College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People's Republic of China.
College of Chemical Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu 610065, People's Republic of China.
Sci Rep. 2016 Aug 1;6:30878. doi: 10.1038/srep30878.
It is known that the adsorption of short single-stranded DNA (ssDNA) on unmodified gold nanoparticles (AuNPs) is much faster than that for long ssDNA, and thus leads to length-dependent AuNPs aggregation after addition of salt, the color of the solutions sequentially changed from red to blue in accordance with the increase of ssDNA length. However, we found herein that the ssDNA sticky end of hairpin DNA exhibited a completely different adsorption behavior compared to ssDNA, an inverse blue-to-red color variation was observed in the colloid solution with the increase of sticky end length when the length is within a certain range. This unusual sequence length-dependent AuNPs aggregation might be ascribed to the effect of the stem of hairpin DNA. On the basis of this unique phenomenon and catalytic hairpin assembly (CHA) based signal amplification, a novel AuNPs-based colorimetric DNA assay with picomolar sensitivity and specificity was developed. This unusual sequence length-dependent AuNPs aggregation of the ssDNA sticky end introduces a new direction for the AuNPs-based colorimetric assays.
已知短单链 DNA（ssDNA）在未经修饰的金纳米粒子（AuNPs）上的吸附速度远快于长 ssDNA，因此在加入盐后会导致长度依赖性的 AuNPs 聚集，溶液的颜色会随着 ssDNA 长度的增加依次从红色变为蓝色。然而，我们在此发现发夹 DNA 的 ssDNA 粘性末端表现出与 ssDNA 完全不同的吸附行为，当粘性末端长度在一定范围内增加时，胶体溶液中观察到颜色从蓝色到红色的反转变化。这种不寻常的序列长度依赖性的 AuNPs 聚集可能归因于发夹 DNA 茎的影响。基于这种独特的现象和基于催化发夹组装（CHA）的信号放大，开发了一种具有皮摩尔灵敏度和特异性的新型基于 AuNPs 的比色 DNA 分析方法。ssDNA 粘性末端的这种不寻常的序列长度依赖性的 AuNPs 聚集为基于 AuNPs 的比色分析方法开辟了新的方向。
