Figure 13

Three stills showing the movement of E. coli under the presence of a magnetic field. These cells, placed on a glass slide, were taken from a cell suspension growing with 2.2 × 10^-3 g/ml silica-iron oxide nanoparticles. A cylindrical neodymium-iron-boron permanent magnet (Arbor Scientific, Ann Arbor, MI) was placed two inches away on the right hand side of a glass slide sitting on a digital confocal microscope for imaging. Some cells exhibited motion along the magnetic field lines, but not all of the cells moved in the direction of the field suggesting that not all cells were in contact with nanoparticles. Image (A) shows a cell (square box) moving from the upper left hand corner between two stationary cells (circled) to the lower right hand corner (C) which is the direction of the magnetic pull on the particles.