Processing of cell magnetophoresis data obtained with a constant gradient separation device

The ability to measure the magnetophoretic mobilities and iron content of a given culture of mammalian cells exposed to magnetic nanoparticles using a magnetic separation device, has the potential to provide immediate feedback about a given labeling process protocol and facilitate its optimization. The commercial device employed in this work generate a constant radial magnetic gradient of 24 T\/m. Magnetophoretic separation of magnetically labeled cell suspensions, was monitored by the decrease of opacity during the separation process. A well stablished theory has been developed for this device permit the calculation of the magnetophoretic velocities that the cells attain in the stationary state during the separation. This communication describes the protocol of the measurement, the approximations made in the determination of the distribution of the magnetophoretic coefficients and the iron quantities per cell in the culture. The methodology was applied to the labelling of L929 mouse fibroblasts and NR8383 rat macrophages cultured in presence of chitosan-coated magnetic nanoparticles. The average iron content per cell obtained was coincident with the obtained by chemical analysis using standard procedures. In order to validate the magnetophoretic results, commercial magnetic beads widely used with known magnetophoretic mobility were measured. The results show that the labelling process is far from uniform, and a wide distribution of magnetophoretic mobilities and iron contents per cell result.