Vibrational Spectroscopy and Cancer - Vibrational Spectroscopy for Tissue Analysis - page 92

components responsible for the spectral dissimilarities, they found consider-
able differences between DNA of normal and cancerous cells [161].
In a proof-of-concept study, M. M. Mossoba et al. made an investigation on
printing microarrays of bacteria for identification by infrared microscopy.
They used the technique as a tool for rapid bacteria identification and could
demonstrate its effectiveness [162].
C. M. Krishna et al. used micro-Raman spectroscopy to investigate ran-
domly mixed cancer cell populations, including human promyelocytic
leukaemia, human breast cancer, human uterine sarcoma, as well as their
respective pure cell lines. In this study, the efficiency of micro-Raman spec-
troscopy to identify a cell type in a randomly distributed mixed cell popu-
lation was assessed. According to the results, cells from different origins
can display variances in their spectral signatures and the technique can
be used to identify a cell type in a mixed cell population via its spectral
sig nat ures [163].
In a research article presented by N. Kuhnert and A. Thumser, Raman
microspectroscopy with a diode laser at 785 nm or an argon ion laser at
512 nm was used for detection of vibrationally labelled compounds in living
human cells and positive results were obtained. They suggested that future
research should concentrate on sensitivity and experimental setup in order
to achieve better detection limits [164].
According to a published paper by D. Naumann, FTIR and FT-NIR Raman
spectra of intact microbial cells are highly specific, fingerprint-like signa-
tures that can be used to (i) discriminate between diverse microbial species
and strains; (ii) detect in situ intracellular components or structures such as
inclusion bodies, storage materials, or endospores; (iii) detect and quantify
metabolically released CO 2 in response to various different substances; and
(iv) characterise growth-dependant phenomena and cell-drug interactions.
Particularly interesting applications arise by means of a light microscope
coupled to the spectrometer. FTIR spectra of microcolonies containing less
than 103 cells can be obtained from a colony replica by a stamping technique
that transfers microcolonies growing on culture plates to a special IR sample
holder. FTIR and FT-NIR Raman spectroscopy can also be used in tandem to
characterise medically important microorganisms [165].
G. I. Dovbeshko et al. carried out an FTIR reflectance study on surface-
enhanced IR absorption of nucleic acids from tumour cells. The application
of this method to nucleic acids isolated from tumour cells revealed some
possible peculiarities of their structural organization, namely, the appear-
ance of unusual sugar and base conformations, modification of the phos-
phate backbone, and redistribution of the H-bond net. The spectra of the
RNA from the tumour cells showed more sensitivity to the grade of malig-
nancy than the spectra of the DNA. After application of the anticancer
drug doxorubicin to sensitive and resistant strains, the DNA isolated from
these strains had different spectral features, especially in the region of the
phosphate I and II bands [166].