Multicore Magnetic Nanoparticles for Magnetic Particle Imaging
Multicore Magnetic Nanoparticles for Magnetic Particle Imaging
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DOI：
10.1109/tmag.2012.2226438
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发表时间：
2013-01-01
影响因子：
2.1
通讯作者：
Westphal, Fritz
中科院分区：
文献类型：
--
作者：
Eberbeck, Dietmar;Dennis, Cindi L.;Westphal, Fritz
生物相容性磁性纳米颗粒是用于诊断成像技术（包括磁共振成像和磁粒子成像（MPI））的有趣示踪剂。在这里，我们将介绍我们的研究的物理和特别是磁性能的葡聚糖涂层的多核磁性氧化铁纳米粒子，与有前途的高MPI信号揭示的磁粒子光谱（MPS）测量。与Resovist相比，流体动力学直径为106 nm的Nanomag-MIP颗粒在第三谐波处显示MPS振幅增加约2倍。特别地，信号随着谐波的阶数逐渐改善，这是获得更好空间分辨率的先决条件。为了理解这种行为，我们研究了样品使用准静态磁化测量产生双峰尺寸分布的两个系统，和磁弛豫提供的平均有效各向异性常数。对于Nanomag-MIP，占主导地位的较大尺寸模式的平均有效磁直径为19 nm，其中色散参数σ = 0.3，对于Resovist，平均有效磁直径为22 nm，其中σ = 0.25。然而，Nanomag-MIP中约80%的磁性纳米颗粒属于这种较大尺寸的模式，而Resovist中只有30%。剩余的Resovist颗粒在5 nm范围内，并且实际上对MPI信号没有贡献。
Biocompatible magnetic nanoparticles are interesting tracers for diagnostic imaging techniques, including magnetic resonance imaging and magnetic particle imaging (MPI). Here, we will present our studies of the physical and especially magnetic properties of dextran coated multicore magnetic iron oxide nanoparticles, with promising high MPI signals revealed by magnetic particle spectroscopy (MPS) measurements. The Nanomag-MIP particles with a hydrodynamic diameter of 106 nm show an increase of the MPS amplitude by a factor of about two at the 3rd harmonic, as compared to Resovist. In particular, the signal improves progressively with the order of the harmonic, a prerequisite for better spatial resolution. To understand this behavior, we investigated the samples using quasistatic magnetization measurements yielding bimodal size distributions for both systems, and magnetorelaxometry providing the mean effective anisotropy constant. The mean effective magnetic diameter of the dominant larger size mode is 19 nm with a dispersion parameter sigma = 0.3 of for Nanomag-MIP, and 22 nm with sigma = 0.25 for Resovist. However, about 80% of the magnetic nanoparticles of Nanomag-MIP belong to this larger size mode whereas in Resovist only 30% do. The remaining Resovist particles are in the range of 5 nm, and, in practice, do not contribute to the MPI signal.