Morphology and in vitro release kinetics of drug-loaded micelles based on well-defined PMPC-b-PBMA copolymer

Well-defined amphiphilic diblock copolymers with different poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) content were successfully synthesized via RAFT polymerization technology. The structure of the copolymers was confirmed using GPC, H-1 NMR and FTIR. The polymers have very low critical micelles concentration (6.32 x 10(-7) mol/L to 1.01 X 10(-6) mol/L), which indicates their high thermodynamic stability needed for intravenous injection. Blank and paclitaxel-loaded polymeric micelles were prepared from the PMPC-b-PBMA copolymers using self-emulsion/evaporation method. TEM analysis revealed a regular spherical shape, small diameter (less than 30 nm) and narrow size distribution of the micelles. The paclitaxel-loaded polymeric micelles had high loading content (above 13%). In vitro release kinetics of paclitaxel from the micelles was also investigated. Less than 30% of the paclitaxel was released within 320 h and the increase of the length of PMPC leads to slower release rate. (C) 2008 Elsevier B.V. All rights reserved.