Moore L R, Zborowski M, Nakamura M, McCloskey K, Gura S, Zuberi M, Margel S, Chalmers J J
Department of Biomedical Engineering, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
J Biochem Biophys Methods. 2000 Jul 10;44(1-2):115-30. doi: 10.1016/s0165-022x(00)00085-3.
Continuous magnetic separation, in which there is no accumulation of mass in the system, is an inherently dynamic process, requiring advanced knowledge of the separable species for optimal instrument operation. By determining cell magnetization in a well-defined field, we may predict the cell trajectory behavior in the well-characterized field environments of our continuous separators. Magnetization is determined by tracking the migration of particles with a technique known as cell tracking velocimetry (CTV). The validation of CTV requires calibration against an external standard. Furthermore, such a standard, devoid of the variations and instabilities of biological systems, is needed to reference the method against day-to-day shifts or trends. To this end, a method of synthesizing monodisperse, magnetite-doped polymeric microspheres has been developed. Five sets of microspheres differing in their content of magnetite, and each of approximately 2.7 microm diameter, are investigated. An average gradient of 0.18 T/mm induces magnetic microsphere velocities ranging from 0.45 to 420 microns/s in the CTV device. The velocities enable calculation of the microsphere magnetization. Magnetometer measurements permit the determination of magnetization at a flux density comparable to that of the CTV magnet's analysis region, 1.57 T. A comparison of the results of the CTV and magnetometer measurements shows good agreement.
连续磁分离是一个本质上动态的过程，系统中不存在质量积累，它需要对可分离物质有深入的了解才能实现仪器的最佳操作。通过在定义明确的磁场中测定细胞的磁化强度，我们可以预测细胞在连续分离器特征明确的磁场环境中的轨迹行为。磁化强度是通过一种称为细胞跟踪测速法（CTV）的技术跟踪颗粒的迁移来确定的。CTV的验证需要根据外部标准进行校准。此外，还需要这样一个不受生物系统变化和不稳定性影响的标准，以便对照日常的变化或趋势来参考该方法。为此，已开发出一种合成单分散、掺杂磁铁矿的聚合物微球的方法。研究了五组磁铁矿含量不同、直径均约为2.7微米的微球。在CTV装置中，平均梯度为0.18 T/mm时，可使磁性微球的速度在0.45至420微米/秒之间。这些速度可用于计算微球的磁化强度。磁力计测量可在与CTV磁体分析区域相同的磁通密度（1.57 T）下测定磁化强度。CTV测量结果与磁力计测量结果的比较显示出良好的一致性。
