The origins of life required the assembly of three key components: a metabolic system, an information system, and a membrane that protected the other components and controlled diffusion of essential components. Before the modern lipids evolved, these membranes were likely composed of simple surfactants that follow basic aggregation behaviors, leading to the first cell membrane. Unfortunately, most membrane research is done with complex phospholipids, that have very different properties than single chain amphiphiles proposed for the origins of life. In this research, bilayer structures were made from short fatty acids, amines, alcohols, and sulfates, which self-assemble under different environmental conditions (see figure). The energetic contribution of hydrophobicity and headgroup interactions to aggregation behaviors were compared showing that the major contribution to aggregation behavior (measured by critical vesicle concentration) were the headgroup interactions with water. This is significantly different that phospholipid bilayers which have much larger hydrophobic contributions to aggregation. Additionally mixtures of these surfactants were found to have emergent properties that allow the bilayer structures formed to persist through large changes in the environment, including changes in temperature, pH and ionic strength. This research helps to define the environmental conditions that were most suitable for self-assembly leading to the formation of life on Earth.

Bilayer self-assembly from single-chain amphiphiles during the origins of life

249th National Meeting (2015)

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