"Off On" Electrochemical Hairpin-DNA-Based Genosensor for Cancer Diagnostics
"Off On" Electrochemical Hairpin-DNA-Based Genosensor for Cancer Diagnostics
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DOI：
10.1021/ac1032929
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发表时间：
2011-03-01
影响因子：
7.4
通讯作者：
Ferapontova, Elena E.
中科院分区：
文献类型：
--
作者：
Farjami, Elaheh;Clima, Lilia;Ferapontova, Elena E.
基于电子DNA发夹分子信标，开发了一种简单、稳健的单核苷酸多态性（SNP）检测选择性提高的“开关”信号基因传感器平台。DNA信标通过3′端链烷硫醇连接物固定在折叠态的金电极上，S′端用亚甲基蓝（MB）氧化还原探针标记。将27-33个核苷酸（nt）长的发夹DNA与靶DNA杂交后，观察到电化学信号的典型“开-关”变化，与迄今为止发表的所有数据一致。将DNA发夹信标截断至20nts，提高了基因传感器对SNP的选择性，并允许电化学基因传感器响应从开到关模式切换。切换与电极与MB氧化还原标签之间电子转移反应机理的变化一致，因为折叠信标是吸附物质的电化学特征，而“开放”双相结构则是由氧化还原标签在吸附层内的扩散所正式控制。两个过程的相对电流强度由形成的DNA双链长度、电位扫描速率和氧化还原物质的表观扩散系数决定。用于检测癌症生物标志物TP53基因序列的关闭基因传感器设计有利于区分健康DNA序列和含有snp的DNA序列，这在短杂交时间内尤为明显。
A simple and robust "off on" signaling genosensor platform with improved selectivity for single-nucleotide polymorphism (SNP) detection based on the electronic DNA hairpin molecular beacons has been developed. The DNA beacons were immobilized onto gold electrodes in their folded states through the alkanethiol linker at the 3'-end, while the S'-end was labeled with a methylene blue (MB) redox probe. A typical "on-off" change of the electrochemical signal was observed upon hybridization of the 27-33 nucleotide (nt) long hairpin DNA to the target DNA, in agreement with all the hitherto published data. Truncation of the DNA hairpin beacons down to 20 nts provided improved genosensor selectivity for SNP and allowed switching of the electrochemical genosensor response from the on off to the off on mode. Switching was consistent with the variation in the mechanism of the electron transfer reaction between the electrode and the MB redox label, for the folded beacon being characteristic of the electrochemistry of adsorbed species, while for the "open" duplex structure being formally controlled by the diffusion of the redox label within the adsorbate layer. The relative current intensities of both processes were governed by the length of the formed DNA duplex, potential scan rate, and apparent diffusion coefficient of the redox species. The off on genosensor design used for detection of a cancer biomarker TP53 gene sequence favored discrimination between the healthy and SNP-containing DNA sequences, which was particularly pronounced at short hybridization times.