This work describes an aptamer based method for highly sensitive determination of Hg(II). A Hg(II)-binding ssDNA aptamer was linked to silica-coated magnetic nanoparticles (magNPs). Then, a conjugate composed of graphene and CdS quantum dots (Gr-CdS) was linked to the complementary ssDNA. On mixing the two components, a duplex of type magNP-dsNNA-Gr/CdS is generated. If Hg(II) is added, it wills capturing the aptamer, and this leads to the release of Gr/CdS because of the formation of a stable thymine-Hg 2+ -thymine link. External magnetic force is used to remove the remaining complex. The released graphene-CdS is decomposed by HNO 3 and injected into a graphite furnace AAS. The detectable amount of Cd is proportional to the concentration of Hg(II) in the sample. Under the optimal conditions, the method has a linear response in the 2.50 aM to 0.25 nM Hg(II) concentration range, and the detection limit is as low as 7.6 aM (at S/ N = 3). It has high selectivity for Hg(II) over other metal ions. Graphical abstract

中文翻译：

---

使用磁性纳米粒子、CdS 量子点和结合汞 (II) 的适体间接测定汞 (II)，并通过石墨炉原子吸收光谱法对释放的 CdS 进行定量

这项工作描述了一种基于适体的高灵敏度测定 Hg(II) 的方法。结合 Hg(II) 的 ssDNA 适体与二氧化硅涂层的磁性纳米粒子 (magNPs) 相连。然后，由石墨烯和 CdS 量子点 (Gr-CdS) 组成的共轭物连接到互补的 ssDNA。在混合这两种成分时，会生成 magNP-dsNNA-Gr/CdS 类型的双链体。如果添加 Hg(II)，它将捕获适体，这会导致 Gr/CdS 的释放，因为形成了稳定的胸腺嘧啶-Hg 2+ -胸腺嘧啶链接。外部磁力用于去除剩余的复合物。释放的石墨烯-CdS 被 HNO 3 分解并注入石墨炉 AAS。可检测的 Cd 量与样品中 Hg(II) 的浓度成正比。在最佳条件下，该方法在 2.50 aM 到 0 具有线性响应。25 nM Hg(II) 浓度范围，检测限低至 7.6 aM（S/N = 3）。与其他金属离子相比，它对 Hg(II) 具有高选择性。图形概要