Ultraviolet-Induced Cross-Linking of a Functionalized Polyaspartamide Carrying Ester Groups

Abstract

New biodegradable hydrogels were obtained by a simple UV irradiation method in two steps. The first step involved functionalization of α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), a synthetic water-soluble biocompatible polymer, with glycidyl methacrylate (GMA) to introduce side chain reactive double bonds and ester groups. The obtained copolymer PHEA-GMA (PHG), contained 29 mol% GMA residues. The second step involved cross-linking this copolymer by UV irradiation at 313 nm to form hydrogel microparticles which were characterized by FTIR spectrophotometry, particle size distribution analysis and differential scanning calorimetry. Swelling measurements at different pH values indicated a high water affinity by these hydrogels. In vitro chemical and enzyme hydrolysis studies showed that the hydrogels were partially hydrolyzed both at pH 1 and pH 10 by enzymes such as, esterase, pepsin and α-chymotripsin, The processes occurring during UV irradiation were characterized by FTIR and 1 H-NMR and rheological analyses.