Superparamagnetic Iron Oxide Nanoparticles with Variable Size and an Iron Oxidation State as Prospective Imaging Agents

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• 作者：Pavel Kucheryavy ; Jibao He ; Vijay T. John ; Pawan Maharjan ; Leonard Spinu ; Galina Z. Goloverda ; Vladimir L. Kolesnichenko
• 刊名：Langmuir
• 出版年：2013
• 出版时间：January 15, 2013
• 年：2013
• 卷：29
• 期：2
• 页码：710-716
• 全文大小：416K
• 年卷期：v.29,no.2(January 15, 2013)
• ISSN：1520-5827

文摘

Magnetite nanoparticles in the size range of 3.2鈥?.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain 纬-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r₁ and r₂ relaxivity measurements in water and diethylene glycol (for OH and CH₂ protons) have shown a decrease in the r₂/r₁ ratio with the particle size reduction, which correlates 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 are similar. Because the 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 may be a better prospective imaging agent because of its chemical stability.