Di-4-ANEPPDHQ probes the response of lipid packing to the membrane tension change in living cells

Membrane tension plays a significant role in many cellular processes including cell adhesion, migration and spreading. Despite the importance of membrane tension, it remains difficult to measure in vivo. Recently, the development of non-invasive fluorescent probes have made great progress, especially excitedstate deplanarization in molecular rotors has been applied to image membrane tension in living cells.Nevertheless, an intrinsic limitation of such kind of probe is that they depend on the lipid packing, and how the lipid packing responds to the membrane tension change remains unclear. Therefore, in this work,we used a polarity-sensitive membrane probe to investigate the possible response mechanism of lipid packing to the change of membrane tension that was regulated by osmotic shocks. The results showed that an increase in membrane tension could stretch the lipids apart with large displacements, and this change was not homogeneous on the whole membrane, instead, increase of membrane tension induced phase separation.