State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China.
Anal Chim Acta. 2013 Jan 31;762:47-53. doi: 10.1016/j.aca.2012.12.008. Epub 2012 Dec 13.
Engineered nucleic acid probes containing recognition and signaling functions find growing interest in biosensor design. In this paper, we developed a novel electrochemical biosensor for sensitive and selective detecting of Hg(2+) based on a bifunctional oligonucleotide signal probe combining a mercury-specific sequence and a G-quadruplex (G4) sequence. For constructing the electrochemical Hg(2+) biosensor, a thiolated, mercury-specific oligonucleotide capture probe was first immobilized on gold electrode surface. In the presence of Hg(2+), a bifunctional oligonucleotide signal probe was hybridized with the immobilized capture probe through thymine-mercury(II)-thymine interaction-mediated surface hybridization. The further interaction between G4 sequence of the signal probe and hemin generated a G4-hemin complex, which catalyzed the electrochemical reduction of hydrogen peroxide, producing amplified readout signals for Hg(2+) interaction events. This electrochemical Hg(2+) biosensor was highly sensitive and selective to Hg(2+) in the concentration of 1.0 nM to 1 μM with a detection limit of 0.5 nM. The new design of bifunctional oligonucleotide signal probes also provides a potential alternative for developing simple and effective electrochemical biosensors capable of detecting other metal ions specific to natural or artificial bases.
含识别和信号功能的工程核酸探针在生物传感器设计中越来越受到关注。本文基于一种具有汞特异性序列和 G-四链体 (G4) 序列的双功能寡核苷酸信号探针，开发了一种用于灵敏和选择性检测 Hg(2+) 的新型电化学生物传感器。为了构建电化学 Hg(2+) 生物传感器，首先将巯基化的、具有汞特异性的寡核苷酸捕获探针固定在金电极表面。在存在 Hg(2+) 的情况下，双功能寡核苷酸信号探针通过胸腺嘧啶-汞 (II)-胸腺嘧啶相互作用介导的表面杂交与固定的捕获探针杂交。信号探针的 G4 序列与血红素之间的进一步相互作用产生了 G4-血红素复合物，该复合物催化过氧化氢的电化学还原，产生用于 Hg(2+) 相互作用事件的放大读出信号。该电化学 Hg(2+) 生物传感器对 1.0 nM 至 1 μM 浓度范围内的 Hg(2+) 具有高度的灵敏性和选择性，检测限为 0.5 nM。双功能寡核苷酸信号探针的新设计也为开发能够检测天然或人工碱基特异性其他金属离子的简单有效的电化学生物传感器提供了一种潜在的替代方法。
