Capsule formation induced by flow.

ABSTRACT

Physical compartments are essential for the origin of life. While lipid vesicles are commonly regarded as precursors of cell membranes, we propose a simpler and more primitive model based on proteinoids. Proteinoids are macromolecules formed by the thermal polymerization of amino acids, mimicking primitive proteins. They self-assemble into spherical microspheres in water. Under a temperature gradient, proteinoid microspheres (PM) dissolve and flow, forming microcapsules with thin shells. The mechanism of this process has not yet been elucidated. We hypothesize that it involves the interplay between the dissolution and flow of PM. We tested our hypothesis by applying forced flow to the PM and observing capsule formation. We found that neither heat nor flow alone can produce capsules, confirming our hypothesis. We conclude that flow-induced capsule formation is a general phenomenon and a plausible model for the origin of physical compartments in early life.