Nanoparticles based on novel amphiphilic polyaspartamide copolymers

In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without using surfactants or stabilizing agents, is described. These copolymers were obtained starting from alpha,beta-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG(2000)) were functionalized with poly(lactic acid) (PLA) through 1,1'-carbonyldiimidazole (CDI) activation to obtain PHEA-PLA and PHEA-PEG(2000)-PLA graft copolymers, respectively. These copolymers were properly purified and characterized by (1)H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that derivatization reactions occurred. Nanoparticles were obtained from PHEA-PLA and PHEA-PEG(2000)-PLA graft copolymers by using the high pressure homogenization-solvent evaporation method, avoiding the use of surfactants or stabilizing agents. Polymeric nanoparticles were characterized by dimensional analysis, before and after freeze-drying process, and Scanning Electron Microscopy (SEM). Zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) analysis demonstrated the presence of PEG and/or PHEA onto the PHEA-PEG(2000)-PLA and PHEA-PLA nanoparticle surface, respectively.