PROCEEDINGS ARTICLE | October 29, 2009
Proc. SPIE. 7519, Eighth International Conference on Photonics and Imaging in Biology and Medicine (PIBM 2009)
KEYWORDS: Confocal microscopy, Proteins, Principal component analysis, Cancer, Spectroscopy, Nondestructive evaluation, Raman spectroscopy, Cell death, Colorectal cancer, Leukemia
An antitumor drug cisplatin was employed to treat the leukemic cells and induce apoptosis of the cancer
cells. Confocal Raman micro-spectroscopy has been applied to investigate the effectiveness of the treatment
using near-infrared laser (785nm) excitation, scanning range from 500 to 2000 cm<sup>-1</sup>. The Raman spectra of
leukemic cell treated with cisplatin for 4, 6, 8, 12 and 14 h were measured separately. The major difference of
the apoptotic cells from the cancer cells are the reduction in intensities of vibration bands generated by
cellular lipids, proteins and nucleic acids. In particular, large intensity reduction in nucleic vibrations at 782,
1092, 1320, 1340, and 1578 cm<sup>-1</sup> was observed upon apoptosis of the leukemic cells. Up to 45% reduction in
the magnitude of the 782 cm<sup>-1</sup> peak in Raman spectra of the apoptotic cells was observed, which suggests the
breakdown of phosphodiester bonds and DNA bases. We showed that the principal components analysis
(PCA), a multivariate statistical tool, can be used to distinguish single apoptotic cells and leukemic cells based
on their Raman spectra. Our results indicate that the Raman spectroscopy with PCA is a novel, nondestructive
mean for studying the cisplatin -treated leukemic cells, which could also provide useful data for clinical
dosage optimization for cisplatin.
