Fabrication of water-soluble magnetic nanoparticles by ligand-exchange with thermo-responsive polymers

We report the use of thermo-responsive polymers in the synthesis of Co and gamma-Fe2O3 nanoparticles using a two-step method involving thermal decomposition of the organometallic complexes in the presence of oleic acid and then followed by ligand-exchange process with thermo-responsive polymer. Among different thermo-responsive polymers investigated, it was found that the polymer based on poly(N-isopropylacrylamide) with a co-monomer component of acrylic acid and acrylamide can be used in the ligand-exchange to coat Co and gamma-Fe2O3 nanoparticles, respectively. The nanoparticles are found to be water-soluble at temperatures below coil-to-globule phase transition of the coating polymer. (C) 2009 Elsevier B.V. All rights reserved.