The application of vibrational spectroscopy to disease diagnosis is a relatively new, rapidly evolving scientific field. Techniques such as Raman and infrared spectroscopy have shown great promise in this regard over the past number of years. This study directly compared Raman spectroscopy and synchrotron infrared (SR-IR) spectroscopy on parallel cervical cancer samples. Both frozen and dewaxed formalin fixed paraffin preserved tissue sections were examined. Both tissue types produced good quality Raman and SR-IR spectra, although the lesser processed, frozen tissue sections displayed the most detailed spectra. Spectroscopy was shown capable of discriminating between different cell types in normal cervical tissue. Spectra recorded from invasive carcinoma showed a marked difference from those recorded from normal cervical epithelial cells. Spectral differences identified with the onset of carcinogenesis include increased nucleic acid contributions and decreased glycogen levels. These investigations pave the way for an enlarged study into this exciting new diagnostic field.
In this study Raman spectroscopy was employed distinguish between normal and abnormal human tissue. Raman spectra were obtained using a confocal Raman microspectrometer and a laser excitation of 514.532nm for a number of healthy tissues (Tonsil and Cervix) as well as for their diseased counterparts. Each tissue type was classified and its various spectral components were associated with vibrations, rotations etc. of the chemical bonds in the tissues' constituent components. Raman bands have been attributed to biological compounds such as proteins, lipids and DNA as well as to chemical bonds within these compounds such as, C=O stretch in Amide I (1645-1680 cm-1), NH bending in Amide III (1230-1310 cm-1), phenyl ring in Phenylalanine (1004 cm-1). Changes in the relative intensities, position, and width of these bands relate to the composition of the sample. Differences between healthy and diseased tissue with progression to malignancy have been identified and include; an increase in intensity of the phenylalanine ring breathing band (1004 cm-1), the C-C stretch of proteins (1082 cm-1), Amide I band (1655 cm-1) and the C-N stretching modes of proteins (1082cm-1). Decreases in relative intensities were also observed, and include a decrease in intensity of the CH2 deformation (1295 cm-1), CH2 bending of proteins and lipids (1445 cm-1), and the C=O stretching of proteins (1695 cm-1). The molecular origin of the observed spectral changes is discussed.
Raman spectroscopy was employed to spectroscopically fingerprint the range of animo acids, purines and pyramidines. Irradiation of these components by 10 Gray gamma rays shows that several of the amino acids and pyrimidines are particularly prone to molecular degradation. The spectroscopic signature of the degradation is utilized to identify the molecular origin of the degradation observed in the various biological macromolecules. Irradiation in solution compared to solid sate is employed in an effort to differentiate between primary and secondary ionization processes.
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