Nickel Ferrite Nanoparticles for In Vivo Multimodal Magnetic Resonance and Magnetic Particle Imaging

Area of Science:

• Biomedical research
• Nanotechnology
• Materials science

Background:

• Magnetic nanoparticles are crucial for biomedical imaging modalities like MRI and MPI.
• Superparamagnetic iron oxide nanoparticles are commonly used, but optimal performance requires specific magnetic properties for each application.
• Nickel substitution in ferrite nanoparticles is explored to tune magnetic properties for enhanced imaging.

Purpose of the Study:

• To investigate the performance of nickel-substituted ferrite nanoparticles (NiₓFe₂₋ₓO₃) against standard maghemite iron oxide nanoparticles (γ-Fe₂O₃).
• To evaluate their suitability for combined magnetic resonance imaging (MRI) and magnetic particle imaging (MPI).
• To assess nanoparticle biodistribution in vivo.

Main Methods:

• Synthesis of γ-Fe₂O₃ and NiₓFe₂₋ₓO₃ nanoparticles coated with a statistical copolymer.
• In vitro characterization using X-ray diffraction (XRD), Mössbauer spectroscopy, magnetometry, magnetic resonance relaxometry, and magnetic particle spectroscopy/imaging.
• In vivo biodistribution studies using MPI and MRI after intracardial application in a murine model.

Main Results:

• NiₓFe₂₋ₓO₃ nanoparticles exhibited lower saturation magnetization but superior magnetic particle imaging (MPI) signal and performance compared to γ-Fe₂O₃.
• Both nanoparticle types demonstrated comparable performance in bimodal MRI/MPI imaging in vivo.
• In vivo, nanoparticles were detected in the liver and spleen, with long-term localization observed in lymph nodes.

Conclusions:

• Nickel substitution in iron oxide nanoparticles alters magnetic properties, enhancing MPI performance.
• Both γ-Fe₂O₃ and NiₓFe₂₋ₓO₃ nanoparticles are suitable for combined MRI/MPI applications.
• MPI offers a highly specific signal complementary to anatomical MRI.