A novel tetrahedral DNA nanostructure (TDN) functionalized paper-based colorimetric sensor was developed for ultrasensitive analysis of mercury ion (Hg²⁺). On the paper-based platform, TDN was used as scaffold to anchor aptamer to improve the capture efficiency owing to the controllably specific orientation, low steric hindrance effect and well-defined spacing. In the absence of Hg²⁺, biotinylated aptamer would bind with streptavidin-labeled HRP. Whereas, in the presence of Hg²⁺, aptamer would preferentially bind to Hg²⁺ owing to the higher binding constant of T–Hg–T than that of T–A, which consequently leading to the biotinylated aptamer releasing from TDN. After introducing TMB-H₂O₂ solution, strong variation of color signal could be observed. Therefore, the quantitative analysis of Hg²⁺ was carried out by using smartphone to monitor the color intensity on paper chip. The proposed strategy exhibits good linearity over a wide range of 10^–13–10^–7 M with a low detection limit of 30 fM. And this method had been successfully applied in real water samples. Our strategy provided a versatile, low-cost and user-friendly paper-based monitoring platform for rapid and ultrasensitive analysis of heavy metal ions and thus had potential applications in food safety and public health.

开发了一种新型四面体 DNA 纳米结构 (TDN) 功能化纸基比色传感器，用于汞离子 (Hg ²⁺ ) 的超灵敏分析。在纸基平台上，由于定向可控、空间位阻效应低、间距明确，TDN被用作锚定适配子的支架，以提高捕获效率。在没有 Hg ²⁺的情况下，生物素化的适体将与链霉亲和素标记的 HRP 结合。而在 Hg ²⁺存在下，由于 T-Hg-T 的结合常数高于 T-A 的结合常数，适体将优先与 Hg ^{2+结合，从而导致生物素化的适体从 TDN 中释放出来。}引入 TMB-H ₂ O _2后溶液中，可以观察到颜色信号的强烈变化。因此，Hg ²⁺的定量分析是通过使用智能手机监测纸片上的颜色强度来进行的。^{所提出的策略在 10 –13} –10 ^–7 M的宽范围内表现出良好的线性，检测限低至 30 fM。该方法已成功应用于真实水样。我们的策略为重金属离子的快速和超灵敏分析提供了一个多功能、低成本和用户友好的纸质监测平台，因此在食品安全和公共卫生方面具有潜在的应用。