Effect of Water on the Structure and Dynamics of Regenerated [3-13C] Ser, [3-13C] , and [3-13C] Ala-Bombyx mori Silk Fibroin Studied with 13C Solid-State Nuclear Magnetic Resonance

Nishimura, Akio; Matsuda, Hironori; Tasei, Yugo; Asakura, Tetsuo

doi:10.1021/acs.biomac.7b01665

Cited by 21 publications

(33 citation statements)

References 82 publications

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“…Evidently, at 60 • C treatment, the β-sheet reached the maximum intensity (47.8%), transformed from the random coil conversion, and the β sheet-to-random coil ratio was maximum (three-fold higher), as shown in Figure 3C; a similar trend of this has also been reported [42,43]. Thus, this enhancement in the β-sheet fraction may be regarded as a key index to estimate the strength of structurally stronger silk materials [44].…”

Section: Ft-ir Analysis Of Hydrothermally Treated Silk Samplessupporting

confidence: 75%

Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

Pandey

Chang

et al. 2020

Polymers

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The superlative mechanical properties of spider silk and its conspicuous variations have instigated significant interest over the past few years. However, current attempts to synthetically spin spider silk fibers often yield an inferior physical performance, owing to the improper molecular interactions of silk proteins. Considering this, herein, a post-treatment process to reorganize molecular structures and improve the physical strength of spider silk is reported. The major ampullate dragline silk from Nephila pilipes with a high β-sheet content and an adequate tensile strength was utilized as the study material, while that from Cyrtophora moluccensis was regarded as a reference. Our results indicated that the hydrothermal post-treatment (50–70 °C) of natural spider silk could effectively induce the alternation of secondary structures (random coil to β-sheet) and increase the overall tensile strength of the silk. Such advantageous post-treatment strategy when applied to regenerated spider silk also leads to an increment in the strength by ~2.5–3.0 folds, recapitulating ~90% of the strength of native spider silk. Overall, this study provides a facile and effective post-spinning means for enhancing the molecular structures and mechanical properties of as-spun silk threads, both natural and regenerated.

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Section: Ft-ir Analysis Of Hydrothermally Treated Silk Samplessupporting

confidence: 75%

Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

Pandey

Chang

et al. 2020

Polymers

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“…In comparison, water exerts more extreme changes in regenerated silkworm silks, although the details depend on the concrete processing parameters 23 . In this case, both R-NoPS and R-3.6PS samples tested in water show a significant reduction in the elastic modulus (over two orders of magnitude for R-NoPS samples), and an increase in the strain at breaking.…”

Section: Resultsmentioning

confidence: 99%

“…Prior to the production of supercontracting regenerated silkworm silk fibers, the basic strategy for analysing the origin of this phenomenon relied on the comparison of the sequences and microstructures of natural fibers, either endowed or not with this property 20–22 . Silks such as those produced by the major and minor ampullate glands of the spiders and that produced by silkworms ( B. mori ) were included in the analysis, but no clear correlation could be established to relate the microstructures of the different fibers and the emergence of supercontraction 23–25 . In particular, solid-state nuclear magnetic resonance (NMR) was a preferred technique for the microstructural characterization of silk fibers, since it allows unveiling some singular microstructural features in the short-range organization of the fibers 26–32 .…”

Section: Introductionmentioning

confidence: 99%

“…The mechanical properties of the fibers were characterized both in air and immersed in water in the as spun and supercontracted states, and their short range organization was explored with the unique insight offered by 13 C solid-state NMR 32 . Both the mechanical properties and NMR characterization were compared with the data obtained from the natural fibers 23 . As shown below, this combined experimental approach allows identifying the microstructural features that may underlie the emergence of supercontraction.…”

Section: Introductionmentioning

confidence: 99%

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Emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers

Pérez‐Rigueiro

Madurga

Gañán‐Calvo

et al. 2019

Sci Rep

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The conditions required for the emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers are assessed through an experimental approach that combines the spinning of regenerated fibers with controlled properties and their characterization by 13C solid-state nuclear magnetic resonance (NMR). Both supercontracting and non-supercontracting regenerated fibers are produced using the straining flow spinning (SFS) technique from 13C labeled cocoons. The short-range microstructure of the fibers is assessed through 13C CP/MAS in air and 13C DD/MAS in water, and the main microstructural features are identified and quantified. The mechanical properties of the regenerated fibers and their microstructures are compared with those of natural silkworm silk. The combined analysis highlights two possible key elements as responsible for the emergence of supercontraction: (1) the existence of an upper and a lower limit of the amorphous phase compatible with supercontraction, and (2) the existence of two ordered phases, β-sheet A and B, which correspond to different packing arrangements of the protein chains.

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“…A combination of techniques can be applied to analyze silk samples by taking into consideration the sample format, intended outputs, and the advantages and limitations associated with each technique 38,40,46,47,51,57,59,121]. …”

mentioning

confidence: 99%

Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

McGill

Holland

Kaplan

2018

Macromol. Rapid Commun.

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Silk proteins are biopolymers produced by spinning organisms that have been studied extensively for applications in materials engineering, regenerative medicine, and devices due to their high tensile strength and extensibility. This remarkable combination of mechanical properties arises from their unique semi-crystalline secondary structure and block copolymer features. The secondary structure of silks is highly sensitive to processing, and can be manipulated to achieve a wide array of material profiles. Studying the secondary structure of silks is therefore critical to understanding the relationship between structure and function, the strength and stability of silk-based materials, and the natural fiber synthesis process employed by spinning organisms. However, silks present unique challenges to structural characterization due to high-molecular-weight protein chains, repetitive sequences, and heterogeneity in intra- and interchain domain sizes. Here, experimental techniques used to study the secondary structure of silks, the information attainable from these techniques, and the limitations associated with them are reviewed. Ultimately, the appropriate utilization of a suite of techniques discussed here will enable detailed characterization of silk-based materials, from studying fundamental processing-structure-function relationships to developing commercially useful quality control assessments.

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Effect of Water on the Structure and Dynamics of Regenerated [3-¹³C] Ser, [3-¹³C] , and [3-¹³C] Ala-Bombyx mori Silk Fibroin Studied with ¹³C Solid-State Nuclear Magnetic Resonance

Cited by 21 publications

References 82 publications

Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

Hydrothermal Effect on Mechanical Properties of Nephila pilipes Spidroin

Emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers

Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins

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