Self-assembly of thermo- and pH-Responsive poly(acrylic acid)-b-poly(N-isopropylacrylamide) micelles for drug delivery

Self-assembled thermo- and pH-responsive poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PAA-b-PNIPAM) micelles for entrapment and release of doxorubicin (DOX) was described. Block copolymer PAA-b-PNIPAM associated into core-shell micelles in aqueous solution with collapsed PNIPAM block or protonated PAA block as the core on changing temperature or pH. Complexation of DOX with PAA-b-PNIPAM triggered by the electrostatic interaction and release of DOX from the complexes due to the changing of pH or temperature were studied. Complex micelles incorporated with DOX exhibited pH-responsive and thermoresponsive drug release profile. The release of DOX from micelles was suppressed at pH 7.2 and accelerated at pH 4.0 due to the protonation of carboxyl groups. Furthermore, the cumulative release of DOX from complex micelles was enhanced around LCST ascribed to the structure deformation of the micelles. (C) 2008 Wiley Periodicals, Inc.