Characterization of Aqueous Hyaluronate Solutions using Static and Quasielastic Light Scattering*

Human vitreous humor contains a hydrogel made up of a network
of dilute collagen and hyaluronic acid. Liquefaction of the vitreous gel with age and in other conditions has been associated with retinal pathologies.
We use static and quasielastic light scattering to study the osmotic compressibility and local dynamics of aqueous hyaluronate solutions, in preparation for studying model vitreous gels. Buffered solutions prepared from commercial sodium hyaluronate were filtered to minimize light scattering heterogeneity. Refractometry was used to assess sample concentration post-filtration. Excess Rayleigh ratios from cleaned low-concentration samples gave molecular weights compatible with manufacturer's data. Higher concentration data give osmotic compressibilities that indicate repulsive intermolecular interactions, which we compare with theoretical models. At all concentrations, quasielastic light intensity autocorrelation functions show two well-separated slower decays and a faster decay. With increasing concentration, the slow component that has a characteristic decay time of tens of microseconds becomes faster as concentration increases, while the slowest component becomes more prominent.