Oral cancer diagnostics based on infrared spectral markers and wax physisorption kinetics

Infrared microspectroscopy is an emerging approach for disease analysis owing to its capability for in situ chemical characterization of pathological processes. Synchrotron-based infrared microspectroscopy (SR-IMS) provides ultra-high spatial resolution for profiling biochemical events associated with disease progression. Spectral alterations were observed in cultured oral cells derived from healthy, precancerous, primary, and metastatic cancers. An innovative wax-physisorption-based kinetic FTIR imaging method for the detection of oral precancer and cancer was demonstrated successfully. The approach is based on determining the residual amount of paraffin wax (C₂₅H ₅₂) or beeswax (C₄₆H₉₂O₂) on a sample surface after xylene washing. This amount is used as a signpost of the degree of physisorption that altered during malignant transformation. The results of linear discriminant analysis (LDA) of oral cell lines indicated that the methylene (CH₂) and methyl group (CH₃) stretching vibrations in the range of 3,000-2,800 cm^-1 have the highest accuracy rate (89.6 %) to discriminate the healthy keratinocytes (NHOK) from cancer cells. The results of wax-physisorption-based FTIR imaging showed a stronger physisorption with beeswax in oral precancerous and cancer cells as compared with that of NHOK, which showed a strong capability with paraffin wax. The infrared kinetic study of oral cavity tissue showed a consistency in the wax physisorption of the cell lines. On the basis of our findings, these results show the potential use of wax-physisorption-based kinetic FTIR imaging for the early screening of oral cancer lesions and the chemical changes during oral carcinogenesis. [Figure not available: see fulltext.]