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IR spectroscopy represents only one section of the entire vibrational spectrum of molecules. Due to the nature of the material analyzed, IR spectra of cell sand tissues always contain features of proteins, lipids, DNA/RNA, carbohydrates and of many small metabolites. The distinction of different tissue structures is achieved by comparing those spectral features, using the fact that cells vary in their chemical composition and therefore also in their spectra. Although cells are composed of different biomolecules, the spectral features expressed in IR spectra normally vary only slightly but are most often more than sufficient for analysis. However, this is where Raman spectroscopy may help enhance the differentiation capabilities of vibration spectroscopy. In contrast to IR spectroscopy, Raman spectroscopy only provides information on some of the many cellular biomolecules, thereby being very specific. Conjugated double bonds, aromatic rings and bonds between heavier atoms can be seen as very sharp features in Raman spectra of biomolecules and cells. In some cases even the distribution of drugs can be cartographed in lining cells. Generating IR and Raman images with similar spatial resolution of the same tissue sections may improve the diagnostic capabilities possible with either spectroscopic method alone. Gland tissue sections are presented and analyzed for the distribution of typical cell components and specific molecules such as thyroglobulines and precursors. In addition, fiber optics measurements on tissue sections in vitro are introduced to illustrate the power of the combination of FT-Raman and FT- NIR fiber optics technology. The use of single band analysis, bivariate statistics and cluster analysis applied to spectra from both spectroscopy methods will be assessed in this study and employed to illustrate the concept.
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