Cui Hui-Fang, Xu Tai-Bin, Sun Yu-Long, Zhou An-Wei, Cui Yu-Han, Liu Wei, Luong John H T
Bioengineering Department, School of Life Sciences, Zhengzhou University , 100# Science Avenue, Zhengzhou, 450001, People's Republic of China.
Anal Chem. 2015 Jan 20;87(2):1358-65. doi: 10.1021/ac504206n. Epub 2015 Jan 2.
Hairpin DNA (hpDNA) as a novel biobarcode was conjugated with gold nanoparticles (AuNPs) and a reporter DNA (rpDNA) to form hpDNA/AuNP/rpDNA nanoparticles for the detection of an oligonucleotide sequence associated with Helicobacter pylori as a model target. The rpDNA is complementary to about a half-portion of the target DNA sequence (tDNA). A capture DNA probe (cpDNA), complementary to the other half of the tDNA, was immobilized on the surface of a gold electrode. In the presence of tDNA, a sandwich structure of (hpDNA/AuNP/rpDNA)/tDNA/cpDNA was formed on the electrode surface. The differential pulse voltammetry (DPV) detection was based on Ru(NH3)5(3-(2-phenanthren-9-yl-vinyl)-pyridine), an electroactive complex that binds to the sandwich structure by its intercalation with the hpDNA and the double-stranded DNA (dsDNA) of the sandwich structure. The several factors--high density of biobarcode hpDNA on the surface of AuNPs, multiple electroactive complex molecules intercalated with each hpDNA and dsDNA molecule, and the intercalation binding mode of the electroactive complex with the DNA sandwich structure--contribute to the DNA sensor with highly selective and sensitive sensing properties. The DNA sensor exhibited a detection limit of 1 × 10(-15) M (i.e., 1 fM), the DNA levels in physiological samples, with linearity down to 2 × 10(-15) M. It can differentiate even one single mismatched DNA from the complementary tDNA. This novel biobarcode-based DNA sensing approach should provide a general platform for development of direct, simple, repetitive, sensitive, and selective DNA sensors for various important applications in analytical, environmental, and clinical chemistry.
发夹DNA（hpDNA）作为一种新型生物条形码，与金纳米颗粒（AuNPs）和报告基因DNA（rpDNA）缀合，形成hpDNA/AuNP/rpDNA纳米颗粒，用于检测与幽门螺杆菌相关的寡核苷酸序列作为模型靶标。rpDNA与靶标DNA序列（tDNA）的大约一半互补。与tDNA另一半互补的捕获DNA探针（cpDNA）固定在金电极表面。在tDNA存在的情况下，电极表面形成（hpDNA/AuNP/rpDNA）/tDNA/cpDNA三明治结构。差分脉冲伏安法（DPV）检测基于Ru(NH3)5(3-(2-菲-9-基-乙烯基)-吡啶)，一种电活性复合物，它通过插入hpDNA和三明治结构的双链DNA（dsDNA）与三明治结构结合。几个因素——AuNPs表面生物条形码hpDNA的高密度、与每个hpDNA和dsDNA分子插入的多个电活性复合物分子，以及电活性复合物与DNA三明治结构的插入结合模式——促成了具有高选择性和灵敏传感特性的DNA传感器。该DNA传感器的检测限为1×10(-15) M（即1 fM），这是生理样品中的DNA水平，线性范围低至2×10(-15) M。它甚至可以区分与互补tDNA的一个单碱基错配DNA。这种基于新型生物条形码的DNA传感方法应为开发用于分析、环境和临床化学中各种重要应用的直接、简单、重复性好、灵敏且选择性高的DNA传感器提供一个通用平台。
