Cholesterol layer keeps out biological contaminants

Cholesterol layer keeps out biological contaminants

Researchers have discovered an effect in springtails that could be used to make new materials.

graues ovales Tier mit Einkerbungen und Fühlern
The giant springtail Tetrodontophora bielanensis keeps its skin clean with the help of cholesterol.

Clean air is important - also for the so-called springtails, a widespread class of arthropods. The animals, which are only a few millimeters in size, have a special feature: they almost all breathe exclusively through their skin. As organisms that frequently live on the ground, springtails face the challenge of keeping this very skin as free as possible from pollutants and pathogens so as not to endanger their respiration. Researchers at the Leibniz Institute of Polymer Research in Dresden have now discovered how the animals manage this. The discovery could be used for the development of new materials.

Spontaneous change of molecular orientation

Initially, the research team led by Carsten Werner noticed that springtails have a high proportion of cholesterol on their skin. In the journal Nature, the experts now report how these molecules help keep the skin of the small arthropods clean. Using experiments, atomistic simulations and analyses of thermodynamics, they found that the orientation of the cholesterol molecules sometimes changes spontaneously. This creates what is known as entropic repulsion, which makes it harder for proteins or bacteria to attach to the cholesterol-containing skin surface. Even tiny changes in molecular orientation nullified this effect. Surfaces that were fixed and therefore could not spontaneously realign themselves also offered no protection against adhering biological surfaces.

Functionalized surfaces with entropic repulsion

Many products or technologies depend on their surfaces not being contaminated by biological material. The research team therefore now wants to use the principle discovered in nature to develop synthetic materials that are kept clean by a comparable entropic repulsion. However, a great deal of research work is likely to be needed before surfaces can be functionalized in this way.