Achievements and open questions in the self-reproduction of vesicles and synthetic minimal cells

Abstract

Supramolecular chemistry was enriched, about twenty years ago, by the discovery of the self-reproduction of micelles and vesicles. The dynamic aspects and complexity of these systems makes them good models for biological compartments. For example, the self-reproduction of vesicles suggests that the growth in size and number of a vesicle population resembles the pattern of living cells in several aspects, but it take place solely due to physical forces. Several reports demonstrate that reverse micelles, micelles, sub-micrometric and giant vesicles can self-reproduce, generating new particles at the expenses of a suitable precursor. Recently, similar studies are in progress on more complex vesicle-based systems, namely semi-synthetic minimal cells. These are artificial cell-like compartments that are built by filling liposomes with the minimal number of biomolecules, such as DNA, ribosomes, enzymes, etc., in order to construct a living cell in the laboratory. This approach aims to investigate the minimal requirements for molecular systems in order to display some living properties, while it finds relevance in origins of life studies and in synthetic (constructive) biology.

Physical autocatalysis driven by a bond-forming thiol–ene reaction

“…The self-reproduction of simple models of membranes, namely micelles and vesicles, has also been studied, most notably by Luisi and co-workers 4 . These systems represent crucial components of protocellular models and provide experimental support for 'lipid world' scenarios for the origins of life 19 , where catalytically active surfactant aggregates, dubbed lipozymes, act as prebiotic analogues of enzymes and under a form of selection promoted the emergence of life.…”

“…Several designs for artificial cells have been put forward [4][5][6][7][8] . A notable and representative design proposed by Szostak, Bartel and Luisi 9 consists of 'the union of two fundamentally different kinds of replicating systems': a self-replicating genetic polymer encapsulated by and coupled to a self-reproducing membrane.…”

Construction of a liposome dialyzer for the preparation of high-value, small-volume liposome formulations

“…Consistent with an autocatalytic reaction, "seeding" of these solutions with vesicles results in an increase in the rate of vesicle formation. 18 The dialyzer is suitable for monitoring of vesicle formation kinetics by transfer of lipid from existing vesicles. For example, it can be used in experiments where one chamber initially contains a high concentration of single-chain amphiphiles vesicles, the other initially contains none, and vesicle formation is monitored by absorbance measurements of the second chamber.…”

Advances in Minimal Cell Models: a New Approach to Synthetic Biology and Origin of Life

“…The first attempts to create a minimal chemical autopoietic systems were done with simple supramolecular systems as micelles and reverse micelles, and later on with vesicles (for a recent review, see Stano & Luisi (2010a). The comment on such systems is outside the scope of this chapter, but it is useful to say that the current research of SSMCs construction still relies on the autopoiesis as a theoretical framework.…”