Polarization gating technique extracts depth resolved fluorescence redox ratio in oral cancer diagnostics.

Mortality of oral cancer is often due to late diagnosis. Effective non-invasive diagnostic techniques may increase the survival rate based on an earlier diagnosis.. We report on the application of the polarization gating technique for isolating weakly scattered and highly scattered components of fluorescence emission from the superficial and deeper layers of tissue due to intrinsic fluorophores NADH and FAD. The fluorescence polarization spectra were collected from 21 normal and 67 oral squamous cell carcinoma biopsy tissues. The tissues were excited at 350 nm and the fluorescence emission had two peaks corresponding to NADH, and FAD respectively. The spectra were analyzed using the polarization gating technique along with the spectral deconvolution method to derive the optical redox ratio from different layers of tissue. The fractional change in redox ratio between superficial and deeper layers of tissue exhibits excellent statistical significance (p<10-3) which may be due to a shift in the metabolic pathway from oxidative phosphorylation to glycolysis in the cancer cell. Further, variation in collagen intensity in deeper layers of tissue is observed which may be attributed to the breakdown of collagen fibers in the stroma. Linear discriminant analysis showed that oral cancer tissue is discriminated with a better accuracy using polarization gating technique than that of conventional fluorescence spectroscopy.

Synchronous Luminescence Spectroscopy as a Tool in the Discrimination and Characterization of Oral Cancer Tissue.

High incidence of oral cancer is primarily due to ongoing tobacco epidemic. In this work, synchronous luminescence spectroscopy (SLS) has been used to characterize and discriminate oral cancer tissue. Spectral deconvolution method is employed to compute the fluorescence intensity, peak wavelength, and full width half maxima for different endogenous fluorophores. The fluorescence measurements were made on 21 normal and 88 oral squamous cell carcinoma biopsy tissues. Besides, variations in relative concentration of collagen, NADH, and FAD, peak shifts and broadening of peaks are observed for tryptophan, NADH, and FAD, in oral cancer tissues indicating both biochemical and micro environmental changes at cellular level. Linear discriminant analysis showed that oral cancer tissue is discriminated with a sensitivity and specificity of 100% and 95.2% respectively.

An in vitro diagnosis of oral premalignant lesion using time-resolved fluorescence spectroscopy under UV excitation-a pilot study.

In spite of rapid advancement in cancer treatment, early diagnosis of cancer and medicable precursors are still the finest approach towards the assurance of patient lives and enhancement in the quality of their life. In this regard, the present study deals with the time-resolved fluorescence spectroscopy of normal and premalignant oral tissues under UV excitations (280nm and 310nm). The decay kinetics at 350nm emission of normal tissues exhibit higher fluorescence lifetime than that of premalignant tissues and subsequent statistical analysis shows that the data were statistically significant. Further, the decay kinetics at 450nm emission for normal and premalignant oral tissues was obtained. Subsequently, statistical analysis revealed that except fast component, rest of the component lifetimes and fractional amplitudes were not statistically significant. An attempt has also been made to explore the better statistical tool to discriminate premalignant tissues from normal ones at 350nm emission. Among stepwise linear discriminant analysis (SLDA) and receiver operator characteristics (ROC), the former discriminates premalignant from normal tissues with 86.7% specificity and 93.3% sensitivity. Hence, fluorescence lifetime spectroscopy at 350nm emission opens a new avenue for early detection of oral cancer.

Polarized Raman spectroscopy unravels the biomolecular structural changes in cervical cancer.

Polarized Raman spectroscopy has emerged as a promising technique giving a wealth of information about the orientation and symmetry of bond vibrations in addition to the general chemical information from the conventional Raman spectroscopy. In this regard, polarized Raman Spectroscopic technique was employed to study the changes in the orientation of biomolecules in normal and cancerous conditions. This technique was compared to the conventional Raman spectroscopic technique and was found to yield additional information about the orientation of tyrosine, collagen and DNA. The statistically analyzed depolarization ratios by Linear Discriminant Analysis yielded better accuracy than the statistical results of conventional Raman spectroscopy. Thus, this study reveals that polarized Raman spectroscopy has better diagnostic potential than the conventional Raman spectroscopic technique.