Magnetic Particles Characterization – Magnetophoretic Mobility and Particle Size

Characterization of magnetic particles is a promising technique for analysis and separation of labeled cells and magnetic particles.  A Hyperflux^TM velocimeter is utilized to directly measure the magnetophoretic mobility, size and other morphology parameters of magnetic particles and labeled cells.  The instrument provides quantitative video analysis of cells and/or particles and their motion.  The trajectories of magnetic particles in a uniform isodynamic magnetic field are recorded using a high-definition camera/microscope system for image collection.  Image analysis software then converts the image data to the parameters of interest.  The distribution of magnetophoretic mobility is determined by combining fast image analysis with velocimetry measurements.  In addition, the particle size distribution has been characterized to provide a better understanding of the sample quality.  List-mode data are acquired, and these are used to correlate quantitative features such as magnetophoretic mobility versus size.  Review of numerous commercial magnetic beads using this technology has demonstrated the expected dependence of magnetophoretic mobility on volume and per cent iron oxide.  Results have also been utilized to assist in the design of a Quadrupole Magnetic Sorter (QMS) and a point-of-care rare cell detector.