Structural properties of hyaluronic acid in moderately concentrated solutions

The solution properties of hyaluronic acid having various d.p. values have been examined at physiological pH and ionic strength by light-scattering techniques at various concentrations. The angular dependence of Kc/R0 was linear at low concentrations, whereas substantial curvature was present at small angles on increasing the concentration. This phenomenon was affected by the conditions of centrifugation. Moreover, the function Kc/R0 exhibited a maximum value at concentrations of polymer inversely related to the molecular weight. The maximum concentration was always higher than the critical concentration. Ageing, molecular-weight distribution, and polymer purity influenced the light-scattering response. A model is proposed in which the polysaccharide chains intertwine at relatively low concentrations of polymer and become entangled at high concentration, eventually leading to a non-homogeneous polymer network.