State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Analyst. 2013 Feb 21;138(4):1067-74. doi: 10.1039/c2an36620g.
In very recent years, polyaniline or its derivatives have been adopted to efficiently immobilize probe DNA via π-π interaction between conjugated interface and DNA bases. In this work, self-doped polyaniline (SPAN)-DNA hybrid was adopted as the platform to construct a DNA biosensor with label-free, reagentless and electrochemical self-signal amplifying features. This was achieved by the π-π interaction between conjugated SPAN and DNA bases, also the intrinsic differences between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The tightly cross-linked hybrid was tethered to Au electrode, which had been anchored by p-aminothiophenol (PATP) self-assembled monolayer (SAM) previously, based on the phosphoramidate bond between PATP and ssDNA. SPAN in the recognition surface exhibited well-defined redox signals under neutral conditions. Due to the intrinsic property differences between ssDNA and dsDNA, such as rigidity, π-stacked bases, charge distribution and long-range electron transfer, SPAN-DNA underwent a major conformational change after hybridization. The redox behaviors of SPAN were modulated by DNA, which served as signals to monitor hybridization. As an example, the gene fragment related to one of the screening genes for the genetically modified plants, cauliflower mosaic virus 35S gene was satisfactorily detected with this strategy. Under optimal conditions, the dynamic range for the DNA assay was from 1.0 × 10(-14) mol L(-1) to 1.0 × 10(-8) mol L(-1) with the detection limit of 2.3 × 10(-15) mol L(-1). This work presents the construction of a recognition surface for the highly-sensitive electrochemical DNA hybridization detection via the self-signal amplifying procedure of conjugated SPAN-DNA hybrid. Unlike most signal amplifying processes using outer indicators, complex labels or other reagents, this procedure possesses simplicity and convenience.
在最近几年中，聚苯胺或其衍生物已被采用通过共轭界面与 DNA 碱基之间的π-π 相互作用来有效地固定探针 DNA。在这项工作中，采用自掺杂聚苯胺（SPAN）-DNA 杂交物作为平台，构建具有无标记、无试剂和电化学自信号放大功能的 DNA 生物传感器。这是通过共轭 SPAN 与 DNA 碱基之间的π-π 相互作用以及单链 DNA（ssDNA）和双链 DNA（dsDNA）之间的固有差异来实现的。紧密交联的杂交物被固定在 Au 电极上，该电极先前已通过 p-氨基苯硫酚（PATP）自组装单层（SAM）锚定，基于 PATP 和 ssDNA 之间的磷酰胺键。在中性条件下，识别表面中的 SPAN 表现出明确的氧化还原信号。由于 ssDNA 和 dsDNA 之间的固有性质差异，如刚性、π 堆积碱基、电荷分布和长程电子转移，SPAN-DNA 杂交后会发生重大构象变化。SPAN 的氧化还原行为被 DNA 调制，作为监测杂交的信号。例如，与用于检测转基因植物的筛选基因之一的花椰菜花叶病毒 35S 基因相关的基因片段可以通过这种策略得到满意的检测。在最佳条件下，该 DNA 测定的动态范围为 1.0×10(-14) mol L(-1)至 1.0×10(-8) mol L(-1)，检测限为 2.3×10(-15) mol L(-1)。这项工作展示了通过共轭 SPAN-DNA 杂交物的自信号放大过程构建用于高灵敏度电化学 DNA 杂交检测的识别表面。与使用外部指示剂、复杂标记物或其他试剂的大多数信号放大过程不同，该过程具有简单方便的特点。
