Development of Fe/Fe₃O₄ Core–Shell Nanocubes as a Promising Magnetic Resonance Imaging Contrast Agent

Here, we report the synthesis, characterization, and properties of Fe/Fe₃O₄ core–shell nanocubes prepared via a simple route. It includes NaBH₄ reduction of FeCl₃ in an ethylene glycol solution in the presence of 2-mercaptopropionic acid (surfactant) and trisodium citrate (cosurfactant) followed by surface oxidation with trimethylamine <i>N</i>-oxide. The morphology and structure of Fe/Fe₃O₄ core–shell nanocubes were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, X-ray powder diffraction, and X-ray photoelectron spectroscopy. All of the methods confirm a Fe/Fe₃O₄ core–shell structure of nanocubes. Magnetic measurements revealed that the Fe/Fe₃O₄ core/shell nanocubes are superparamagnetic at 300 K with a saturation magnetization of 129 emu/g. The <i>T</i>₂ weighted imaging and the <i>T</i>₂ relaxation time showed high MRI contrast and sensitivity, making these nanocubes viable candidates as enhanced MRI contrast agents