Figure 6

PMLI, carried out in the BF mode, demonstrates a temporal variation of GNR orientations to take place in live GNR-loaded cells. (a) The bright-field images (top row), do not disclose any significant temporal post-loading variation in cells’ structures. However, such post-loading changes are clearly visible by the polarization modulation imaging (bottom row), which is sensitive to a local optical anisotropy within the samples. In particular, the fine pattern of intracellular black curves (bottom row), coarsening as a function of time, suggests that the distribution of GNR orientations is time-dependent and non-random. The observed time-evolution of GNR-loaded cells may have an impact on their biological behavior, yet remains unnoticed by the conventional imaging methods. The imaging times, post-loading, are labeled on top. (b) The temporal evolution of the intracellular GNR orientations, following the GNR loading into the cell, exhibits a coarsening of the GNR orientation domains, unnoticed by the conventional imaging methods. The black boundaries separate between distinct strong intensity areas in the PMLI images. A threshold on the intensity was employed to remove the background noise. Pixels below the threshold appear in white. The color map (in angle degrees) corresponds to the GNR orientations. Scale bars in both (a,b) correspond to 10 μm. The same raw data are used here, as for the cell A in (a).