Ellipsometry, Raman spectroscopy and SOI- nanowire biosensor in diagnosis of colorectalcancer

Differences in the rate constants of specific interactions between serum tumor M2-pyruvate kinase (Tumor M2-PK) and highly specific monoclonal antibodies deposited on the surface of biochips were found in colorectal cancer patients using surface plasmon resonance enhanced ellipsometry. Scanning ellipsometry revealed a significant increase in the biomolecular layer thickness caused by antigen-antibody reaction in patients with hepatic and extra-hepatic metastases compared to that in healthy subjects (p<0.001-0.042).The specificity of the interaction was confirmed by fluorescence optical spectrometry. The Raman spectra of serum samples revealed differences in the intensity of peaks appeared at 1005-1520 cm^-1 in the same groups of patients (p<0.0001-0.05) with a predictive accuracy of 90 % for early-stage disease. The pilot experiments with a nanowire biosensor based on SOI (silicon on insulator), for example Tumor M2-PK, were carried out. High sensitivity (10^-13-10^-15M) and specificity in identifying antigens in serum samples of patients with colorectal cancer were demonstrated. The results obtained were useful for detecting early-stage disease, metastases and recurrence as well as for monitoring the quality of treatment in colorectal cancer patients.