Gold nanoparticle-incorporated core and shell crosslinked micelles fabricated from thermoresponsive block copolymer of N-isopropylacrylamide and a novel primary-amine containing monomer

A novel primary amine-containing monomer, 1-(3'-aminopropyl)-4-acrylamido-1,2,3-triazole hydrochloride (APAT), was prepared from N-propargylacrylamide and 3-azidopropylamine hydrochloride via copper-catalyzed Huisgen 1,3-dipolar cyclo-addition (click reaction). Poly(N-isopropylaci-ylamide)-b-poly(1-(3'-aminopropyl)-4-acrylamido-1,2,3-triazole hydrochloride), PNIPAM-b-PAPAT, was then synthesized via consecutive reversible addition-fragmentation chain transfer polymerizations of N-iso-propylacrylamide and APAT. In aqueous solution, the obtained thermoresponsive double hydrophilic block copolymer dissolves molecularly at room temperature and self-assembles into micelles with PNIPAM cores and PAPAT shells at elevated temperature. Because of the presence of highly reactive primary amine moieties in PAPAT block, two types of covalently stabilized nanoparticles namely core crosslinked and shell crosslinked micelles with 'inverted' core-shell nanostructures were facilely prepared upon the addition of glutaric dialdehyde at 25 and 50 degrees C, respectively. In addition, the obtained structure-fixed micelles were incorporated with gold nanoparticles via in situ reduction of preferentially loaded HAuCl4. High resolution transmission electron microscopy revealed that gold nanoparticles can be selectively loaded into the crosslinked cores or shells, depending on the micelle templates employed. (C) 2008 Wiley Periodicals, Inc.