Pegylated nanoparticles based on a polyaspartamide. Preparation, physico-chemical characterization and intracellular uptake

Nanoparticles with different surface PEGylation degree were prepared by using as starting material R,â-poly(N-
2-hydroxyethyl)-D,L-aspartamide (PHEA). PHEA was functionalized with a PEG amino-derivative for obtaining
PHEA-PEG2000 copolymer. Both PHEA and PHEA-PEG2000 were derivatized with methacrylic anhydride (MA)
for obtaining poly(hydroxyethylaspartamide methacrylated) (PHM) and poly(hydroxyethylaspartamide methacrylated)-
PEGylated (PHM-PEG2000), respectively. Nanoparticles were obtained by UV irradiation of an inverse
microemulsion, using as internal phase an aqueous solution of PHM alone or of the PHM/PHM-PEG2000 mixture
at different weight ratio and as external phase a mixture of propylene carbonate and ethyl acetate. Obtained
nanoparticles were characterized by FT-IR analysis, dimensional analysis, and TEM micrography. XPS analysis
and zeta potential measurements demonstrated the presence of PEG onto the nanoparticle surface. Moreover, the
partial degradation of nanoparticles in the presence of esterase as a function of time was demonstrated. Finally,
nanoparticles did not possess any cytotoxic activity against K-562 cells and were able to escape from phagocytosis
depending on the surface PEGylation degree.