Network formation of low molecular weight hyaluronic acid derivatives

The oscillatory and steady shear rheological properties of the benzyl esters of hyaluronic acid (HA), partially esterified (Hyaff 11p50), at low molecular weight (150 kDa) were evaluated and compared to the properties of HA at the same molecular weight. At concentrations up to 40 mg cm(-3) both Hyaff 11p50 solutions and HA solutions, behaved as viscous fluids. At higher concentrations, HA ester solutions exhibited an elastic response typical of weak gels, whereas HA exhibited a viscous behaviour. A solid-like response was also observed by lowering the temperature. These results indicate that hyaluronic acid ester solutions can form a weak gel network. The rheological properties of HA derivatives changed significantly compared to HA solutions. The improved elasticity and residence times of these solutions expand the possible applications of hyaluronic acid in the biomedical field.