Novel thermosensitive nano-micelles from triblock copolymer for drug delivery.

Novel thermosensitive nano-micelles, based on Poly(D,L-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA), as carriers for drug delivery were researched. The critical micelle concentration of the copolymer in aqueous solution was determined to be 2.34 microgram/ml by fluorescence spectroscopy using pyrene as a fluorescence probe. The lower critical solution temperature (LCST) of the copolymer was measured in distilled water by optical transmittance, and the LCST was varied from 35 to 55 degrees C depending on polymer concentration. Acetaminophen as a model drug was loaded in nano-micelles by solvent evaporation method. In vitro acetaminophen release from micelles showed a sustained modality compared with the free drug as a control, and an obviously high release rate when temperature was increased above LCST. The studies showed that nano-micelles made from PLGA-PEG-PLGA could be ideal candidate carriers for tumor-special drug delivery.