Brush-like amphiphilic copolymers based on polylactide and poly(ethylene glycol): Synthesis, self-assembly and evaluation as drug carrier

Abstract

A series of novel amphiphilic poly(poly(ethylene glycol) methacrylate)-block-poly(l-lactide)-block-poly(poly(ethylene glycol) methacrylate) (P(PEGMA)-b-PLLA-b-P(PEGMA)) copolymers were synthesized by combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). First, two α,ω-telechelic PLLA ATRP macroinitiators were prepared in two steps via ROP of l-lactide using a difunctional initiator, and subsequent reaction of the hydroxyl end groups with 2-bromoisobutyryl bromide. Then, the ATRP of poly(ethylene glycol) methacrylate was carried out using PLLA macroinitiators. The resulting brush-like triblock copolymers were characterized by 1H NMR, size exclusion chromatography and DOSY NMR. The aggregation behavior of the copolymers in aqueous medium was investigated by fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The critical aggregation concentration was in the range of 0.08–0.12 g L−1. The diameter of the nanoparticles (NPs), determined by DLS, was around 100 nm. TEM images showed that these nano-sized objects were spherical in shape. Preliminary studies with a hydrophobic model drug, namely clofazimine, exhibited that such NPs could be potential candidates for drug delivery carrier.