Surface spectroscopy and microscopy studies of molecular films at electrified interfaces

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The general objective of this project is to study the structure and reactivity of functional monolayers and bilayers of phospholipids deposited onto a metal electrode at the metal-solution interface. The functionality of these films will be determined by the presence of peptides and proteins. Our goal is to learn how the electric field affects the stability of mixed bilayers composed of phospholipids and cholesterol, incorporation of proteins into the bilayer and electron and ion transfer through proteins incorporated into the supported bilayer. To achieve these goals, we will employ electrochemical methods, scanning probe microscopies such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM), in situ photon polarization modulation Fourier transform infrared reflection absorption spectroscopy (PM-IRRAS), surface enhanced infrared and Raman spectroscopies and the neutron scattering technique. We will use electrochemical techniques to control the physical state of the film and the scanning probe microscopies to image the field driven transformations of the membranes. In addition, spectroscopic and neutron scattering techniques will be employed to study conformational changes of organic molecules and their ordering within the membrane. Our goal is to obtain fundamental understanding of several biorelevant processes such as:(i) interactions of antimicrobial (AMPs) and amyloid peptides with phospholipid bilayers, (ii) interactions of monolayers and bilayers of nucleolipids with complementary nucleobases in solution, (iii) conformational and orientational changes of blue copper oxidase enzymes occurring during oxidation/reduction of their redox center. The metal electrode surface, covered by a biomimetic membrane, can be charged and electric fields on the order of 10^7 – 10^8V/m can be applied to the membrane. These fields have comparable magnitude to the fields acting on biological membranes. Our goal is to use this unique opportunity to manipulate biomolecules with the field and to monitor conformational and orientational changes induced by the filed using the surface analytical techniques. In addition, for the membrane supported at a metal electrode, the electrochemical methods could be used for transduction of analytical information about the host guest interactions in the membrane to an electrical signal for analytical detection.