Molecular characterization of two host–guest associating hyaluronan derivatives

Molecular characteristics were determined of two high-molecular-weight water-soluble hyaluronan derivatives, namely beta-cyclodextrin (HA-beta-CD) and N-acylurea (EDC-HA). The weight-average molecular weight (M(w)) of HA-beta-CD and of EDC-HA, determined with a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system, was respectively 185.3 and 86.8 kDa. However the M(w) value determined for the equimolar mixture of the two HA derivatives equaled 556.0 kDa. Similarly, the gyration radius of the above equimolar mixture, Rg = 80.6 nm, was significantly greater than the values found for the single HA derivative, i.e. 40.2 nm for HA-beta-CD and 23.8 nm for EDC-HA. These data indicate that the two kinds of substituents, bound to the polymeric chains, form host-guest/inclusion complexes resulting in polymacromolecular associates/aggregates.