Research Center of Analytical Instrumentation, Key Laboratory of Bio-resource and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, 610065, Sichuan, PR China.
Research Center of Analytical Instrumentation, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an, 710069, Shanxi, PR China.
Talanta. 2020 Sep 1;217:121056. doi: 10.1016/j.talanta.2020.121056. Epub 2020 Apr 20.
DNA-modified gold nanoparticles (AuNPs) are useful nanomaterials for detecting multiple molecules. However, their performance is greatly dependent on the density of probe DNA on the surface of AuNPs. Here, we used Poly-adenine (PolyA) to regulate the surface density of probe DNA to achieve a highly efficient DNA walking biosensor system to detection miRNA-21. The movement track of the biosensor system consists of PolyA-DNA probe was connected to AuNPs, and exonuclease III (Exo III) acted as a motor driving the walker movement to achieve signal amplification. By optimizing the length of PolyA, the surface density of probe DNA was changed, thereby affecting the target binding and enzymatic processing of the bound probes, which ultimately enhanced the sensitivity and reduced timeliness of the DNA walker. Furthermore, the designed PolyA-DNA probe exhibits an outstanding sensitivity, due to the effect of density regulation, which is 7.9 times and 11.1 times lower than those of the SH-DNA and the free-DNA, respectively. In addition, the hairpin structure of DNA probe locates fluorophore at a zone adjacent to AuNPs surface, which reduces the background signal by 1.1 times compared with traditional straight probe. In this work, the biosensor system shows a high selectivity towards miRNA-21. Moreover, the biosensor system has been demonstrated to be potentially useful for the miRNA-21 detection in human serum with the recoveries of 93.2%-110.0% and has high repeatability. Considering these advantages, this PolyA-regulated DNA walking biosensor system has great potential as a routine tool for miRNA detection and has wide applications in the field of biomedical analysis.
DNA 修饰的金纳米粒子（AuNPs）是用于检测多种分子的有用纳米材料。然而，其性能在很大程度上取决于 AuNPs 表面探针 DNA 的密度。在这里，我们使用聚腺嘌呤（PolyA）来调节探针 DNA 的表面密度，以实现高效的 DNA 行走生物传感器系统来检测 miRNA-21。生物传感器系统的运动轨迹由与 AuNPs 连接的 PolyA-DNA 探针组成，外切酶 III（Exo III）作为驱动行走器运动的马达，实现信号放大。通过优化 PolyA 的长度，可以改变探针 DNA 的表面密度，从而影响结合探针的靶标结合和酶处理，最终增强了 DNA 行走的灵敏度并降低了时间。此外，由于密度调节的影响，设计的 PolyA-DNA 探针具有出色的灵敏度，其灵敏度分别比 SH-DNA 和游离 DNA 低 7.9 倍和 11.1 倍。此外，DNA 探针的发夹结构将荧光团定位在与 AuNPs 表面相邻的区域，与传统的直探针相比，背景信号降低了 1.1 倍。在这项工作中，该生物传感器系统对 miRNA-21 具有高选择性。此外，该生物传感器系统已被证明在人血清中对 miRNA-21 的检测具有潜在的用途，回收率为 93.2%-110.0%，具有较高的重复性。考虑到这些优势，这种 PolyA 调控的 DNA 行走生物传感器系统作为 miRNA 检测的常规工具具有很大的潜力，并在生物医学分析领域具有广泛的应用。
