Formation and properties of polyelectrolyte complexes of chitosan hydrochloride and sodium dextransulfate

Methods of potentiometry, turbidimetry, colorimetry, IR spectroscopy, and element analysis were used to investigate the conditions of formation and the properties of non-stoichiometric polyelectrolyte complexes of chitosan hydrochloride (CHC) and sodium dextransulfate (the molecules of both polysaccharides appear as semirigid chains, but their charges are opposite). It was determined that the complexes' formation of polyelectrolytes studied is predominantly electrostatic in the presence of urea. As was also found turbidity and stability of the polycomplexes solutions depended markedly on pH value of CHC and a nature of the low-molecular-weight salts added. The complexes obtained were soluble in water, aqueous urea, and water-organic mixtures. The extent of solubility depended on the composition of the complexes and could be influenced by addition of appropriate concentrations of certain low-molecular-weight salts. (C) 2002 Elsevier Science Ltd. All rights reserved.