writer：Qingqing Bian, Yan Xiao*, Meidong Lang*
keywords：Thermoresponsive, Star Amphiphilic Block Copolymer, Self-assembly, Specific Recognition
source：期刊
Issue time：2012年

A novel star amphiphilic block copolymer star poly(caprolactone)-b-poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide)-DDAT [SPCL-b-P(NIPAAm-co-DMAAm)-DDAT] was synthesized by combination of ring-opening polymerization (ROP) and reversible addition-fragment chain transfer (RAFT) polymerization. The DDAT-terminated groups was further transformed into hydroxyl groups by one-pot strategy for aminolysis of DDAT and Michael addition reaction of an α,β-unsaturated ester of 2-hydroxyethyl acrylate (HEA). The biotinylated star amphiphilic block copolymer SPCL-b-P(NIPAAm-co-DMAAm)-Biotin was obtained by coupling the hydroxyl-terminated star copolymer with carboxyl-capped biotin using carbodiimide coupling chemistry. These star amphiphilic copolymers with DDAT, hydroxyl, and biotin end groups were capable of self assembling into core-shell structural micelles in aqueous solution. The variation of end groups significantly affected the micellar characters, such as hydrodynamic diameter (D_h), critical micellar concentration (CMC), and lower critical solution temperature (LCST). The amount of biotin on the micelle surface as well as the specific recognition of biotinylated micelle/avidin (ligand/receptor) was determined by HABA/avidin binding assay and dynamic light scattering (DLS). In addition, the biotinylated star copolymer displayed good biocompatibility according to a preliminary cytotoxicity study. The novel polymeric micelle with biodegradability, thermoresponse, and targetability was expected to be a promising polymeric carrier material for targeted drug delivery.