Abstract: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.
