Headgroup hydration in egg-lecithin multibilayers affects the behaviour of DPH probes

Abstract

Angle-resolved fluorescence depolarization experiments were carried out on DPH molecules embedded in egg-licithin bilayers of different water contents. It was found that the order parameter 〈 P 2〉 of the absorption moment is significantly higher than that of the emission moment and that the difference increases on hydrating the lecithin headgroups. The changes in the order parameter 〈 P 2〉 and 〈 P 4〉 of the DPH molecules induced by hydration are consistent with X-ray diffraction data. Furthermore the reorientational motions of the DPH molecules were found to become faster with increasing hydration.