Hydrodynamic characterisation of chemically degraded hyaluronic acid

Hyaluronic acid (HA) is a natural macromolecule with importance in the pharmaceutical, medical and cosmetic industries. The knowledge of its hydrodynamic properties is fundamentally important for further study on its applications. The aim of our study was to investigate and provide hydrodynamic parameters for six different molar mass samples chemically produced by depolymerisation of a high molar mass ‘parent’ HA using five different hydroxyl free radical concentrations. The main tools employed for these studies were size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS), sedimentation velocity in the analytical ultracentrifuge and intrinsic viscosity. The results indicated that values for intrinsic viscosity, molar mass and sedimentation coefficient decreased with increasing hydroxyl free radical starting concentration. The six samples investigated here also represent a homologous series of a polysaccharide thus conformational information could be obtained, and the results indicate that HA adopts a ‘stiffish’ coil conformation in solution. Where appropriate our results were compared with previously published data.