Self-Heating Temperature and AC Hysteresis of Magnetic Iron Oxide Nanoparticles and Their Dependence on Secondary Particle Size
Self-Heating Temperature and AC Hysteresis of Magnetic Iron Oxide Nanoparticles and Their Dependence on Secondary Particle Size
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DOI：
10.1109/tmag.2012.2226567
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发表时间：
2013-01-01
影响因子：
2.1
通讯作者：
Takemura, Yasushi
中科院分区：
文献类型：
--
作者：
Nakamura, Kosuke;Ueda, Koji;Takemura, Yasushi
磁性纳米粒子有望用作热疗剂。磁性纳米颗粒在交流磁场下的自加热机制根据其尺寸的不同而不同。在这项研究中，评估了磁性纳米粒子的交流/直流磁滞回线的温升，以阐明尼尔松弛和布朗松弛对散热的贡献。样品是不同流体动力学直径（40、54 和 86 nm）的葡聚糖包被的磁性氧化铁纳米颗粒，但初级直径相同，均为 10 nm。根据这些直径，计算出布朗松弛和尼尔松弛的峰值频率。由初级颗粒尺寸决定的尼尔弛豫时间比这些样品的布朗弛豫时间短得多。尽管尼尔弛豫占主导地位，但86 nm样品的自热温升高于40和54 nm样品。这些结果表明纳米颗粒之间的磁相互作用的效果取决于流体动力学直径。
Magnetic nanoparticles are expected to be used as hyperthermia agents. The mechanism of self-heating of the magnetic nanoparticles under an ac magnetic field is different according to their size. In this study, the temperature rise for the ac/dc hysteresis loops of magnetic nanoparticles were evaluated to clarify the contribution of the Neel and Brownian relaxations to heat dissipation. The samples were dextran-coated magnetic iron oxide nanoparticles of different hydrodynamic diameters ( 40, 54, and 86 nm), but the same primary diameter of 10 nm. From these diameters, the peak frequencies for the Brownian and Neel relaxations were calculated. The Neel relaxation time, determined by the primary particle size, is much shorter than the Brownian relaxation time for these samples. Although the Neel relaxation is dominant, the self-heating temperature rise of the 86 nm sample was higher than that of the 40 and 54 nm samples. These results suggest that the effect of the magnetic interaction between the nanoparticles depends on the hydrodynamic diameter.