Simple rapid stabilization method through citric acid modification for magnetite nanoparticles

A highly stable and magnetized citric acid (CA)-functionalized iron oxide aqueous colloidal solution (Fe3O4@CA) was synthesized by using a simple and rapid method of one-step co-participation via a chemical reaction between Fe3+ and Fe2+ in a NaOH solution at 65 °C, followed by CA addition to functionalize the Fe3O4 surface in 25 min. The NPs were synthesized at lower temperatures and shortened time compared with conventional methods. Surface functionalization is highly suggested because bare Fe3O4 nanoparticles (Fe3O4 NPs) are frequently deficient due to their low stability and hydrophilicity. Hence, 19 nm-sized Fe3O4 NPs coated with CA (Fe3O4@CA) were synthesized, and their microstructure, morphology, and magnetic properties were characterized using X-ray diffraction, transmission electron microscopy, Zeta potential, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. CA successfully modified the Fe3O4 surface to obtain a stabilized (homogeneous and well dispersed) aqueous colloidal solution. The Zeta potential value of the as-prepared Fe3O4@CA increases from - 31 to - 45 mV. These CA-functionalized NPs with high magnetic saturation (54.8 emu/g) show promising biomedical applications.