THE IMPORTANCE OF STANDARDIZATION OF CARBOXYMETHYLCHITIN CONCENTRATION BY THE DYE-BINDING CAPACITY OF ALCIAN BLUE BEFORE ADSORPTION ON LIPOSOMES

A new method based on the measurement of the relative dye-binding capa city of Alcian Blue to carboxymethylchitin (CMC) at various molecular weights (MW) has been developed to facilitate the standardization of t he initial polyelectrolyte concentration. In the absence of standardiz ation, non-reproducible adsorption patterns are encountered during the adsorption of the MW CMC on neutral and positively charged liposomes. This method is sensitive down to a concentration of 5 mu g/ml of poly mer in water. Static Light Scattering (SLS) measurements are used to o btain the weight average molecular weight (M(W)) and the size of the p olyelectrolyte (R(g)) and overlap concentrations (c). The M(W)s are t hen used to determine the constants K and a of the Mark-Houwink equati on which are 1.65 x 10(-2) dl/g and 0.4701, respectively, evaluated at kappa = 0.154 M, pH = 7.4 and T = 25 degrees C. The critical electrol yte concentration decreases with molecular weight for M(W)s ranging fr om 5.0 x 10(4)-1.2 x 10(6). The dye-binding capacity changes with the molecular weight distribution of the polyelectrolyte demonstrating the sensitivity of this technique to polydispersity.