Surface force analysis of glycine adsorption on different crystal surfaces of titanium dioxide (TiO₂)

Surface force analysis with atomic force microscope (AFM) in which a single amino acid residue was mounted on the tip apex of AFM probe was carried out for the first time at the molecular level on titanium dioxide (TiO₂) as a representative mineral surface for prebiotic chemical evolution reactions. The force analyses on surfaces with three different crystal orientations revealed that the TiO₂ (110) surface has unique characteristics for adsorbing glycine molecules showing different features compared to those on TiO₂ (001) and (100). To examine this difference, we investigated thermal desorption spectroscopy (TDS) and the interaction between the PEG cross-linker and the three TiO₂ surfaces. Our data suggest that the different single crystal surfaces would provide different chemical evolution field for amino acid molecules.