Magnetic particle imaging (MPI) is a promising medical imaging technique for visualizing the three-dimensional distribution of tracer materials, specifically iron oxide nanoparticles (IONP). The optimization of magnetic nanoparticles (MNP) plays an essential role to improve the image resolution and sensitivity of imaging techniques. Objective. In this work, the optimization of commercial IONP (EMG 700, Ferrotec) coated with anionic surfactants was carried out using magnetic separation (MS) technique, by a low gradient magnetic separation (LGMS) (<15 T m⁻¹) method, to improve their performance as MPI tracers. Approach. The magnetophoretical behavior of the samples in different concentrations ranging from 2 to 120 mmol l⁻¹ was investigated over 24 h of separation. The samples were characterized by dynamic light scattering (DLS), AC susceptibility (ACS), magnetic particle spectroscopy (MPS) and they were imaged in a preclinical MPI scanner, before and after MS. Main results. DLS results showed that by increasing the concentration from 2 to 120 mmol l⁻¹ the hydrodynamic diameter of MNP decrease from 75 to 47 nm and size distribution decrease from 0.19 to 0.11 after 4 min MS. In addition, the MPS results demonstrated the third harmonic amplitude normalized to the iron amount and harmonic ratio of signal increase from 8.38 to 10.59 Am² kg⁻¹ (Fe) and 24.21–26.60, respectively. Furthermore, the MPI images of the samples after separation showed higher MPI resolution. Significance. Therefore, LGMS can be considered as a valuable method to narrow and control the size distribution of MNP for MPI.

磁粉成像 (MPI) 是一种很有前途的医学成像技术，用于可视化示踪材料的三维分布，特别是氧化铁纳米粒子 (IONP)。磁性纳米粒子（MNP）的优化对于提高成像技术的图像分辨率和灵敏度起着至关重要的作用。客观的。在这项工作中，使用磁分离 (MS) 技术，通过低梯度磁分离 (LGMS) (<15 T m ^-1 ) 方法对涂覆有阴离子表面活性剂的商业 IONP (EMG 700, Ferrotec) 进行了优化，以提高它们作为 MPI 跟踪器的性能。方法。样品在 2 到 120 mmol l ^{-1的不同浓度下的磁泳行为}经过 24 小时的分离研究。样品通过动态光散射 (DLS)、交流磁化率 (ACS)、磁粉光谱 (MPS) 进行表征，并在 MS 前后在临床前 MPI 扫描仪中成像。主要结果。DLS 结果表明，通过将浓度从 2 增加到 120 mmol l ^-1，MNP 的流体动力学直径从 75 nm 减小到 47 nm，并且尺寸分布在 4 分钟 MS 后从 0.19 减小到 0.11。此外，MPS 结果表明，归一化为铁量的三次谐波幅度和信号的谐波比从 8.38 增加到 10.59 Am ² kg ^-1(Fe) 和 24.21–26.60，分别。此外，分离后样品的 MPI 图像显示出更高的 MPI 分辨率。意义。因此，LGMS可以被认为是一种有价值的方法来缩小和控制MPI的MNP尺寸分布。