Reversing multidrug resistance by intracellular delivery of Pluronic® P85 unimers.

Pluronics have been demonstrated as excellent multidrug resistance (MDR) reversal agent in the form of unimers rather than micelles. However, the effective intracellular delivery of Pluronic(®) unimers to MDR cancer cells still remains a big challenge. To address this issue, a mixed micellar system based mainly on the pH-sensitive copolymer of poly (L-histidine)-poly (D,L-lactide)-polyethyleneglycol-poly (D,L-lactide)-poly (L-histidine) (PHis-PLA-PEG-PLA-PHis) and Pluronic(®) F127, some of which was conjugated with folate, was constructed to intracellularly deliver the unimers of Pluronic(®) P85 to MDR cells.