Abstract In this study, the fluorescence enhancement effect of guanine base on DNA-Cu/AgNCs was reported and fluorescent methods for the determination of Hg2+ or Cu2+ 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 G5 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 Hg2+ and Cu2+ ions due to fluorescence quenching by the two metal ions while the DNA1-Cu/AgNCs only can determine Hg2+ ions. Specific assays for Hg2+ ions and Cu2+ ions were established through masking Cu2+ ions by EDTA and Hg2+ ions by NaBH4, respectively. In Hg2+ determination, a linear range from 5.0 nM to 40 nM was obtained with a detection limit of 1.0 nM. In Cu2+ 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 Cu2+ ions and 90.6–106.2% for Hg2+ ions were obtained in the measurements of Hg2+ and Cu2+ ions spiked lake samples, respectively. The results indicate the potential application of the DNA-Cu/AgNCs as a metal ions probes in real samples.

中文翻译：

---

基于 DNA 模板化的 Cu/Ag 纳米团簇对汞 (II) 和铜 (II) 离子的荧光传感

摘要 本研究报道了鸟嘌呤碱对DNA-Cu/AgNCs的荧光增强作用，建立了测定Hg2+或Cu2+离子的荧光方法。研究了 DNA 模板中相邻和插入的鸟嘌呤碱基 (G) 序列对 DNA-Cu/AgNCs 荧光强度的影响。发现从典型的富含 C 的 DNA 链 5'-CCCTTAATCCCC-3' (DNA1) 的 5' 末端延伸的 G5 序列在 DNA-Cu/AgNCs 的制备中表现出荧光增强作用。此外，由于两种金属离子的荧光猝灭，该 G5-DNA-Cu/AgNCs 可用于测定 Hg2+ 和 Cu2+ 离子，而 DNA1-Cu/AgNCs 只能测定 Hg2+ 离子。Hg2+ 离子和 Cu2+ 离子的特定检测是通过分别用 EDTA 掩蔽 Cu2+ 离子和用 NaBH4 掩蔽 Hg2+ 离子来建立的。在 Hg2+ 测定中，线性范围为 5.0 nM 至 40 nM，检测限为 1.0 nM。在 Cu2+ 测定中，获得了从 0.01 µM 到 5.0 µM 的宽线性范围，检测限为 5.0 nM。在测量 Hg2+ 和 Cu2+ 离子加标湖样品中，Cu2+ 离子的回收率分别为 89.6-106.8% 和 Hg2+ 离子的 90.6-106.2%。结果表明 DNA-Cu/AgNCs 作为金属离子探针在实际样品中的潜在应用。分别。结果表明 DNA-Cu/AgNCs 作为金属离子探针在实际样品中的潜在应用。分别。结果表明 DNA-Cu/AgNCs 作为金属离子探针在实际样品中的潜在应用。