Fluorescent sensing of mercury (II) and copper (II) ions based on DNA-templated Cu/Ag nanoclusters
In this study, the fluorescence enhancement effect of guanine base on DNA-Cu/AgNCs was reported and fluorescent methods for the determination of Hg 2+ or Cu 2+ ion were established. The effect of adjacent and inserted guanine base (G) sequences in DNA template on the fluorescence intensity of DNA-Cu/AgNCs was investigated. It was found that G 5 sequence extended from the 5′ end of a typical C-riched DNA strand, 5′-CCCTTAATCCCC-3′ (DNA1), demonstrated fluorescence enhancement effect in the preparation of the DNA-Cu/AgNCs. Moreover, this G5-DNA-Cu/AgNCs can be used to determine Hg 2+ and Cu 2+ ions due to fluorescence quenching by the two metal ions while the DNA1-Cu/AgNCs only can determine Hg 2+ ions. Specific assays for Hg 2+ ions and Cu 2+ ions were established through masking Cu 2+ ions by EDTA and Hg 2+ ions by NaBH 4 , respectively. In Hg 2+ determination, a linear range from 5.0 nM to 40 nM was obtained with a detection limit of 1.0 nM. In Cu 2+ determination, a wide linear range from 0.01 µM to 5.0 µM was obtained with a detection limit of 5.0 nM. The recoveries of 89.6–106.8% for Cu 2+ ions and 90.6–106.2% for Hg 2+ ions were obtained in the measurements of Hg 2+ and Cu 2+ ions spiked lake samples, respectively. The results indicate the potential application of the DNA-Cu/AgNCs as a metal ions probes in real samples.
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