Hydration force parameters of phosphatidylcholine lipid bilayers as determined from 2H-NMR studies of deuterated water.

The continuous decrease of the quadrupolar splitting of deuterated water interacting with phosphocholine lipid bilayers with growing water concentration is analyzed as a function of the water activity. From the apparent linear dependence on water activity a measure for hydration forces is obtained. The forces calculated are in the range of published data using sorption isotherms and osmotic stress technique in combination with SAXS. A simple interaction potential which includes orientational order of water adsorbed on surfaces gives a physical base for these findings. Therefore, deuterium NMR may become a powerful tool for hydration force analysis complementing well-known methods.