Anisotropic structure of calcium-induced alginate gels by optical and small-angle X-ray scattering measurements

Yasuyuki Maki, Kei Ito, Natsuki Hosoya, Chikayoshi Yoneyama, Kazuya Furusawa, Takao Yamamoto, Toshiaki Dobashi, Yasunobu Sugimoto, Katsuzo Wakabayashi

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Abstract

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 (Af) calculated from the SAXS intensity data confirmed that the orientation of the fibrils was perpendicular to the direction of Ca2+ flow.

Original languageEnglish
Pages (from-to)2145-2152
Number of pages8
JournalBiomacromolecules
Volume12
Issue number6
DOIs
Publication statusPublished - Jun 13 2011
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Maki, Y., Ito, K., Hosoya, N., Yoneyama, C., Furusawa, K., Yamamoto, T., ... Wakabayashi, K. (2011). Anisotropic structure of calcium-induced alginate gels by optical and small-angle X-ray scattering measurements. Biomacromolecules, 12(6), 2145-2152. https://doi.org/10.1021/bm200223p