Zaffino Rosa Letizia, Mir Mònica, Samitier Josep
Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.
Department of Engineering: Electronics, University of Barcelona, Barcelona, Spain.
Electrophoresis. 2017 Nov;38(21):2712-2720. doi: 10.1002/elps.201600554. Epub 2017 Jun 5.
Nanogap electrodes have attracted a lot of consideration as promising platform for molecular electronic and biomolecules detection. This is mainly for their higher aspect ratio, and because their electrical properties are easily accessed by current-voltage measurements. Nevertheless, application of standard current-voltages measurements used to characterize nanogap response, and/or to modify specific nanogap electrodes properties, represents an issue. Since the strength of electrical fields in nanoscaled devices can reach high values, even at low voltages. Here, we analyzed the effects induced by different methods of surface modification of nanogap electrodes, in test-voltage application, employed for the electrical detection of a desoxyribonucleic acid (DNA) target. Nanogap electrodes were functionalized with two antisymmetric oligo-probes designed to have 20 terminal bases complementary to the edges of the target, which after hybridization bridges the nanogap, closing the electrical circuit. Two methods of functionalization were studied for this purpose; a random self-assembling of a mixture of the two oligo-probes (OPs) used in the platform, and a selective method that controls the position of each OP at selected side of nanogap electrodes. We used for this aim, the electrophoretic effect induced on negatively charged probes by the application of an external direct current voltage. The results obtained with both functionalization methods where characterized and compared in terms of electrode surface covering, calculated by using voltammetry analysis. Moreover, we contrasted the electrical detection of a DNA target in the nanogap platform either in site-selective and in randomly assembled nanogap. According to our results, a denser, although not selective surface functionalization, is advantageous for such kind of applications.
纳米间隙电极作为分子电子学和生物分子检测的有前景平台已引起了广泛关注。这主要是因为它们具有更高的纵横比，并且其电学性质可通过电流-电压测量轻松获取。然而，应用用于表征纳米间隙响应和/或改变特定纳米间隙电极性质的标准电流-电压测量存在问题。因为即使在低电压下，纳米级器件中的电场强度也可达到很高的值。在此，我们分析了在用于脱氧核糖核酸（DNA）靶标电检测的测试电压应用中，不同的纳米间隙电极表面修饰方法所产生的影响。纳米间隙电极用两种反义寡核苷酸探针进行功能化，设计这两种探针使其20个末端碱基与靶标的边缘互补，杂交后它们会在纳米间隙上架桥，闭合电路。为此研究了两种功能化方法；一种是平台中使用的两种寡核苷酸探针（OPs）混合物的随机自组装，另一种是控制每个OP在纳米间隙电极选定侧位置的选择性方法。我们为此目的利用了施加外部直流电压对带负电荷探针产生的电泳效应。通过伏安法分析计算，对两种功能化方法获得的结果在电极表面覆盖方面进行了表征和比较。此外，我们对比了在纳米间隙平台中对DNA靶标的电检测，该平台既有位点选择性的纳米间隙，也有随机组装的纳米间隙。根据我们的结果，对于此类应用，更密集但无选择性的表面功能化是有利的。
