Effect of high pressure on the structure of dipalmitoylphosphatidylcholine bilayer membranes: a synchrotron-X-ray diffraction and FT-IR spectroscopy study using the diamond anvil technique

Abstract

The effect of high pressure, up to 20 kbar, on multilamellar vesicles of 1,2-dipalmitoyl- sn-glycero-3-phosphatidylcholine (DPPC) was examined by using FT-IR spectroscopy and Synchrotron-X-ray diffraction in the small- and wide-angle scattering region. The temperature and pressure range studied permitted us to explore the phase behaviour of DPPC from the liquid–crystalline phase through various gel phases up to the pressure region where bulk water freezes and freeze-induced dehydration of the membrane occurs. To our knowledge this is the first study where the structure and phase behaviour of an amphiphilic lipid system has been studied up to these high pressures. The use of pressure to study the lipid gel state has revealed several new phases which may not exist at very low temperatures at ambient pressure.