierarchical Structure To Produce Spider Dragline Microfibrils. Biomacromolecules 2017; 18:1350-1355. [DOI: 10.1021/acs.biomac.7b00086] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ting-Yu Lin
- Enzyme
Research Team, RIKEN Center for Sustainable Resource Science, 2-1
Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Hiroyasu Masunaga
- Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Ryota Sato
- Enzyme
Research Team, RIKEN Center for Sustainable Resource Science, 2-1
Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Ali D. Malay
- Enzyme
Research Team, RIKEN Center for Sustainable Resource Science, 2-1
Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Kiminori Toyooka
- Mass
Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
| | - Takaaki Hikima
- RIKEN SPring-8 Center, 1-1-1
Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Keiji Numata
- Enzyme
Research Team, RIKEN Center for Sustainable Resource Science, 2-1
Hirosawa, Wako-shi, Saitama 351-0198, Japan
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64
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Lang G, Neugirg BR, Kluge D, Fery A, Scheibel T. Mechanical Testing of Engineered Spider Silk Filaments Provides Insights into Molecular Features on a Mesoscale. ACS APPLIED MATERIALS & INTERFACES 2017; 9:892-900. [PMID: 27935285 DOI: 10.1021/acsami.6b13093] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Spider dragline silk shows the highest toughness in comparison to all other known natural or man-made fibers. Despite a broad experimental foundation concerning the macroscopic silk thread properties as well as a thorough simulation-based molecular understanding, the impact of the mesoscale building blocks, namely nano-/submicrometer-sized filaments, on the mechanical properties of the threads remains the missing link. Here, we illustrate the function of these mesoscaled building blocks using electrospun fibers made of a recombinant spider silk protein and show the impact of β-sheet content and fiber hydration on their mechanical performance. Specifically elucidating the interplay between β-sheet-cross-linking (fiber strength) and structural water (fiber extensibility), the results bridge the gap between the molecular and the macroscopic view on the mechanics of spider silk. It is demonstrated that the extensibility of the here used single (MaSp2-like) protein system is in good accordance with the simulated extensibilities published by other groups. Furthermore, sufficient hydration of the fibers is shown to be a prerequisite to obtain a toughness in the range of that of natural dragline silk. Preliminary studies on electrospun fibers of the MaSp2-based recombinant spider silk proteins used in this work have indicated their basic applicability in the technical field of filter systems as well as in regenerative medicine. The presented work provides a fundamental understanding of the mechanical performance of such fibers under different wetting conditions, a prerequisite to further specify their potential for such applications.
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Affiliation(s)
| | | | | | - Andreas Fery
- Leibniz-Institut für Polymerforschung Dresden e. V., Institute of Physical Chemistry and Polymer Physics , Dresden 01069, Germany
- Chair for Physical Chemistry of Polymeric Materials, Technical University Dresden , Dresden 01069, Germany
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65
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Riekel C, Burghammer M, Dane TG, Ferrero C, Rosenthal M. Nanoscale Structural Features in Major Ampullate Spider Silk. Biomacromolecules 2016; 18:231-241. [PMID: 28001374 DOI: 10.1021/acs.biomac.6b01537] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spider major ampullate silk is often schematically represented as a two-phase material composed of crystalline nanodomains in an amorphous matrix. Here we are interested in revealing its more complex nanoscale organization by probing Argiope bruennichi dragline-type fibers using scanning X-ray nanodiffraction. This allows resolving transversal structural features such as an about 1 μm skin layer composed of around 100 nm diameter nanofibrils serving presumably as an elastic sheath. The core consists of a composite of several nm size crystalline nanodomains with poly(l-alanine) microstructure, embedded in a polypeptide network with short-range order. Stacks of nanodomains separated by less ordered nanosegments form nanofibrils with a periodic axial density modulation which is particularly sensitive to radiation damage. The precipitation of larger β-type nanocrystallites in the outer core-shell is attributed to MaSp1 protein molecules.
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Affiliation(s)
- Christian Riekel
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Manfred Burghammer
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France.,Department of Analytical Chemistry, Ghent University , Krijgslaan 281, S12B-9000 Ghent, Belgium
| | - Thomas G Dane
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Claudio Ferrero
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
| | - Martin Rosenthal
- The European Synchrotron (ESRF) , CS40220, F-38043 Grenoble Cedex 9, France
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66
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Das R, Kumar A, Patel A, Vijay S, Saurabh S, Kumar N. Biomechanical characterization of spider webs. J Mech Behav Biomed Mater 2016; 67:101-109. [PMID: 27988439 DOI: 10.1016/j.jmbbm.2016.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 11/26/2016] [Accepted: 12/12/2016] [Indexed: 12/01/2022]
Abstract
In light of recent focus on the behaviour of the natural structures for revolutionary technological growth, spider web seems to have seized considerable attention of product designer due to its amazing behaviour. In present work, mechanism behind the structural integrity of the spider web along with the materialistic analysis of its constituent silk threads has been extensively investigated. The nanoindentation tool both in static and dynamic mode has been utilized for complete analysis of the mechanical behaviour of the spiral and radial threads separately. Both the average elastic modulus and hardness of the radial silk thread is higher than the spiral silk thread which reveals the radial silk thread is the major structural component of the web. The sustainability of spider webs under storm, windy conditions and during the impact of pray has been investigated under dynamic conditions. The radial silk thread exhibits elastic like response and the spiral silk thread exhibits viscous like response in a wide frequency range (1-200Hz). The damping characteristic of the radial and spiral silk threads, an important parameter to investigate the energy dissipation properties of the materials has also been investigated in windy conditions.
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Affiliation(s)
- Rakesh Das
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India
| | - Amit Kumar
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India
| | - Anurag Patel
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India
| | - Sahil Vijay
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India
| | - Shashank Saurabh
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India
| | - Navin Kumar
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India.
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67
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Localised semicrystalline phases of MaSp1 proteins show high sensitivity to overshearing in β -sheet nanocrystals. Int J Biol Macromol 2016; 92:1006-1011. [DOI: 10.1016/j.ijbiomac.2016.07.081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/22/2016] [Accepted: 07/23/2016] [Indexed: 11/22/2022]
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68
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Krasnov I, Seydel T, Greving I, Blankenburg M, Vollrath F, Müller M. Strain-dependent fractional molecular diffusion in humid spider silk fibres. J R Soc Interface 2016; 13:20160506. [PMID: 27628174 PMCID: PMC5046950 DOI: 10.1098/rsif.2016.0506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/22/2016] [Indexed: 11/12/2022] Open
Abstract
Spider silk is a material well known for its outstanding mechanical properties, combining elasticity and tensile strength. The molecular mobility within the silk's polymer structure on the nanometre length scale importantly contributes to these macroscopic properties. We have therefore investigated the ensemble-averaged single-particle self-dynamics of the prevailing hydrogen atoms in humid spider dragline silk fibres on picosecond time scales in situ as a function of an externally applied tensile strain. We find that the molecular diffusion in the amorphous fraction of the oriented fibres can be described by a generalized fractional diffusion coefficient Kα that is independent of the observation length scale in the probed range from approximately 0.3-3.5 nm. Kα increases towards a diffusion coefficient of the classical Fickian type with increasing tensile strain consistent with an increasing loss of memory or entropy in the polymer matrix.
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Affiliation(s)
- Igor Krasnov
- Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany Institute of Materials Research, Helmholtz-Zentrum Geesthacht (HZG), 21502 Geesthacht, Germany
| | - Tilo Seydel
- Institut Max von Laue-Paul Langevin (ILL), CS 20156, 38042 Grenoble, France
| | - Imke Greving
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht (HZG), 21502 Geesthacht, Germany
| | - Malte Blankenburg
- Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany Institute of Materials Research, Helmholtz-Zentrum Geesthacht (HZG), 21502 Geesthacht, Germany
| | - Fritz Vollrath
- Department of Zoology, University of Oxford, Oxford OX13PS, UK
| | - Martin Müller
- Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany Institute of Materials Research, Helmholtz-Zentrum Geesthacht (HZG), 21502 Geesthacht, Germany
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69
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Su I, Buehler MJ. Nanomechanics of silk: the fundamentals of a strong, tough and versatile material. NANOTECHNOLOGY 2016; 27:302001. [PMID: 27305929 DOI: 10.1088/0957-4484/27/30/302001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Spider silk is a remarkable material that provides a template for upscaling molecular properties to the macroscale. In this article we review fundamental aspects of the mechanisms behind these behaviors, discuss the molecular makeup, chemical designs, and how these integrate in a complex arrangement to form webs, cocoons and other material architectures. Moreover, this review paper explores the unique ability of silk to tolerate various kinds of defects, in a way enabling this material platform to serve as one of the most resilient materials in nature. We conclude the discussion with a summary of key scaling laws, an attempt model and define hierarchical length-scales, and the translation to synthetic materials.
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Affiliation(s)
- Isabelle Su
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
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70
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Fang G, Sapru S, Behera S, Yao J, Shao Z, Kundu SC, Chen X. Exploration of the tight structural-mechanical relationship in mulberry and non-mulberry silkworm silks. J Mater Chem B 2016; 4:4337-4347. [PMID: 32263416 DOI: 10.1039/c6tb01049k] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Bombyx mori silkworm is well known as it has been bred by our ancestors with mulberry tree leaves for thousands of years. However, Bombyx mori is not the only silkworm that can produce silk, many other kinds of silkworms can also make silks for commercial use. In this research, we compare the mechanical properties of five different commercial silk fibres including domesticated mulberry Bombyx mori, non-mulberry semi-domesticated eri Samia ricini, and wild tropical tasar Antheraea mylitta and muga Antheraea assamensis. The results demonstrate that the non-mulberry silk fibres have a relatively high extensibility as compared to the mulberry silk fibres. In the meantime, the non-mulberry silk fibres show comparatively unique toughness to the mulberry silk fibres. Synchrotron radiation FTIR microspectroscopy, synchrotron radiation wide angle X-ray diffraction, and Raman dichroism spectroscopy are used to analyze the structural differences among the five species of silk fibres comprehensively. The results clearly show that the mechanical properties of both mulberry and non-mulberry silk fibres are closely related to their structures, such as β-sheet content, crystallinity, and the molecular orientation along the fibre axis. This study aims to understand the differences in the structural and mechanical properties of different mulberry and non-mulberry silk fibres, which are of importance to the related research on understanding and utilizing the non-mulberry silk as a biomaterial. We believe these investigations not only provide insight into the biology of silk fibroins from the non-mulberry silkworms but also offer guidelines for further biomimetic investigations into the design and manufacture of artificial silk protein fibres with novel morphologies and associated material properties for future use in different fields like bioelectronics, biomaterials and biomedical devices.
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Affiliation(s)
- Guangqiang Fang
- State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People's Republic of China.
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71
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Giesa T, Perry CC, Buehler MJ. Secondary Structure Transition and Critical Stress for a Model of Spider Silk Assembly. Biomacromolecules 2016; 17:427-36. [PMID: 26669270 DOI: 10.1021/acs.biomac.5b01246] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Spiders spin their silk from an aqueous solution to a solid fiber in ambient conditions. However, to date, the assembly mechanism in the spider silk gland has not been satisfactorily explained. In this paper, we use molecular dynamics simulations to model Nephila clavipes MaSp1 dragline silk formation under shear flow and determine the secondary structure transitions leading to the experimentally observed fiber structures. While no experiments are performed on the silk fiber itself, insights from this polypeptide model can be transferred to the fiber scale. The novelty of this study lies in the calculation of the shear stress (300-700 MPa) required for fiber formation and identification of the amino acid residues involved in the transition. This is the first time that the shear stress has been quantified in connection with a secondary structure transition. By study of molecules containing varying numbers of contiguous MaSp1 repeats, we determine that the smallest molecule size giving rise to a "silk-like" structure contains six polyalanine repeats. Through a probability analysis of the secondary structure, we identify specific amino acids that transition from α-helix to β-sheet. In addition to portions of the polyalanine section, these amino acids include glycine, leucine, and glutamine. The stability of β-sheet structures appears to arise from a close proximity in space of helices in the initial spidroin state. Our results are in agreement with the forces exerted by spiders in the silking process and the experimentally determined global secondary structure of spidroin and pulled MaSp1 silk. Our study emphasizes the role of shear in the assembly process of silk and can guide the design of microfluidic devices that attempt to mimic the natural spinning process and predict molecular requirements for the next generation of silk-based functional materials.
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Affiliation(s)
- Tristan Giesa
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Carole C Perry
- Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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72
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Madurga R, Plaza GR, Blackledge TA, Guinea GV, Elices M, Pérez-Rigueiro J. Material properties of evolutionary diverse spider silks described by variation in a single structural parameter. Sci Rep 2016; 6:18991. [PMID: 26755434 PMCID: PMC4709512 DOI: 10.1038/srep18991] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/06/2015] [Indexed: 11/24/2022] Open
Abstract
Spider major ampullate gland silks (MAS) vary greatly in material properties among species but, this variation is shown here to be confined to evolutionary shifts along a single universal performance trajectory. This reveals an underlying design principle that is maintained across large changes in both spider ecology and silk chemistry. Persistence of this design principle becomes apparent after the material properties are defined relative to the true alignment parameter, which describes the orientation and stretching of the protein chains in the silk fiber. Our results show that the mechanical behavior of all Entelegynae major ampullate silk fibers, under any conditions, are described by this single parameter that connects the sequential action of three deformation micromechanisms during stretching: stressing of protein-protein hydrogen bonds, rotation of the β-nanocrystals and growth of the ordered fraction. Conservation of these traits for over 230 million years is an indication of the optimal design of the material and gives valuable clues for the production of biomimetic counterparts based on major ampullate spider silk.
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Affiliation(s)
- Rodrigo Madurga
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain.,Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Gustavo R Plaza
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain.,Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Todd A Blackledge
- Department of Biology and Integrated Bioscience Program. The University of Akron, Akron, OH44325-3908. USA
| | - Gustavo V Guinea
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain.,Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - Manuel Elices
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain.,Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
| | - José Pérez-Rigueiro
- Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain.,Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain
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73
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Sintya E, Alam P. Self-assembled semi-crystallinity at parallel β -sheet nanocrystal interfaces in clustered MaSp1 (spider silk) proteins. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 58:366-71. [DOI: 10.1016/j.msec.2015.08.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/25/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
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74
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Ebrahimi D, Tokareva O, Rim NG, Wong JY, Kaplan DL, Buehler MJ. Silk-Its Mysteries, How It Is Made, and How It Is Used. ACS Biomater Sci Eng 2015; 1:864-876. [PMID: 27398402 PMCID: PMC4936833 DOI: 10.1021/acsbiomaterials.5b00152] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article reviews fundamental and applied aspects of silk-one of Nature's most intriguing materials in terms of its strength, toughness, and biological role-in its various forms, from protein molecules to webs and cocoons, in the context of mechanical and biological properties. A central question that will be explored is how the bridging of scales and the emergence of hierarchical structures are critical elements in achieving novel material properties, and how this knowledge can be explored in the design of synthetic materials. We review how the function of a material system at the macroscale can be derived from the interplay of fundamental molecular building blocks. Moreover, guidelines and approaches to current experimental and computational designs in the field of synthetic silklike materials are provided to assist the materials science community in engineering customized finetuned biomaterials for biomedical applications.
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Affiliation(s)
- Davoud Ebrahimi
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Olena Tokareva
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Nae Gyune Rim
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Joyce Y. Wong
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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75
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Sinko R, Keten S. Understanding emergent functions in self-assembled fibrous networks. NANOTECHNOLOGY 2015; 26:352501. [PMID: 26267869 DOI: 10.1088/0957-4484/26/35/352501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding self-assembly processes of nanoscale building blocks and characterizing their properties are both imperative for designing new hierarchical, network materials for a wide range of structural, optoelectrical, and transport applications. Although the characterization and choices of these material building blocks have been well studied, our understanding of how to precisely program a specific morphology through self-assembly still must be significantly advanced. In the recent study by Xie et al (2015 Nanotechnology 26 205602), the self-assembly of end-functionalized nanofibres is investigated using a coarse-grained molecular model and offers fundamental insight into how to control the structural morphology of nanofibrous networks. Varying nanoscale networks are observed when the molecular interaction strength is changed and the findings suggest that self-assembly through the tuning of molecular interactions is a key strategy for designing nanostructured networks with specific topologies.
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76
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The role of mechanics in biological and bio-inspired systems. Nat Commun 2015; 6:7418. [DOI: 10.1038/ncomms8418] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 05/07/2015] [Indexed: 12/31/2022] Open
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77
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Lin S, Ryu S, Tokareva O, Gronau G, Jacobsen MM, Huang W, Rizzo DJ, Li D, Staii C, Pugno NM, Wong JY, Kaplan DL, Buehler MJ. Predictive modelling-based design and experiments for synthesis and spinning of bioinspired silk fibres. Nat Commun 2015; 6:6892. [PMID: 26017575 PMCID: PMC4996357 DOI: 10.1038/ncomms7892] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 03/10/2015] [Indexed: 11/08/2022] Open
Abstract
Scalable computational modelling tools are required to guide the rational design of complex hierarchical materials with predictable functions. Here, we utilize mesoscopic modelling, integrated with genetic block copolymer synthesis and bioinspired spinning process, to demonstrate de novo materials design that incorporates chemistry, processing and material characterization. We find that intermediate hydrophobic/hydrophilic block ratios observed in natural spider silks and longer chain lengths lead to outstanding silk fibre formation. This design by nature is based on the optimal combination of protein solubility, self-assembled aggregate size and polymer network topology. The original homogeneous network structure becomes heterogeneous after spinning, enhancing the anisotropic network connectivity along the shear flow direction. Extending beyond the classical polymer theory, with insights from the percolation network model, we illustrate the direct proportionality between network conductance and fibre Young's modulus. This integrated approach provides a general path towards de novo functional network materials with enhanced mechanical properties and beyond (optical, electrical or thermal) as we have experimentally verified.
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Affiliation(s)
- Shangchao Lin
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Mechanical Engineering, Materials Science and Engineering Program, Florida State University, Tallahassee, Florida 32310, USA
| | - Seunghwa Ryu
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-338, Korea
| | - Olena Tokareva
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Greta Gronau
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Institute for Particle Technology, Technische Universitat Braunschweig, Braunschweig 38104, Germany
| | - Matthew M Jacobsen
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Wenwen Huang
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Daniel J Rizzo
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, Massachusetts 02155, USA
| | - David Li
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Cristian Staii
- Department of Physics and Astronomy, Center for Nanoscopic Physics, Tufts University, Medford, Massachusetts 02155, USA
| | - Nicola M Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, I-38123 Trento, Italy
- Centre for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, I-38123 Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Joyce Y Wong
- Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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78
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Zhao Z, Li Y, Xie MB. Silk fibroin-based nanoparticles for drug delivery. Int J Mol Sci 2015; 16:4880-903. [PMID: 25749470 PMCID: PMC4394455 DOI: 10.3390/ijms16034880] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/01/2015] [Accepted: 02/02/2015] [Indexed: 01/12/2023] Open
Abstract
Silk fibroin (SF) is a protein-based biomacromolecule with excellent biocompatibility, biodegradability and low immunogenicity. The development of SF-based nanoparticles for drug delivery have received considerable attention due to high binding capacity for various drugs, controlled drug release properties and mild preparation conditions. By adjusting the particle size, the chemical structure and properties, the modified or recombinant SF-based nanoparticles can be designed to improve the therapeutic efficiency of drugs encapsulated into these nanoparticles. Therefore, they can be used to deliver small molecule drugs (e.g., anti-cancer drugs), protein and growth factor drugs, gene drugs, etc. This paper reviews recent progress on SF-based nanoparticles, including chemical structure, properties, and preparation methods. In addition, the applications of SF-based nanoparticles as carriers for therapeutic drugs are also reviewed.
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Affiliation(s)
- Zheng Zhao
- State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
- Institute of Textiles and Clothing, the Hong Kong Polytechnic University, Hong Kong 999077, China.
- Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan 430070, China.
| | - Yi Li
- Institute of Textiles and Clothing, the Hong Kong Polytechnic University, Hong Kong 999077, China.
| | - Mao-Bin Xie
- Institute of Textiles and Clothing, the Hong Kong Polytechnic University, Hong Kong 999077, China.
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79
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Meyer A, Pugno NM, Cranford SW. Compliant threads maximize spider silk connection strength and toughness. J R Soc Interface 2015; 11:20140561. [PMID: 25008083 DOI: 10.1098/rsif.2014.0561] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Millions of years of evolution have adapted spider webs to achieve a range of functionalities, including the well-known capture of prey, with efficient use of material. One feature that has escaped extensive investigation is the silk-on-silk connection joints within spider webs, particularly from a structural mechanics perspective. We report a joint theoretical and computational analysis of an idealized silk-on-silk fibre junction. By modifying the theory of multiple peeling, we quantitatively compare the performance of the system while systematically increasing the rigidity of the anchor thread, by both scaling the stress-strain response and the introduction of an applied pre-strain. The results of our study indicate that compliance is a virtue-the more extensible the anchorage, the tougher and stronger the connection becomes. In consideration of the theoretical model, in comparison with rigid substrates, a compliant anchorage enormously increases the effective adhesion strength (work required to detach), independent of the adhered thread itself, attributed to a nonlinear alignment between thread and anchor (contact peeling angle). The results can direct novel engineering design principles to achieve possible load transfer from compliant fibre-to-fibre anchorages, be they silk-on-silk or another, as-yet undeveloped, system.
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Affiliation(s)
- Avery Meyer
- Laboratory for Nanotechnology in Civil Engineering (NICE), Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Nicola M Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, via Mesiano 77, 38123 Trento, Italy Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo (Trento), Italy
| | - Steven W Cranford
- Laboratory for Nanotechnology in Civil Engineering (NICE), Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, USA
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80
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Carrascoza Mayen JF, Lupan A, Cosar C, Kun AZ, Silaghi-Dumitrescu R. On the roles of the alanine and serine in the β-sheet structure of fibroin. Biophys Chem 2015; 197:10-7. [DOI: 10.1016/j.bpc.2014.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 10/20/2014] [Accepted: 11/09/2014] [Indexed: 11/26/2022]
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81
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Malho JM, Ouellet-Plamondon C, Rüggeberg M, Laaksonen P, Ikkala O, Burgert I, Linder MB. Enhanced plastic deformations of nanofibrillated cellulose film by adsorbed moisture and protein-mediated interactions. Biomacromolecules 2014; 16:311-8. [PMID: 25420190 DOI: 10.1021/bm501514w] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Biological composites are typically based on an adhesive matrix that interlocks rigid reinforcing elements in fiber composite or brick-and-mortar assemblies. In nature, the adhesive matrix is often made up of proteins, which are also interesting model systems, as they are unique among polymers in that we know how to engineer their structures with atomic detail and to select protein elements for specific interactions with other components. Here we studied how fusion proteins that consist of cellulose binding proteins linked to proteins that show a natural tendency to form multimer complexes act as an adhesive matrix in combination with nanofibrillated cellulose. We found that the fusion proteins are retained with the cellulose and that the proteins mainly affect the plastic yield behavior of the cellulose material as a function of water content. Interestingly, the proteins increased the moisture absorption of the composite, but the well-known plastifying effect of water was clearly decreased. The work helps to understand the functional basis of nanocellulose composites as materials and aims toward building model systems for molecular biomimetic materials.
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Affiliation(s)
- Jani-Markus Malho
- VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland
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82
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Erickson DP, Renzetti S, Jurgens A, Campanella OH, Hamaker BR. Modulating state transition and mechanical properties of viscoelastic resins from maize zein through interactions with plasticizers and co-proteins. J Cereal Sci 2014. [DOI: 10.1016/j.jcs.2014.08.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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83
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Zaera R, Soler A, Teus J. Uncovering changes in spider orb-web topology owing to aerodynamic effects. J R Soc Interface 2014; 11:20140484. [PMID: 24966235 DOI: 10.1098/rsif.2014.0484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater-and not negligible-advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs.
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Affiliation(s)
- Ramón Zaera
- Department of Continuum Mechanics and Structural Analysis, University Carlos III of Madrid, 28911 Leganés, Madrid, Spain
| | - Alejandro Soler
- Department of Continuum Mechanics and Structural Analysis, University Carlos III of Madrid, 28911 Leganés, Madrid, Spain
| | - Jaime Teus
- Department of Continuum Mechanics and Structural Analysis, University Carlos III of Madrid, 28911 Leganés, Madrid, Spain
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84
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Kwan K, Cranford SW. Quantifying Cooperativity via Geometric Gyration-Based Metrics of Coupled Macromolecules. JOURNAL OF NANOMECHANICS AND MICROMECHANICS 2014. [DOI: 10.1061/(asce)nm.2153-5477.0000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Kenny Kwan
- Graduate Research Assistant, Laboratory of Nanotechnology in Civil Engineering, Dept. of Civil and Environmental Engineering, Northeastern Univ., Boston, MA 02115
| | - Steven W. Cranford
- Assistant Professor, Laboratory of Nanotechnology in Civil Engineering, Dept. of Civil and Environmental Engineering, Northeastern Univ., Boston, MA 02115 (corresponding author)
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85
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Electrostatic charges instigate ‘concertina-like’ mechanisms of molecular toughening in MaSp1 (spider silk) proteins. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 41:329-34. [DOI: 10.1016/j.msec.2014.04.062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 04/26/2014] [Indexed: 11/20/2022]
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86
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Silva LP, Rech EL. Unravelling the biodiversity of nanoscale signatures of spider silk fibres. Nat Commun 2014; 4:3014. [PMID: 24345771 DOI: 10.1038/ncomms4014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/26/2013] [Indexed: 11/09/2022] Open
Abstract
Living organisms are masters at designing outstanding self-assembled nanostructures through a hierarchical organization of modular proteins. Protein-based biopolymers improved and selected by the driving forces of molecular evolution are among the most impressive archetypes of nanomaterials. One of these biomacromolecules is the myriad of compound fibroins of spider silks, which combine surprisingly high tensile strength with great elasticity. However, no consensus on the nano-organization of spider silk fibres has been reached. Here we explore the biodiversity of spider silk fibres, focusing on nanoscale characterization with high-resolution atomic force microscopy. Our results reveal an evolution of the nanoroughness, nanostiffness, nanoviscoelastic, nanotribological and nanoelectric organization of microfibres, even when they share similar sizes and shapes. These features are related to unique aspects of their molecular structures. The results show that combined nanoscale analyses of spider silks may enable the screening of appropriate motifs for bioengineering synthetic fibres from recombinant proteins.
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Affiliation(s)
- Luciano P Silva
- Embrapa Genetic Resources and Biotechnology, PBI, Parque Estação Biológica Final W5 Norte, Brasilia 70770-917, Brazil
| | - Elibio L Rech
- Embrapa Genetic Resources and Biotechnology, PBI, Parque Estação Biológica Final W5 Norte, Brasilia 70770-917, Brazil
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87
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Ruiz L, Keten S. Thermodynamics versus Kinetics Dichotomy in the Linear Self-Assembly of Mixed Nanoblocks. J Phys Chem Lett 2014; 5:2021-2026. [PMID: 26273889 DOI: 10.1021/jz500776g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report classical and replica exchange molecular dynamics simulations that establish the mechanisms underpinning the growth kinetics of a binary mix of nanorings that form striped nanotubes via self-assembly. A step-growth coalescence model captures the growth process of the nanotubes, which suggests that high aspect ratio nanostructures can grow by obeying the universal laws of self-similar coarsening, contrary to systems that grow through nucleation and elongation. Notably, striped patterns do not depend on specific growth mechanisms, but are governed by tempering conditions that control the likelihood of depropagation and fragmentation.
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88
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Golinska MD, Włodarczyk-Biegun MK, Werten MWT, Stuart MAC, de Wolf FA, de Vries R. Dilute Self-Healing Hydrogels of Silk-Collagen-Like Block Copolypeptides at Neutral pH. Biomacromolecules 2014; 15:699-706. [DOI: 10.1021/bm401682n] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Monika D. Golinska
- Laboratory
of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, NL-6703 HB Wageningen, The Netherlands
| | - Małgorzata K. Włodarczyk-Biegun
- Laboratory
of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, NL-6703 HB Wageningen, The Netherlands
| | - Marc W. T. Werten
- Wageningen
UR
Food and Biobased Research, Bornse
Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Martien A. Cohen Stuart
- Laboratory
of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, NL-6703 HB Wageningen, The Netherlands
| | - Frits A. de Wolf
- Wageningen
UR
Food and Biobased Research, Bornse
Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Renko de Vries
- Laboratory
of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, NL-6703 HB Wageningen, The Netherlands
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89
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Ukpebor OT, Shah A, Bazov E, Boutis GS. Inverse temperature transition of elastin like motifs in major ampullate dragline silk: MD simulations of short peptides and NMR studies of water dynamics. SOFT MATTER 2014; 10:773-785. [PMID: 24511323 PMCID: PMC3914981 DOI: 10.1039/c3sm52001c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Using deuterium 2D T1 − T2 Inverse Laplace Transform (ILT) NMR, we have investigated the distribution, population, and dynamics of waters of hydration in major ampullate N. clavipes and A. aurantia silk as a function of temperature. In both samples studied, correlation times much larger than that of free water are measured, and in some cases, appear to increase with increasing temperature over the range of 5 to 60 °C (corresponding to reduced tumbling). In addition, the experimental data point to a reduction in the population of water localized in the silk with increasing temperature in the range of 20 to 50 °C. Molecular dynamics simulations were performed to probe the thermal characteristics of a variety of repeating motifs found in the two silk samples. The repeating motifs GLGSQ, GAAAAAAG, GPGGY, GPGQQ, GPSG, and GPSGPGS found in N. clavipes, GLGSQ, GYGSG, GPGSG, and GPGSQ found in A. aurantia silk were found to exhibit a thermal property observed in short elastin peptides known as the "inverse temperature transition". This is a well known characteristic exhibited by short peptides consisting of (VPGXG)n motifs (where X is any amino acid other than proline) found in elastin--a protein responsible for the elasticity of vertebrate tissues. In qualitative agreement with experimental measurements of water in the silks, all the peptides studied in simulation show evidence of an increase in sidechain contacts and peptide hydrogen bonds, concomitant with a decrease in radius of gyration and localized water as the temperature is raised from approximately 5 to 60 °C.
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90
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Giesa T, Pugno NM, Wong JY, Kaplan DL, Buehler MJ. What's inside the box? - Length-scales that govern fracture processes of polymer fibers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:412-7. [PMID: 24431127 PMCID: PMC4976486 DOI: 10.1002/adma.201303323] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 05/15/2023]
Abstract
This work shows that multiple length-scales must be considered concurrently to explain a polymer fiber's impressive mechanical performance and resilience. The considerations of interatomic interactions alone cannot explain the fracture strength observed in biological fibers. Instead, the fracture strength of a fiber depends strongly on the length-scale of observation, including a fiber's sensitivity with respect to cracks and other flaws.
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Affiliation(s)
- Tristan Giesa
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave. Room 1-235A&B, Cambridge, MA, 02139, USA
| | - Nicola M. Pugno
- Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, Via Mesiano, 77, I-38123, Trento, Italy
- Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive, 18, I-38123, Trento, Italy
| | - Joyce Y. Wong
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave. Room 1-235A&B, Cambridge, MA, 02139, USA
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91
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Silva LP, Rech EL. Scrutinizing the datasets obtained from nanoscale features of spider silk fibres. Sci Data 2014; 1:140040. [PMID: 25977795 PMCID: PMC4411006 DOI: 10.1038/sdata.2014.40] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 09/19/2014] [Indexed: 11/10/2022] Open
Abstract
Spider silk fibres share unprecedented structural and mechanical properties which span from the macroscale to nanoscale and beyond. This is possible due to the molecular features of modular proteins termed spidroins. Thus, the investigation of the organizational scaffolds observed for spidroins in spider silk fibres is of paramount importance for reverse bioengineering. This dataset consists in describing a rational screening procedure to identify the nanoscale features of spider silk fibres. Using atomic force microscopy operated in multiple acquisition modes, we evaluated silk fibres from nine spider species. Here we present the complete results of the analyses and decrypted a number of novel features that could even rank the silk fibres according to desired mechanostructural features. This dataset will allow other researchers to select the most appropriate models for synthetic biology and also lead to better understanding of spider silk fibres extraordinary performance that is comparable to the best manmade materials.
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Affiliation(s)
- Luciano P Silva
- Embrapa Genetic Resources and Biotechnology, PBI, Parque Estação Biológica Final W5 Norte , Brasília 70770-917, DF, Brazil
| | - Elibio L Rech
- Embrapa Genetic Resources and Biotechnology, PBI, Parque Estação Biológica Final W5 Norte , Brasília 70770-917, DF, Brazil
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92
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Ke P, Jiao XN, Ge XH, Xiao WM, Yu B. From macro to micro: structural biomimetic materials by electrospinning. RSC Adv 2014. [DOI: 10.1039/c4ra05098c] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Bionics provides a model for preparation of structural materials.
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Affiliation(s)
- Peng Ke
- School of Textiles
- Tianjin Polytechnic University
- Tianjin 300387, China
| | - Xiao-Ning Jiao
- School of Textiles
- Tianjin Polytechnic University
- Tianjin 300387, China
- Key Laboratory of Advanced Textile Composites
- Ministry of Education
| | - Xiao-Hui Ge
- College of Physics
- Qingdao University
- Qingdao 266071, China
- Key Laboratory of Photonics Materials and Technology in Universities of Shandong
- Qingdao 266071, China
| | - Wei-Min Xiao
- College of Textiles
- Donghua University
- Shanghai 201620, China
| | - Bin Yu
- School of Textiles
- Tianjin Polytechnic University
- Tianjin 300387, China
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93
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Ridgley DM, Claunch EC, Barone JR. Characterization of large amyloid fibers and tapes with Fourier transform infrared (FT-IR) and Raman spectroscopy. APPLIED SPECTROSCOPY 2013; 67:1417-1426. [PMID: 24359656 DOI: 10.1366/13-07059] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Amyloids are self-assembled protein structures implicated in a host of neurodegenerative diseases. Organisms can also produce "functional amyloids" to perpetuate life, and these materials serve as models for robust biomaterials. Amyloids are typically studied using fluorescent dyes, Fourier transform infrared (FT-IR), or Raman spectroscopy analysis of the protein amide I region, and X-ray diffraction (XRD) because the self-assembled β-sheet secondary structure of the amyloid can be easily identified with these techniques. Here, FT-IR and Raman spectroscopy analyses are described to characterize amyloid structures beyond just identification of the β-sheet structure. It has been shown that peptide mixtures can self-assemble into nanometer-sized amyloid structures that then continue to self-assemble to the micrometer scale. The resulting structures are flat tapes of low rigidity or cylinders of high rigidity depending on the peptides in the mixture. By monitoring the aggregation of peptides in solution using FT-IR spectroscopy, it is possible to identify specific amino acids implicated in β-sheet formation and higher order self-assembly. It is also possible to predict the final tape or cylinder morphology and gain insight into the structure's physical properties based on observed intermolecular interactions during the self-assembly process. Tapes and cylinders are shown to both have a similar core self-assembled β-sheet structure. Soft tapes also have weak hydrophobic interactions between alanine, isoleucine, leucine, and valine that facilitate self-assembly. Rigid cylinders have similar hydrophobic interactions that facilitate self-assembly and also have extensive hydrogen bonding between glutamines. Raman spectroscopy performed on the dried tapes and fibers shows the persistence of these interactions. The spectroscopic analyses described could be generalized to other self-assembling amyloid systems to explain property and morphological differences.
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Affiliation(s)
- Devin M Ridgley
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
| | - Elizabeth C Claunch
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
| | - Justin R Barone
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
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94
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Xu Z. Mechanics of metal-catecholate complexes: the roles of coordination state and metal types. Sci Rep 2013; 3:2914. [PMID: 24107799 PMCID: PMC3794374 DOI: 10.1038/srep02914] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/02/2013] [Indexed: 11/09/2022] Open
Abstract
There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.
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Affiliation(s)
- Zhiping Xu
- Applied Mechanics Laboratory, Department of Engineering Mechanics and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China
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95
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Varongchayakul N, Johnson S, Quabili T, Cappello J, Ghandehari H, Solares SDJ, Hwang W, Seog J. Direct observation of amyloid nucleation under nanomechanical stretching. ACS NANO 2013; 7:7734-7743. [PMID: 23987654 DOI: 10.1021/nn402322k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Self-assembly of amyloid nanofiber is associated with both functional biological and pathological processes such as those in neurodegenerative diseases. Despite intensive studies, the stochastic nature of the process has made it difficult to elucidate a molecular mechanism for the key amyloid nucleation event. Here we investigated nucleation of the silk-elastin-like peptide (SELP) amyloid using time-lapse lateral force microscopy (LFM). By repeated scanning of a single line on a SELP-coated mica surface, we observed a sudden stepwise height increase. This corresponds to nucleation of an amyloid fiber, which subsequently grew perpendicular to the scanning direction. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction. The probability of nucleation correlated with the maximum stretching force and extension, implying that stretching of SELP molecules is a key molecular event for amyloid nucleation. The mechanically induced nucleation allows for positional and directional control of amyloid assembly in vitro, which we demonstrate by generating single nanofibers at predetermined nucleation sites.
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Affiliation(s)
- Nitinun Varongchayakul
- Department of Materials Science and Engineering, ‡Fischell Department of Bioengineering, ¶Department of Mechanical Engineering, University of Maryland , College Park, Maryland 20742, United States
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96
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97
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Pugno NM, Cranford SW, Buehler MJ. Synergetic material and structure optimization yields robust spider web anchorages. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:2747-2756. [PMID: 23585296 DOI: 10.1002/smll.201201343] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 11/01/2012] [Indexed: 06/02/2023]
Abstract
Millions of years of evolution have adapted spider webs to achieve a range of properties, including the well-known capture of prey, with efficient use of materials. One feature that remains poorly understood is the attachment disc, a network of silk fibers that mechanically anchors a web to its environment. Experimental observations suggest that one possible attachment disc adheres to a substrate through multiple symmetrically branched structures composed of sub-micrometer scale silk fibers. Here, a theoretical model is used to explore the adaptation of the strength of attachment of such an anchorage, and complementary mesoscale simulations are applied to demonstrate a novel mechanism of synergetic material and structural optimization, such that the maximum anchorage strength can be achieved regardless of the initial anchor placement or material type. The optimal delamination (peeling) angle is facilitated by the inherent extensibility of silk, and is attained automatically during the process of delamination. This concept of self-optimizing peeling angle suggests that attachment discs do not require precise placement by the spider, irrespective of adhesion strength. Additional hierarchical branching of the anchorage increases efficiency, where both the delamination force and toughness modulus increase with a splitting of the cross-sectional area.
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Affiliation(s)
- Nicola M Pugno
- Laboratory of Bioinspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, Via Mesiano, 77 I-38123 Trento, Italy.
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98
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Ruiz L, VonAchen P, Lazzara TD, Xu T, Keten S. Persistence length and stochastic fragmentation of supramolecular nanotubes under mechanical force. NANOTECHNOLOGY 2013; 24:195103. [PMID: 23594966 DOI: 10.1088/0957-4484/24/19/195103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Cyclic peptide nanotubes (CPNs) exhibit impressive structural, mechanical and chemical properties in resemblance to beta-sheet proteins found in silks and amyloids, and show potential as supramolecular nanotubes that can be utilized to generate novel nanocomposites and nanoporous thin films. Quantifying the persistence length and thermomechanical fragmentation of CPNs is of great importance for establishing a theoretical basis of how to generate rectilinear nanostructures with controlled aspect ratio and rigidity. However, factors governing the elasticity and dynamical breaking of these supramolecular nanostructures remain to be fully understood. Here we present a statistical analysis of the Young's modulus and persistence length of CPNs using fully-atomistic molecular dynamic simulations in explicit solvent. We show that the measured properties exhibit a dependence on the magnitude of the shear force applied, and extrapolation to the quasi-static deformation case yields 0.46 μm for the persistence length and 7.8 GPa for the Young's modulus, in agreement with our experimental observations from TEM images. We establish a theoretical model for the spatial and temporal distribution of stochastic fracture, which we use to explain the simulation-based observations of spontaneous fragmentation under an applied shear force. Our methodology, blending theory, simulation and experiments provide a framework that can be utilized to investigate the mechanical behavior of self-assembling protein materials, paving the way for their design towards biological and industrial applications.
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Affiliation(s)
- L Ruiz
- Department of Civil and Environmental Engineering and Mechanical Engineering, Northwestern University, Evanston, IL 60208-3111, USA
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99
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Affiliation(s)
- Tristan Giesa
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, and
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, and
- Center for Computational Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139;
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100
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Cranford SW. Increasing silk fibre strength through heterogeneity of bundled fibrils. J R Soc Interface 2013; 10:20130148. [PMID: 23486175 PMCID: PMC3627094 DOI: 10.1098/rsif.2013.0148] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 02/21/2013] [Indexed: 12/17/2022] Open
Abstract
Can naturally arising disorder in biological materials be beneficial? Materials scientists are continuously attempting to replicate the exemplary performance of materials such as spider silk, with detailed techniques and assembly procedures. At the same time, a spider does not precisely machine silk-imaging indicates that its fibrils are heterogeneous and irregular in cross section. While past investigations either focused on the building material (e.g. the molecular scale protein sequence and behaviour) or on the ultimate structural component (e.g. silk threads and spider webs), the bundled structure of fibrils that compose spider threads has been frequently overlooked. Herein, I exploit a molecular dynamics-based coarse-grain model to construct a fully three-dimensional fibril bundle, with a length on the order of micrometres. I probe the mechanical behaviour of bundled silk fibrils with variable density of heterogenic protrusions or globules, ranging from ideally homogeneous to a saturated distribution. Subject to stretching, the model indicates that cooperativity is enhanced by contact through low-force deformation and shear 'locking' between globules, increasing shear stress transfer by up to 200 per cent. In effect, introduction of a random and disordered structure can serve to improve mechanical performance. Moreover, addition of globules allows a tuning of free volume, and thus the wettability of silk (with implications for supercontraction). These findings support the ability of silk to maintain near-molecular-level strength at the scale of silk threads, and the mechanism could be easily adopted as a strategy for synthetic fibres.
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Affiliation(s)
- Steven W Cranford
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.
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