Surface-Assisted Self-Assembly of Fatty Acids to Cell-Like Compartments

Abstract

In contemporary biological cells, lipid membrane-enclosed, spatially distinct microenvironments confine and protect biochemical reactions and other processes. On the early Earth, the formation of independent compartments is believed to have led to the encapsulation of nucleotides, possibly aiding and facilitating the emergence of life. In this context, solid surfaces have recently been investigated as potential supports for the self-assembly of prebiotic membrane containers, as significantly enhanced compartment formation was reported in the presence of solid interfaces. Particularly, the spontaneous transformation of solid-surface-adhered phospholipid reservoirs to unilamellar vesicular compartments was shown, where the deposits undergo a well-defined progression of topological changes, starting from two-dimensional molecular lipid films, via a network of interconnected lipid nanotubes to unilamellar giant compartments. However fatty acids, having only one hydrophobic tail, are structurally simpler than phospholipids, and could have been synthesized earlier than the more intricate phospholipids, and were therefore available earlier to form protocellular compartments. We show in our latest work that, starting from simple fatty acids on solid supports, the formation of protocells can occur in the same fashion as observed in earlier experiments with phospholipids. The compartments are generated from initially unstructured deposits of fatty acids on high energy surfaces, such as SiO2, where spontaneous surface wetting, film rupturing and giant vesicle formation occurs. The new findings indicate that the earlier observed surface-assisted protocell formation route is not exclusive to phospholipids, but may have been a more general pathway in the development of early life.