Highly sensitive and specific detection of silver ions using a dual-color fluorescence co-localization strategy

Ag⁺ ions are widely used in various fields of human life due to their unique properties and they threaten the environment and human health. The traditional methods for Ag⁺ detection commonly suffer from disadvantages including limited sensitivity, expensive equipment and complicated operating steps. Herein, we developed a highly specific dual-color fluorescence co-localization (DFC) strategy based on the C-Ag⁺-C structure for Ag⁺ detection. In this strategy, Ag⁺ ions can be captured to form C-Ag⁺-C base pairs, and these ions enable single-stranded DNAs to form double strands. The DFC strategy can exclude nonspecific interaction sites and greatly improve the sensitivity and specificity. By DFC of the QDs and Cy5 linked to the DNA strands, highly sensitive Ag⁺ detection was achieved in the concentration range from 0.14 pM to 200 nM, with a limit of detection (LOD) of 0.14 pM. Moreover, this method has been applied for the detection of Ag⁺ ions in real environmental samples with satisfactory recoveries. We believe that the DFC strategy is promising for Ag⁺ detection.