Nanoscale surface properties and interaction with fundamental biomolecules of chlorite and phlogopite

Moro, Daniele (2014) Nanoscale surface properties and interaction with fundamental biomolecules of chlorite and phlogopite, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Scienze della terra, 26 Ciclo. DOI 10.6092/unibo/amsdottorato/6352.
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The surface properties of minerals have important implications in geology, environment, industry and biotechnology and for certain aspects in the research on the origin of life. This research project aims to widen the knowledge on the nanoscale surface properties of chlorite and phlogopite by means of advanced methodologies, and also to investigate the interaction of fundamental biomolecules, such as nucleotides, RNA, DNA and amino acid glycine with the surface of the selected phyllosilicates. Multiple advanced and complex experimental approaches based on scanning probe microscopy and spatially resolved spectroscopy were used and in some cases specifically developed. The results demonstrate that chlorite exposes at the surface atomically flat terraces with 0.5 nm steps typically generated by the fragmentation of the octahedral sheet of the interlayer (brucitic-type). This fragmentation at the nanoscale generates a high anisotropy and inhomogeneity with surface type and isomorphous cationic substitutions determining variations of the effective surface potential difference, ranging between 50-100 mV and 400-500 mV, when measured in air, between the TOT surface and the interlayer brucitic sheet. The surface potential was ascribed to be the driving force of the observed high affinity of the surface with the fundamental biomolecules, like single molecules of nucleotides, DNA, RNA and amino acids. Phlogopite was also observed to present an extended atomically flat surface, featuring negative surface potential values of some hundreds of millivolts and no significant local variations. Phlogopite surface was sometimes observed to present curvature features that may be ascribed to local substitutions of the interlayer cations or the presence of a crystal lattice mismatch or structural defects, such as stacking faults or dislocation loops. Surface chemistry was found similar to the bulk. The study of the interaction with nucleotides and glycine revealed a lower affinity with respect to the brucite-like surface of chlorite.

Tipologia del documento
Tesi di dottorato
Moro, Daniele
Dottorato di ricerca
Scuola di dottorato
Scienze della terra e dell'ambiente
Settore disciplinare
Settore concorsuale
Parole chiave
Chlorite, phlogopite, AFM, KPFM, mineral surfaces, nucleotides, DNA, RNA, amino acids.
Data di discussione
7 Aprile 2014

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