It is important to precisely monitor mercury (II) ions (Hg²⁺) for environment protection and human health monitoring. Although many strategies have been developed in the past decades, there still remains a challenge for developing an ultrasensitive, simple and reliable approach to detect Hg²⁺. Herein, we report a ratiometric surface-enhanced Raman scattering (SERS) aptasensor by employing aptamer-modified [email protected] core-shell nanoparticles ([email protected] NPs) as highly functional sensing probes, allowing for ultrasensitive detection of Hg²⁺. In principle, the thiolated 5′-Cy3 labeled aptamer probe (Cy3-aptamer) is firstly immobilized on the SERS substrate surface and then hybridizes with the 5′-Rox labeled complementary DNA (cDNA) to form a rigid double-stranded DNA (dsDNA), in which the Cy3 and Rox Raman labels are used to produce the ratiometric Raman signals. In the presence of Hg²⁺, the aptamer DNA turns into the thymine (T)-Hg²⁺-T mediated hairpin structure, leading to the dissociation of dsDNA. As a result, the Rox labels are away from the [email protected] NP SERS substrate while Cy3 labels are close to it. Therefore, the intensity of SERS signal from Cy3 labels increases while that from Rox labels decreases. The ratio between the Raman intensities of Cy3 labels and Rox labels is linear with Hg²⁺ concentrations in the range from 0.001 to 1.0 nM, and the limit of detection is estimated to be 0.4 pM. The proposed strategy provides a new rapid, simple and reliable approach for sensitive detection of Hg²⁺ and may create a universal methodology for developing analogous aptasensors for a wide range of other analytes determination.

重要的是要精确地监视汞（II）离子（汞²⁺）为保护环境和人类健康监测。尽管在过去的几十年中已经开发了许多策略，但是仍然需要开发一种超灵敏，简单且可靠的方法来检测Hg ²⁺的挑战。在这里，我们报告通过采用适体修饰的[受电子邮件保护的]核壳纳米粒子（[受电子邮件保护的] NPs）作为功能强大的传感探针，进行比例表面增强拉曼散射（SERS）适体传感器，从而可以超灵敏地检测Hg ²⁺。原则上，首先将硫醇化的5'-Cy3标记的适体探针（Cy3-aptamer）固定在SERS底物表面，然后与5'-Rox标记的互补DNA（cDNA）杂交以形成刚性双链DNA（dsDNA） ），其中Cy3和Rox拉曼标记用于产生比例拉曼信号。在存在Hg ²⁺的情况下，适体DNA变成胸腺嘧啶（T）-Hg ²⁺ -T介导的发夹结构，导致dsDNA的解离。结果，Rox标签远离了[电子邮件保护的] NP SERS基材，而Cy3标签则靠近它。因此，来自Cy3标签的SERS信号强度增加，而来自Rox标签的SERS信号强度降低。Cy3标签和Rox标签的拉曼强度比与Hg ²⁺呈线性关系浓度范围为0.001至1.0 nM，检测极限估计为0.4 pM。所提出的策略为灵敏地检测Hg ²⁺提供了一种新的快速，简单和可靠的方法，并且可以为开发用于多种其他分析物测定的类似适体传感器创建通用方法。