We analyzed the influence of water activity on the lateral self-diffusion of supported phospholipid monolayers. Lipid monolayer membranes were supported by polysaccharide cushions (chitosan and agarose), or glass. A simple diffusion model was derived, based on activated diffusion with an activation energy, Ea, which depends on the hydration state of the lipid headgroup. A crucial assumption of the derived model is that Ea can be calculated assuming an exponential decay of the humidity-dependent disjoining pressure in the monolayer/substrate interface with respect to the equilibrium separation distance. A plot of In(D) against In(po/p), where D is the measured diffusion coefficient and po and p are the partial water pressures at saturation and at a particular relative humidity, respectively, was observed to be linear in all cases (i.e., for differing lipids, lateral monolayer pressures, temperatures, and substrates), in accordance with the above-mentioned diffusion model. No indications for humidity-induced first-order phase transitions in the supported phospholipid monolayers were found. Many biological processes such as vesicle fusion and recognition processes involve dehydration/hydration cycles, and it can be expected that the water activity significantly affects the kinetics of these processes in a manner similar to that examined in the present work.
CITATION STYLE
Baumgart, T., & Offenhäusser, A. (2002). Lateral diffusion in substrate-supported lipid monolayers as a function of ambient relative humidity. Biophysical Journal, 83(3), 1489–1500. https://doi.org/10.1016/S0006-3495(02)73919-2
Mendeley helps you to discover research relevant for your work.