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Label-free electrical detection of DNA hybridization for the example of influenza virus gene sequences

Kukol, A and Li, P and Estrela, P. M. and Ko-Ferrigno, P and Migliorato, P (2008) Label-free electrical detection of DNA hybridization for the example of influenza virus gene sequences. Analytical Biochemistry, 374 (1). pp. 143-153. ISSN 0003-2697

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Microarrays based on DNA–DNA hybridization are potentially useful for detecting and subtyping viruses but require fluorescence labeling and imaging equipment. We investigated a label-free electrical detection system using electrochemical impedance spectroscopy that is able to detect hybridization of DNA target sequences derived from avian H5N1 influenza virus to gold surface-attached single-stranded DNA oligonucleotide probes. A 23-nt probe is able to detect a 120-nt base fragment of the influenza A hemagglutinin gene sequence. We describe a novel method of data analysis that is compatible with automatic measurement without operator input, contrary to curve fitting used in conventional electrochemical impedance spectroscopy (EIS) data analysis. A systematic investigation of the detection signal for various spacer molecules between the oligonucleotide probe and the gold surface revealed that the signal/background ratio improves as the length of the spacer increases, with a 12- to 18-atom spacer element being optimal. The optimal spacer molecule allows a detection limit between 30 and 100 fmol DNA with a macroscopic gold disc electrode of 1 mm radius. The dependence of the detection signal on the concentration of a 23-nt target follows a binding curve with an approximate 1:1 stoichiometry and a dissociation constant of KD = 13 ± 4 nM at 295 K.

Item Type:Article
Uncontrolled Keywords:DNA; Biosensor; Avian influenza; Label-free detection; Electrochemical impedance spectroscopy; Sulfhydryl chemistry; Spacer molecule; Oligonucleotide
Subjects:Analytical Science > Microscopy and probe methods
Biomedical Science > Nanoscale biological processes
ID Code:411
Deposited By:Lesley Tobin
Deposited On:02 Dec 2008 14:07
Last Modified:25 Feb 2009 11:53

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