The adsorption of nucleic acid components onto the serpentinite-hosted hydrothermal mineral brucite has been investigated experimentally by determining the equilibrium adsorption isotherms in aqueous solution. Thermodynamic characterization of the adsorption data has been performed using the extended triple-layer model (ETLM) to establish a model for the stoichiometry and equilibrium constants of surface complexes. Infrared characterization of the molecule-mineral complexes has helped gain insight into the molecular functional groups directly interacting with the mineral surface. Quantum mechanical calculations have been carried out to identify the possible complexes formed on surfaces by nucleic acid components and their binding configurations on mineral surfaces, both in the presence of water molecules and in water-free conditions. The results indicate that brucite favors adsorption of nucleotides with respect to nucleosides and nucleobases from dilute aqueous environments. The surface of this mineral is able to induce well-defined orientations of the molecules through specific molecule-mineral interactions. This result suggests plausible roles of the mineral brucite in assisting prebiotic molecular self-organization. Furthermore, the detection of the infrared spectroscopic features of such building blocks of life adsorbed on brucite at very low degrees of coverage provides important support to life detection investigations.
Keywords: Adsorption; Brucite; Infrared spectroscopy; Molecule; Nucleic acid components; mineral interactions.