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Monocrystalline iron oxide nanocompounds (MION): physicochemical properties
T Shen1, R Weissleder, M Papisov
1Department of Radiology, Massachusetts General Hospital, Boston 02114.
Magnetic Resonance in Medicine
|May 1, 1993
Summary
Monocrystalline iron oxide nanocomcompound (MION) exhibits superparamagnetic properties and a hydrodynamic radius of 20 nm. These MION nanoparticles show potential for target-specific MR imaging with high R2 relaxivity.
Area of Science:
- Nanotechnology
- Materials Science
- Biomedical Imaging
Background:
- Monocrystalline iron oxide nanocomcompound (MION) is a novel stable colloid.
- MION enables target-specific magnetic resonance (MR) imaging.
Purpose of the Study:
- To characterize the physicochemical properties of MION.
- To evaluate MION's suitability for MR imaging applications.
Main Methods:
- High-resolution electron microscopy for core size and shape.
- X-ray powder diffraction for crystal structure.
- Laser light scattering for hydrodynamic radius.
- Mössbauer studies for magnetic properties.
- Relaxivity measurements at physiological conditions.
Main Results:
- MION cores are hexagonal, 4.6 nm in diameter, with an inverse spinel structure.
- Dextran coating results in a 20 nm hydrodynamic radius.
- MION exhibits superparamagnetism with high magnetization (68 emu/g Fe).
- R1 and R2 relaxivities are 16.5 and 34.8 (mM·sec)⁻¹, respectively.
- Detectability in liver tissue is below 50 nmol Fe/g.
Conclusions:
- MION possesses well-defined physicochemical and magnetic properties.
- The nanoparticle's characteristics are suitable for MR imaging contrast agents.
- MION demonstrates high sensitivity for detecting low concentrations in tissues.