Developing an economical and universal method to measure the magnetic moments of magnetic mesenchymal stem cells (MSCs) labelled with superparamagnetic iron oxide (SPIO) nanoparticles is crucial for cell tracking. In this study, we used a gradient magnetic field created by a nickel needle to track the motion of cells. A simple and quantifiable magnetic sensor was employed to evaluate the magnetic properties of single viable MSCs. We measured the magnetic moments of microbeads and MSCs using the proposed method and compared the results with magnetic moments measured using a superconducting quantum interference device and with iron contents measured using an inductively coupled plasma spectrometer, respectively. The correlation coefficients indicated satisfactory agreement in both cases, thus confirming the accuracy of the system. By labelling MSCs with SPIOs, we implemented a miniature magnetic sensor to measure the magnetic moments of single magnetic MSCs quantitatively using an image-processing algorithm. Existing methods for the measurement of magnetic moments at the micro/nanoscale have various limitations. Our system realised the measurement of single viable cells, thereby providing a theoretical foundation for the labelling and tracking of MSCs with SPIO nanoparticles. Additionally, the proposed system is both economical and universal.

开发一种经济且通用的方法来测量用超顺磁性氧化铁（SPIO）纳米颗粒标记的间充质干细胞（MSC）的磁矩对于细胞跟踪至关重要。在这项研究中，我们使用了镍针产生的梯度磁场来跟踪细胞的运动。一个简单和可量化的磁传感器被用来评估单个活MSC的磁性。我们使用所提出的方法测量了微珠和MSC的磁矩，并将结果分别与使用超导量子干涉仪测量的磁矩和与电感耦合等离子体光谱仪测量的铁含量进行了比较。相关系数表明在两种情况下均具有令人满意的一致性，从而确认了系统的准确性。通过用SPIO标记MSC，我们实现了一个微型磁传感器，使用图像处理算法定量测量单个磁性MSC的磁矩。在微米/纳米尺度上测量磁矩的现有方法具有各种局限性。我们的系统实现了单个活细胞的测量，从而为用SPIO纳米颗粒标记和跟踪MSC提供了理论基础。另外，所提出的系统既经济又通用。从而为用SPIO纳米粒子标记和跟踪MSC提供理论基础。另外，所提出的系统既经济又通用。从而为用SPIO纳米粒子标记和跟踪MSC提供理论基础。另外，所提出的系统既经济又通用。