Label-free imaging of intracellular motility by low-coherent quantitative phase microscopy.

The subject study demonstrates the imaging of cell activity by quantitatively assessing the motion of intracellular organelles and cell plasma membranes without any contrast agent. The low-coherent interferometric technique and phase-referenced phase shifting technique were integrated to reveal the depth-resolved distribution of intracellular motility. The transversal and vertical spatial resolutions were 0.56 μm and 0.93 μm, respectively, and the mechanical stability of the system was 1.2 nm. The motility of the cell was assessed by mean squared displacement (MSD) and we have compensated for the MSD by applying statistical noise analysis. Thus we show the significant change of intracellular motility after paraformaldehyde treatment in non-labeled cells.