Spectroscopy and Molecular Changes in Cancer Cells - Vibrational Spectroscopy for Tissue Analysis - page 21

Table 2.1 ( Continued )
Peak Definitions and Assignments of Lung Cancer Samples

Lipid
Assignment Peak Position (cm −1 ) Protein Assignment Others

973mw (sh) ρ(CH 3 ) δ(CCH), olefinic

963w Unassigned

935w ν(C-C), α-helix, proline,

valine, keratin
ρ(CH 3 ) terminal

883mw ρ(CH 2 )

876w (sh) ν(C-C), hydroxyproline

855ms ν(C-C), proline δ(CCH)

ring breathing, tyrosine,
phenylalanine, olefinic

Polysaccharide

823w Out-of-plane ring

breathing, tyrosine

752w Symmetric breathing,

tryptophan

Source: Z. Huang, A. McWilliams, M. Lui, D. I. McLean, S. Lam, and H. Zeng. Near-infrared
Raman spectroscopy for optical diagnosis of lung cancer. Int. J. Cancer 107(2003):
1047-1052; Z. Huang, H. Lui, D. I. McLean, M. Korbelik, and H. Zeng. Raman spectros-
copy in combination with background near-infrared autofluorescence enhances the
in vivo assessment of malignant tissues. Photochem. Photobiol. 81(2005): 1219-1226.
With permission.
Note: ν: stretching mode, ν s : symmetric stretch, ν as : asymmetric stretch, δ: bending mode,
ρ: rocking, ν: very, s: strong, m: medium, w: weak, sh: shoulder.

Other articles [22-24] have mentioned the characteristic bands of lipids and
proteins. For example, lipids give a weak band at 1754 cm −1 (C=O), a sharp
band at 1656 cm −1 (C=C), a very strong band at 1440 cm −1 (CH 2 bend), and a
sharp band of medium intensity at 1300 cm −1 (CH 2 twist). Three bands are
indicative of phospholipids. These include 1656 cm −1 , 1367 cm −1 (νCH 3 , sym-
metric), and 1268 cm −1 (δ=CH). In protein molecules, the 1754 cm −1 band is
absent. At 1656 cm −1 we observe a broad, very strong band (amide I). The CH 2
bend comes at 1450 cm −1 and several bands of moderate intensity appear in
the region of 1100-1375 cm −1 (amide III and other groups). A sharp band of
moderate intensity is observed at 1004 cm −1 (phenylalanine). The 1558 cm −1
(amide II, COO − ) and 951 cm −1 (ν s CH 3 ) are other bands related to proteins.
In a review paper published by Mahadevan-Jansen and Richards-Kortum
[25], a collection of biological studies done by Raman are presented. In the
spectra of brain tissue, for instance, primary peaks due to lipids and proteins
in white and grey matter are shown. Using the characteristic peak defini-
tions of different cellular compounds, it is shown that the spectra of white
matter show a greater contribution from lipids, cholesterol, and proteins as
compared to the spectra of grey matter.