Complex Micelles Formed from Two Diblock Copolymers for Applications in Controlled Drug Release

Double-responsive core-shell-corona complex micelles for applications in drug release were formed from self-assembly of two diblock copolymers PtBA-b-PNIPAM and PtBA-b-P4VP. The two diblock copolymers coaggregated into core-shell complex micelles in acidic water with the hydrophobic PtBA blocks as the common core and soluble PNIPAM/P4VP blocks as the mixed shell. Increasing temperature or pH value, the micelles converted into core-shell-corona micelles because of the collapse of PNIPAM or P4VP blocks as the inner shell and soluble P4VP or PNIPAM chains stretching outside as the outer corona. The anti-inflammation drug naproxen (NAP) was loaded as the model drug in micelles in acidic water and released because of the ionization of NAP in alkaline solutions. Compared with pure core-shell micelles, release of NAP from core-shell-corona complex micelles avoided the burst diffusion and the release rate is more easily controlled by tuning the composition of the mixtures or by adjusting the pH of the medium. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym, Chem 47: 1804-1810, 2009