The use of spectral ellipsometry and Raman spectroscopy in the screening diagnosis of colorectal cancer

Diagnostic monitoring of groups of healthy patients and patients with colorectal cancer (CRC) at various stages of the development of the disease was carried out using Raman spectroscopy (CRS) and measuring the state of polarized light in the vicinity of surface plasmon resonance (SPR) observation conditions. For the diagnosis, the reaction of serum antigens with antibodies to serum M2-pyruvate kinase (M2-PK) was used near the observation conditions of SPR, for which we used the Ellips-SPEC spectral ellipsometric complex created in the Institute of Semiconductor Physics of the Siberian Branch of the Russian Academy of Sciences (ISP SB RAS). The complex has high sensitivity, accuracy and non-destructive impact on the sample under study. The intensities of the peaks at 1005, 1157 and 1520 cm$^{-1}$ in the CRS spectra of CRC patients as compared with healthy individuals as well as the intensity of the equilibrium plasmon signal were significantly lower, correlating with the stage of the disease and the presence of metastases. It allows us to consider these optical methods as a promising diagnostic approaches in the diagnosis of CRC, including in the early stages of the disease.