LIFE IN HYDROCARBON: IS WATER THE OPTIMAL SOLVENT OF LIFE?

Abstract

The origin of life is a fascinating and still unresolved issue. That notwithstanding, there are some certainties. One is the fundamental role played by lipid vesicles in the development of cellular life form, as well as their intimate relation with water. This explains the significant effort, both experimental and theoretical, that is still currently underway in elucidating the mechanism by which these vesicles form, change shape and respond to external inputs. Life-as-we-know-on-Earth is water-based, with cell membranes composed by phospholipids having hydrophilic head and a lypophilic tail. Yet, other paradigms are also possible. Saturn’s giant satellite Titan is surrounded by an atmosphere that makes this moon remarkably similar to the Earth, a unique case in the solar system. However, it has been argued that because of the extremely low temperatures involved (as low as 94 K), the observed liquid can only be a hydrocarbon liquid. This raises the natural question of a possible cell membrane formation in a non-aqueous environment, akin to that present in the Earth in aqueous solvent, with organic chemical processes occuring in liquid hydrocarbons leading to compounds analogous to proteins, life in liquid hydrocarbons. In this thesis, I will use a molecular dynamics approach to study this possible alternative scenario, in which one invertes the philicity of the surfactant (hydrophobic head and a polar tail) as well as that of the solvent (a hydrocarbon apolar solvent).