Anisotropic Structure of Calcium-Induced Alginate Gels by Optical and Small-Angle X-ray Scattering Measurements

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• 作者：Yasuyuki Maki ; Kei Ito ; Natsuki Hosoya ; Chikayoshi Yoneyama ; Kazuya Furusawa ; Takao Yamamoto ; Toshiaki Dobashi ; Yasunobu Sugimoto ; Katsuzo Wakabayashi
• 刊名：Biomacromolecules
• 出版年：2011
• 出版时间：June 13, 2011
• 年：2011
• 卷：12
• 期：6
• 页码：2145-2152
• 全文大小：944K
• 年卷期：v.12,no.6(June 13, 2011)
• ISSN：1526-4602

文摘

It was more than 50 years ago that an appearance of birefringence in alginate gels prepared under cation flow was reported for the first time, however, the anisotropic structure of the alginate gel has not been studied in detail. In the present study, anisotropic Ca-alginate gels were prepared within dialysis tubing in a high Ca²⁺-concentration external bath, and optical and small-angle X-ray scattering (SAXS) measurements were performed to characterize the structure of the gel. The observations of the gel with crossed polarizers and with circular polarizers revealed the molecular orientation perpendicular to the direction of Ca²⁺ flow. Analyses of the SAXS intensity profiles indicated the formation of rod-like fibrils consisting of a few tens of alginate molecules and that the anisotropy of the gel was caused by the circumferential orientation of the large fibrils. From the observed asymmetric SAXS pattern, it was found that the axis of rotational symmetry of the anisotropic structure was parallel to the direction of Ca²⁺ flow. The alignment factor (A_f) calculated from the SAXS intensity data confirmed that the orientation of the fibrils was perpendicular to the direction of Ca²⁺ flow.