(770d) Surface Modification of Monodisperse Magnetic Nanoparticles with Fluorescent-Thermo-Responsive Polymeric Shells for Biomedical Applications

Magnetic nanoparticles such as magnetite (Fe3O4) or cobalt ferrite (CoFe2O4) were synthesized in presence of oleic acid by the thermodecomposition method. These nanoparticles were modified with silane-functional molecules to graft acrylate (CH2=C(CH3)-C(=O)-O) end groups onto the nanoparticles surface. Functionalization of these modified nanoparticles with N-isopropyl acrylamide monomers such as NIPAM and NIPMAM were carried out by free radical polymerization using an azo-initiator such as AIBN and a methyl bis-acrylamide (MBA) crosslinking agent. The hydrodynamic size of these functionalized nanoparticles was studied as function of temperature. Measurements of the specific absorption rate (SAR) of magnetic nanoparticles coated with thermo-responsive polymeric shells were performed in presence of a magnetic field to determine their potential therapeutic applications. Fluorescent magnetic nanoparticles were also synthesized by the incorporation of a fluorescent modified acrylamide monomer (FMA). The temperature of the medium surrounding a collection of nanoparticles was determined by monitoring fluorescence changes in the FMA monomer resulting from the decrease in polarity of the NIPAM/NIPMAM copolymer chain with increasing temperature.