Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, PR China.
Biosens Bioelectron. 2012 Mar 15;33(1):211-5. doi: 10.1016/j.bios.2012.01.003. Epub 2012 Jan 15.
Herein we report a sensitive electrochemical biosensor for DNA detection by making use of exonuclease III and probe DNA functionalized gold nanoparticles. While probe DNA P1 modified on a gold electrode surface can self-hybridize into a stem-loop structure with an exonuclease III-resistant 3' overhang end, in the presence of target DNA, P1 may also hybridize with the target DNA to form a duplex region. Therefore, exonuclease III may selectively digest P1 from its 3'-hydroxyl termini until the duplex is fully consumed. Since a single target DNA can trigger exonuclease III digestion of numerous P1 strands, the first signal amplification is achieved. On the other hand, since the digested P1, exposing its complementary sequence to probe DNA P2, can further hybridize with P2 that has been previously modified on the surface of gold nanoparticles, many nanoparticles loaded with numerous DNA strands are immobilized onto the electrode surface. Consequently, large amount of electroactive molecules Ru(NH(3))(6) can bind with the DNA strands to produce an intense electrochemical response as the second signal amplification. Based on the studies with cyclic voltammetry (CV) and chronocoulometry (CC) techniques, the proposed biosensor can sensitively detect specific target DNA at a picomolar level with high specificity.
在这里，我们报道了一种基于exonuclease III 和探针 DNA 功能化金纳米粒子的灵敏电化学 DNA 生物传感器。当探针 DNA P1 修饰在金电极表面时，可以自杂交形成带有exonuclease III 抗性 3'突出端的茎环结构，而在存在靶 DNA 的情况下，P1 也可以与靶 DNA 杂交形成双链区域。因此，exonuclease III 可以选择性地从其 3' -羟基末端消化 P1，直到双链完全消耗。由于单个靶 DNA 可以触发 exonuclease III 消化许多 P1 链，因此实现了第一个信号放大。另一方面，由于被消化的 P1 暴露出与其互补序列相匹配的 P2，进一步与之前修饰在金纳米粒子表面的 P2 杂交，许多负载有许多 DNA 链的纳米粒子被固定在电极表面上。因此，大量的电化学活性分子Ru(NH(3))(6)可以与 DNA 链结合，产生强烈的电化学响应作为第二个信号放大。通过循环伏安法 (CV) 和计时库仑法 (CC) 技术的研究，该生物传感器可以在皮摩尔水平上灵敏地检测特定的靶 DNA，具有很高的特异性。
