A glucose-based diblock copolymer: synthesis, characterization and its injectable/temperature-sensitive behaviors

To be more biocompatible, poly(N-isopropyl acrylamide) (PNIPAM) hydrogel, as a typical temperature-sensitive hydrogel, is expected to be linked with other materials of excellent biocompatibility. For this propose, poly(N-isopropyl acrylamide)-block-poly(3-O-allyl-alpha-D-glucose) (PNIPAM-b-POAG), a new diblock copolymer, was successfully synthesized from N-isopropyl acrylamide (NIPAM) and 3-O-allyl-1,2:5,6-di-O-isopropynylene-alpha-D-glucose (OAIG) via reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of cumyl dithiobenzoate (CDB). PNIPAM-b-POAG was characterized byFourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (H-1 NMR) spectroscopy, and gel permeation chromatography (GPC). The critical micelle concentration (CMC) of the copolymer was 0.045 mg/ml measured by fluorescence spectroscopy. The copolymer solution exhibited a reversible sol-gel phase transitions with the increase or decrease of temperature. An in situ gel formed rapidly after subcutaneously injecting the copolymer solution into a Sprague Dawley (SD) rat, which indicated the copolymer has a good injectable property. The in vitro release result showed that methylene blue (MB) as a model was sustainably released by the temperature-sensitive PNIPAM-b-POAG diblock copolymer at 37 A degrees C within 120 h. The copolymer showed no apparent cytotoxicity on L929 cells by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The novel temperature-sensitive hydrogel is a promising candidate for drug delivery.