Preparation and Characterization of Amino-Coated Maghemite Nanoparticles

The ferrous salt and ferric salt were used as raw materials to prepare magnetite (Fe₃O₄) nanoparticles as precursors, and then maghemite (γ-Fe₂O₃) nanoparticles were obtained from the precursors via high temperature pyrolysis for further oxidation, and corresponding amino-coated maghemite nanoparticles are also obtained via surface modification of 3-aminopropyltriethyloxy silane (APTES). The properties and structure of nanoparticles are characterized by transmission electron microscopy(TEM), energy dispersive spectroscopy (EDS), X-Ray photoelectron spectroscopy (XPS), ultraviolet visible spectra (UV-vis) , fourier transform infrared (FT-IR) spectrometer and magnetic property measurement system (MPMS) with superconducting quantum interference device (SQUID) magnetometry. The result reveals that the amino-coated maghemite particles have a slight dimensional increase in average diameter, and maintain almost original saturation magnetization that decreases from 109.2 emu·g^-1 to 102.3 emu·g^-1 after APTES coating. The finding is instructive for surface functionalization of MNPs related to sensing application.