Template-Independent, in Situ Grown DNA Nanotail Enabling Label-Free Femtomolar Chronocoulometric Detection of Nucleic Acids
Template-Independent, in Situ Grown DNA Nanotail Enabling Label-Free Femtomolar Chronocoulometric Detection of Nucleic Acids
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不依赖模板、原位生长的 DNA 纳米尾可实现无标记飞摩尔计时库仑核酸检测
DOI：
10.1021/ac503728s
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发表时间：
2014-12-02
影响因子：
7.4
通讯作者：
Zhang，Guo-Jun
中科院分区：
文献类型：
--
作者：
Yang，Fan;Yang，Xian;Zhang，Guo-Jun
常规的电化学DNA （E-DNA）传感器要么需要一个精致的构象可切换识别探针的设计，这对于促进传感界面上的电子转移至关重要，要么需要一个模板依赖的DNA扩增，这通常涉及设计正假“粘端”并在信号探针的一端标记氧化还原标签。在这里，我们报道了一种原位生长DNA纳米尾（IGT）介导的直接无模板信号扩增策略，用于高灵敏度和序列特异性DNA检测。这种新型的电化学IGT (E-IGT) DNA传感器可以以无标记的方式量化目标核酸，因为电化学信号是通过对氧化还原[Ru(NH3)6]3+的计时测量产生的，该氧化还原[Ru(NH3)6]3+在电极表面附着的DNA中以静电和定量的方式与带负电荷的磷酸基团结合。通过引入末端脱氧核苷转移酶（TdT），该传感器的灵敏度和选择性都得到了显著提高。该DNA传感器对含有22个核苷酸的DNA序列的检测限为20 fM，比类似的光学DNA传感器低2个数量级。更重要的是，它对单碱基错配序列也有很好的选择性。此外，这种新型DNA传感器具有可靠的可重复使用性，能够以最小的干扰测量复杂基质中的目标DNA，例如未稀释的人血清。这些优势使我们的E-IGT传感器成为医学诊断E-DNA传感器家族中有前途的竞争者。
A routine electrochemical DNA (E-DNA) sensor requires either an exquisite design of conformation-switchable recognition probe that is critical to facilitate electron transfer at a sensing interface, or a template-dependent DNA amplification, which often involves designing prone-to-false “sticky ends” and labeling redox tags at one end of the signal probes. Here we report an in situ grown DNA nanotail (IGT)-mediated straightforward and template-free signal amplification strategy for highly sensitive and sequence-specific DNA detection. This novel electrochemical IGT (E-IGT) DNA sensor can quantify target nucleic acids in a label-free manner because the electrochemical signals are generated by chronocoulometric interrogation of redox [Ru(NH3)6]3+that electrostatically and quantitatively binds to the negatively charged phosphate moieties in the electrode surface-attached DNA. By introduction of terminal deoxynucleoside transferase (TdT) to this sensor design, both the sensitivity and selectivity have been significantly enhanced. This DNA sensor achieves an impressive detection limit of 20 fM for a DNA sequence with 22 nucleotides, which is lower than that of an analogous optical DNA sensor by 2 orders of magnitude. More importantly, it exhibits excellent selectivity against even a single-base mismatched sequence. In addition, this novel DNA sensor presents reliable reusability and is capable of measuring target DNA in complex matrixes, such as undiluted human serum, with minimal interference. These advantages make our E-IGT sensor a promising contender in the E-DNA sensor family for medical diagnostics.