Raman spectroscopic studies of silk fibroin fromBombyx mori

Monti, Patrizia; Freddi, Giuliano; Bertoluzza, A.; Kasai, Nobutami; Tsukada, Masaru

doi:10.1002/(sici)1097-4555(199804)29:4<297::aid-jrs240>3.0.co;2-g

Cited by 155 publications

(146 citation statements)

References 12 publications

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“…In particular, the I 850 /I 830 ratio allows to study the hydrogen-bonding state of protein's tyrosine phenoxyl group-a more hydrophobic tyrosine environment (i.e., reduction of structural water in the protein) corresponds to higher I 850 /I 830 ratio (25,32). The analysis of the Amide III scattering showed a Raman shift to lower wavenumbers during the water evaporation process, which is an indication of increased β-sheet formation during the gel-solid process (26,27). The study of the I 850 /I 830 ratio during the gel-solid transition showed that the ratio increased during water evaporation, which can be considered as an indication of increased structural hydrophobicity that can be correlated with a more "crystalline" silk configuration.…”

Section: Resultssupporting

confidence: 87%

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Programming function into mechanical forms by directed assembly of silk bulk materials

Marelli

Patel

Duggan

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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We report simple, water-based fabrication methods based on protein self-assembly to generate 3D silk fibroin bulk materials that can be easily hybridized with water-soluble molecules to obtain multiple solid formats with predesigned functions. Controlling self-assembly leads to robust, machinable formats that exhibit thermoplastic behavior consenting material reshaping at the nanoscale, microscale, and macroscale. We illustrate the versatility of the approach by realizing demonstrator devices where large silk monoliths can be generated, polished, and reshaped into functional mechanical components that can be nanopatterned, embed optical function, heated on demand in response to infrared light, or can visualize mechanical failure through colorimetric chemistries embedded in the assembled (bulk) protein matrix. Finally, we show an enzyme-loaded solid mechanical part, illustrating the ability to incorporate biological function within the bulk material with possible utility for sustained release in robust, programmably shapeable mechanical formats.iomimicry draws inspiration from multiple material functions (e.g., antibacterial and antifouling, light manipulation, heat dissipation, water sequestration, superhydrophobicity, adhesiveness, and enhanced mechanical properties) to develop universal fabrication strategies to design new structural materials with utility in a variety of fields ranging from the biomedical, to the technological and architectural. Naturally occurring materials are generated through a bottom-up "generative" process that involves a nontrivial interplay of mechanisms acting across scales from the atomic to the macroscopic. In this context, the assembly of structural biopolymers, the fundamental building blocks of natural materials, leads to hierarchically organized architectures that impart unique functionality to the end material formats.Among the several structural proteins that have been studied, silk fibroin was recently shown to be suited for the generation of a number of biopolymer-based advanced material formats leveraging control of form (through sol-gelsolid transitions) and function (through material modification). The ability to generate functional materials based on water-based silk assembly is predicated on the control of the sol-gel-solid transitions of silk fibroin materials in ambient conditions. In Fig. 1A, the formation of 3D silk fibroin constructs is depicted through its dimensional hierarchy, from the nano-to the macroscales. Silk is extracted from natural sources (i.e., Bombyx mori cocoons) with a previously developed protocol (1) that yields a water suspension of the fibroin protein, where the protein molecules are organized in nanoscopic micelles (or nanoparticles) (top row of Fig. 1A), with an average diameter that changes as a function of concentration and molecular weight (Fig. S1).Control over the dynamics of water evaporation regulates silk-fibroin assembly at the molecular level and the endmaterial format properties. This has been previously observed for natural silk ...

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Section: Resultssupporting

confidence: 87%

“…1B). In particular, the study of the Raman shifts in the Amide I (1,700-1,600 cm (26)(27)(28). The interplay between silk fibroin and water during the material fabrication process was investigated through differential scanning calorimetry (DSC) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Programming function into mechanical forms by directed assembly of silk bulk materials

Marelli

Patel

Duggan

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…The water-insolubility of these silk films after water annealing (but in the absence of methanol treatment) appears to be due to the formation of a stable silk I structure. [25,26] In order to induce the silk II structure, physical shear (between glass slides), physical stretching, or methanol treatments were used. However, once the silk films had significant silk I structural content, there was no transition to silk II, even with methanol (50 %) treatment (Fig.…”

Section: Resultssupporting

confidence: 81%

Water-Stable Silk Films with Reduced β-Sheet Content

et al. 2005

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Silk fibers have outstanding mechanical properties. These fibers are insoluble in organic solvents and water, are biocompatible, and exhibit slow biodegradation in vitro and in vivo due to the hydrophobic nature of the protein and the presence of a high content of β‐sheet structure. Regenerated silk fibroin can be processed into a variety of materials normally stabilized by the induction of β‐sheet formation through the use of solvents or by physical stretching. To extend the biomaterial utility of silk proteins, options to form water‐stable silk‐based materials with reduced β‐sheet formation would be desirable. To address this need for more rapidly degradable silk biomaterials, we report the preparation of water‐stable films from regenerated silk fibroin solutions, with reduced β‐sheet content. The keys to this process are the preparation of concentrated (8 % by weight) aqueous solutions of fibroin and a subsequent water‐based annealing procedure. These new materials degrade more rapidly due to the reduced β‐sheet content, as determined in vitro via enzymatic hydrolysis, yet support human adult stem‐cell expansion in vitro in a similar or improved fashion to the crystallized proteins in film form. These new silk‐based materials extend the range of biomaterial properties that can be generated from this unique family of proteins.

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“…The amide I band appeared at 1665 cm -1 , and the amide III range showed a complex structure at 1277 and 1243 cm -1 . [28] This was a characteristic spectral pattern of SF with a prevailing silk I conformation, in good agreement with the IR results. After PPy deposition, the typical bands of PPy located at 1570 and 1324 cm -1 , assigned to C=C backbone stretching and ring-stretching were observed.…”

Section: Preparation and Characterization Of Sf-ppy Filmsupporting

confidence: 87%

Toward Biodegradable Mg–Air Bioelectric Batteries Composed of Silk Fibroin–Polypyrrole Film

Jia

Wang

Zhao

et al. 2016

Adv Funct Materials

109

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Biodegradable active implantable devices can be used to diagnose and/or treat disease and eventually disappear without surgical removal. If an "external" energy source is required for effective operation then a biocompatible and biodegradable battery would be ideal. In this study, a partially biodegradable Mg-air bioelectric battery (biobattery) is demonstrated using a silk fibroin-polypyrrole (SF-PPy) film cathode coupled with bioresorbable Mg alloy anode in phosphate buffered saline (PBS) electrolyte. PPy is chemically coated onto one side of the silk substrate. SF-PPy film shows a conductivity of ≈1.1 S cm−1 and a mild catalytic activity toward oxygen reduction. It degrades in a concentrated buffered protease XIV solution, with a weight loss of 82% after 15 d. The assembled Mg-air biobattery exhibits a discharge capacity up to 3.79 mA h cm−2 at a current of 10 μA cm−2 at room temperature, offering a specific energy density of ≈4.70 mW h cm−2. This novel partially biodegradable battery provides another step along the route to biodegradable batteries. Abstract:Biodegradable active implantable devices can be used to diagnose and/or treat disease and eventually disappear without surgical removal. If an "external" energy source is required for effective operation then a biocompatible and biodegradable battery would be ideal. In this study, a partially biodegradable Mg-air bioelectric battery (bio-battery) was demonstrated using a silk fibroin-polypyrrole (SF-PPy) film cathode coupled with bioresorbable Mg alloy anode in phosphate buffered saline (PBS) electrolyte. Polypyrrole (PPy) is chemically coated onto one side of the silk substrate. SF-PPy film shows a conductivity of ~1.1 S cm -1 and a mild catalytic activity towards oxygen reduction. It degrades in a concentrated buffered 2 protease XIV solution, with a weight loss of 82% after 15 days. The assembled Mg-air biobattery exhibit a discharge capacity up to 3.79 mA h cm -2 at a current of 10 µA cm -2 at room temperature, offering a specific energy density of ∼4.70 mW h cm -2 . This novel partially biodegradable battery provides another step along the route to biodegradable batteries.

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Raman spectroscopic studies of silk fibroin fromBombyx mori

Cited by 155 publications

References 12 publications

Programming function into mechanical forms by directed assembly of silk bulk materials

Programming function into mechanical forms by directed assembly of silk bulk materials

Water-Stable Silk Films with Reduced β-Sheet Content

Toward Biodegradable Mg–Air Bioelectric Batteries Composed of Silk Fibroin–Polypyrrole Film

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