Characterization and Diagnosis of Cancer by Native Fluorescence Spectroscopy of Human Urine

Abstract

Urine is one of the diagnostically important bio fluids, as it has different metabolites in it, where many of them are native fluorophores. Native fluorescence characteristics of human urine samples were studied using excitation-emission matrices (EEMs) over a range of excitation and emission wavelengths, and emission spectra at 405 nm excitation, to discriminate patients with cancer from the normal subjects. The fluorescence spectra of urine samples of cancer patients exhibit considerable spectral differences in both EEMs and emission spectra with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values of the emission spectra and they were used as input variables for a multiple linear discriminant analysis across different groups. The discriminant analysis classifies 94.7% of the original grouped cases and 94.1% of the cross-validated grouped cases correctly. Based on the fluorescence emission characteristics of urine and statistical analysis, it may be concluded that the fluorophores nicotinamide adenine dinucleotide (NADH) and flavins may be considered as metabolomic markers of cancer.

Evaluation of Urinary Tryptophan Metabolite Levels in Non-diabetic Compared to Diabetic Rats

“…The bands centered at ~525 and ~615 nm are mostly due to flavin and porphyrins (Rajasekaran et al, 2013;Masilamani et al, 2010;Wolfbeis and Leiner, 1985).…”

“…As can be seen in Figure 2a the fluorescence intensity of free NADH (the band at around 444 nm) is affected in diabetic rats compared to non-diabetic rats. This is because the healthy glomerulus of non-diabetic rats can filter the free NADH and therefore, this can be found in urine (Rajasekaran et al, 2013;Gropper et al, 2009). In this context, in the case of non-diabetic rats, the fluorescence of urine is enhanced by the presence of more free NADH.…”

“…The mean (±standard deviation) and the p values of the peak height for the urine samples of diabetic and non-diabetic rats are presented To further attribute the emission wavelengths at the excitation of 400 nm, it has been reported that the peak at ~444 nm may be attributed to bound NADH (nicotinamide adenine dinucleotide), and the band at ~485 nm is due to free NADH (Rajasekaran et al, 2013;Masilamani et al, 2010;Wolfbeis and Leiner, 1985). The bands centered at ~525 and ~615 nm are mostly due to flavin and porphyrins (Rajasekaran et al, 2013;Masilamani et al, 2010;Wolfbeis and Leiner, 1985).…”

“…In addition, due to its richness in metabolites, the majority of which are recognized as fluorophores, it is recommended and used for spectrofluorimetric analysis (Dubayova et Saude et al, 2007). Despite the fact that numerous studies have analyzed the pathobiochemical characteristics of urine by means of fluorescence spectroscopy (Dubayova et al 2003), the study of the fluorescence of urine for diabetes diagnosis in particular and disease diagnosis in general is still at the beginning, as evidenced in a recent research article (Rajasekaran et al, 2013).…”

“…In the present study, we performed the spectrofluorimetric analysis of urine, given that this biological fluid is known for its role in the diagnosis and prognosis of diseases (Dubayova et al, 2003;Anwer et al, 2009;Rajasekaran et al, 2013). In addition, due to its richness in metabolites, the majority of which are recognized as fluorophores, it is recommended and used for spectrofluorimetric analysis (Dubayova et Saude et al, 2007).…”