Dysprosium-doped iron oxide nanoparticles boosting spin-spin relaxation: a computational and experimental study

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Imaging

Background:

• Contrast-enhanced magnetic resonance imaging (MRI) aids early disease diagnosis using iron oxide superparamagnetic nanoparticles (IOSNPs).
• Low magnetic sensitivity of IOSNPs limits their application.
• Optimizing IOSNP properties is crucial for advanced medical imaging.

Purpose of the Study:

• To enhance the magnetic sensitivity of IOSNPs for improved MRI contrast agents.
• To investigate dysprosium (Dy) doping as a strategy to boost IOSNP performance.
• To develop a novel synthesis method for Dy-doped IOSNPs.

Main Methods:

• First-principles calculations using spin-polarized density functional theory (SDFT) to determine optimal Dy doping.
• Synthesis of ultrasmall γ-iron oxide superparamagnetic nanoparticles (γ-IOSNPs) via a phase transfer-coprecipitation method.
• Characterization of Dy-doped γ-IOSNPs, including hydrodynamic size, dispersion, and MRI relaxivity.

Main Results:

• SDFT identified an optimal Dy-doping scheme.
• Synthesized Dy-doped γ-IOSNPs exhibited improved superparamagnetism and high dispersion.
• T2-weighted MRI relaxivity (r2) of Dy-doped γ-IOSNPs reached 123.2 s-1 mM-1, nearly double that of pure γ-IOSNPs.
• Performance surpassed clinically approved agents Feridex and Resovist.

Conclusions:

• Low-level dysprosium doping effectively enhances the magnetic sensitivity and MRI relaxivity of γ-IOSNPs without inducing significant nanotoxicity.
• Dy-doped γ-IOSNPs show high potential as superior T2-weighted MRI contrast agents.
• The computational and synthetic approaches are valuable for designing next-generation MRI contrast agents.