• International Journal of Industrial Entomology and Biomaterials
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• v.20 no.2
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• pp.99-105
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• 2010

In this paper, the regenerated silk fibroins were dissolved in LiBr aqueous solution with different dissolution temperature and time, and the effects of the dissolution condition on the regeneration yield, molecular weight, wet spinnability, and electrospinnability of regenerated silk fibroin were investigated. The regeneration yield, molecular weight distribution, and wet spinnability of regenerated silk fibroin were nearly affected by the dissolution temperature and time. However, the electrospinning performance of silk fibroin was influenced by the dissolution condition implying the electrospinning of silk fibroin is more sensitive process than the wet spinning in the range tested in this study. While $25^{\circ}C$ of dissolution temperature resulted in a good electrospinnability of regenerated silk fibroin, the electrospinnability was slightly deteriorated when silk fibroin was dissolved at $60^{\circ}C$ for 6 hours. Also, though the fiber diameters of electrospun silk fibroin produced by the dissolution at $25^{\circ}C$ for 6 hours and 24 hours were 443 and 451 nm, respectively, that at $60^{\circ}C$ for 5 min was reduced to 411 nm. The fiber diameter was more decreased to 393 nm when the dissolution time increased up to 6 hours at $60^{\circ}C$.

• Journal of Sericultural and Entomological Science
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• v.45 no.2
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• pp.121-125
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• 2003

Dissolution of Antheraea pernyi silk fiber was carried out in a zinc nitrate 6 hydrate (Zn(NO$_3$)$_2$ㆍ6$H_2O$) solution with various dissolving conditions. The solubility was significantly dependent on the concentration of zinc nitrate, dissolving temperature and time. Regenerated A. pernyi silk fibroin powder was obtained through dialysis process to remove chaotropic salt. FTIR and X-ray diffractometer showed that the conformation of regenerated A. pernyi silk powder was sheet structure.

• International Journal of Industrial Entomology and Biomaterials
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• v.21 no.1
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• pp.145-150
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• 2010

The regenerated silk fibroin with various molecular weights (MW) was prepared by different dissolution condition and the effect of coagulant on the wet spinnability of the various MW silk fibroin solutions dissolved in formic acid was investigated by the observation of wet spun filament in coagulant and the measurement of maximum draw ratio. The observation on the wet spun filament in coagulation bath revealed that good fibers without bead were formed in a high MW and a very high MW silk fibroin samples. In contrast, beads were observed in the silk fibroin sample with medium MW. The maximum draw ratio of wet spun silk fibroin filament decreased with MW reduction. The decrease of maximum draw ratio in isopropanol, acetone, DMF and THF was remarkably higher than that in methanol and ethanol, indicating that the coagulant type strongly influenced the wet spinnability. The two simple evaluation methods used in this study showed complementary information for wet spinnability: (a) The observation of filament in coagulant was effective to check a continuous fiber formation and a bead formation, and (b) the maximum draw ratio measurement was useful to examine the post drawing ability related to molecular orientation.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.2
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• pp.75-80
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• 2015

The wet spinning of silk solution has attracted researchers' attention because of 1) unique properties of silk as a biomedical material and 2) easy control of the structure and properties of the regenerated silk fiber. Recently, studies have reported that different silkworm varieties produce silk with differences in the molecular weight (MW) and other mechanical properties of the regenerated silk fibroin (SF) film. In this study, we look at the effect of different Bombyx mori varieties on the wet spinning of SF. Although five regenerated SFs from different silkworm varieties have different MWs and solution viscosity, the wet spinnability and post drawing performance of regenerated SFs were not different. This result is due to low variability in the MW of the regenerated SF samples from the different silkworm varieties. In addition, unlike regenerated SF films, the mechanical properties of wet spun regenerated SF filament were not affected by silkworm variety. This result suggests that the mechanical properties of wet spun SF filament are less affected by MW than those of SF film are.

• Fibers and Polymers
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• v.2 no.2
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• pp.58-63
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• 2001

Silk fibroin (SF) was dissolved in calcium chloride/ethanol/water mixture(1/2/8 in mole ratio) at $70^{\circ}C$ for 4h. The dissolved silk fibroin was regenerated by casting the dialyzed solution into films. The films were treated with 50% aqueous solution of methanol for different times, and their antithrombogenicity was evaluated by in vivo tests. In vivo blood tests were made by a method of peripheral vein indwelling suture. It was found that the silk fibroin had a good antithrombogenicity and an absorbability even though the polymer showed foreign body reaction. Finally, the blood compatibilty of silk fibroin films which were subjected to structural change by the methoanl treatment, was examined in connection with their interfacial surface energy, and a correlation between these properties was found to be present.

• Fashion & Textile Research Journal
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• v.4 no.2
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• pp.198-202
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• 2002

Degummed silk from Bombyx mori was dissolved in 9.3M lithium bromide solution. The regenerated silk fibroin films were completely ${\alpha}$-randomcoil type as shown by x-ray diffraction and infrared spectroscopy. The structural changes in silk fibroin induced by immersion into methanol and dilute hydrochloric acid and its photo-yellowing effect was studied. The changes of crystallinity were measured by infrared spectrometer. Yellowness index caused by ultraviolet irradiation were observed as a function of the structural change on silk fibroin. On treatment with methanol, ${\alpha}$-randomcoil silk film is converted to the ${\beta}$-form structure. After the treatment of hydrochloric acid on ${\beta}$-form structure in silk induced by immersion into methanol, ${\beta}$-form in silk fibroin is partially decreased. Crystallization owing to ${\beta}$-form transition reduced the initial yellowness index by ultraviolet irradiation. A little ${\beta}$-form structure in silk fibroin increased the initial yellowness in comparison with more ${\beta}$-form structure.

• International Journal of Industrial Entomology and Biomaterials
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• v.45 no.2
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• pp.70-77
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• 2022

Wet-spun regenerated silk fibroin (RSF) fibers have been extensively studied owing to their 1) useful properties as biomaterials, including good blood compatibility and cyto-compatibility; 2) the various methods available to control the structural characteristics and morphology of the fiber, and 3) the possibility of fabricating blended fibers and new material-embedded fibers. In this study, silk nanofibrils prepared using a new method were embedded in RSF to fabricate wet-spun silk nanofibril/RSF composite fibers. Up to 2% addition of silk nanofibril, the silk nanofibril/RSF dope solution showed slight shear thinning, and the G' and G" of the dope solution were similar. However, above 3% silk nanofibril content, the viscosity of the dope solution significantly increased. In addition, shear thinning was remarkably evident, and the G' of the dope solution was much higher than the G", indicating a very elastic state. As the silk nanofibril content was increased, the wet-spun silk nanofibril/RSF composite fiber became uneven, with a rough surface, and more beaded fibers were produced. Scanning electron microscopy observations revealed that the beaded fibers were attributed to the inhomogeneous dispersion and presence of agglomerates of the silk nanofibrils. As the silk nanofibril content and RSF concentration increased, the maximum draw ratio decreased, indicating the deterioration of the wet spinnability and post-drawing performance of silk nanofibril/RSF.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.496-499
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• 1996

In order to develop the functional diet food, characteristics of chitosan and silk fibroin composite was designed. Chitosan extracted from a prawn and silk fibroin was prepared from silkworm. The silk fibroin was dissolved rapidly in the 8M LiBr at a temperature of more than 4$0^{\circ}C$. Amino acid composition of fibroin composite revealed the same pattern that of native silk fibroin and regenerated silk fibroin. Predominant amino acid of chitosan-fibroin composite contained glycine, alanine, serine, tyrosine, threonine, and glutamic acid in order. According to the basis on the infrared spectrum, chitosan-silk fibroin composite is not distinguished differents composite ratio of chitosan and silk fibroin.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.1
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• pp.183-186
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• 2011

The various molecular weight (MW) regenerated silk fibroins were prepared with different dissolution condition and the effect of MW on the gelation behavior of regenerated aqueous silk fibroin (SF) solution was investigated. The result of gelation time measurement indicated that the gelation of SF aqueous solution was accelerated by the increase of MW and SF concentration. When formic acid was added in SF aqueous solution, the gelation time of SFL and SFC30 aqueous solution showed a significant decreaseat 0.03% formic acid addition. In case of the lowest MW sample, SFC180, SF molecules became aggregated and precipitated without gelation after 28 days storage time. These findings indicate that MW control of SF can be utilized to control the gelation time of SF aqueous solution.

• Journal of Sericultural and Entomological Science
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• v.44 no.2
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• pp.87-92
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• 2002

Dissolution of Antheraea pernyi silk fiber was carried out in a zinc chloride solution with various dissolving conditions. The solubility was significantly dependent on the concentration of zinc chloride, dissolving temperature and time. The proper conditions of dissolution were found as 8 M zinc chloride, 70$^{\circ}C$ temperature and 30 min dissolving time. Regenerated A. pernyi silk fibroin powder was obtained through dialysis. FTIR and XRD showed that regenerated A. pernyi silk powder was composed of a ${\beta}$-sheet as well as an ${\alpha}$-helix conformation.