Effect of easy axis alignment on dynamic magnetization of immobilized and suspended magnetic nanoparticles
Effect of easy axis alignment on dynamic magnetization of immobilized and suspended magnetic nanoparticles
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DOI：
10.1063/5.0041215
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发表时间：
2021-03-07
影响因子：
3.2
通讯作者：
Yoshida, Takashi
中科院分区：
文献类型：
--
作者：
Elrefai, Ahmed L.;Enpuku, Keiji;Yoshida, Takashi
磁性纳米粒子（MNP）已被广泛研究用于生物医学应用，如磁性粒子成像和磁热疗。我们研究了固定化和悬浮MNP的易轴排列对动态磁化的影响。对于固定化的样品，容易磁化轴对齐，通过在固定过程中施加直流电场。对于悬浮样品，设置所施加的交流场，使得易磁化轴的对齐由交流场引起。在外加交流磁场下，测量了具有不同易轴取向程度的MNP的磁化强度（M-H）曲线。我们发现，MNP的易轴排列对其M-H曲线和谐波谱有很大的影响，这表明了这种排列在其生物医学应用中的重要性。数值模拟考虑了样品中易磁化轴的排列和核尺寸的分布，对实验结果进行了定量解释。对于固定和悬挂的情况，我们可以使用易轴角的分布函数来表示易轴对齐的程度。分布函数将是有用的定量评估MNP在生物医学应用中的性能。
Magnetic nanoparticles (MNPs) have been widely studied for use in biomedical applications such as magnetic particle imaging and magnetic hyperthermia. We studied the effect of easy axis alignment on dynamic magnetization of both immobilized and suspended MNPs. For immobilized samples, easy axes of magnetization were aligned by applying a dc field during immobilization. For suspended samples, the applied ac field was set so that the alignment of the easy axes was caused by the ac field. Magnetization (M-H) curves of MNPs with different degrees of easy axis alignment were measured with an applied ac field. We found that the easy axis alignment of MNPs considerably affects their M-H curve and harmonic spectra, which indicates the importance of this alignment for their biomedical applications. The experimental results were quantitatively explained with numerical simulation that took account of easy axis alignment and core size distribution in the sample. We can express the degree of easy axis alignment using a distribution function of the easy axis angle for both immobilized and suspended cases. The distribution function will be useful for quantitatively evaluating MNP performance in biomedical applications.