Chemistry Reference
In-Depth Information
Table 21.7
Mid-IR spectral features applied in cancer detection via tissue
analysis.
Spectral Region
Functional Group
Vibration
Related Biochemicals
960-970
C-O, C-C
Stretching
DNA
1010-1030
C-O-H
Bending
Glycogen
1040-1055
C-O
Stretching
DNA
1070-1080
PO
2
-
Stretching
DNA
1075-1085
C-C
Stretching
Glycogen
1115-1120
O-H
Bending
Glycoproteins
1145-1160
C-O
Stretching
Glycogen
1165-1170
C-C
Stretching
Glycoproteins
1230-1240
C-N
Stretching
Amide III
1245-1265
N-H
Bending
Amide III
1280-1300
C-H
Stretching
Amide III
1405-1440
C-H
Bending
Amides
*1540-1550
C-N
Stretching
Amide II
1545-1560
N-H
Bending
Amide II
*1630-1640
C
=
O
Stretching
Amide I
*the most common signal position shifting is observed (from healthy to malignant cases the shift
is from higher to lower wavenumbers).
Malignant
Healthy
1800
1600
1400
Wavenumber (cm
−
1
)
1200
1000
800
Figure 21.4
Typical IR spectra of normal and malignant tissue samples.
Table 21.7 details the main isolated signal variations (intensity and shifting) observed in tissue samples
used to recognize the cancer or healthy cases via IR spectroscopic analysis of biopsies.
Considering all the above mentioned variations, chemometric based data processing algorithms based
upon statistical-mathematical approaches would improve the reliability of diagnostic results. Of course,
intensity ratios are also effective in cancer diagnosis. Reduction in amide I/amide II and RNA/DNA, and
increments in glycoproteins/amide I signal intensity ratios during the progress of malignancy have been
reported to be informative. Figure 21.4 shows typical IR spectra of normal and malignant tissue samples.
Initial spectra data are usually transformed to matrices to be processed by chemometric classification
techniques. Analysis of variance (ANOVA) is a useful starting process by which it is possible to study the
