Currently the most studied type of magnetic nanoparticles are of cubic structure, inverse spinel, because these materials have very interesting features and possible applications since they facilitate building more complex systems. We must consider that due to the presence of transition metal on the surface of nanoparticles is that the conditions for funcionalizarlas with other molecules through complex functional groups obtaining materials with polar or apolar characteristics, depending on the type of implementation that want to use. Considering that when working with biological systems nanoparticles are detected by the reticuloendothelial system (RES). This functionalization is responsible for preventing agglomeration there of allowing them to remain in stable suspension (magnetic colloids) that can be driven by external magnetic fields. In this work, we show in detail the results obta...

Magnetite (Fe3O4) nanoparticles coated with organic material are of considerable importance in various areas of engineering, as well as in biomedicine. Several papers show drastic changes in the magnetic properties related to the surface effects and the particle-particle interactions strength. However, there is no consensus about the origin or mechanisms that produce these changes, which could be different depending on the particle size and shape, coating efficiency and particle-particle interaction strength. Aiming to shed light on these issues, oleic acid (OA) coated Fe3O4 nanoparticles with different sizes were synthesized by a thermal decomposition method. Structural and microscopic results revealed Fe3O4 nanoparticles with good crystallinity and almost-spherical or polyhedral shapes depending on the solvent used for the synthesis. Infrared (FTIR) spectroscopy indicated OA molecules ...