作为最具毒性的重金属之一，银在食品和环境中的污染对人体健康会造成严重危害。该研究基于稀土铽离子（Tb3+）能够结合单链DNA发出特征荧光的原理，利用Ag+能与胞嘧啶（C）结合形成C-Ag+-C结构以组成双链DNA的特性，构建了一种特异性识别Ag+的非标记核酸适配体荧光传感器。该传感器通过Tb3+对单双链DNA结构变化灵敏的特征荧光响应，能够实现对Ag+的高灵敏和快速的定量检测。该方法对Ag+的检测限为391.50 nmol/L，满足国家对于饮用水中Ag+限量检测的要求（0.05 mg/L，即 463.50 nmol/L）。该方法的回收率测定结果在93.02%~102.72%范围内，其相对标准差范围为1.27%~7.14%，证明了它的应用有效性；相较于其他的分子检测方法，该方法具有无需进行化学标记以降低成本，且操作简便，检测响应速度快等优点，为临场快速检测重金属银污染提供了一种可能的途径。

As one of the most toxic heavy metals, silver (Ag+), when contaminating food or the environment, causes serious harm to human health. Based on the principle that terbium ions (Tb3+) can combine with single-stranded DNA (ssDNA) to emit characteristic fluorescence, this study took advantage of the ability of Ag+ to combine with cytosine (C) to form a C-Ag+-C structure that enables the formation of double-stranded DNA (dsDNA), and a label-free fluorescent nucleic acid aptasensor was constructed that specifically recognizes Ag+. This sensor achieved the highly sensitive and rapid quantitative detection of Ag+ through the characteristic fluorescent response of Tb3+, which is sensitive to the structural change of ssDNA to dsDNA. The detection limit of Ag+ in the proposed method is 391.5 nmol/L, which meets the national requirement for the detection of Ag+ in drinking water (0.05 mg/L, i.e., 463.5 nmol/L). The recovery rate of this method ranges of from 0.02% to 102.72%, and the relative standard deviation ranges from 1.27% to 7.14%, which proves the effectiveness of the method. Compared with other detection methods, the proposed method does not require chemical labeling to reduce costs, is easier to operate, and has a fast detection response, thereby providing method for the rapid on-site detection of silver contamination.

国家自然科学基金面上项目（22074100）