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Issue 9, 2016
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An oligonucleotide-functionalized carbon nanotube chemiresistor for sensitive detection of mercury in saliva

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Abstract

Divalent mercuric (Hg2+) ion and monomethyl mercury (CH3Hg+) are two forms of mercury that are known to be highly toxic to humans. In this work, we present a highly selective, sensitive and label-free chemiresistive biosensor for the detection of both, Hg2+ and CH3Hg+ ions using DNA-functionalized single-walled carbon nanotubes (SWNTs). The SWNTs were functionalized with the capture oligonucleotide, polyT, using a linker molecule. The polyT was hybridized with polyA to form a polyT:polyA duplex. Upon exposure to mercury ions, the polyT:polyA duplex dehybridizes and a T–Hg2+–T duplex is formed. This structure switch leads to the release of polyA from the SWNT surface and correspondingly a change in the resistance of the chemiresistive biosensor is observed, which is used to quantify the mercury ion concentration. The biosensor showed a wide dynamic range of 0.5 to 100 nM for the detection of CH3Hg+ ions in buffer solution with a sensitivity of 28.34% per log (nM) of CH3Hg+. Finally, real world application of the biosensor was demonstrated by the detection of Hg2+ and CH3Hg+ ions in simulated saliva samples spiked with a known concentration of mercury ions.

Graphical abstract: An oligonucleotide-functionalized carbon nanotube chemiresistor for sensitive detection of mercury in saliva

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Publication details

The article was received on 04 Jan 2016, accepted on 15 Feb 2016 and first published on 15 Feb 2016


Article type: Paper
DOI: 10.1039/C6AN00018E
Citation: Analyst, 2016,141, 2756-2760

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    An oligonucleotide-functionalized carbon nanotube chemiresistor for sensitive detection of mercury in saliva

    D. N. Wordofa, P. Ramnani, T. Tran and A. Mulchandani, Analyst, 2016, 141, 2756
    DOI: 10.1039/C6AN00018E

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