Figure 8.

CARS microspectroscopy. A full spectral series of CARS microscopy images covering the C-H vibrational region 2,760 to 2,960 cm⁻¹ was scanned for Ctrl, LL, and NS cells. Normalized and power-compensated CARS signals averaged over lipid droplets are shown as spectra in A. a.u., Arbitrary units. Average lipid fluidity ratios (I₂₈₄₅/I₂₈₈₅) for lipid droplets in the different cell categories are plotted in B, illustrating a significantly lower value for NS compared with Ctrl. This is further confirmed in the fluidity ratio images in C to E, where the lipid droplets in Ctrl (C) and LL (D) appear in yellow in contrast to the lipid droplets for NS in E, which all are color coded in red (see intensity bar in C). All measurements were conducted at room temperature. Lower lipid fluidity is reported for saturated lipids at constant temperatures. This indicates that NS cells contain larger amounts of saturated lipids.