The major objectives of the proposed research are to develop electrochemical and Raman methods for monitoring electron transfer and determining molecular structure of biomolecules at electrode surfaces. Ideally, the methods will be applicable not only to isolated molecules, but to intact, functional systems as well. To reach these objectives, the research will proceed in three phases. First, procedures for selective, nondestructive adsorption of a specific type of molecule at an electrode will be developed. If the molecule is redox active, reversible electron transfer will be an inportant prerequisite in addition to adsorption. Second, the highly sensitive surface enhanced Raman (SER) effect will be exploited to determine the vibrational spectra of the adsorbed molecules as a function of electrode potential. Third, having determined the appropriate experimental conditions for studying the isolated molecules and their spectral properties, an attempt will be made to use these methods to examine more complex systems. Membranes and membrane preparations from photosynthetic bacteria will be used in this phase of the research. The significance of the proposed reserach is related to fundamental studies of molecules at electrodes, as well as to potential practical applications of the combined electrochemical and Raman methods for the analytical determination of specific molecules in complex milieu (cellular fluids, tissues, and membranes). For example, Raman or resonance Raman spectra of adsorbed molecules will be useful for structural, kinetic, and mechanistic studies of electron transfer phenomena in biomolecules. In addition, the species selective SER procedures, when coupled with multichannel detection, provide a sensitive and unambiguous method for the identification of a given molecule.
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