Crosslinking of cellulose derivatives and hyaluronic acid with water-soluble carbodiimide

Hydrogels with good mechanical stability are generally obtained by chemical crosslinking. However, the compounds used as crosslinking agents are often highly toxic, and thus they are not recommended as starting materials in view of an environmentally safe production process and a biocompatible product. In this work chemically crosslinked superabsorbent hydrogels have been synthesized from water solutions of hydroxyethylcellulose (HEC), carboxymethylcellulose sodium salt (CMCNa) and hyaluronic acid (HA), using a non-toxic water-soluble carbodiimide (WSC) as crosslinking agent. Sorption capacity both in water and in water solutions at different ionic strength has been investigated, taking into account the effect of different chemical compositions. Moreover, uniaxial compression tests and dynamic-mechanical measurements on water swollen samples have been performed to probe the elastically effective degree of crosslinking of the polymeric network. In vivo tests on humans for the application of this material as a bulking agent in dietary regimes are in process and preliminary results are encouraging.