# Preparation and Characterization of Coated ZnFe2O4 Magnetic Nanoparticles for Potential Use as Magnetic Particle Imaging Tracers

## TL;DR

Researchers created and tested magnetic nanoparticles coated with different acids for use in medical imaging, finding them highly effective as tracers.

## Contribution

The study introduces novel ZnFe2O4 magnetic nanoparticles coated with citric, ascorbic, and tartaric acids for potential use in magnetic particle imaging.

## Key findings

- Coated ZnFe2O4 nanoparticles showed superparamagnetic behavior and excellent colloidal stability.
- Magnetic particle spectroscopy results indicated superior performance compared to commercial tracers in terms of relaxation time and spatial resolution.

## Abstract

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
(ZnFe2O4) by coprecipitation of Zn­(II) and Fe­(III)
salts with ammonium hydroxide, followed by a mixture under N2 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 ZnFe2O4, 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 ZnFe2O4 nanoparticles showed a superparamagnetic behavior.
The primary aim of this study was to investigate the potential ability
of coated ZnFe2O4 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 ZnFe2O4 samples
yielded the best results, with the shortest effective relaxation time
(2.09 μs for ZnFe2O4@CA and 2.85 μs
for ZnFe2O4@AA) and an excellent spatial resolution
(fwhm, 5.89 mT for ZnFe2O4@CA and 5.14 mT for
ZnFe2O4@AA). The structural and magnetic characterizations
of CA, AA, and TA-coated ZnFe2O4 nanoparticles
indicate that they are suitable for biomedical applications and especially
have great potential as tracer agents for MPI.