title: Characterization of the Adsorption of Nucleic Acid Bases onto Ferrihydrite via Fourier Transform Infrared and Surface-Enhanced Raman Spectroscopy and X-ray Diffractometry.
abstract: Minerals could have played an important role in concentration, protection, and polymerization of biomolecules. Although iron is the fourth most abundant element in Earth's crust, there are few works in the literature that describe the use of iron oxide-hydroxide in prebiotic chemistry experiments. In the present work, the interaction of adenine, thymine, and uracil with ferrihydrite was studied under conditions that resemble those of prebiotic Earth. At acidic pH, anions in artificial seawater decreased the pH at the point of zero charge (pHpzc) of ferrihydrite; and at basic pH, cations increased the pHpzc. The adsorption of nucleic acid bases onto ferrihydrite followed the order adenine >> uracil > thymine. Adenine adsorption peaked at neutral pH; however, for thymine and uracil, adsorption increased with increasing pH. Electrostatic interactions did not appear to play an important role on the adsorption of nucleic acid bases onto ferrihydrite. Adenine adsorption onto ferrihydrite was higher in distilled water compared to artificial seawater. After ferrihydrite was mixed with artificial seawaters or nucleic acid bases, X-ray diffractograms and Fourier transform infrared spectra did not show any change. Surface-enhanced Raman spectroscopy showed that the interaction of adenine with ferrihydrite was not pH-dependent. In contrast, the interactions of thymine and uracil with ferrihydrite were pH-dependent such that, at basic pH, thymine and uracil lay flat on the surface of ferrihydrite, and at acidic pH, thymine and uracil were perpendicular to the surface. Ferrihydrite adsorbed much more adenine than thymine; thus adenine would have been better protected against degradation by hydrolysis or UV radiation on prebiotic Earth.
authors.affiliation: 1 Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: José E
authors.initials: JE
authors.lastname: Canhisares-Filho
authors.affiliation: 1 Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: Cristine E A
authors.initials: CE
authors.lastname: Carneiro
authors.affiliation: 1 Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: Henrique
authors.initials: H
authors.lastname: de Santana
authors.affiliation: 2 Departamento de Física-CCE, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: Alexandre
authors.initials: A
authors.lastname: Urbano
authors.affiliation: 3 Departamento de Agronomia-CCA, Universidade Estadual de Maringá , Maringá-PR, Brazil .
authors.forename: Antonio C S
authors.initials: AC
authors.lastname: da Costa
authors.affiliation: 4 Departamento de Ciências Fisiológicas-CCB, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: Cássia T B V
authors.initials: CT
authors.lastname: Zaia
authors.affiliation: 1 Laboratório de Química Prebiótica, Departamento de Química-CCE, Universidade Estadual de Londrina , Londrina-PR, Brazil .
authors.forename: Dimas A M
authors.initials: DA
authors.lastname: Zaia
mesh_terms: D000327:Adsorption; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009696:Nucleic Acids / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D055672:Static Electricity; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D005290:Ferric Compounds; D009696:Nucleic Acids; C092844:ferric oxyhydroxide