Polyelectrolyte Complexes of Chitosan with Sodium Carboxymethyldextran

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Abstract
Mixing of chitosan with sodium carboxymethyldextran having opposite charge gave rise to the formation of novel water-insoluble precipitates. The mole ratios of N/COO− in the polyelectrolyte complexes thus prepared were estimated to be 0.248–1.658. It was found that pH, mole ratio of N/Na and the order of mixing play an important role in determining the composition ratio of N/COO− in the polyelectrolyte complexes. IR spectroscopic studies, blood clotting test, elementary analyses, the color reaction with Toluidine Blue and studies on solubility of polyelectrolyte complexes revealed that there is no noticeable interactions between –COOH groups and –OH groups. However, the –NH3+ groups in chitosan participate in the binding with carboxymethyldextran, probably through its –COO− groups, in the polyelectrolyte complexes. It seems that the number of binding sites between –NH3+and -COO− groups in the polyelectrolyte complexes at pH 3.0 is smaller than those prepared at pH 6.5. Both the polyelectrolyte complexes prepared at pH 3.0 and 6.5 suppressed the coagulation of blood. This anti-thrombogenic property should be related to elution of anti-thrombogenic carboxymethyldextran.