Synthesis and characterization of magnetic maghemite/catecholamine core/shell nanoparticles

In this work, maghemite (gamma-Fe2O3) nanoparticles were synthesized by a modified method in an alkaline medium, and then an ultra-thin layer of polydopamine (FDA), as a catecholamine, was constructed on the surface of the nanoparticles in an ex-situ process. The chemical structure of the coating was confirmed by Fourier-transform infrared spectrum (FT-IR) spectroscopy. X-ray diffraction (XRD) analysis revealed that the crystallite size is about 8 nm. From transmission electron microscopy (TEM) images the core/shell nanoparticles size was estimated to be 10 nm. The size in agreement with the results obtained by vibrating sample magnetometer (VW) is in the superparamagnetic size range. Thermogravimetric analysis (TGA) showed a significant decrease in the decomposition temperature of PDA (i.e. from 470 to 310 degrees C) in the presence of the nanoparticles, showing the catalytic effect of the nanoparticles. Through TGA and TEM analyses the coating thickness was estimated to be about 0.95 and 1 nm, respectively. The polydopamine modified nanoparticles exhibited an enhanced wettability in contact with water. The ultra-thin layer coating, without disturbing the magnetic nature of the particles, changed the surface morphology and surface properties of the particles, which is encouraging from practical and industrial points of view as addressed in this paper. (C) 2014 Elsevier B.V. All rights reserved .