TRANSFORMATION OF PHOSPHATIDYLCHOLINE MULTILAYER SYSTEMS IN A LARGE EXCESS OF WATER

The swelling of similar samples of prehydrated phosphatidylcholine in excess water (> 99 wt/wt%) was studied microscopically and by X-ray di ffraction. The Bragg peaks of the lamellar repeat distance were monito red for up to ten days. After a short period of rapid water uptake, th e peaks remained stable in width and position, thus indicating that th e so-called equilibrium distance was established in the fluid membrane stack. Within the next days we usually found the peaks to decrease co ntinuously before they vanished in the background. The results suggest that the multilayer system desintegrates because the membranes peel o ff from it. Their separation may be driven by a tendency of the unstre ssed fluid membranes to develop a superstructure.