SEMINAR: Physics Seminar

We have developed instrumentation to measure magnetic properties of a single live cell by measuring its motion in physiologic electrolyte solutions in strong magnetic fields and gradients. A highly automated and rapid process of cell image track acquisition and computer-aided tracking velocimetry allows us to sample a large number of cells (up to tens of thousands in under an hour) and determine cell magnetophoretic mobility distribution in a cell population. The cell magnetophoretic mobility is directly proportional to its magnetic susceptibility (relative to that of the fluid medium) or its spin density. We have shown that the results of such quantitative magnetophoretic analysis agrees to within the experimental error with those calculated based on the low-spin to high-spin intracellular iron compound conversion in red blood cells and malaria parasite infected RBCs. Other applications include intracellular iron uptake by mammalian cells and paramagnetic metal incorporation by bacteria. Such information is inaccessible by the current state-of-the-art magnetic susceptometers limited to measuring the bulk magnetic properties of matter, and therefore the cell magnetophoretic mobility analysis offers unique opportunities to probe the magnetic properties at a single cell level.

Maciej Zborowski, Ph.D. is Staff in the Department of Biomedical Engineering, Lerner Research Institute of the Cleveland Clinic, Cleveland, Ohio, USA, and the Associate Professor in the Department of Molecular Medicine of the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (CWRU), Cleveland, Ohio. He received M.Sc. degree (Biophysics 1975) from Warsaw University, and Ph.D. degree (Biomedical Engineering 1985) from Polish Academy of Sciences, Warsaw, Poland. He directs Cell Separation Research Laboratory whose focus is research and development in the area of instrumentation for fast cell sorting, in particular, magnetic cell sorting. This often requires application of fine magnetic particles (nanoparticles) for cell tagging and separation and developing new instrumentation for cell motion analysis induced by the applied magnetic field (magnetophoresis). The approaches are tested in applications to separation of circulating tumor cells from blood, malaria-infected red blood cells and bacteria suspensions.