Synthesis of amphiphilic [PEO(PCL)2] triarm star-shaped block copolymers: a promising system for in cell delivery

The paper reports on a simple method of synthesizing [PEO(PCL)2] triarm star-shaped copolymers by a combination of Michael-addition type reaction and ring-opening polymerization. A Michael-addition reaction yielded a PEO end-capped by two hydroxyl groups—a [PEO(OH)2] macroinitiator—which was used for sequential building of PCL blocks. The macroinitiator and copolymers were analyzed by FTIR, 1H NMR spectroscopy and SEC. The self-assembly behavior of the copolymers in aqueous media was studied by UV–Vis spectroscopy. The size and morphology of the obtained micelles were determined by TEM. None of the polymers had cytotoxic effects in vitro. Cellular uptake studies showed the accumulation of neutral red loaded micelles in the perinuclear area of human hepatocellular carcinoma cells revealing a cellular uptake associated with macropinocytosis and caveolae mediated endocytosis. The accumulation had a sustained effect over 3 days pointing at the potential application of the copolymers micelles as a drug delivery system.