Biodegradable polylactide/poly(ethylene glycol)/polylactide triblock copolymer micelles as anticancer drug carriers

Adriamycin (ADR) was selected as a model drug to evaluate the potential app lications of polylactide/poly(ethylene glycol)/polylactide (PLA/PEG/PLA) mi celles as drug carriers in parenteral delivery systems. The PLA/PEG/PLA tri block copolymer micelles were characterized by dynamic light scattering and transmission electron microscopy. It was found that the micelle size incre ased with the increasing of the PLA chain length. The average size of ADR-l oaded micelles was 143.2 nm. The histogram analysis showed that the ADR-loa ded micelles possessed a narrow unimodal size distribution. The ADR loading contents of the micelles and ADR entrapment efficiency were dependent on t he PLA chain length and PEG chain length in the copolymer. They increased w ith the increase of the PLA chain length, but the PEG chain length was iden tical and decreased with the increase of the PEG chain length; the length o f the PLA block was similar. The initial amount of ADR also influenced the drug contents and entrapment efficiency (i.e., the more the initial amount added, the more the drug contents and the higher encapsulation efficiency). The drug release experiments indicated that the ADR-loaded micelles posses sed sustained release characteristics. (C) 2001 John Wiley & Sons, Inc.