Water-soluble superparamagnetic manganese ferrite nanoparticles for magnetic resonance imaging

We report here a thermal decomposition approach to the synthesis of water-soluble superparamagnetic manganese ferrite (MnFe2O4) nanoparticles (NPs) for magnetic resonance (MR) imaging applications. In this approach, tetraethylene glycol was utilized as a coordination and stabilization agent, rendering the NPs water-soluble and stable. The formed NPs had a diameter of 7 nm with a narrow size distribution, and were superparamagnetic with a saturated magnetization (Ms) of 39 emu/g. In vitro cytotoxicity test revealed that the MnFe2O4 NPs were biocompatible at a particle concentration below 200 mu g/mL The transverse relaxivity of MnFe2O4 NPs in water and cells after incubation were determined to be 189.3 mM(-1) s(-1) and 36.8 mM(-1) s(-1) based on iron concentration, respectively. In vivo MR imaging studies in conjunction with inductively coupled plasma-atomic emission spectroscopy showed that the MnFe2O4 NPs were preferentially accumulated in liver after intravenous injection for 4 h. This suggests that the developed MnFe2O4 NPs can serve as a sensitive MR imaging contrast agent for liver imaging. By appropriately modifying or functionalizing the surface of the NPs, these particles may be used for MR detection of other diseases. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.