In situ surface modification by oleic acid of magnetite nanoparticles: surface interaction, structure, and its magnetic properties

Magnetite (Fe₃O₄) is a type of superparamagnetic iron oxide nanoparticles (SPIONs) with potential for biomedical applications, such as targeted drug delivery in cancer treatment. This research aimed to obtain oleic acid-coated Fe₃O₄ nanoparticles with optimal superparamagnetic properties. Fe₃O₄ nanoparticles were synthesized using a co-precipitation method, followed by an in-situ coating process with oleic acid for surface modification at three different volumes to enhance their dispersibility and stability. Samples appear to be spherical and in size range of 11.39–36.94 nm. Transmission electron microscopy (TEM) and Fourier transform infra-red spectroscopy (FTIR) measurement confirmed the successful coating process by showing strong interactions between carboxyl group of oleic acid and Fe₃O₄ surface. Based on X-ray diffraction (XRD) measurement, the oleic acid-coated nanoparticles have a cubic inverse spinel structure indicating that variations in stirring speed during synthesis process and various volume of oleic acid do not change the crystal structure of nanoparticles. Superconducting Quantum Interference Device (SQUID) measurement showed that the nanoparticles have superparamagnetic-like property with temperature blocking of 279.94 K. Analysis of measurement results will provide a comprehensive understanding of how oleic acid coating affects the superparamagnetic properties and biomedical suitability of Fe₃O₄ nanoparticles.