Properties of single- and multi-core magnetic nanoparticles assessed by magnetic susceptibility measurements
Properties of single- and multi-core magnetic nanoparticles assessed by magnetic susceptibility measurements
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通过磁化率测量评估单核和多核磁性纳米粒子的特性
DOI：
10.1016/j.jmmm.2021.167812
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发表时间：
2021
影响因子：
2.7
通讯作者：
K. Tsukada
中科院分区：
文献类型：
--
作者：
M. M. Saari;M. Sulaiman;N. A. C. Lah;Zulkifly Aziz;K. Sakai;T. Kiwa;K. Tsukada
表征MNP系综的结构和磁性对于定制其用于生物医学应用的性能至关重要。在这项工作中，我们评估的单核和多核纳米粒子在水悬浮液中的磁性核心的尺寸分布，使用透射电子显微镜（TEM）和静态磁化曲线，与几何核心尺寸范围从8.3到40.2 nm。通过与TEM图像的几何尺寸进行比较，得到了由磁化曲线导出的合理磁芯尺寸。磁矩分布可能揭示了有效磁芯尺寸的减小是由于磁芯中的磁化退化。从5 Hz至100 kHz的MNP的AC磁化率响应获得的流体动力学尺寸和平均各向异性能量比也进行了评价。弛豫时间的复杂分布构造通过应用非负最小二乘法的AC磁化率模型，该模型结合了间和内势阱的贡献。结果发现，对数正态分布可能不足以代表流体动力学粒度分布重建的悬浮样品的交流磁化率响应。结果表明，在这项研究中使用的AC磁化率模型可以用来公平地估计平均各向异性能量比的MNP系综占主导地位的热阻塞粒子。此外，可以认为，除了几何核心的大小，核心聚集的程度也起着重要的作用，在确定各向异性能量比和有效磁矩。
Characterization of structural and magnetic properties of MNP ensembles is crucial in tailoring their performance for biomedical applications. In this work, we evaluate the size distribution of magnetic cores in single- and multi-core nanoparticles in water suspension using transmission electron microscopy (TEM) and static magnetization curve, with the geometrical core size ranges from 8.3 to 40.2 nm. A reasonable core size derived from the magnetization curve is obtained in comparison to the geometrical size from TEM image. The magnetic moment distribution possibly reveals that the reduction of effective magnetic core size is due to the magnetization degradation in cores. The hydrodynamic size and average anisotropy energy ratio obtained from the AC susceptibility response of MNPs from 5 Hz to 100 kHz are also evaluated. The complex distribution of relaxation time is constructed by applying a non-negative least square method to an AC susceptibility model that incorporates the inter- and intra-potential-well contributions. It is found that a log-normal distribution might not be adequate to represent the hydrodynamic size distribution reconstructed from the AC susceptibility responses of the suspended samples. It is demonstrated that the AC susceptibility model used in this study can be used to fairly estimate the average anisotropy energy ratio for MNP ensembles dominated by thermally blocked particles. Moreover, it can be suggested that besides the geometrical core size, the degree of core aggregation also plays an important role in determining the anisotropy energy ratio and effective magnetic moment.
影响因子：
10.8
作者：
Yu EY;Bishop M;Zheng B;Ferguson RM;Khandhar AP;Kemp SJ;Krishnan KM;Goodwill PW;Conolly SM
通讯作者：
Conolly SM