New biodegradable hydrogels based on an acryloylated polyaspartamide cross-linked by gamma irradiation

alpha, beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), a synthetic bioco mpatible macromolecule, was functionalized with glycidyl methacrylate (GMA) in order to introduce in its side chains residues having double bonds and ester groups. The copolymer (PHG), obtained from PHEA and GMA, had a degree of derivatiza tion of 29 mol%. PHG aqueous solutions are cross linked by gamma radiation at 0 degrees C either in the presence or absence of N.N'-methylenebisacryla mide (BIS) giving rise to new hydrogel systems. In both cases gelation occu rs at quite low doses (0.26 and 0.4 kGy, respectively). The obtained networ ks were characterized by FT-IR spectrophotometry which confirmed that the c ross-linking process involves the vinyl groups of the polymer chains. Swell ing measurements evidenced the high affinity of aqueous media at different pH-values towards PHG hydrogels. The sol fractions of the irradiated sample s, properly purified, were characterized by FT-IR and H-1-NMR analyses and reduced viscosity measurements. Finally, in vitro chemical or enzymatic hyd rolysis studies suggested that the prepared samples undergo a partial degra dation at pH 1 and 10 or after incubation with enzymes such as esterase, pe psin, and alpha-chymotrypsin.