Raman spectroscopy at different excitation wavelengths (1064, 785 and 532 nm) as a tool for diagnosis of colon cancer

Raman spectroscopy is structure sensitive non-destructive method that allows observing the status of biological tissues with minimal impact. This method has a great potential in the diagnosis of various types of degenerative diseases including cancer damages. Near-infrared Fourier transform (NIR-FT)-Raman ((ex) similar to 1064nm), NIR-visible (Vis)-Raman ((ex) similar to 785nm) and Vis-Raman ((ex) similar to 532nm) spectra of normal and colorectal carcinoma colon tissue samples were recorded in macroscopic mode at 10-20 randomly chosen independent sites. In the cases of NIR-Vis- and Vis-Raman spectra, enhanced resonance effects were observed for tissue chromophores absorbing in the visible area. Evident spectral differences were noticed for Raman spectra of normal colon tissue samples in comparison with abnormal samples. The average Raman spectra of colon tissue samples were analysed by principal component analysis (PCA) to discriminate normal and abnormal tissues. PCA of combined dataset containing Raman intensities of chosen NIR-FT, NIR-Vis or Vis-Raman bands led to discrimination of normal and abnormal colon tissue samples. Therefore, combination of these three Raman methods can be helpful for recognizing cancer lesions in colon for diagnostic purposes. Copyright (c) 2014 John Wiley & Sons, Ltd.