Study of the interaction of water with phospholipid bilayers by FTIR spectroscopy

The hydration of the dimyristoylphosphatidylcholine multi-bilayers has been studied by means of Fourier transform infrared spectroscopy. The structure of water confined in lipid membrane, under water-rich and water-poor conditions has been investigated by examining the OH stretching band region. We found that the structure of solvation water of lipid bilayer differs from bulk water. In addition, interaction of water molecules with carbonyl group and phosphate group of phosphatidylcholine have been observed through the downshift of the relative vibrational components representing hydrogen bonded groups. We infer  that the disorder of the water network occurs especially in the interfacial region of phospholipids and it increases above the gel to liquid crystalline phase transition, giving rise to an increase of the absorption around 3600 cm -1 which indicates the presence of weakly hydrogen bonded water aggregates.