title: Local structure of Ca(2+) induced hydrogels of alginate-oligoguluronate blends determined by small-angle-X-ray scattering.
abstract: Short oligoguluronates, oligoG's, are reported to affect the ionotropic gelation of alginates both with respect to altered gelation kinetics and elastic properties of the resulting gels. The local structure of Ca(2+) induced changes in oligoguluronates and blends of oligoguluronates and alginates was determined by small angle X-ray scattering (SAXS). Calcium was introduced in the aqueous polysaccharide solutions by in situ release of Ca(2+) from Ca-EGTA. The scattering profiles of the Ca(2+)-induced structures in the alginate-oligoG blends were accounted for by a two-component broken rod-like model, also with an additional term representing structural inhomogeneity by a Debye-Bueche term. Adding oligoG to the alginate yields an increase in the largest cross-sectional radius in the region of fractional Ca(2+) saturation of α-l-GulA units from 0.5 to 1. The time-lapse characterization during the Ca-induced changes in the alginate-oligoG blends shows that oligoG delays the emergence of the more extensive laterally aggregated junction zones.
authors: Department of Environmental Science, Faculty of Engineering, Osaka Electro-Communication University, 18-8, Hatsu-cho, Neyagawa, Osaka 572-8530, Japan.
authors: Yoshiaki
authors: Y
authors: Yuguchi
authors: Department of Environmental Science, Faculty of Engineering, Osaka Electro-Communication University, 18-8, Hatsu-cho, Neyagawa, Osaka 572-8530, Japan.
authors: Ami
authors: A
authors: Hasegawa
authors: Biophysics and Medical Technology, Department of Physics, The Norwegian University of Science and Technology, NTNU, NO-7491 Trondheim, Norway.
authors: Anna Maria
authors: AM
authors: Padoł
authors: Department of Biotechnology, The Norwegian University of Science and Technology, NTNU, NO-7491 Trondheim, Norway.
authors: Kurt Ingar
authors: KI
authors: Draget
authors: Biophysics and Medical Technology, Department of Physics, The Norwegian University of Science and Technology, NTNU, NO-7491 Trondheim, Norway. Electronic address: bjorn.stokke@ntnu.no.
authors: Bjørn Torger
authors: BT
authors: Stokke
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; C007896:guluronic acid; D020723:Glucuronic Acid; D002118:Calcium
keywords: Alginate; Ionotropic gelation; Oligoguluronate; Small angle X-ray scattering