Simple lipids form stable higher-order structures in concentrated sulfuric acid

TL;DR

This study demonstrates that simple lipids can form stable higher-order structures in concentrated sulfuric acid, suggesting potential for life-like structures in extreme extraterrestrial environments like Venus's clouds.

Contribution

The paper reveals that certain simple lipids resist degradation and form membrane-like structures in sulfuric acid, a novel finding relevant to astrobiology and extremophile research.

Findings

Simple lipids resist sulfuric acid degradation.

Lipids form stable micelles and vesicles in sulfuric acid.

Molecular dynamics explain lipid stability in extreme conditions.

Abstract

Venus has become a target of astrobiological interest because it is physically accessible to direct exploration, unlike exoplanets. So far this interest has been motivated not by the explicit expectation of finding life but rather by a desire to understand the limits of biology. The venusian surface is sterilizing, but the cloud deck includes regions with temperatures and pressures conventionally considered compatible with life. However, the venusian clouds are thought to consist of concentrated sulfuric acid. To determine if any fundamental features of life as we understand them here on Earth could in principle exist in these extreme solvent conditions, we tested several simple lipids for resistance to solvolysis and their ability to form structures in concentrated sulfuric acid. We find that single-chain saturated lipids with sulfate, alcohol, trimethylamine, and phosphonate head groups are resistant to sulfuric acid degradation at room temperature. Furthermore, we find that they form stable higher-order structures typically associated with lipid membranes, micelles, and vesicles. Finally, results from molecular dynamics simulations suggest a molecular explanation for the observed robustness of the lipid structures formed in concentrated sulfuric acid. We conclude with implications for the study of Venus as a target of experimental astrobiology.