• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.299-308
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• 1976

Cerium (Ⅳ) ion-initiated graft copolymerizations of acrylamide and of acrylonitirile to silk fibroins were investigated. When acrylamide was used, the change in ceric ammonium nitrate concentration exhibited a maximum in degree of grafting at 0.01 M. Also observed was that the change in acetic acid content in reaction media gave a maximum in degree of grafting at 7% acetic acid in water. Degree of grafting was increased generally with increase in acrylamide concentration reaction time and reaction temperature. When acrylonitrile monomer was used for grafting,different results were obtained. Addition of nitric acid was more effective in enhancing the degree of grafting than the addition of acetic acid.Generally the grafting of acrylonitrile to silk fibroins was less efficient than the grafting of acrylamide. The portion of grafted silk fibroins insoluble in Lowe's reagent exhibited the IR absorption bands characteristics to both vinyl polymers and silk fibroins, indicating the grafting of vinyl monomers to silk fibroins. To examine the molecular weight of graft vinyl polymer, a sample of grafted silk was hydrolyzed by 10% sodium hydroxide. Viscosity measurements indicated that the molecular weight of the graft polymer was in the range of 105.

• 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.4
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• pp.85-95
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• 1965

This report is to observe the amino acid composition at silk fibroins among varieties by using paper chromatography method and to study how they may concern with the genetical problem and the biochemical synthesis of the fibroin in silkgland. The results reached are as follows: 1. The amino acid composition of silk fibroin among varieties were observed as similar with each other on the paper chromatogram pictures. 2. In spite of the results of the amino acid composition analysis was similar with other workers results, there was some difference among varieties in numerical analysis. 3. The amino acid composition was considered to concern somewhat with the genetic problem of silkworm. 4. Some nutritive amino acids are considered to related with the worm growth more than the silk fibroin. 5. The paper chromatography of this report showed an unknown amino acid which was not found before in specific species silk fibroin and it is imagined as Hydroxyproline in view of other worker's graphy result. 6. The biochemical synthesis mechanism of silk fibroin in the silk gland, neither Stepwise process nor Template, could stand with the results of this paper satisfactory one side.

• 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.

• KSBB Journal
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• v.24 no.5
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• pp.458-462
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• 2009

Silk fibroin is a structural protein from Bombyx mori and can be sulfated to provide biofunctional polypeptides showing antiviral and anticoagulating activities. However, the sulfated fibroins have not been characterized enough to present their compositions and structures. In this report, sulfation reaction was investigated by varying the reaction temperature and sulfuric acid concentration and analysis of the resulting peptides were carried out. The degree of sulfation was proportion to sulfuric acid concentration but the maximum product yield was obtained at $60^{\circ}C$ and 5% of sulfuric acid concentration. FT-IR spectrum, UV absorption and NMR spectrum support that o-sulfate ester was formed at the hydroxyl group of serine and tyrosine residues. Size exclusion chromatography identified that sulfated fibroin was composed of a highly hydrolyzed polypeptide mixtures and peptides of relatively higher molecular weight.

• Journal of Fashion Business
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• v.8 no.5
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• pp.31-40
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• 2004

The purpose of this study is to investigate the change of the physical properties, bending and luster properties, which are related to the touch and appearance of silk fabrics modified by the degumming process. The silk has long been known as one of the most elegant and soft textile materials. The raw silk yarn, or cocoon bave, spun from the spinneret, is rather stiff due to the sericin covering the two fibroins together. The sericin can be removed during a degumming process. The removal of the sericin would result in remarkable change in the physical properties of the raw silk fabrics, including luster of the fabrics, which process parameters could possibly be utilized to adequately control the silk fabric properties. The KES(Kawabata Evaluation System) is a testing methodology that has been used with considerable success for predicting the hand and tailorability of apparel fabrics. This study uses one of the KES, bending tester, to measure the bending properties of the silk fabrics degummed for specified period to change the physical/mechanical properties of the fabric. The KES bending measurement revealed that the bending rigidity decreased for both the warp and weft direction of the silk fabrics with the increase of the degumming period. It has been shown in this study that the some of the hand-related physical properties, including the bending rigidity, drapability, and luster, could be modified with the change in the degumming period.

• Journal of Fashion Business
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• v.14 no.6
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• pp.39-52
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• 2010

Interests in creating three-dimensionally designed fabric materials are growing rapidly in the sectors of the fashionable textiles with the creativity, new functions, and aesthetics. A number of finishing methods have been developed and proposed to add or create new functions and designs for silk fabrics. Due to the strong hydrogen bonds between the molecules of silk fibroins, the thermal treatment methods used in thermoplastic fiber processing, which can easily deform the synthetic filament fabrics to endow three-dimensional appearance to the fabrics, are not applicable to the silk fabric treatment. In order to modify the fine structure of silk fiber, neutral salt solution treatment methods have been suggested. In this study, the effect of the calcium nitrate solution on the physical and mechanical properties of silk fabrics was investigated by using the KES(Kawabata Evaluation System) equipment. Based on these findings, relationships between parameters, for example, the thickness and the compressional energy, the thickness and the compressional linearity, and the air permeability and the pore area statistical analysis were investigated. The relationships between the process parameters such as treatment temperature/time and the resulting fabric property parameters were also analyzed by using several SAS procedures.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.366-374
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• 2010

Introduction: This study evaluated the capability of silk fibroin (SF) and recombinant human bone morphogenetic protein-2 loaded SF (SF-BMP) as a bone defect replacement matrix when grafted in a calvarial bone defect of rats in vivo. Materials and Methods: A total 70 calvarial critical size defects (5.0 mm in diameter) made on 35 adult female Sprague-Dawley rats were used in this study. The defects were transplanted with (1) rhBMP-2 loaded silk fibroin graft (SF-BMP: 0.8+$10\;{\mu}g$), (2) Silk fibroin (SF: $10\;{\mu}g$), and (3) no graft material (Raw). The samples were evaluated with soft x-rays, alkaline phosphatase activity, calcium/phosphate quantification, histological and histomorphometric analysis at postoperative 4 and 8 weeks. Results: The SF-BMP group ($48.86{\pm}14.92%$) had a significantly higher mean percentage bone area than the SF group ($24.96{\pm}11.01%$) at postoperative 4 weeks.(P<0.05) In addition, the SF-BMP group ($40.01{\pm}12.43%$) had a higher % bone area at postoperative 8 weeks than the SF group ($33.26{\pm}5.15%$). The mean ratio of gray scale levels to the host bone showed that the SF-BMP group ($0.67{\pm}0.08$) had a higher mean ratio level than the SF group ($0.61{\pm}0.09$) at postoperative 8 weeks. These differences were not statistically significant.(P=0.168 and P=0.243, respectively) The ratio of the calcium and phosphate contents of the SF-BMP ($0.93{\pm}0.22$) group was lower than that of the SF ($1.90{\pm}1.42$) group at postoperative 4 weeks. However, the SF-BMP group ($0.75{\pm}0.31$) had a higher Ca/$PO_4$ ratio than the SF ($0.68{\pm}0.04$) at postoperative 8 weeks. These differences were not statistically significant.(P=0.126 and P=0.627, respectively) For the bone-specific alkaline phosphatase (ALP) activity, which is recognized as a reliable indicator of the osteoblast function, the SF-BMP ($23.71{\pm}8.60\;U/L$) groups had a significantly higher value than the SF group ($12.65{\pm}6.47\;U/L$) at postoperative 4 weeks.(P<0.05) At postoperative 8 weeks, the SF-BMP ($21.65{\pm}10.02\;U/L$) group had a lower bone-specific ALP activity than the SF group ($16.72{\pm}7.35\;U/L$). This difference was not statistically significant.(P=0.263) For the histological evaluation, the SF-BMP group revealed less inflammation, lower foreign body reactions and higher bone healing than the SF group at postoperative 4 and 8 weeks. The SF group revealed more foreign body reactions at postoperative 4 weeks. However, this immunogenic reaction decreased and the remnant of grafted material was observed at postoperative 8 weeks. For histomorphometric analysis, the SF-BMP group had a significantly longer bone length to total length ratio than those of the SF group at postoperative 4 and 8 weeks.(P<0.05) Conclusion: The rhBMP-2 loaded silk fibroin graft revealed fewer immunoreactions and inflammation as well as more new bone formation than the pure silk fibroin graft. Therefore, silk fibroin may be a candidate scaffold for tissue engineered bone regeneration.