Critical properties of the lipid bilayer probed by fluorescence correlation spectroscopy and its variants

Mechanical properties of the lipid bilayer are perturbed by small signaling molecules such as serotonin, which alters the rates of cellular exo- and endocytosis. A combination of tools, which include 4Pi rotational FCS, z-scan FCS, triple correlation FCS, radical-quenching FCS, and FCS in combination with AFM and single molecule photobleaching, help us understand how the structural modulations are caused by these small molecules. Our work shows that the lipid bilayer can be a novel target for a new class of membrane-active drugs.