An impedimetric biosensor based on electrophoretically assembled ZnO nanorods and carboxylated graphene nanoflakes on an indium tin oxide electrode for detection of the DNA of Escherichia coli O157:H7
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Aminopropyltrimethoxysilane (APTMS)-functionalized zinc oxide (ZnO) nanorods and carboxylated graphene nanoflakes (c-GNF) were used in a composite that was electrophoretically deposited on an indium tin oxide (ITO) coated glass substrate. The modified ITO electrodes were characterized using various microscopic and spectroscopic techniques which confirm the deposition of the APTMS-ZnO/c-GNF composite. The electrodes have been used for the covalent immobilization of an Escherichia coli O157:H7 (E. coli)-specific DNA prob. Impedimetric studies revealed that the gene sensor displays linear response in a wide range of target DNA concentration (10−16 M to 10−6 M) with a detection limit of 0.1 fM. The studies on the cross-reactivity to other water-borne pathogens show that the bioelectrode is highly specific.
KeywordsBiosensor Escherichia coli Zinc oxide Graphene nanoflakes Electrophoretic deposition
N.J. and S.S. are thankful to CSIR, India for the award of SRF and RA, respectively. C.M.P. acknowledges the Department of Science and Technology, New Delhi, India for DST-INSPIRE Faculty Award (DST/INSPIRE/04/2015/000932). We thank Dr. Gajjala Sumana (CSIR-National Physical Laboratory) for interesting discussions. N.J. and I.T. are sincerely thankful to Prof. O.N Srivastava (Dept. of Physics, I.Sc. B.H.U) and Prof. Rajiv Prakash (IIT B.H.U) for providing TEM and SEM facilities respectively. B.D.M. thanks Science & Engineering Research Board (Govt. of India) for the award of a Distinguished Fellowship (SB/S9/YSCP/SERB-DF/2018).
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Conflict of interest
The authors declare no conflict of interest.
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