Sen'i Gakkaishi
Online ISSN : 1884-2259
Print ISSN : 0037-9875
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Volume 67, Issue 8
Displaying 1-10 of 10 articles from this issue
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  • Fabrication and Characterization of Poly-γ-glutamic Acid Nanofiber with the Difunctional Epoxy cross-linker
    Takeharu Tajima, Seiichiro Ueno, Naoyasu Yabu, Sachiko Sukigara
    2011 Volume 67 Issue 8 Pages 169-175
    Published: 2011
    Released on J-STAGE: September 23, 2011
    DOIhttps://doi.org/10.2115/fiber.67.169
    JOURNAL FREE ACCESS
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    Poly-γ-glutamic acid (γ-PGA) is a natural polymer that is widely recognized as a component in the viscous filaments of fermented soybean (natto). γ-PGA is known for its superior biodegradability, biocompatibility and water retention characteristics. Crosslinked γ-PGA is commonly used as hydrogel, but it is not used in the fiber form because it is soluble in water. In this study, we demonstrate the use of γ-PGA-Na with Polyethylene Glycol Diglycidyl Ether (PEGDE) for crosslinking agent to produce water insoluble γ-PGA nanofibers by electrospinning. The presence of PEGDE in electrospun γ-PGA and the crosslinking reaction of the epoxy group with γ-PGA carboxyl groups were confirmed by FTIR. We confirmed with the pulse NMR the existence of the component of long relaxation time which was not ingredient in γ-PGA. Reflecting the properties of γ-PGA, this γ-PGA/PEGDE nanofiber web showed high level of water absorption capability. The γ-PGA/PEGDE nanofiber web had the tensile properties of a level equal to skin, and elastic recovery characteristics. This nanofiber became strong by adding hydrochloric acid or more safety acid of citric acid in electrospinning solution.
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  • Colorimetric Investigation of Oxidative Dyeing Behavior on Wool Fibers
    Satomi Kuwabara, Kyohei Joko
    2011 Volume 67 Issue 8 Pages 176-184
    Published: 2011
    Released on J-STAGE: September 23, 2011
    DOIhttps://doi.org/10.2115/fiber.67.176
    JOURNAL FREE ACCESS
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    A colorimetric investigation was performed on the analysis of the color of wool substrates dyed by the reaction between p -aminophenol(pAP) or p -phenylenediamine(pPDA) and p -amino- o -cresol (pAOC) in the presence of hydrogen peroxide and in media at different pH values. In particular, it was investigated the L ∗ a ∗ b ∗ color variations, namely the reflectance of the formed color, that take place on the wool in dependent on different reaction conditions. The oxidation of a mixture of pAP or pPDA and pAOC results in the formation of an orange-red indo-phenol and a bluish purple indo-aniline, respectively. From the color changes with increasing dyeing time in the a ∗ b ∗ diagram and the L ∗ C ∗ diagram, it was found that the dyed fabrics changed dark shades at longer dyeing time, suggesting that these oxidative dyes formed easily the molecular aggregates with increasing dyeing time. Furthermore, in the case of pPDA/ pAOC binary mixture, the obtained reflectance curves of the dyed wool fabrics indicated the presence of indo-dyes produced by the self coupling of pPDA. The rate of an amount of uptake of self coupling dyes increased largely, with decreasing pH, over the pH range 8 to 10. Although one has been believed that the diamines and monoimines produced from pPDA and pAP, respectably, react preferentially with pAOC to produce indo-dyes which adsorbed into fibers over the pH range 8 to 10, these colorimetric results obtained for the both dyeing system suggested that the oxidative reaction occurred in the solution contacted with the fiber surface included the self coupling reaction considered negligible in the bulk solution.
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  • Evaluation of Bioactivity and Effect of Polymeric Stabilizers During Heat Treatment for the Unfolded Fraction of Human Epidermal Growth Factor
    Akon Higuchi, Jen-Hao Lee, Yu Wang, Wen-Yih Chen, Qing-Dong Ling, Yung ...
    2011 Volume 67 Issue 8 Pages 185-191
    Published: 2011
    Released on J-STAGE: September 23, 2011
    DOIhttps://doi.org/10.2115/fiber.67.185
    JOURNAL FREE ACCESS
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    A method independent of the use of radioisotope monomers such as [ 3 H]-thymidine was developed to evaluate the bioactivity of human epidermal growth factor (hEGF). Briefly, DNA synthesis of fibroblasts in hEGF- containing culture medium was evaluated via cell cycle experiments using flow cytometry ; the DNA synthesis ratio was used to evaluate the bioactivity of hEGF. The unfolded fraction of hEGF, a physical parameter, was also evaluated by circular dichroism measurements. The hEGF with a higher unfolded fraction showed less bioactivity than hEGF from fibroblasts. There was a good relationship between the bioactivity of hEGF (i.e., DNA synthesis ratio) and the evaluated physical parameter of hEGF (i.e., unfolded fraction). The stability of hEGF solution containing several polymeric stabilizers during heat treatment was also determined by physical evaluation of the unfolded fraction and by bioactivity measurement of the DNA synthesis ratio. Heparin and a low molecular weight chemical of mannitol were effective stabilizers of hEGF during heat treatment.
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