Non-Newtonian properties of hyaluronic acid aqueous solution

Abstract

The systems comprising hyaluronic acid (HA) aqueous solution and acetylsalicylic a cid salt in the HA solution were studied. It was found that both systems display pseudoplastic behaviour. The viscosity (η) dependence of the shear rate (γ) of thes systems was fitted using non-linear regression, with the best accuracy achieved by the empirical formula η γ − 3 4 . The radius of equivalent spheres ( r eq) representing non-interacting, compressed macromolecular chains was calculated from the regression constant, and was plotted as a function of salt concentration. The compressing effect of the HA chains is caused by the presence of acetylsalicylic acid salt in the aqueous solution; the polymer chains change their shape into contracted structures as a result of suppressing the repulsion in the polyelectrolyte chain by adding salt counterions. At low salt concentrations, the lowest values of r eq were found if the acetylsalicylic acid salt with the highest ionic strength (magnesium salt) in the HA solution was present.