Evaluation of radius of gyration and intrinsic viscosity molar mass dependence and stiffness of Hyaluronan

Gyration radius and intrinsic viscosity molar mass dependence for Hyaluronan (HA) were investigated over a very wide range of molar masses. Nine HA samples were fractionated by size exclusion chromatography and molar mass M, gyration radius Rg and intrinsic viscosity [n] were measured by on-line multi-angle light scattering and viscometer detectors. The Rg=f(M) and [n]=f(M) power laws found indicated that while the Rg=f(M) power law was substantially linear in the whole range of molar mass explored the [n]=f(M) power law had a marked curve shape. However by dividing the whole range of molar mass into three sub-sections represented by M<100 Kg/mol, 100<M<1000 Kg/mol, and M>1000 Kg/mol the three particular [n]=f(M) power laws have been fittable with quite straight lines. The persistence length for HA derived by using both the Odijk's model (7.5 nm) and the Bohdanecky’s plot (6.8 nm) were similar. These values are congruent with a semi-stiff conformation of HA macromolecules.