Suspension of Fe3O4 nanoparticles stabilized by chitosan and o-carboxymethylchitosan

In this study, a well-dispersed suspension of superparamagnetic Fe3O4 nanoparticles was stabilized by chitosan (CS) and o-carboxymethylchitosan (OCMCS), respectively. The resulting magnetic Fe3O4 nanoparticles were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), zeta-potential measurement and vibrating sample magnetometry (VSM). TEM results demonstrated a spherical or ellipsoidal morphology with an average diameter of 14–20 nm. The adsorbed layer of CS and OCMCS on the magnetite surface was confirmed by FTIR. XRD illustrated that the resulting magnetic nanoparticles have a spinel structure and lastly VSM results showed the modified magnetic Fe3O4 nanoparticles were superparamagnetic. The adsorption mechanism of CS and OCMCS onto the surface of Fe3O4 nanoparticles is believed to be the electrostatic and coordination interactions, respectively. The mechanisms of both CS and OCMCS stabilizing the suspension of Fe3O4 nanoparticles were supposed electrostatic repulsion. These well-dispersed superparamagnetic Fe3O4 nanoparticles stabilized by the biocompatible CS or OCMCS dispersant should have potential applications in biotechnology fields.