Fluorescence spectroscopic characterization of salivary metabolites of oral cancer patients

Abstract

A pilot study has been carried out using human saliva in differentiating the normal subjects from that of oral squamous cell carcinoma (OSCC) patients, using the autofluorescence spectroscopy at 405nm excitation. A markable difference in the spectral signatures between the saliva of normal subjects and that of oral cancer patients has been noticed. The possible reasons for the altered spectral signature may be due to the presence of endogenous porphyrin, NAD(P)H and FAD in the exfoliated cells from saliva. The elevated level of porphyrin in saliva of OSCC patients may be attributed to the disturbances in the amino acid degradation pathway and heme biosynthetic pathway, during the transformation of normal into malignant cells. The integrated area under the curve of fluorescence emission spectrum at 405nm excitation and also fluorescence excitation spectrum for 625nm emission were compared for the saliva of normal and oral cancer patients. The area under the curve for the emission spectrum provides 85.7% sensitivity and 93.3% specificity, where as the fluorescence excitation spectrum discriminates the same with 84.1% sensitivity and 93.2% specificity.

Keywords: Excited state kinetics; Intrinsic fluorophores; Metabolomic markers; Oral cancer; Saliva autofluorescence.