Synthesis and characterization of poly-α,β-[N-(2-hydroxyethyl)-L-aspartamide]-g-poly(glycolide) amphiphilic graft copolymers as potential drug carriers

A series of biodegradable amphiphilic graft polymers were successfully synthesized by grafting poly(glycolide) (PGA) sequences onto a water-soluble poly-α,β-N-(2-hydroxyethyl)-_L-aspartamide] (PHEA) backbone. These novel graft polymers were synthesized by the ring-opening polymerization initiated by the macroinitiator PHEA bearing hydroxyl groups without adding any catalyst. The graft polymers were characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance spectroscopy (¹H NMR), combined size-exclusion chromatography (SEC) and multiangle laser light scattering (MALLS) analysis, and differential scanning calorimetry (DSC). By controlling the feed ratio of the macroinitiator to the monomer, graft polymers with different branch lengths can be obtained. The degradation behaviors of the copolymers were studied. Based on the amphiphilicity of the graft copolymers, nanoparticle drug delivery systems were prepared by the direct dissolution method and the dialysis method, and the in vitro drug release behavior was investigated. Transmission electron microscopy (TEM) images demonstrated that these nanoparticles were regularly spherical in shape. The particle size and distribution of the nanoparticles were measured.