Optical redox ratio using endogenous fluorescence to assess the metabolic changes associated with treatment response of bioconjugated gold nanoparticles in streptozotocin-induced diabetic rats
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Date
2017-12
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Publisher
Laser Physics Letters
Abstract
Fluorescence spectroscopic techniques have the potential to assess the metabolic changes
during disease development and evaluation of treatment response in a non-invasive and
label-free manner. The present study aims to evaluate the effect of mulberry-mediated
gold nanoparticles (MAuNPs) in comparison with mulberry leaf extract alone (MLE) for
monitoring endogenous fluorophores and to quantify the metabolic changes associated
with mitochondrial redox states during streptozotocin-induced diabetic liver tissues using
fluorescence spectroscopy. Two mitochondrial metabolic coenzymes, reduced nicotinamide
dinucleotide (NADH) and oxidized flavin adenine dinucleotide (FAD) are autofluorescent and
are important optical biomarkers to estimate the redox state of a cell. Significant differences
in the autofluorescence spectral signatures between the control and the experimental diabetic
animals have been noticed under the excitation wavelength at 320 nm with emission ranging
from 350–550 nm. A direct correlation between the progression of diabetes and the levels of
collagen and optical redox ratio was observed. The results revealed that a significant increase
in the emission of collagen in diabetic liver tissues as compared with the control liver tissues.
Moreover, there was a significant decrease in the optical redox ratio (FAD/(FAD + NADH))
observed in diabetic control liver tissues, which indicates an increased oxidative stress
compared to the liver tissues of control rats. Further, the extent of increased oxidative stress
was confirmed by the reduced levels of reduced glutathione (GSH) in diabetic liver tissues.
On a comparative basis, treatment with MAuNPs was found to be more effective than MLE
for reducing the progression of diabetes and improving the optical redox ratio to a near normal
range in streptozotocin-induced diabetic liver tissues. Furthermore, principal component analysis followed by linear discriminant analysis (PC-LDA) has been used to classify the
autofluorescence emission spectra from the control and the experimental group of diabetic
rats. The results of this study raise the important possibility that fluorescence spectroscopy in
conjunction with multivariate statistical analysis has tremendous potential for monitoring or
potentially predicting responses to therapy.
Description
Keywords
endogenous fluorophores, multivariate analysis, redox ratio, MAuNPs, diabetics
Citation
Adavallan K, Gurushankar K, Nazeer SS, GohulkumarM, Jayasree RS, Krishnakumar N. Optical redox ratio using endogenous fluorescence to assess the metabolic changes associated with treatment response of bioconjugated gold nanoparticles in streptozotocin-induced diabetic rats. Laser Physics Letters. 2017 Apr; 14(6).