APPLICATION OF NEW RAMAN TECHNIQUES TO BIOLOGICAL SAMPLE

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The long term goal of this research is to develop new Raman techniques for the study of intact biological samples, including cell membranes, cell surfaces, and tissues. The specific aims during the proposed award period include the following: (1). the continuation of current research efforts relating to the application of surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) techniques to the study of biomolecules; (2). the extension of these techniques to complex biological systems; (3). the application of the various Raman techniques to the study of hemoglobins, metal-substituted enzymes, and metal-nucleotide complexes; and (4). the development of expertise in Raman microprobe techniques. The newly discovered surface-enhanced Raman effect has considerable potential for applications in the fields of biology and medicine. The enormous increase in Raman scattering which results when molecules are adsorbed at Ag, Au, or Cu surfaces permits detection of submonolayer amounts of materials. Thus, there are many possible bioanalytical applications. In addition, however, the technique should prove valuable in basic biomedical research. The surface sensitivity should allow the detection of molecules near, or on, membrane surfaces. It may also be possible to monitor reactions of these molecules and probe their functions as well. The experiments will proceed by first examining the behavior of isolated biomolecules by surface-enhanced Raman techniques. Amino acids, proteins, and lipids will be studied. The effect of adsorption on the structure of proteins will be examined by monitoring the activity of enzymes on the surfaces. Next, more complex systems will be examined. These will include preparations isolated from photosynthetic membranes. These studies will be followed by an examination of intact membranes. The goal is to detect the natural probe molecules present in these membranes (chlorophylls, carotenoids, hemes, etc.). Techniques developed for the study of the photosynthetic membrane should then be applicable for other types of membranes. The possibility of combining surface-enhanced Raman techniques with Raman microprobe spectroscopy will be investigated. If successful, this approach could be used in areas such as pathology, histology, as well as basic research.