Superparamagnetic iron oxide nanoparticles with variable size and an iron oxidation state as prospective imaging agents.
Superparamagnetic iron oxide nanoparticles with variable size and an iron oxidation state as prospective imaging agents.
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DOI：
10.1021/la3037007
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发表时间：
2013-01-15
期刊：
影响因子：
--
通讯作者：
Kolesnichenko VL
中科院分区：
文献类型：
--
作者：
Kucheryavy P;He J;John VT;Maharjan P;Spinu L;Goloverda GZ;Kolesnichenko VL
在二甘醇溶液中，利用前驱体铁（II）和铁（III）烷氧化物的高温水解，在不同的反应条件下，以较高的收率合成了尺寸为3.2 ~ 7.5 nm的纳米磁铁矿。通过改变反应温度和时间以及采用顺序生长技术来调整颗粒的平均大小。为了获得相同尺寸范围的γ-铁（III）氧化物颗粒，磁铁矿颗粒在室温下用干氧在二甘醇中氧化。通过DLS、TEM、x射线粉末衍射、热重分析、化学分析和磁测等手段对产物进行了表征。在水和二甘醇（OH和CH2质子）中的核磁共振r1和r2弛豫率测量结果表明，r2/r1比随着颗粒尺寸的减小而减小，这与磁铁矿纳米颗粒的磁性测量结果有关。氧化颗粒的饱和磁化强度比相同粒径的Fe3O4低20%，但其r1弛豫率相似。由于磁铁矿的氧化在环境条件下是自发的，因此了解氧化产物与其前体相比没有缺点是很重要的，因此由于其化学稳定性，它可能是一种更好的前瞻性显像剂。
Magnetite nanoparticles in the size range of 3.2-7.5 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 γ-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.
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