Preparation and Characterization of Coated ZnFe ₂ O ₄ Magnetic Nanoparticles for Potential Use as Magnetic Particle Imaging Tracers

High Resolution Image Download MS PowerPoint Slide Magnetic nanoparticles (MNPs) exhibit unique behaviors that make them appealing for a variety of clinical applications, including their use as tracer agents in magnetic particle imaging (MPI) and magnetic resonance imaging (MRI) systems, as heat generators in hyperthermia treatment, and in targeted drug delivery. We prepared maghemite cores (ZnFe 2 O 4 ) by coprecipitation of Zn(II) and Fe(III) salts with ammonium hydroxide, followed by a mixture under N 2 gas. The cores were coated with coating agents: citric acid monohydrate (CA), l -ascorbic acid (AA), and l -(+)-tartaric acid (TA). State-of-the-art techniques characterized their structural and magnetic properties. XRD results showed that all the particles were consistent with the crystal structure of ZnFe 2 O 4, and the average crystallite size ranged from 14 to 19 nm. The hydrodynamic diameters were found between 112 and 218 nm. Zeta potential values for negatively charged particles in the range of −29.7 to −60.3 mV provided good colloidal stabilization. FTIR analysis showed the existence of coating agents on the structures. SEM measurements confirmed the spherical geometry of all samples. All synthesized ZnFe 2 O 4 nanoparticles showed a superparamagnetic behavior. The primary aim of this study was to investigate the potential ability of coated ZnFe 2 O 4 nanoparticles to serve as molecular magnetic contrast agents in imaging studies for MPI systems. Consequently, the prepared samples were also tested with magnetic particle spectroscopy (MPS), and the results were compared with those of commercial reference tracers, Perimag and VivoTrax, which are used in MPI. The MPS results show that ZnFe 2 O 4 samples yielded the best results, with the shortest effective relaxation time (2.09 μs for ZnFe 2 O 4 @CA and 2.85 μs for ZnFe 2 O 4 @AA) and an excellent spatial resolution (fwhm, 5.89 mT for ZnFe 2 O 4 @CA and 5.14 mT for ZnFe 2 O 4 @AA). The structural and magnetic characterizations of CA, AA, and TA-coated ZnFe 2 O 4 nanoparticles indicate that they are suitable for biomedical applications and especially have great potential as tracer agents for MPI.