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 (Dh), 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.