Li Xiaohong, Lee Jeremy S, Kraatz Heinz-Bernhard
Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5.
Anal Chem. 2006 Sep 1;78(17):6096-101. doi: 10.1021/ac060533b.
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.
电极直径为10微米的金电极阵列，用于通过电化学阻抗谱（EIS）检测未标记和预杂交DNA中的八个单核苷酸错配。由于在pH≥8.6时，双链DNA（B型正常双链DNA）薄膜在有和没有Zn(2+)的情况下电学性质存在差异，因此采用兰德尔等效电路来评估EIS结果。B-DNA（pH≥8.6时无Zn2+）和M-DNA（pH≥8.6时有Zn2+）之间的电荷转移电阻差异（ΔR(CT)），使得能够明确检测20聚体DNA序列中的所有八个单核苷酸错配。与靶DNA进行去杂交/再杂交后，ΔR(CT)能够区分浓度低至10 fM的靶链单核苷酸错配。尽管存在蛋白质杂质（牛血清白蛋白，10微克/毫升）会干扰靶链的检测（检测限为1 pM），但非靶DNA（小牛胸腺DNA，10(-8) M）的存在不会产生干扰，识别靶链的检测限仍为10 fM。
