Intelligent polymeric micelles from functional poly(ethylene glycol)-poly(amino acid) block copolymers

This review describes our recent efforts on the design and preparation of intelligent polymeric micelles from functional poly(ethylene glycol)-poly(amino acid) (PEG-PAA) block copolymers. The polymeric micelles feature a spherical sub-100 nm core-shell structure in which anticancer drugs are loaded avoiding undesirable interactions in vivo. Chemical modification of the core-forming block of PEG-PAA with a hydrazone linkage allows the polymeric micelles to release drugs selectively at acidic pH (4-6). Installation of folic acids on the micelle surface improves cancer cell-specific drug delivery efficiency along with pH-controlled drug release. These intelligent micelles appear to be superior over classical micelles that physically incorporate drugs. Studies showed both controlled drug release and targeted delivery features of the micelles reduced toxicity and improved efficacy significantly. Further developments potentiate combination delivery of multiple drugs using mixed micelles. Therefore clinically relevant performance of the polymeric micelles provides a promising approach for more efficient and patient-friendly cancer therapy. (C) 2009 Elsevier B.V. All rights reserved.