July 3-7, 2016
Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized with high yields under variable reaction conditions using high temperature hydrolysis of the precursor iron(II) and iron(III) chelated alkoxide complexes in surfactant-free diethylene glycol solutions. The average sizes of the particles were adjusted by changing the reaction temperature and time, and by using sequential growth technique. Reaction products formed as shelf-stable colloids. In order to obtain γ‑iron(III) oxide particles in the same range of sizes, diethylene glycol colloids of magnetite were oxygenated at room temperature. As-obtained colloids were characterized by DLS; powdery products obtained by coagulating them with oleic acid, were characterized by TEM, XRD, TGA, FTIR and magnetic measurements. In order to evaluate the potential of these particles for biomedical imaging, 1H NMR r1 and r2 relaxivity measurements were performed in diethylene glycol (for OH and CH2-protons) and in water. The results have shown the decrease in r2/r1 ratio with the particle size reduction, which correlate with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe3O4 with the same particle size, but their r1 relaxivities were similar. Since oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor, and therefore it may be a better imaging agent due to its chemical stability.
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Vladimir Kolesnichenko, Galina Goloverda, Pavel Kucheryavy, and Leonard Spinu, "Iron oxide nanoparticles with a variable size and an iron oxidation state for imaging applications" in "Nanotechnology in Medicine: From Molecules to Humans", Prof. Lola Eniola-Adefeso, Department of Chemical Engineering, University of Michigan, USA Prof. Paolo Decuzzi, Italian Institute of Technology, Italy Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/nanotech_med/26