Background: Land-living organisms face the challenge that the ambient air is much drier than what is found in a living cell. One strategy to counter this drying-out threat is through lipid-protein barrier membranes, like the human skin. The water transport across an inert diffusional barrier is proportional to the difference in water chemical potential between inside and outside. However, measurements show that for a typical human skin the water loss increases as RH is lowered from 99% but it levels off around a value of RH≈80%. Thus the skin responds to drier conditions by decreasing its water permeability. Questions addressed: When a liquid sample (or a water-rich tissue) is exposed to ambient air, there are typically non-equilibrium conditions at the air-liquid interface. There is then possibility that phase transitions are induced in the water gradient, leading to interfacial phase separation. In the present study, we aim at the basic mechanisms behind the formation of multilayer interfacial films in a water gradient and how this control evaporation of water. Results and discussion: We show that simple amphiphiles/water systems reproduce the responding behavior seen for skin that the water evaporation is maintained at nearly constant level independently of air humidity. Based on this together with previous theoretical and experimental studies coupling between structure and transport in membranes in lipid systems and skin, we propose a mechanism originating from responding self-assembly structures.

Controlling water evaporation through self-assembly

255th National Meeting (2018)

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