Structural elucidation of hyaluronic acid gels after heat sterilisation

The influence of heat sterilisation and hyaluronic acid (HA) concentration on the micro- and macrostructure of HA hydrogels was investigated. HA hydrogels of different concentrations were prepared and heat sterilised. The microstructures of the polymer gels were characterised by positron annihilation lifetime spectroscopy (PALS) based on their ortho-positronium lifetime values and distributions, while their macrostructures were characterised by rheological measurements. As expected, the heat sterilisation modified both the micro- and macrostructures of the gels. The HA concentration was also observed to influence the hydrogel structure. At a concentration of 7.5 mg/ml HA, the thermal treatment did not cause significant microstructural changes, and the viscoelastic properties of the treated gels were similar to those of the untreated samples.