Water-Soluble Spinel Ferrites by a Modified Polyol Process as Contrast Agents in MRI

Magnetic nanoparticles have recently been very attractive for biomedical applications. In this study, we have synthesized ferrite nanoparticles for application as contrast agents in MRI experiments. Fe₃O₄ and MnFe₂O₄ spinel ferrites with a mean size of 11-12 nm, were prepared by a modified polyol route in commercially available polyethylene glycol with molecular weight 600 (PEG-600). The reaction takes place in the presence of water soluble and non-toxic tri-block copolymer known as Pluronic® F-127 (PEO₁₀₀-PPO₆₅-PEO₁₀₀). The nanoparticles have saturation magnetization values of 52 and 68 emu/g for MnFe₂O₄ and Fe₃O₄, respectively. Both the Fe₃O₄, and MnFe₂O₄ nanoparticles make stable solutions in water known as ferrofluids. Preliminary data demonstrated the capability of these nanoparticles to induce imaging contrast in T₂ weighted MRI experiments, making these materials suitable for biomedical applications such as medical MRI.