Issue 9, 2016

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

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

Supplementary files

Article information

Article type
Paper
Submitted
04 jan. 2016
Accepted
15 feb. 2016
First published
15 feb. 2016

Analyst, 2016,141, 2756-2760

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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