Synthesis, Self-Assembly, Fluorescence, and Thermosensitive Properties of Star-Shaped Amphiphilic Copolymers with Porphyrin Core

Star-shaped amphiphilic poly(epsilon-caprolactone)-block-poly(oligo(ethylene glycol) methyl ether methacrylate) with porphyrin core (SPPCL-b-POEGMA) was synthesized by combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Star-shaped PCL with porphyrin core (SPPCL) was prepared by bulk polymerization of epsilon-caprolactone (CL) with tetrahydroxyethyl-terminated porphyrin initiator and tin 2-ethylexanote (Sn(Oct)(2)) catalyst. SPPCL was converted into SPPCLBr macroinitiator with 2-bromoisobutyryl bromide. Star-shaped SPPCL-b-POEGMA was obtained via ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). SPPCL-b-POEGMA can easily self-assemble into micelles in aqueous solution via dialysis method. The formation of micellar aggregates were confirmed by critical micelle formation concentration, dynamic light scattering, and transmission electron microscopy. The micelles also exhibit property of temperature-induced drug release and the lower critical solution temperature (LCST) was 60.6 degrees C. Furthermore, SPPCL-b-POEGMA micelles can reversibly swell and shrink in response to external temperature. In addition, SPPCL-b-POEGMA can present obvious fluorescence. Finally, the controlled drug release of copolymer micelles can be achieved by the change of temperatures. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2303-2313, 2011