323
cells. In addition, no traces of carotenoids were found in the nuclei [7–10, 45]. As
it was concluded for several other subjects, carotenoids as hydrophobic compounds
prefer lipid-rich environment, therefore they accumulate in the cytoplasm containing less water than nuclei [4].
Raman spectroscopy was also used to characterize gastric carcinoma cells in
both cultured conditions and in the human gastric mucosa tissue [5]. Authors
aimed at determining of the differences between healthy and malignant tissues
of human mucosa. In the first step, single Raman spectra of cultured cells were
recorded. Further analysis based on the assignment of the bands showed that carotenoids are present in the cells, next to proteins, lipids, carbohydrates and nucleic
acids. Furthermore, a series of single Raman spectra of normal and malignant
gastric mucosa tissues was obtained and analyzed. due to significant tissue heterogeneity, a number of small spectral variations inside each studied group i.e.
the normal and malignant tissue was recognized. Nevertheless, small differences
between the malignant and normal tissue were also found. the malignant tissue
compared to the normal one is characterized by the decrease in the relative intensity of the bands at 1525 cm
−1
(carotenoids), 1005 cm
−1
(phenylalanine ring
breathing) and 1660 cm
−1
(amide I). moreover, significant changes in the intensity
ratio of the bands at 1525 and 1156 cm
−1
were observed. the intensity ratio was
higher for malignant gastric mucosa relative to the control that indicates for the
increased content of carotenoids in the malignant tissue. this results demonstrate
that carotenoids accumulation increased in the malignant gastric mucosa tissue
relative to the control one [5].
Another potentially diagnostic application of Raman spectroscopy is the “optical
biopsy” of breast cancer. Raman imaging was applied to characterize the breast cancer tissue and distinguish between noncancerous and cancerous specimens based on
the spectroscopic features [6, 46, 47]. the most significant differences related to the
cancer were found for marker bands due to carotenoids, lipids and proteins. Raman
spectra of the cancerous tissue seem to be dominated by the protein component
while the spectra of the noncancerous tissue are richer in lipids. Simultaneously,
the carotenoids content is much lower in the case of the cancer tissue compared to
the healthy one. these conclusions were obtained with the help of chemometrics
by the application of cluster analysis (K-means algorithm). the presented results
demonstrate that Raman spectra may be used to indicate cancerous changes in human breast [6, 46, 47].
11.5 Conclusions
the foregoing overview demonstrates that Raman spectroscopy and Raman imaging are sensitive and effective methods of studying carotenoids in single cells.
Although research in this area focus on the experimental approach, first trials to
use quantum-chemical methods as a tool to analyse Raman spectra of cells were
already undertaken. Additionally, chemometric methods are used quite routinely
11 Structural and Spatial Analysis of Carotenoids in a Single Cell monitored …
cells. In addition, no traces of carotenoids were found in the nuclei [7–10, 45]. As
it was concluded for several other subjects, carotenoids as hydrophobic compounds
prefer lipid-rich environment, therefore they accumulate in the cytoplasm containing less water than nuclei [4].
Raman spectroscopy was also used to characterize gastric carcinoma cells in
both cultured conditions and in the human gastric mucosa tissue [5]. Authors
aimed at determining of the differences between healthy and malignant tissues
of human mucosa. In the first step, single Raman spectra of cultured cells were
recorded. Further analysis based on the assignment of the bands showed that carotenoids are present in the cells, next to proteins, lipids, carbohydrates and nucleic
acids. Furthermore, a series of single Raman spectra of normal and malignant
gastric mucosa tissues was obtained and analyzed. due to significant tissue heterogeneity, a number of small spectral variations inside each studied group i.e.
the normal and malignant tissue was recognized. Nevertheless, small differences
between the malignant and normal tissue were also found. the malignant tissue
compared to the normal one is characterized by the decrease in the relative intensity of the bands at 1525 cm
−1
(carotenoids), 1005 cm
−1
(phenylalanine ring
breathing) and 1660 cm
−1
(amide I). moreover, significant changes in the intensity
ratio of the bands at 1525 and 1156 cm
−1
were observed. the intensity ratio was
higher for malignant gastric mucosa relative to the control that indicates for the
increased content of carotenoids in the malignant tissue. this results demonstrate
that carotenoids accumulation increased in the malignant gastric mucosa tissue
relative to the control one [5].
Another potentially diagnostic application of Raman spectroscopy is the “optical
biopsy” of breast cancer. Raman imaging was applied to characterize the breast cancer tissue and distinguish between noncancerous and cancerous specimens based on
the spectroscopic features [6, 46, 47]. the most significant differences related to the
cancer were found for marker bands due to carotenoids, lipids and proteins. Raman
spectra of the cancerous tissue seem to be dominated by the protein component
while the spectra of the noncancerous tissue are richer in lipids. Simultaneously,
the carotenoids content is much lower in the case of the cancer tissue compared to
the healthy one. these conclusions were obtained with the help of chemometrics
by the application of cluster analysis (K-means algorithm). the presented results
demonstrate that Raman spectra may be used to indicate cancerous changes in human breast [6, 46, 47].
11.5 Conclusions
the foregoing overview demonstrates that Raman spectroscopy and Raman imaging are sensitive and effective methods of studying carotenoids in single cells.
Although research in this area focus on the experimental approach, first trials to
use quantum-chemical methods as a tool to analyse Raman spectra of cells were
already undertaken. Additionally, chemometric methods are used quite routinely
11 Structural and Spatial Analysis of Carotenoids in a Single Cell monitored …