The interactions between amino acids and conductive metal surfaces, such as copper, have recently been the subject of Ultra-High Vacuum Scanning Tunneling Microscopy (UHV STM) studies. In almost all cases, the amino acids have been shown to induce the formation of metal islands on the surface under UHV and low temperature (55 K) conditions. However, in order to make these findings generally applicable, it would be helpful to examine how these molecules act in more relevant conditions, such as in liquids and at room temperature. Our research project investigates the amino acid-surface interactions in solution at a physiological pH (pH ~ 7.4) and at room temperature using Electrochemical STM (EC-STM). Specifically, our research is focused on the interaction between a nonpolar amino acid, isoleucine, and a Au(111) surface. Electrochemistry in the form of cyclic voltammetry is used to anchor the molecules to the surface at room temperature. Additionally, this experiment also uses elevated temperatures to examine how thermal energy can be used to surmount activation barriers to molecular ordering. Importantly, the experiments will expand to study the ordering of pyruvate, a precursor of essential L-amino acids, such as L-alanine, hoping to gain more information on the effect of chirality on molecular and substrate interactions. The role of the amino acid side chain in surface bonding and interaction will also be investigated by observing tyrosine, a polar amino acid, under EC-STM at physiological conditions. These studies will be used in combination with UHV STM studies as a method to bridge the temperature and pressure gap between UHV, low temperature and ambient, <i>in situ</i> STM studies. The study of amino acids and surfaces is critical to understanding how simple, organic molecules may have developed and propagated as the initial steps to life on this planet.

Using EC-STM to study the binding of amino acids to metal surfaces

255th National Meeting (2018)

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