Evaluation of biodegradability on polyaspartamide-polylactic acid based nanoparticles by chemical hydrolysis studies

Here, the synthesis of two graft copolymers based on α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) and poly(lactic acid) (PLA), the O-(2-aminoethyl)-O′-galactosyl polyethylene glycol (GAL-PEG-NH2) or the methoxypolyethylene glycol amine (H2N-PEG-OCH3) is described. Starting from the obtained PHEA-PLA-PEG-GAL and PHEA-PLA-PEG copolymers, polymeric nanoparticles were prepared by high pressure homogenization-solvent evaporation method.To demonstrate their biodegradability as a function of the matrix composition, a chemical stability study was carried out until 21 days by incubating systems in two media mimicking physiological compartments (pH 7.4 and pH 5.5). The degradability of both nanosystems was firstly confirmed by the reduction of the pH of the incubation medium. Moreover, the percentage yield of recovered nanoparticles show a gradual reduction while mean size increases as a function of incubation time. Degradation seems to be mainly attributed to the loss of water-soluble portions of PLA, and proceeds with greater speed at pH 5.5, than at pH 7.4 and as a function of matrix composition.