Studies on the molecular parameters of cetyl pyridinium hyaluronate in alcoholic media by sedimentation, diffusion, and double refraction of flow methods are reported in this paper. Although the physicochemical characteristics of a polyelectrolyte such as hyaluronic acid depend in large measure on the extent of its dissociation, the net charge, and the solute-solvent interaction, the properties of the modified molecule were investigated to gain a new insight into the nature of the native polyelectrolyte.The recent work of Scott's2 on the preparation of quaternary ammonium salts of acid polysaccharides has prompted this investigation of such derivatives of hyaluronic acid in nonaqueous media. Cetyl pyridinium hyaluronate is insoluble in water but can be dissolved in methyl alcohol and to a lesser degree in other aliphatic alcohols.Laurent3 recently investigated some of the molecular parameters of cetyl pyridinium hyaluronate by light-scattering and viscosity measurements, using hyaluronic acid prepared from human umbilical cord. He found that the molecular weight of cetyl pyridinium hyaluronate shows an increase of SO% over the molecular weight of sodium hyaluronate and observed a decrease of almost 50% in the radius of gyration, which he explained as a contraction of the cetyl pyridinium hyaluronate molecule caused by a loss in net charge and a decrease in solvation of the hyaluronic acid molecule.
EXPERIMENTAL
Apparatus and MethodsA Spinco-Beckman analytical ultracentrifuge, having a Philpot-Svensson cylindrical lens optical system equipped with a phase plate, was used *
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