Yang Cuiyun, Shi Kai, Dou Baoting, Xiang Yun, Chai Yaqin, Yuan Ruo
Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, P.R. China.
ACS Appl Mater Interfaces. 2015 Jan 21;7(2):1188-93. doi: 10.1021/am506933r. Epub 2015 Jan 7.
On the basis of the use of silver nanoclusters (AgNCs) in situ synthesized by cytosine (C)-rich loop DNA templates as signal amplification labels, the development of a label-free and highly sensitive method for electrochemical detection of microRNA (miRNA-199a) is described. The target miRNA-199a hybridizes with the partial dsDNA probes to initiate the target-assisted polymerization nicking reaction (TAPNR) amplification to produce massive intermediate sequences, which can be captured on the sensing electrode by the self-assembled DNA secondary probes. These surface-captured intermediate sequences further trigger the hybridization chain reaction (HCR) amplification to form dsDNA polymers with numerous C-rich loop DNA templates on the electrode surface. DNA-templated synthesis of AgNCs can be realized by subsequent incubation of the dsDNA polymer-modified electrode with AgNO3 and sodium borohydride. With this integrated TAPNR and HCR dual amplification strategy, the amount of in situ synthesized AgNCs is dramatically enhanced, leading to substantially amplified current response for highly sensitive detection of miRNA-199a down to 0.64 fM. In addition, the developed method also shows high selectivity toward the target miRNA-199a. Featured with high sensitivity and label-free capability, the proposed sensing scheme can thus offer new opportunities for achieving sensitive, selective, and simple detection of different types of microRNA targets.
基于使用由富含胞嘧啶（C）的环状DNA模板原位合成的银纳米簇（AgNCs）作为信号放大标签，本文描述了一种用于电化学检测微小RNA（miRNA-199a）的无标记且高灵敏度方法的开发。目标miRNA-199a与部分双链DNA探针杂交，引发目标辅助聚合切口反应（TAPNR）扩增，产生大量中间序列，这些中间序列可被自组装的DNA二级探针捕获在传感电极上。这些表面捕获的中间序列进一步触发杂交链式反应（HCR）扩增，在电极表面形成带有大量富含C的环状DNA模板的双链DNA聚合物。通过随后用硝酸银和硼氢化钠孵育双链DNA聚合物修饰的电极，可以实现DNA模板合成AgNCs。采用这种集成的TAPNR和HCR双重放大策略，原位合成的AgNCs的量显著增加，从而导致用于高灵敏度检测miRNA-199a的电流响应大幅放大，检测下限低至0.64 fM。此外，所开发的方法对目标miRNA-199a也表现出高选择性。该传感方案具有高灵敏度和无标记能力，因此可为实现对不同类型微小RNA靶标的灵敏、选择性和简单检测提供新的机会。
