ABC block copolymer as “smart” pH-responsive carrier for intracellular delivery of hydrophobic drugs

Amphiphilic triblock copolymer of poly(ethylene glycol)-block-poly(dimethylaminoethyl methacrylate)-block-poly(ε-caprolatone) (PEG-PDMA-PCL) was synthesized using a one-pot sequential oxyanionic polymerization of DMA and ε-CL, associated with a PEG-O−K+ macroinitiator. The pH-responsive micellization behavior of the copolymer was studied using dynamic light scattering (DLS), steady-state fluorescence and TEM techniques. The anti-cancer drug of doxorubicin (DOX) was chosen as a model drug to investigate the potential application of this triblock copolymer in drug controlled release. The results indicated the important roles of the PCL block for drug loading, the PDMA block for pH-responsive release, and PEG block for good bio-affinity. Cell cytotoxicity tests showed that the DOX-loaded PEG-PDMA-PCL micelles were pharmaceutically active to suppress the growth of SKOV-3 cells. This novel stimuli-responsive block copolymer is an attractive candidate as the “smart” pH-responsive carrier for intracellular delivery of hydrophobic drugs.