α,β-Poly(N-Hydroxyethyl)-DL-Aspartamide Hydrogels as Drug Delivery Devices

α,β-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) was exposed to gamma radiation to obtain micromatrices able to swell in an aqueous medium. Crosslinked PHEA was loaded with an anti-inflammatory drug, 4-biphenylacetic acid (BPAA) and the drug dispersion in the network was investigated by X-ray analysis. The BPAA loaded PHEA microparticles were also characterized by dimensional analysis, which showed the presence of quasispherical shapes. The drug release from PHEA hydrogel was studied in vitro in a pH 1.1 (simulated gastric juice) and in a pH 7.4 buffer solution, respectively. The experimental data indicate that an anomalous delivery occurs, but Fickian diffusion through swollen PHEA hydrogel seems to be the predominant release mechanism. The interactions between PHEA microparticles and dimyristoil-phosphatidylcholine (DMPC) liposomes, chosen as biomembrane model, were studied by a differential scanning calorimetry (DSC) technique. The calorimetric results show that the cross-linked PHEA network does not interact with the DMPC liposomes.