利用铜离子与荧光素标记的寡核苷酸链、氰根离子结合能力的差异, 发展了一种水相中氰根离子检测的新方法。研究表明, 该检测方法可以较灵敏地检测水相中的氰根离子, 其检测下限达到0.02 μmol/L, 且具有较好的选择性和潜在的实际应用价值。%In this paper, a new fluorescence turn-on sensor for cyanide in aqueous solution was established with fluo- rescein-labeled oligo DNA. The design rationale is explained as follows: (1) Fluorescein-labeled oligoDNA (FAM-DNA) shows strong fluorescence in aqueous solution. But, it is expected that the fluorescence of FAM-DNA will be quenched be- cause of the formation of stable complex of FAM-DNA with Cu^2+; (2) Demetallation from the complex of FAM-DNA with Cu^2+ because of the reaction of CN and Cu^2+ and formation Cu(CN)2 ; as a result the fluorescence of FAM-DNA emerges again. Therefore, it is anticipated that the fluorescence of the ensemble of FAM-DNA and Cu^2+ increases by in- creasing the concentration ofCN . Thus, the ensemble of FAM-DNA and Cu^2+ can be utilized for the detection ofCN . The results revealed that the fluorescence of FAM-DNA were quenched efficiently in the presence of Cu^2+ (1.35 μmol/L) due to the intramolecular photoinduced electron transfer within the ensemble of FAM-DNA and Cu^2+. Other metal ions, such as K^+, Ca^2+, Ba^2+, Mg^2+, Fe^3+, Hg^2+, Ni^2+, Pb^2+, Zn^2+ and Ag^+, induced negligible fluorescence quenching for FAM-DNA under the same conditions. However, fluorescence of the system increased gradually by increasing the concentration of CN-in the ensemble solution, and the fluorescence intensity varies almost linearly vs. the concentration of CN . The detection limit of CN- with the ensemble of FAM-DNA and Cu^2+ was estimated to be 0.02 μmol/L, which is much lower than the maximum level (1.9 μmol/L) of CN- in drinking water permitted by the World Health Organization (WHO). Moreover, the response of the ensemble of FAM-DNA and Cu^2+ to solutions containing CN- (40 μmol/L) in the presence of relevant ionic species, including F^-, CI^-, Br^-, I^-, NO3^-, HSO4^-,CO3^2-, CH3COO^-, H2PO4^-, SCN^-, and N3^- (at a concentration level over 10 times higher to that of CN-), was investigated. The results indicated no significant interference effect was found. Furthermore, the experiments conducted in various water samples spiked with cyanide confirmed the potential practical application of this probe in real samples.
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