Native Fluorescence Characterization of Blood Plasma for Early Diagnosis of Oral Potentially Malignant Disorders

Oral potentially malignant disorders (PMD) are heterogenous group of oral conditions characterized by increased risk of malignant transformation that are commonly diagnosed clinically and treated. Tissue biopsy is an invasive tool for diagnosis of oral PMDs. Native fluorescence spectroscopy of biofluids has been considered as an alternative and/or complimentary tool in the characterization of tissues of various pathological conditions. In the present study, it is primarily aimed to characterize different fluorophores present in the blood plasma of normal subjects and PMD patients, using excitation-emission matrix (EEM) and to compare their diagnostic potentials in delineating PMD cases from normal subjects. From EEM measurements of blood plasma, it was observed that there is a maximum emission around 340 ± 5 nm at 307 ± 3 nm excitation for normal subjects and around 337 ± 5 nm emission at 300 ± 3 nm excitation for PMD patients. In addition to the maxima, the contours exhibit other secondary emissions such as 480 ± 5 nm at 335 ± 3 nm excitation for both normal and PMD blood plasma. It was also observed that an emission at 520 ± 5 nm for 440 ± 3 nm excitation is seen for PMD blood plasma and the same is absent in the cases of normal blood plasma. The three contours centred around 340, 480 and 520 nm may be attributed to emissions from tryptophan, NADH and FAD, respectively. Results of stepwise multiple linear discriminant analysis reveal that fluorescence spectral features of NADH classify samples more effectively with 100% sensitivity and 95% specificity.