Self-Reproduction of Micelles and Liposomes and the Transition to Life

Abstract

Micelles and vesicles (liposomes) are examples of geometrically bounded molecular structures. Conditions have been found under which micelles can be brought to self-reproduction by a simple chemical reaction which takes place at the boundary of the micellar system, at the interface between the micelles' interior and the exterior bulk solvent. During this reaction, the molecules of the boundary are produced which leads to the formation of more micelles as time progresses. The examples are micelles and reverse micelles build by octanoate molecules, and the reactions which lead to self-reproduction are ester hydrolysis or alcohol oxidations.

In another approach, the reproducing micelles are first created chemically by a simple hydrolysis reaction in a two-phase system made of an alkaline aqueous phase and an organic fatty acid ester phase. In an extension of this concept, as upper organic phase octanoic anhydride was used. The initial conditions of the alkaline aqueous phase were so that the pH drop during the reaction led to the formation of vesicles which were able to take up anhydride molecules and to act as a catalyst for the hydrolysis of the remaining anhydride molecules.

The investigation of fatty acid micelles and vesicles is related to the possible role of bounded molecular structures during the early prebiotic evolution on Earth. Because self-reproducing micelles and vesicles can be considered as examples for the chemical version of an autopoietic unit, the requirements of the minimal and universal definition of the living are fulfilled. (According to the definition by Maturana and Varela, an autopoietic unit is a structure which is self-generating and self-perpetuating as a consequence of its own activities within a boundary of its own making).