Self-assembled, thermosensitive PCL-g-P(NIPAAm-co-HEMA) micelles for drug delivery

A novel thermosensitive amphiphilic copolymer (PCL-g-P(NIPAAm-co-HEMA)) comprised of hydrophobic PCL segments and hydrophilic P(NIPAAm-co-HEMA) segments was designed and synthesized. The structure of the copolymer was characterized by FT-IR, H-1 NMR and GPC analysis. The copolymer may self-assemble into micelles in water and the resulting micelles demonstrated temperature sensitivity with a lower critical solution temperature (LCST) of 33 degrees C. The critical micellar concentration (CMC) obtained from surface tension measurements and the fluorescence method was around 30 mg center dot L-1. Transmission electron microscopy (TEM) showed that the micelles exhibit a nanospheric morphology within a narrow size range of 150-160 nm. A cytotoxicity study showed that the PCL-g-P(NIPAAm-co-HEMA) copolymer exhibits good biocom- patibility. The controlled drug release of the resulting micelles was investigated and it was found that micelles loaded with prednisone acetate showed improved drug release behavior due to the special micellar structure.