New biodegradable hydrogels based on a photo-cross-linkable polyaspartamide and poly(ethylene glycol) derivatives. Release studies of an anticancer drug

The functionalization of alpha,beta -poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with glycidyl methacrylate (GMA) gives rise to a water-soluble photo sensitive copolymer PHEA-GMA (PHG). Aqueous solutions of PHG alone or in co mbination with various concentrations of poly(ethylene glycol) dimethacryla te or poly(ethylene glycol) diacrylate (PEGDA) have been exposed to a sourc e of UV rays at 313 nm in order to obtain polymeric networks. All samples h ave been prepared both as water-swellable microparticles and as gel systems . Microparticles have been characterised by Fourier transform IR spectropho tometry, dimensional analysis and swelling measurements in aqueous media mi micking biological fluids. In vitro chemical and enzymatic hydrolysis studi es showed that all the prepared samples undergo a partial degradation at pH 1, 7.4 and 10 as well as after incubation with enzymes such as esterase. T he effect of the cross-linking density on the rheological behavior of gel s ystems has also been investigated. PHG/PEGDA hydrogel is able to incorporat e, during UV-irradiation. 5-fluorouracil (5-FU), chosen as a model drug, an d to release it in simulated biological fluids, as confirmed by in vitro dr ug release studies at pH 1 and 7.4. PHG/PEGDA get containing 5-FU is able t o release this drug in a prolonged way, more slowly than a commercial ointm ent, as confirmed by in vitro studies at pH 5.5 and 7.4 using a Franz diffu sion cell system and a synthetic membrane.