Associating Hyaluronan Derivatives: A Novel Horizon in Viscosupplementation of Osteoarthritic Joints

The association of two high‐molecular‐weight hyaluronan (HA) derivatives, namely a β ‐cyclodextrin (HA β ‐CD) and an N ‐acylurea (EDCHA), dissolved in aqueous NaCl, was studied. The weight‐average of the molecular weights ( M w ) of HA β ‐CD and of EDCHA was 185.3 and 86.8 kDa, respectively. However, the M w value determined for the equimolar mixture of the two biopolymers equaled 556.0 kDa. Similarly, the radius of gyration (dimension) Rg =80.6 nm of the above equimolar mixture was significantly greater than the values found for the single macromolecules, i.e. , 40.2 nm for HA β ‐CD and 23.8 nm for EDCHA. These data indicate that the two kinds of substituents, borne by the HA polymeric chains, form hostguest inclusion complexes resulting in polymacromolecular associates/aggregates.