Vibrational Spectroscopy and Cancer - Vibrational Spectroscopy for Tissue Analysis - page 95

Vo-Dinh et al. have described the development of the SERS method
for cancer gene detection, using DNA gene probes based on SERS labels.
Nanostructured metallic structures were used as SERS-active platforms.
The surface-enhanced Raman gene (SERGen) probes were used to detect
DNA targets via hybridisation to DNA sequences complementary to these
probes. The details of the usefulness of the approach and its applications in
cancer gene diagnosis (e.g., BRCA1 breast cancer gene and BAX gene) were
discussed [172].
FTIR and NIR-FT Raman spectral features of the anticancer drug
combretastatin-A4 were studied by J. Binoy et al. The vibrational analysis
showed that the molecule exhibits similar geometric behaviour as cis -stil-
bene, and has undergone steric repulsion resulting in phenyl ring twisting
with respect to the ethylenic plane [173].
E. O. Faolin et al. carried out a study examining the effects of tissue pro-
cessing on human tissue sections using vibrational spectroscopy. This study
investigated the effect of freezing, formalin fixation, wax embedding, and
de-waxing. Spectra were recorded from tissue sections to examine biochemi-
cal changes before, during, and after processing with both Raman and FTIR
spectroscopy. New peaks due to freezing and formalin fixation as well as
shifts in the amide bands resulting from changes in protein conformation and
possible cross-links were found. Residual wax peaks were observed clearly
in the Raman spectra. In the FTIR spectra a single wax contribution was seen
that may contaminate the characteristic CH 3 deformation band in biological
tissue. This study confirmed that formalin-fixed paraffin-processed (FFPP)
sections have diagnostic potential [174].
Sokolov et al. applied fluorescence and reflectance spectroscopy to assess
tissue structure and metabolism in vivo in real time, providing improved
diagnosis of precancerous lesions. Reflectance spectroscopy can probe
changes in epithelial nuclei that are important in precancer detection, such
as mean nuclear diameter, nuclear size distribution, and nuclear refractive
index. Fluorescence spectroscopy can probe changes in epithelial cell metab-
olism, by assessing mitochondrial fluorophores, and epithelial-stromal
interaction, by assessing the decrease in collagen cross-link fluorescence that
occurs with precancer. Thus, it was believed that these techniques provide
complementary information useful for precancer diagnosis [175].
To detect a subsurface tumour labelled by fluorescent contrast agents,
Y. Chen et al. developed a phase cancellation imaging system for fast and
accurate localisation of a fluorescent object embedded several centimetres
deep inside the turbid media. The excitation wavelength was 780 nm and
the fluorescence photons were collected through an 830 ± 10 nm band-pass
filter. It was concluded that using this method, the localisation of fluorescent
objects inside the scattering media could be accomplished. The localisation
error for a 5-mm diameter sphere filled with one nanomole of fluorescent dye
3 cm deep inside the turbid media is about 2 mm. In addition, the accuracy
of the localisation could suggest that this system can be helpful in guiding