Trivalent metal-mediated gelation of novel supergiant sulfated polysaccharides extracted from Aphanothece stagnina

• Published in: Colloid and polymer science Vol. 290; no. 2; pp. 163 - 172
• Main Authors: le Nguyen, Quyen Thi, Okajima, Maiko, Mitsumata, Tetsu, Kan, Kai, Tran, Hang Thi, Kaneko, Tatsuo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 2012; Springer; Springer Nature B.V
• Subjects: Applied sciences; Bacteriology; Biological and medical sciences; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Exact sciences and technology; Food Science; Fundamental and applied biological sciences. Psychology; Microbiology; Morphology, structure, chemical composition; Nanotechnology and Microengineering; Natural polymers; Original Contribution; Physical Chemistry; Physicochemistry of polymers; Polymer Sciences; Soft and Granular Matter; Starch and polysaccharides; Polysaccharides; Gel beads; Metal binding property; Cyanobacteria; Complexation; Molecular structure; Gelation; Metal ion; Experimental study; Solvent extraction; Polyelectrolyte; Microbial origin; Organic sulfate; Bacteria; Oside polymer; Trivalent cation; Hydrogel; Aqueous solution
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-011-2528-3

Anionic polysaccharide (PS) was extracted from
Aphanothece stagnina
biomaterials where trivalent metal ions were remarkably condensed from environmental water. Structural analyses indicated that the PS was considered to be a kind of sulfated rhamnoglucan-containing uronic acid at a composition of 23 mol% and that the total composition of anionic groups such as sulfate and carboxylate was 31 mol% to the monosaccharide residues. Since the PS was found to be a huge macromolecule with an ultra-high molecular weight (3.14 × 10
7
 g/mol), the simple calculation indicated that about 9.5 × 10
4
anions exist on one chain of the PS. The electric conductivity of the highly anionic PS solutions indicated that the metal ions such as Ga
3+
, La
3+
, and Ca
2+
complexed ionically with PS chains. The PS formed the gels as a result of trivalent metal complexation, but the gelation behavior of the PS was different from that of the representative metal-complexable polysaccharide, alginate, in terms of the minimum gel formation concentration and the average molecular weight between cross-linking points.
Figure