Slow tumbling but large protrusion of phospholipids in the cell sized giant vesicle

Lipid membrane dynamics in cell sized vesicles (CSVs) in water is characterized by the solution-state NMR. CSV is successfully prepared by natural swelling method using osmotic effect. Broad 1H NMR signal and large 31P NMR chemical shift anisotropy show the slow tumbling of the lipid with the rotational correlation time 0.2–2.8 s in CSV of 10–20 μm-diameters. The 1H–1H nuclear Overhauser effect enhancement reveals the proximity between the lipid headgroup and alkyl chains, in which the close distance, ∼0.4 nm. The proximity is due to the large protrusion of the lipids in the vertical direction to the CSV surface.