School of Life Science, Jiangsu Normal University, Xuzhou 221116, PR China; Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Biosens Bioelectron. 2016 Dec 15;86:454-458. doi: 10.1016/j.bios.2016.07.001. Epub 2016 Jul 2.
The ultrasensitive electrochemical detection of miRNA-21 was realized by using a novel redox and catalytic "all-in-one" mechanism with an iridium(III) complex as a catalyst. To construct such a sensor, a capture probe (CP) was firstly immobilized onto the gold electrode surface. In the presence of miRNA-21, a sandwiched DNA complex could form between CP and a methylene blue (MB) labeled G-rich detection probe modified onto a gold nanoparticle (AuNP) surface (DP-AuNPs). Upon addition of K(+), the structure of DP changed to a G-quadruplex. Then, the iridium(III) complex could selectively interact with the G-quadruplex, catalyzing the reduction of H2O2, which was accompanied by an electrochemical signal change using MB as an electron mediator. Under optimal conditions, the electrochemical signal of MB reduction peak was proportional to miRNA concentration in the range from 5.0 fM to 1.0 pM, with a detection limit of 1.6 fM. In addition, satisfactory results were obtained for miRNA-21 detection in human serum samples, indicating a potential application of the sensor for bioanalysis.
通过利用一种新型的氧化还原和催化“一体化”机制，使用铱(III)配合物作为催化剂，实现了对 miRNA-21 的超灵敏电化学检测。为了构建这样的传感器，首先将捕获探针 (CP) 固定在金电极表面。在 miRNA-21 的存在下，CP 和修饰在金纳米粒子 (AuNP) 表面的亚甲基蓝 (MB) 标记的富含 G 的检测探针 (DP-AuNPs) 之间可以形成夹杂物 DNA 复合物。加入 K(+)后，DP 的结构转变为 G-四链体。然后，铱(III)配合物可以选择性地与 G-四链体相互作用，催化 H2O2 的还原，同时使用 MB 作为电子介体伴随着电化学信号的变化。在最佳条件下，MB 还原峰的电化学信号与 miRNA 浓度在 5.0 fM 至 1.0 pM 范围内呈正比，检测限为 1.6 fM。此外，在人血清样本中对 miRNA-21 的检测获得了令人满意的结果，表明该传感器在生物分析中有潜在的应用。
