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Peroxidase mimetic activity of fluorescent NS-carbon quantum dots and its application for colorimetric detection of H2O2 and glutathione in human blood serum

Abstract

At present scenario the growing interest toward the development of artificial enzyme to overcome the problem of natural enzyme. Herein, we report one step hydrothermal synthesis of nitrogen sulphur dual doped carbon quantum dots (NS-CQDs) having small size and significant fluorescent quantum yield (46 %). The attractiveness of NS-CQDs to exhibits peroxidase mimetic enzyme activity without any support of metals and polymeric materials and efficiently catalyzed the oxidation of peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2 to produced blue colour charge transfer complex with characteristic absorption band at 652 nm. The mechanistic studies suggested that the small size and high electron density of NS-CQDs play a vital role and accelerate the reduction of H2O2 to generate the active species .OH radical which facilitates the oxidation of TMB. The catalytic activity based on Michaelis-Menten kinetic behaviour and steady state Kinetic analysis suggested that NS-CQDs exhibited higher affinity towards H2O2 than TMB like natural enzyme Horseradish Peroxidase (HRP). Moreover, the catalytic pathway followed the ping pong mechanism. Therefore, these finding offered a worthy platform for colorimetric detection of H2O2, which showed the good linearity in the concentration range 0.02mmol to 0.1mm with detection limit of 0.004 mmol. More importantly, the blue colour of oxidized TMB showed excellent selectivity over non thiolate biological molecule especially amino acid and potentially detect glutathione up to 0.07 µM via colorimetric and fluorimetric assay. Moreover, we also demonstrated the glutathione detection in human blood serum which showed excellent recovery range 96.0 to 108.3%. Thus, our proposed sensing system is simple, convenient and straightforward and could be potentially applied for real time monitoring of H2O2 and glutathione in the biological environment.

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Publication details

The article was received on 15 May 2018, accepted on 26 Jun 2018 and first published on 27 Jun 2018


Article type: Paper
DOI: 10.1039/C8TB01286E
Citation: J. Mater. Chem. B, 2018, Accepted Manuscript
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    Peroxidase mimetic activity of fluorescent NS-carbon quantum dots and its application for colorimetric detection of H2O2 and glutathione in human blood serum

    V. K. Singh, P. K. Yadav, S. Chandra, D. Bano, M. Talat and S. H. Hasan, J. Mater. Chem. B, 2018, Accepted Manuscript , DOI: 10.1039/C8TB01286E

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