Electrochemical Biosensors for Hypoxia Markers
An inadequate oxygen supply to cells/tissues causes hypoxia at high altitude, resulting in alteration in the levels of nitric oxide (NO) and its metabolites, viz. nitrite (NO2 −) and nitrate (NO3 −) and simultaneous increase in the formation of peroxynitrite which triggers the cell death by releasing cytochrome c (cyt c) from mitochondria. Therefore, measurements of these biologically important hypoxia biomarkers are imperative in human physiology as it provides valuable information regarding the personnel at high altitude. So, we have developed a cost-effective and portable electrochemical biosensor assay for the measurement of various hypoxia biomarkers in volume miniaturized samples using screen-printed electrodes (SPE). Modification of SPE surface with nanocomposites of polypyrrole and carbon nanotube/self-assembled layer on gold nanoparticle for biofunctionalization of specific biorecognization (enzymes/antibody) elements provides a selective and sensitive determination of various hypoxia biomarkers. Copper, zinc superoxide dismutase, and nitrate reductase-functionalized electrodes were used as biosensors for the determination of NO, NO2 −, and NO3 −. Supplementation of NO3 − rich beetroot juice to human and several animal models enhanced the NO-like bioactivity. So, we have measured the total NO2 − and NO3 − levels in beetroot supplements and in human plasma before and after beetroot intake. Further, novel cyt c biosensor based on cyt c reductase was employed to measure cyt c release from the hypoxic-induced cell death and the results agreed well with the standard assay methods.
KeywordsNitric Oxide Nitric Oxide Synthases Electrochemical Response Electrochemical Biosensor Flavin Adenine Dinucleotide
Thanks are due to the support provided by the DIPAS-DRDO, DBT, New Delhi, and the Managing Board of Virudhunagar Hindu Nadar’s Senthikumara Nadar College (Autonomous), Virudhunagar, Tamil Nadu, India.
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