Near-infrared surface-enhanced Raman spectroscopy (NIR-SERS) studies on oxyheamoglobin (OxyHb) of liver cancer based on PVA-Ag nanofilm

A near-infrared surface-enhanced Raman spectroscopy (NIR-SERS) method was employed for oxyheamoglobin (OxyHb) detection to develop a simple blood test for liver cancer detection. Polyvinyl alcohol protected silver nanofilm (PVA-Ag nanofilm) used as the NIR-SERS active substrate to enhance the Raman scattering signals of OxyHb. High quality NIR-SERS spectrum from OxyHb adsorbed on PVA-Ag nanofilm can be obtained within 16s using a portable Raman spectrometer. NIR-SERS measurements were performed on OxyHb samples of healthy volunteers (control subjects, n=30), patients (n=40) with confirmed liver cancer (stage I, II and III) and the liver cancer patients after surgery (n=30). Meanwhile, the tentative assignments of the Raman bands in the measured NIR-SERS spectra were performed, and the results suggested cancer specific changes on molecule level, including a decrease in the relative concentrations and the percentage of aromatic amino acids of OxyHb, changes of the vibration modes of the CaHm group and pyrrole ring of OxyHb of liver cancer patients. In this paper, principal component analysis (PCA) combined with independent sample T test analysis of the measured NIR-SERS spectra separated the spectral features of the two groups into two distinct clusters with the sensitivity of 95.0% and the specificity of 85.7%. Meanwhile, the recovery situations of the liver cancer patients after surgery were also assessed using the method of discriminant analysis-predicting group membership based on PCA. The results show that 26.7% surgeried liver cancer patients were distinguished as the normal subjects and 63.3% were distinguished into the cancer. Our study demonstrated great potentials for developing NIR-SERS OxyHb analysis into a novel clinical tool for non-invasive detection of liver cancers. Copyright (c) 2013 John Wiley & Sons, Ltd.