Minor changes in moisture level can promote lipid molecules to reorganise themselves in biomaterial or biomembranes. This can affect how the skin, lungs and tear film protect us from dehydration. A new discovery from Lund University in Sweden could be the inspiration for smart materials and new drug delivery techniques.
Imagine a membrane that separates dry air from a moist interior. When moisture levels become lower, the lipid molecules organise themselves in an adaptive way – and now researchers in Lund have characterized this process.
"What surprised me was how powerful the sorting of the lipid molecules was even at small changes in the moisture level. I had not expected this based on what we know about the systems in conditions where there is no evaporation," says Nikol Labecka, researcher in chemistry at Lund University.
The body's barriers – skin, tear film and lung membrane – are constantly subjected to evaporation of water. Lipid molecules and proteins form structures that separate the body's moist interior from the dry surroundings. But how these structures respond when the environment becomes drier has remained a mystery.
The new study, which has been published in the research journal PNAS, investigate membranes composed of molecules that form different membrane structures with different water uptake capacities. When the environment dries out, the molecules reorganise between these structures, which creates a feedback mechanism: dehydration affects the structure and composition at different depth in the membrane– and this, in turn, controls the transport of water and other substances.
"Being able to now explain why lipid molecules redistribute between more and less tightly packed structures when the surrounding conditions changes between dry and humid provides a whole new understanding of the membrane's transport properties," says Emma Sparr, professor in chemistry at Lund University.
Using new quantitative approach, the study identifies a general sorting mechanism with respect to how changes in the surrounding moister levels. The understanding of this fundamental mechanism can help us to better understand the skin's moisture balance and the lungs' protection against dehydration.
"An understanding of these fundamental mechanisms has practical significance and could also be used to improve lipid-based drug delivery systems, understand changes in food caused by dehydration, and lead to the development of smart materials that adapt to humidity," concludes Nikol Labecka.
