Polyelectrolytic behaviour of ionic polysaccharides

An important aim of physico-chemical studies on natural and synthetic ionic-polysaccharides is to help elucidate the correlations between chemical structure-conformational characteristics of such polymers and their equilibrium properties in solution. In this context, attention is being given in our laboratory to the thermodynamics of macroion-counterion interactions and of polyion-polyion interactions, including [soluble] complex formation between polysaccharide macroions and different polyampholites (e.g. proteins) in dilute aqueous solution. Our experimental approach is mainly based on the use of micro calorimetric, potentiometric, and chirooptical techniques. Polymers considered include: 1) sulfated polysaccharides (i-carrageenan, dextran sulfate); 2) glycosaminoglycans (heparins); 3) microbial polysaccharides (Xanthan, PS-10). Species listed above (sodium salts) have been characterized in water and/or aqueous NaCl solution in terms of Na+ counterion activity coefficient, heat of dilution, and heat of Cu2+ ions binding. These experiments are part of a systematic investigation on the relationship between "charge-density" along polyelectrolyte chains and (metal) ion-binding, comparing experimental