Structural Properties of Colloidal Complexes between Condensed Tannins and Polysaccharide Hyaluronan

Abstract

Interactions of plant tannins with polysaccharide hyaluronan are studied by means of light scattering and small-angle X-ray scattering (SAXS). In this paper, we show that (1) the tannin–polysaccharide complexes remain stable in colloidal suspension; (2) the masses and structures of colloidal tannin–polysaccharide objects depend on the tannin degree of polymerization; and (3) the densities of tannin–polysaccharide aggregates are about 7 times lower than the density of a single solvated polysaccharide molecule. Short tannins and polysaccharides are aggregated in loose oligomeric structures whose sizes are comparable to a single polysaccharide molecule. Tannins longer than 10 nm and polysaccharides are aggregated in larger microgel-like particles whose sizes exceed 200 nm.