Statistical measures characterizing cell trajectories.
(A) The mean-square displacement for cells in buffer and CMC solutions (concentration c = 0, 35, 60, 100 ppm, MW = 7 × 105). At short times, , where is the mean run time, the cell motion is ballistic and . At longer times, , the cell motion is diffusive and . As c increases, the magnitudes of the MSD curves increase. (B) The mean-square angular displacement of cells in buffer and polymeric solutions increases linearly over time, indicating diffusive reorientations. (C) The translational diffusion coefficient increases from 10.8 to 101.6 μm2/s as c increases. The result for buffer (c = 0 ppm) provides a reference (dashed line). (D) The rotational diffusion coefficient decreases from 5.6 to 0.7 rad2/s as c increases, reflecting suppressed tumbling in polymeric solutions.