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  • br The peak at cm is assigned to

    2022-08-31


    The peak at 1080 cm−1 is assigned to CeC stretch vibrations of the lipid and it is present only in the normal subjects. As the main function of phospholipids in cells is to maintain the membrane structure, the same is observed in normal cases and probably the peak is absent in cancer cases due to disturbance of cell membrane surface activity [57]. The peak maxima at 1490 cm-1 may be attributed to lauric DCFH-DA of the fatty acids which is higher for normal subjects with that of the malig-nant group. And this peak is shifted to 1495 cm−1. Earlier report on plasma lipids reveals that changes in lipid contents occur in cancer patients are due to their increased usage of neoplastic cells for new organelles [58]. Lipid peroxidation plays a crucial role in the control of cell division during this process a free radical acquire an electron from the lipid bi-layer, thereby causing damage to the cell [59–62]. This is further correlated with the results of Daniel et al. and Manoharan et al., who reported that there is a DCFH-DA loss of lipid content in cancer due to the interaction of ROS with lipid causes lipid peroxidation [63,64]. It is noted that free radicals are controlled in a normal human system by antioxidants pathways but the same was not sufficient to neutralize in the malignant environment [57]. Free radicals may alter the normal cells and tissue into cancer either by endogenous metabolic reaction or by induced metabolic changes due to lifestyle, pollution and radiation hazards. Antioxidants prevent cellular damage by quenching and eliminating oxidizing free radicals [65,66]. The Raman peaks which are observed at 1190, 1517 and 1533 cm−1 are the characteristic peaks of β-carotene shows lesser vibration in the cancer group compared with that of normal. The carotenoids present in the blood had been used in the detection of malignancy by Raman spectroscopy [54]. Hence the β-carotene may also be used as an additional Biomolecular marker in the discrimination of normal and malignant subjects by Raman Spectro-scopy.
    As the Raman spectral signature shows considerable variations be-tween the normal and cervical cancer group, multivariate statistical analysis have been carried out for the acquired Raman data. Initially, the vector normalized Raman data was given as input to the principal component analysis which used to reduce the dimension of the given data set into principal components/factors. Thus, obtained factors (PCs) are mutually orthogonal to each other. Linear discriminant analysis (LDA) with leave one out cross validation was used in the further analysis of these PCs to differentiate the cancer group from that of the normal group. The original grouped cases produced 100% sensitivity and specificity with 100% accuracy whereas the cross-validated group produced 94.4% sensitivity and 96.7% specificity with 95.8% accuracy. Further to evaluate the diagnostic performance of the PCA-LDA, re-ceiver operating characteristic (ROC) curves were plotted. The area under the curve obtained from ROC analysis reveals that the PCA-LDA diagnostic algorithm employing the fingerprint region of Raman blood plasma spectra gives a more effective diagnostic performance and better classification between normal and cervical cancer group.
    5. Conclusion
    Cervical cancer is the common malignancy in the female, the pre-sent method for detection or diagnosis is the biopsy, Pap smear and colposcopy etc. To overcome the drawbacks of diagnosis an alternative complimentary technique are in need, optical spectroscopy is a new emerging technique where the discrimination of normal and cancer subjects provides valuable potential information in the diagnostic on-cology at an early stage. The Nucleic acids, proteins–amide groups, amino acids (tryptophan, tyrosine and phenylalanine), lipids and  Vibrational Spectroscopy 102 (2019) 1–7
    antioxidant present in the blood plasma play a vital role in the dis-crimination of malignant from the normal subjects. The DNA, protein, tyrosine and tryptophan showed an elevated level in the malignancy. The lipids and antioxidant (β-carotene) in the normal is higher than that of cancer. The classification results, of Raman Spectroscopy of Label-free blood plasma of cervical cancer and normal using PCA-LDA diagnostic algorithm yields, an accuracy of 100% and 95.8% for ori-ginal and cross-validated group respectively. As the results are appre-ciable, it is necessary to carry out the analysis for more number of samples to explore the facts hidden at different stages during the de-velopment of cervical cancer.