One-Step Preparation of Highly Stable Copper-Zinc FerriteNanoparticles in Water Suitable for MRI Thermometry

Superparamagnetic ferrite nanoparticles coated witha polymer layer are widely used for biomedical applications. Theobjective of this work is to design nanoparticles as a magneticresonance imaging (MRI) temperature-sensitive contrast agent.Copper-zinc ferrite nanoparticles coated with a poly(ethyleneglycol) (PEG) layer are synthesized using a one-step thermaldecompositionmethodinapolymermatrix.Theresultingnanoparticles are stable in water and biocompatible. UsingMo??ssbauer spectroscopy and magnetometry, it was determinedthat the grown nanoparticles exhibit superparamagnetic properties.Embedding these particles into an agarose gel resulted in significantmodification of water proton relaxation timesT1,T2, andT2*determined by nuclear magnetic resonance measurements. Theresults of the spin-echoT2-weighted MR images of an aqueous phantom with embedded Cu0.08Zn0.54Fe2.38O4nanoparticles in thepresence of a strong temperature gradient show a strong correlation between the temperature and the image intensity. The presentedresults support the hypothesis that CuZn ferrite nanoparticles can be used as a contrast agent for MRI thermometry.