Reducible self-assembled micelles for enhanced intracellular delivery of doxorubicin

This study developed novel reducible micelles that are approximately 100 nm in diameter and consist of poly(beta-amino ester)-graft-poly(ethylene glycol) amphiphilic copolymers (PAE) with phenylbutylamine functional side groups. Our report is unique in the following ways: (1) the reductively degradable micelles provide a safe and efficient doxorubicin intracellular delivery, (2) the synthesis procedure is a simple and mild pathway with a well-defined structure, and (3) the aromatic phenylbutylamine side groups increase hydrophobicity and strengthen the interaction with doxorubicin (DOX) to improve the drug-loading capability. In vitro, micelles exhibit faster release of DOX upon the action of dithiothreitol (DTT). Drug-laden micelles present higher cell inhibition efficiency in comparison to free doxorubicin, while the blank micelles show very low cytotoxicity. The copolymeric micelles show a rapid internalization and efficient cytoplasmic doxorubicin release in both human hepatocellular carcinoma HepG2 and human breast adenocarcinoma MCF-7 cell lines observed by confocal laser scanning microscopy (CLSM). The micelle is promising for enhanced intracellular drug delivery in tumour cells.