Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
Chemistry. 2011 Aug 1;17(32):8904-12. doi: 10.1002/chem.201100601. Epub 2011 Jul 1.
Thiolated nucleic acid hairpin nanostructures that include in their stem region a "caged" G-quadruplex sequence, and in their single-stranded loop region oligonucleotide recognition sequences for DNA, adenosine monophosphate (AMP), or Hg(2+) ions were linked to bare Au surfaces or to Au nanoparticles (NPs) linked to Au surfaces. The opening of the hairpin nanostructures associated with the bare Au surface by the complementary target DNA, AMP substrate, or Hg(2+) ions, in the presence of hemin, led to the self-assembly of hemin/G-quadruplexes on the surface. The resulting dielectric changes on the surface exhibited shifts in the surface plasmon resonance (SPR) spectra, thus providing a readout signal for the recognition events. A similar opening of the hairpin nanostructures, immobilized on the Au NPs associated with the Au surface, by the DNA, AMP, or Hg(2+) led to an ultrasensitive SPR-amplified detection of the respective analytes. The amplification originated from the coupling between the localized surface plasmon associated with the NPs and the surface plasmon wave, an effect that cooperatively amplifies the SPR shifts that result from the formation of the hemin/G-quadruplexes. The different sensing platforms reveal impressive sensitivities and selectivities toward the target analytes.
巯基化核酸发夹纳米结构在其茎区包含一个“笼状”G-四链体序列，在其单链环区包含寡核苷酸识别序列，用于 DNA、腺苷一磷酸（AMP）或 Hg(2+) 离子，这些结构连接到裸露的 Au 表面或连接到 Au 表面的 Au 纳米颗粒（NPs）。在血红素存在的情况下，发夹纳米结构与裸 Au 表面通过互补的靶 DNA、AMP 底物或 Hg(2+) 离子的相互作用而打开，导致血红素/G-四链体在表面上的自组装。表面上的介电变化表现为表面等离子体共振（SPR）光谱的位移，从而为识别事件提供了读出信号。类似地，固定在与 Au 表面相关联的 Au NPs 上的发夹纳米结构通过 DNA、AMP 或 Hg(2+) 的打开，导致各自分析物的超灵敏 SPR 放大检测。这种放大源自与 NPs 相关的局域表面等离子体与表面等离子体波之间的耦合，这种效应协同放大了由于血红素/G-四链体形成而导致的 SPR 位移。不同的传感平台对目标分析物表现出令人印象深刻的灵敏度和选择性。
