Synthesis and characterization of thermo-sensitive magnetic maghemite nanoparticles

The modification of magnetic nanoparticles (MNPs) with a thermo-sensitive organic shell of poly(N-isopropylacrylamide) (PNIPAm) is reported. The surface of maghemite MNPs was modified in two steps: firstly, using a silane coupling agent and leaving vinyl pending groups on the MNPs surface; and secondly, grafting PNIPAm chains from the modified MNPs via a free radical polymerization. The results indicate that the method developed here for the modification of MNPs is an effective way of synthesizing thermo-responsive MNPs. They present a magnetic behavior due to the maghemite core and a thermal response based on a deswelling/swelling of their polymeric shell (PNIPAm).