Electrochemical detection of single-nucleotide mismatches using an electrode microarray.
Gold electrode arrays with electrode diameters of 10 mum were used for the detection of eight single-nucleotide mismatches in unlabeled and prehybridized DNA by electrochemical impedance spectroscopy (EIS). Because of the differences in the electrical properties of films of duplex DNA (normal duplex DNA in B-form) in the presence and absence of Zn(2+) at pH > or = 8.6, Randles equivalent circuits were employed to evaluate the EIS results. The difference in the charge-transfer resistance (DeltaR(CT)) between B-DNA (absence of Zn2+ at pH > or = 8.6) and M-DNA (presence of Zn2+ at pH > or = 8.6) allows unequivocal detection of all eight single-nucleotide mismatches within a 20-mer DNA sequence. After dehybridization/rehybridization with target DNA, DeltaR(CT) allows the discrimination of single-nucleotide mismatches with concentrations of the target strand as low as 10 fM. Although the presence of protein impurities (bovine serum albumin, 10 microg/mL) interferes with the detection of the target strand (1 pM detection limit), the presence of nontarget DNA (calf thymus DNA, 10(-8) M) does not interfere, and the detection limit for recognition of the target strand remains at 10 fM.
Li
Xiaohong
X
Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5.
Lee
Jeremy S
JS
Kraatz
Heinz-Bernhard
HB
D004563:Electrochemistry; D004566:Electrodes; D017403:In Situ Hybridization; D009711:Nucleotides / Q000032:analysis* / Q000737:chemistry*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012680:Sensitivity and Specificity
D009711:Nucleotides