Superparamagnetic Fe3O4 nanoparticles, synthesis and surface modification

Magnetite nanoparticles have been synthesized through a co-precipitation of iron (Fe3+ and Fe2+), and were characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and superconducting quantum interference device magnetometer (SQUID). The particles have been modified by several types of stabilizers such as polyethylene glycol (PEG 4000), sodium citrate, and ethylenediaminetetraacetic acid (Na2H2Y·2H2O). These nanoparticles are nearly spherical with an average diameter 12 nm. The capping agents have been successfully anchored to the surface, as revealed by the absorption bands in infrared, and the adsorbed quantities are evaluated by TGA analysis. Magnetization of these magnetic nanoparticles was almost zero at room temperature in the absence of an applied magnetic field, indicating their superparamagnetic behavior. Such NPs magnetite could serve as a magnetic core to an eventual core-shell structure when coated with various materials.