The rapid and sensitive detection of Hg²⁺ is highly required to protect the environmental safety and human healthy. In the present work, a ratiometric fluorescent sensing platform, consisting of silicon quantum dots (SiQDs), Rox-labelled DNA (Rox-DNA), and Exonuclease III (Exo III), is developed for the accurate detection of Hg²⁺. As for fluorescent probe, we report the first use of glutathione as reduction reagent for the microwave synthesis of SiQDs, achieving the facile (using a house-hold microwave oven) and rapid (within 8 min) synthesis. Such SiQDs show pH-independent spectra and reversible fluorescent behavior with temperature. Moreover, experimental results revealed that the electrostatic interaction-induced aggregation of Rox-DNA and SiQDs facilitated the occurring of energy transfer (ET). And detection principle based on the regulation of ET between Rox and SiQDs with Exo III was designed for analysis. ET effect resulted in the fluorescent fading of Rox while that of SiQDs kept stable. For analysis, the addition of Hg²⁺ led to the formation of double-stranded Rox-DNA via T-Hg²⁺-T. Exo III would cut these double-stranded DNA to release Rox and Hg²⁺, thereby impeding the ET effect and recovering the fluorescent of Rox. Such SiQDs/Rox-DNA/Exo III ratiometric fluorescent sensing platform exhibited a linear response concentration range of 0.02 nM–10 nM with a detection limit of 0.01 nM. It was successfully used to analyze the water and soil samples. The reliability was validated by ICP-MS. Our work should promote the practical application of ratiometric fluorescent assay.

为了保护环境安全和人类健康，对Hg ²⁺的快速灵敏检测非常必要。在目前的工作中，开发了一种比例荧光检测平台，该平台由硅量子点（SiQD），Rox标记的DNA（Rox-DNA）和核酸外切酶III（Exo III）组成，用于精确检测Hg ²⁺。至于荧光探针，我们报道了首次将谷胱甘肽用作还原剂用于微波合成SiQDs，实现了简便（使用家用微波炉）和快速（8分钟内）合成。此类SiQD显示出与pH无关的光谱以及随温度可逆的荧光行为。此外，实验结果表明，静电相互作用诱导的Rox-DNA和SiQDs聚集促进了能量转移（ET）的发生。设计了基于Exo III在Rox和SiQDs之间的ET调控的检测原理进行分析。ET效应导致Rox的荧光褪色，而SiQD的荧光保持稳定。为了进行分析，添加Hg ²⁺导致通过T-Hg ²⁺形成双链Rox-DNA-T Exo III会切割这些双链DNA以释放Rox和Hg ²⁺，从而阻碍ET效应并恢复Rox的荧光。这种SiQDs / Rox-DNA / Exo III比率荧光传感平台的线性响应浓度范围为0.02 nM–10 nM，检测极限为0.01 nM。它已成功用于分析水和土壤样品。通过ICP-MS验证了可靠性。我们的工作应促进比例荧光测定法的实际应用。