Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China.
Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Langmuir. 2022 May 10;38(18):5542-5549. doi: 10.1021/acs.langmuir.2c00119. Epub 2022 Apr 21.
With extremely high extinction coefficients and other unique optical properties, gold nanoparticles (AuNPs) have received growing interest in developing biosensors. DNA hairpin structures are very popular probes for the detection of not only complementary DNA or RNA but also aptamer targets. This work aims to understand the effect of the structure and sequence of hairpin DNA for the stabilization of AuNPs and its implications in AuNP-based label-free colorimetric biosensors. A series of hairpin DNA with various loop sizes from 4 to 26 bases and sequences (random sequences, poly- and poly-) were tested, but they showed similar abilities to protect AuNPs from aggregation. Using hairpin DNA with a tail under the same conditions, optimal protection was achieved with a six-base or longer tail. DNA hairpins are likely adsorbed via their tail regions or with their terminal bases if no tail is present. Molecular dynamics simulations showed that the rigidity of the hairpin loop region disfavored its adsorption to AuNPs, while the flexible tail region is favored. Finally, a DNA sensing assay was conducted using different structured DNA, where hairpin DNA with a tail doubled the sensitivity compared to the tail-free hairpin.
具有极高的消光系数和其他独特的光学特性，金纳米粒子（AuNPs）在开发生物传感器方面引起了越来越多的关注。发夹 DNA 结构是一种非常流行的探针，不仅可用于检测互补 DNA 或 RNA，还可用于检测适体靶标。本工作旨在了解发夹 DNA 的结构和序列对 AuNPs 稳定性的影响及其在基于 AuNP 的无标记比色生物传感器中的意义。我们测试了一系列具有从 4 到 26 个碱基和序列（随机序列、多聚体和多聚体）的不同环大小的发夹 DNA，但它们显示出相似的能力来保护 AuNPs 免受聚集。在相同条件下使用带有尾部的发夹 DNA，六碱基或更长的尾部可实现最佳保护。如果没有尾部，发夹 DNA 可能通过其尾部区域或末端碱基进行吸附。分子动力学模拟表明，发夹环区域的刚性不利于其吸附到 AuNPs 上，而柔性尾部区域则有利于其吸附。最后，我们使用不同结构的 DNA 进行了 DNA 传感测定，带有尾部的发夹 DNA 的灵敏度比无尾部的发夹 DNA 提高了一倍。
