Models for prebiotically-relevant self-reproducing systems

Autocatalysis is central to the propagation of living systems and is widely agreed to have played a central role in the emergence of life on earth. Chemical systems which self-reproduce like living cells can offer insight into the transition from chemistry to biology. Self-reproducing micelles and vesicles, or physical autocatalysts, are an important class of autocatalytic chemical systems that have used to model the first living systems for several decades. The study of physical autocatalysis has been restricted to a limited set of reactions, and hindered by experimental difficulties precluding full characterisation. Together these limitations pose both conceptual and technical barriers to a deeper understanding of this important class of prebiotic system. This thesis addresses both limitations in turn. Chapter 1 introduces the concept of physical autocatalysis and argues for its importance in the field of prebiotic chemistry. A survey of chemical models of physical autocatalysis is presented and the present work is placed into context. Chapter 2 describes the development of the first examples of physical autocatalysis driven by irreversible bond-forming reactions. Steps towards the development of asymmetric variations and systems of self-reproducing vesicles are discussed. Chapter 3 describes the application of interferometric scattering microscopy to physical autocatalysis, allowing for the first time the observation of micellar self-reproduction on the single particle level. Chapter 4 discusses the limitations of this work and argues that the results described in Chapters 2 and 3 respectively address major conceptual and technical barriers to the study of physical autocatalysis, with recommendations for future work.