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Journal Article

Lateral diffusion in substrate-supported lipid monolayers as a function of ambient relative humidity


Baumgart,  T.
MPI for Polymer Research, Max Planck Society;


Offenhäusser,  Andreas
MPI for Polymer Research, Max Planck Society;

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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. doi:10.1016/S0006-3495(02)73919-2.

Cite as: https://hdl.handle.net/11858/00-001M-0000-000F-6519-A
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, E-a, which depends on the hydration state of the lipid headgroup. A crucial assumption of the derived model is that E- a 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(p(o)/p), where D is the measured diffusion coefficient and p(o) 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.