TITLE:
Surface Force Analysis of Pyrite (FeS2): Its Reactivity to Amino Acid Adsorption
AUTHORS:
Narangerel Ganbaatar, Nina Matsuzaki, Yuya Nakazawa, Rehana Afrin, Masashi Aono, Taka-aki Yano, Tomohiro Hayashi, Masahiko Hara
KEYWORDS:
Pyrite, Mineral-Organic Interface, Atomic Force Microscopy, Amino Acid Adsorption
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.6 No.7,
June
30,
2016
ABSTRACT: It is well known
that mineral surfaces play an important role as catalysts for abiotic polymerization
of amino acids to form peptides, which are the main components of the first
self-replicating system. Understanding the mechanism behind the adsorption of
simple amino acids on mineral surfaces is a topic of great interest not only in
field of prebiotic evolution and but also in many other branches of material
sciences. Various clay minerals have been suggested for studying how organic
molecules were first synthesized in a prebiotic “inorganic” environment. Among
them, pyrite (FeS2) is one of the most potential minerals as it
possesses a highly reactive surface to drive molecular adsorption in prebiotic
chemistry reactions. Recent theoretical experiments suggest that amino acids
are adsorbed on the pyrite surface depending on its surface structures.
However, these results have not been tested experimentally, and the exact
mechanism of the specific interactions on this mineral has not been fully
resolved yet at the molecular level. In this work, through quantitative force
analysis with atomic force microscope (AFM) in which a single amino acid residue
was mounted on the tip apex of AFM probe, we were able to find the reaction
sites and study the interaction forces between the amino acid and the pyrite
surface. Our results of Raman spectroscopic studies and force measurements with
a well-designed AFM probe demonstrated for the first time that pyrite provided
higher adsorption probabilities of amino acid residues for the chemical reactions
at surfaces.