High gradient magnetic capture of cells and ferritin-bound particles

The magnetic retention of biological cells is of interest as a convenient system in which essentially identical particles can be used to study HGMS and, conversely, as an area in which the HGMS technique can be applied to make biologically important cell separations. Previously, red blood cells have provided data which confirmed theoretical predictions concerning the dependence of particle capture on field, flow rate, particle magnetic susceptibility and diameter of wire in the magnetized matrix. In these experiments the technique has been extended to examine the retention of more weakly paramagnetic (ferritin-labelled) particles and the use of weaker magnetic fields. Latex particles with the iron storage protein ferritin attached and a 7 Tesla magnet have been used to model the expected HGMS capture of ferritin-labelled cells. Red cell retention in weak fields was demonstrated using .3 - .45 Tesla permanent magnet assemblies and stainless steel wire of three diameters. A decrease in HGMS capture efficiency for the finest wire was observed.