Prebiotic organic microstructures

Abstract

Micro- and sub-micrometer spheres, tubules and fiber-filament soft structures have been synthesized in our experiments conducted with 3 MeV proton irradiations of a mixture of simple inorganic constituents, CO, N(2) and H(2)O. We analysed the irradiation products, with scanning electron microscopy (SEM) and atomic force microscopy (AFM). These laboratory organic structures produced a wide variety of proteinaceous and non-proteinaceous amino acids after HCl hydrolysis. The enantiomer analysis for D,L-alanine confirmed that the amino acids were abiotically synthesized during the laboratory experiment. We discuss the presence of CO(2) and the production of H(2) during exothermic processes of serpentinization and consequently we discuss the production of hydrothermal CO in a ferromagnesian silicate mineral environment. We also discuss the low intensity of the Earth's magnetic field during the Paleoarchaean Era and consequently we conclude that excitation sources arising from cosmic radiation were much more abundant during this Era. We then show that our laboratory prebiotic microstructures might be synthesized during the Archaean Eon, as a product of the serpentinization process of the rocks and of their mineral contents.

Fig. 1

a Three-Dimensional Scanning Electron Microscopy, 3D-SEM, images of the dried product, abiotically synthesized from a gas mixture of CO-N₂-H₂O excited with 3 MeV proton irradiation; bar is 1 μm, acceleration voltage 2.0 kV, magnification ×7,000, working distance 8 mm. b 3D-SEM, image of the dried proton irradiation product; bar is 1 μm, acceleration voltage 2.0 kV, magnification ×20,000, working distance 8 mm

Fig. 2

a 3D-Atomic Force Microscopy, 3D-AFM, images of the dried product, abiotically synthesized from a gas mixture of CO-N₂-H₂O, excited with 3 MeV proton irradiation. b 3D-AFM images of the same structure

Fig. 3

a Relative abundance of amino acids detected after acid hydrolysis of the dried irradiation product. Abbreviations. Gly, glycine; D,L-ala, D,L-alanine; D,L-α-ABA, D,L-α-aminobutyric acid; D,L-asp, D,L-aspartic acid; β-ala, β-alanine; D,L ser, D,L-serine; others, including very minor amino acids. b Relative abundance of amino acids on a logarithmic scale

Fig. 4

Gas chromatograph (GC) separation and its mass fragment pattern of the N-pivaloyl-(S)-2-butyl esters of D,L-alanine