Magnetic domains orientation in (Fe3O4/γ-Fe2O3) nanoparticles coated by Gadolinium-diethylenetriaminepentaacetic acid (Gd3+-DTPA)

In this work, the magnetic domains (MDs) orientation was evaluated from magnetite/maghemite nanoparticles (Fe3O4/gamma-Fe2O3) NPs coated with Gadolinium (Gd3+) chelated with diethylenetriamine pentaacetate acid (Gd-DTPA). The (Fe3O4/gamma-Fe2O3) superparamagnetic cores were configured by adding a DTPA organic layer and paramagnetic Gd as (Fe3O4/gamma-Fe2O3)@Gd-DTPA NPs. The cores were obtained by coprecipitation and coated with additional modifications to the synthesis with Gd-DTPA. Analysis of properties showed that particles 9-12 nm, with Gd-DTPA layer thickness similar to 10 nm increased their magnetisation from 62.72 to 75.82 emu/g. The result showed that the structure, particle size, composition, thickness and interface defects, as well as the anisotropy, play an important role in MDs orientation of (Fe3O4/gamma-Fe2O3)@Gd-DTPA NPs. Magnetic force microscopy (MFM) analysis showed an MDs uniaxial orientation of 90 degrees at magnetisation and disorder at zero conditions and demagnetisation. The MDs interactions showed uniaxial anisotropy defined in the direction of the magnetic field. These addressable and rotational features could be considered for potential applications to induce hydrogen proton alignment in water by longitudinal spin-lattice relaxation T (1) and transversal spin-spin relaxation T (2) as a dual contrast agent and as a theranostic trigger.