Self-assembly of regenerated silk fibroin from random coil nanostructures to antiparallel β-sheet nanostructures

Centrifugal spinning converts the conformation of silk fibroin from random coil to β-sheet more easily than electrospinning, which results in fiber differences on secondary structures, orientation and thermal properties.

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Effect of Solvent on the Characteristics of Electrospun Regenerated Silk Fibroin Nanofibers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.342-343.813 ◽

2007 ◽

Vol 342-343 ◽

pp. 813-816 ◽

Cited By ~ 13

Author(s):

Lim Jeong ◽

Kuen Yong Lee ◽

Won Ho Park

Keyword(s):

Secondary Structure ◽

Formic Acid ◽

Silk Fibroin ◽

Structural Changes ◽

Effective Means ◽

Electrospun Nanofibers ◽

Random Coil ◽

Regenerated Silk Fibroin ◽

Silk Fibroin Nanofibers ◽

Β Sheet

Nonwoven nanofiber matrices were prepared by electrospinning a solution of silk fibroin (SF) dissolved either in formic acid or in 1,1,1,3,3,3-hexafluoro-2-isopropyl alcohol (HFIP). The mean diameter of the electrospun nanofibers prepared from SF dissolved in formic acid was 80 nm with a unimodal size distribution, which was smaller than those prepared from HFIP (380 nm). SF nanofibers were then treated with an aqueous methanol solution, and structural changes due to solvent-induced crystallization of SF were investigated using IR and 13C solid-state CP/MAS NMR spectroscopy. SF nanofibers prepared from formic acid were found to have a higher proportion of β-sheet conformations than those prepared from HFIP. Methanol treatment provided a fast and effective means to alter the secondary structure of both types of SF nanofibers from a random coil form to a β-sheet form. As demonstrated in the present study, this approach to controlling the dimensions and secondary structure of proteins using various solvents may be useful for the design and tailoring of materials for biomedical applications, especially for tissue engineering applications.

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Effect of Concentration on Structure and Properties of Concentrated Regenerated Silk Fibroin Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.311-313.1653 ◽

2011 ◽

Vol 311-313 ◽

pp. 1653-1656 ◽

Cited By ~ 1

Author(s):

Fang Xie ◽

Hao Liang

Keyword(s):

Silk Fibroin ◽

Conformational Transition ◽

Random Coil ◽

Scanning Calorimetry ◽

Regenerated Silk Fibroin ◽

Lower Temperature ◽

Α Helix ◽

Β Sheet ◽

Dsc Curves ◽

Fibroin Solution

The thermal properties and rheological behavior of concentrated regenerated silk fibroin aqueous solution from 15% to 37% was investigated by differential scanning calorimetry (DSC) and rheometer. Also the conformation of solutions was characterized by Raman spectra. It was discovered that the major endothermic peak in the DSC curves shifted toward the lower temperature region with increasing the concentration. This behavior suggests increasing the concentration can accelerate conformational transition of silk fibroin from random coil and α-helix to β-sheet structure. In addition, it was found that the viscosity of solution increased with increasing concentration in favor of spinning.

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SILK FIBROIN FILMS CRYSTALLIZED BY MULTIWALLED CARBON NANOTUBES

International Journal of Modern Physics B ◽

10.1142/s0217979208047456 ◽

2008 ◽

Vol 22 (09n11) ◽

pp. 1807-1812 ◽

Cited By ~ 4

Author(s):

H.-S. KIM ◽

W.-I. PARK ◽

Y. KIM ◽

H.-J. JIN

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Multiwalled Carbon Nanotubes ◽

Silk Fibroin ◽

Composite Films ◽

Tensile Modulus ◽

Multiwalled Carbon ◽

Regenerated Silk Fibroin ◽

Silk Films ◽

Β Sheet

Silk films prepared from regenerated silk fibroin are normally stabilized by β-sheet formation through the use of solvents (methanol, water etc.). Herein, we report a new method of preparing water-stable films without a β-sheet conformation from regenerated silk fibroin solutions by incorporating a small amount (0.2 wt%) of multiwalled carbon nanotubes (MWCNTs). To extend the biomaterial utility of silk proteins, forming water-stable silk-based materials with enhanced mechanical properties is essential. Scanning electron microscopy and transmission electron microscopy were used to observe the morphology of the MWCNT-incorporated silk films. The wide-angle X-ray diffraction provided clear evidence of the crystallization of the silk fibroin induced by MWCNT in the composite films without any additional annealing processing. The tensile modulus and strength of the composite films were improved by 108% and 51%, respectively, by the incorporation of 0.2 wt% of MWCNTs, as compared with those of the pure silk films. The method described in this study will provide an alternative means of crystallizing silk fibroin films without using an organic solvent or blending with any other polymers, which may be important in biomedical applications.

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Fabrication and Characterization of Vitamin E TPGS Loaded Silk Fibroin/Hyaluronic Acid Nanofibrous Scaffolds

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.721.274 ◽

2013 ◽

Vol 721 ◽

pp. 274-277

Author(s):

Li Li Ji ◽

Qiao Ling Li ◽

Zeng Hu Yang ◽

Wei Jing Hu ◽

Kui Hua Zhang

Keyword(s):

Hyaluronic Acid ◽

Vitamin E ◽

Silk Fibroin ◽

Ethanol Vapor ◽

Random Coil ◽

Burst Release ◽

Nanofibrous Scaffolds ◽

Vitamin E Tpgs ◽

Polyethylene Glycol 1000 ◽

Β Sheet

Vitamin E d-alpha-tocopheryl polyethylene glycol 1000 succinate (VE TPGS) loaded silk fibroin (SF)/ hyaluronic acid (HA) nanofibrous scaffolds were fabricated by means of electrospinning to biomimic the natural extracellular matrix. Scanning electronic microscopy (SEM) results indicated that electrospun VE TPGS loaded SF/HA nanofibers were ribbon-shaped, the width of nanofibers decreased slightly with the addition of VE TPGS to SF/HA blended solutions. Fourier transform infrared (FTIR) spectroscopy and Wide-angle X-ray diffraction (WAXD) curves revealed that VE TPGS did not induce SF conformation from random coil to β-sheet. SF conformation converted from random coil to β-sheet after being treated with 75% ethanol vapor. In vitro release studies confirmed VE TPGS had no obvious burst release and present good release behavior.

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Research on Structure and Property of Silk Fibroin Modified Viscose Fiber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.175-176.176 ◽

2011 ◽

Vol 175-176 ◽

pp. 176-180

Author(s):

Hui Ying Wu ◽

Bao Qi Zuo

Keyword(s):

Amino Acid ◽

Silk Fibroin ◽

Amino Acid Content ◽

Longitudinal Section ◽

Decomposition Temperature ◽

Viscose Fiber ◽

Random Coil ◽

Wet Strength ◽

Structure And Property ◽

Β Sheet

Silk fibroin modified viscose fiber (SFVF) was a new fiber with silken handling and luster, which was produced via adding silk fibroin (SF) during the viscose process. In this paper, a series of testing had been done to study the structure and properties of SFVF. The amino acid content of SFVF was measured by HITACHI-835-50 amino acid tester. The morphology, structure, thermal and mechanical property of SFVF were characterized by SEM, FTIR, DSC and electronic strength tester. The results indicated that SFVF consisted of many kinds of amino acids compared with pure viscose fiber (VF) yarn. The results of SEM showed more continuous multi fine slots existed in the longitudinal section of SFVF than in that of VF, demonstrating that wet permeability and vapor transmission could be enhanced for the SFVF to certain extent. Results from FTIR indicated that the secondary structure of SFVF was mainly β-sheet and random coil, and its absorption peaks were 1616cm-1 and 1644 cm-1 respectively. The DSC curve shown the thermal decomposition temperature of SFVF was about 328.39°C, which was close to that of VF. It suggested that the SF modification had no obvious influence on thermal stability of VF. At last, the dry-strength and wet-strength of SFVF was close to that of VF. Therefore, the application of VF would be expanded with the SF modification.

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Effect of pH on the Conformational Transition of Silk Fibroin in Aqueous Solution Monitored by Thioflavin-T Fluorescence

10.21203/rs.3.rs-699204/v1 ◽

2021 ◽

Author(s):

Ben Jia ◽

Lan Jia ◽

Jingxin Zhu

Keyword(s):

Aqueous Solution ◽

Secondary Structure ◽

Silk Fibroin ◽

Conformational Transition ◽

Thioflavin T ◽

Random Coil ◽

Fluorescence Dye ◽

Assembly Behavior ◽

Β Sheet

Abstract In this work, the potential application of the fluorescence dye Thioflavin-T (ThT), which can specifically bind to amyloid, as a powerful tool for monitoring secondary structure transitions of silk fibroin (SF) induced by pH was examined. Results showed that ThT emission intensities substantially increased when pH decreased from 6.8 to 4.8. This increase may be due to conformational transitions from random coil to β-sheet. The morphology and secondary structure of SF were also investigated via TEM, AFM and circular dichroism spectroscopy. The information obtained herein can be utilized not only for the development of convenient and efficient noninvasive method for monitoring the assembly behavior of SF in aqueous solution but also for in vitro fluorescence imaging.

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Comparison of Porosity Improvement of Silk Fibroin Membrane Using Polyethylene Glycol and Glutaraldehyde for Increasing Oxygen Permeability

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.750-752.1601 ◽

2013 ◽

Vol 750-752 ◽

pp. 1601-1608

Author(s):

Pacharawan Ratanasongtham ◽

Ruangsri Watanesk ◽

Surasak Watanesk

Keyword(s):

Polyethylene Glycol ◽

Silk Fibroin ◽

Oxygen Permeability ◽

Porous Membrane ◽

Swelling Behavior ◽

Random Coil ◽

Environmental Friendliness ◽

Ft Ir ◽

Water Swelling ◽

Β Sheet

Biomaterial is one of the good candidates for porous membrane preparation according to its environmental friendliness. In this work, the porous membranes of silk fibroin (SF) were prepared by solution casting with the addition of polyethylene glycol (PEG) and glutaraldehyde (GTA) aiming to improve the porosity and oxygen permeability of SF membrane. The conformation of SF was changed from random coil to β sheet form after treatment with MeOH. The interaction existing between SF chains and both PEG and GTA were characterized using Fourier Transform Infrared spectroscopy (FT-IR). The addition of PEG could produce more porosity in the membrane than GTA confirmed by their morphology observed from scanning electron microscopy (SEM). Moreover, the swelling behavior of the SF-PEG and SF-GTA membranes depended on the porous structure of the membrane which directly correlated to their oxygen permeability. The porosity of the SF membranes increased with the increase of PEG and GTA contents up to 40% and 3%w/w, respectively. After that, their porosity decreased as seen through the SEM and water swelling results. In addition, the SF-PEG membrane turned out to have higher degrees of both porosity and oxygen permeability than the SF-GTA membrane which related to its water swelling behavior.

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Raman Spectroscopic Investigation of the Denaturation Process of Silk Fibroin

Applied Spectroscopy ◽

10.1366/0003702894203525 ◽

1989 ◽

Vol 43 (7) ◽

pp. 1269-1272 ◽

Cited By ~ 36

Author(s):

Siding Zheng ◽

Guanxian Li ◽

Wenhuo Yao ◽

Tongyin Yu

Keyword(s):

Raman Spectroscopy ◽

Silk Fibroin ◽

Conformational Transition ◽

Transition Process ◽

Random Coil ◽

Helical Conformation ◽

Extension Rate ◽

Α Helix ◽

Β Sheet ◽

Denaturation Process

The mechanical denaturation process of silk fibroin is examined by Raman spectroscopy. The fresh silk fibroins from the middle gland of mature silkworms are drawn to various ratios on a tensile tester ( R = ldrawn/ linitial, where l is length) and their conformations are measured with Raman spectroscopy. Undrawn silk fibroin is mainly in the random coil structure with some α-helical conformation, the characteristic bands appearing at 1252 and 1660 (random coil) and at 942, 1106, and 1270 cm−1 (α-helix). When the samples are drawn up to R = 4 at an extension rate of 500 mm/min, two peaks at 1233 cm−1 (the amide III band) and 1085 cm−1 appear; it is shown that the β-sheet conformation is then formed. With an increase in drawing ratios, the intensities of these β-sheet bands increase and those of the random coil and α-helical bands decrease gradually. These changes indicate that, under the action of stress, the conformation of fibroin is altered from random coil and α-helix to β-sheet structures. This result is quite similar to the results achieved by the spinning of the silkworm. The effect of the water content in liquid silk on this conformational transition process is revealed and discussed.

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