Autocatalytic self-replicating micelles as models for prebiotic structures

MICELLES that can catalyse their replication have been described recently1–3. In the previous experiments, micelles (or bilayer vesicles4) were always present in the initial reaction mixture—that is, the system was presented with the bounded structures required for autocatalysis. Here we describe a system in which autocatalytic micelles are formed from amphiphiles that are themselves generated from a hydrolysis reaction in the absence of compartmental structures. Alkaline hydrolysis of ethyl caprylate (itself insoluble in water) yields sodium caprylate, initially at a very slow rate; but as soon as sufficient caprylate is formed for aggregation into micelles to take place, there is an exponential increase in reaction rate owing to micellar catalysis. These self-assembling surfactant structures may consequently provide a model system for studies of prebiotic chemistry. The possible relevance of this process to prebiotic chemistry is emphasized by our observation that the micelles can be converted into more-robust vesicles by a pH change induced by dissolved CO2.