Preparation and characterization of temperature-responsive magnetite nanoparticles conjugated with N-isopropylacrylamide-based functional copolymer

In this study, magnetite nanoparticles conjugated with the temperature-responsive N-isopropylacrylamide-based functional copolymer were prepared. Observations using a transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) spectral measurements proved that the surrounding polymer layers bind to the magnetite surfaces. The particles showed a very sensitive temperature-responsive behavior, which was confirmed by particle size analysis and investigation of retention in a hydrophobic octadecylsilane (ODS)-modified column. In the magnetic field that was induced by an alternating electric current, the nanoparticles also demonstrated a sensitive temperature-responsive behavior and this result meant that the temperature-responsive polymer layer could absorb the heat induced in the magnetite cores. The temperature-responsive magnetite nanoparticles could show effective aggregation formation or hydrophobic interaction in response to an alternating magnetic field. These interesting phenomena would be used for embolization therapy or targeted drug delivery aiming at a cancer treatment. (c) 2005 Elsevier B.V. All rights reserved.