| Abstract
| - Langmuir films of amphiphilic biomolecules represent promising systems to study diffusional propertiesin model membranes under controlled area conditions. Here, we present for the first time single moleculefluorescence imaging experiments on phospholipid monolayers at the air−water interface. The techniqueis used to track the lateral diffusion of single molecules of N-(6-tetramethylrhodaminethiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt (TRITC−DHPE), in phospholipid monolayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (sodium salt) (DMPG) at different areas per phospholipid molecule. Our trackingdata of the averaged mean-square displacement indicate for both phospholipids that surface flow couldbe suppressed significantly. The diffusion behavior of TRITC−DHPE in DMPC and DMPG monolayersis characterized by unobstructed diffusion and can be described well by a free area model. Our experimentsshow that single molecule fluorescence imaging can be successfully applied to monolayers of amphiphilesat the air−water interface. This opens the door to future studies of hindered diffusion in monolayers ofspecific heterogeneity.
|
