College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China.
School of Material Sciences & Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Int J Mol Sci. 2022 Jun 5;23(11):6326. doi: 10.3390/ijms23116326.
Graphene oxide is well known for its excellent fluorescence quenching ability. In this study, positively charged graphene oxide (pGO25000) was developed as a fluorescence quencher that is water-soluble and synthesized by grafting polyetherimide onto graphene oxide nanosheets by a carbodiimide reaction. Compared to graphene oxide, the fluorescence quenching ability of pGO25000 is significantly improved by the increase in the affinity between pGO25000 and the DNA strand, which is introduced by the additional electrostatic interaction. The FAM-labeled single-stranded DNA probe can be almost completely quenched at concentrations of pGO25000 as low as 0.1 μg/mL. A simple and novel FAM-labeled single-stranded DNA sensor was designed for Hg detection to take advantage of exonuclease I-triggered single-stranded DNA hydrolysis, and pGO25000 acted as a fluorescence quencher. The FAM-labeled single-stranded DNA probe is present as a hairpin structure by the formation of T-Hg-T when Hg is present, and no fluorescence is observed. It is digested by exonuclease I without Hg, and fluorescence is recovered. The fluorescence intensity of the proposed biosensor was positively correlated with the Hg concentration in the range of 0-250 nM (R = 0.9955), with a seasonable limit of detection (3σ) cal. 3.93 nM. It was successfully applied to real samples of pond water for Hg detection, obtaining a recovery rate from 99.6% to 101.1%.
氧化石墨烯以其优异的荧光猝灭能力而闻名。在这项研究中，开发了带正电荷的氧化石墨烯（pGO25000）作为荧光猝灭剂，它是通过碳二亚胺反应将聚醚酰亚胺接枝到氧化石墨烯纳米片上合成的，水溶性好。与氧化石墨烯相比，pGO25000 与 DNA 链之间的亲和力增加，通过额外的静电相互作用引入，显著提高了 pGO25000 的荧光猝灭能力。在浓度低至 0.1μg/mL 的 pGO25000 下，FAM 标记的单链 DNA 探针几乎可以完全猝灭。为了利用外切核酸酶 I 触发的单链 DNA 水解，设计了一种简单新颖的 FAM 标记的单链 DNA 传感器用于 Hg 检测，pGO25000 作为荧光猝灭剂。当存在 Hg 时，FAM 标记的单链 DNA 探针通过形成 T-Hg-T 呈现发夹结构，观察不到荧光。没有 Hg 时，它被外切核酸酶 I 消化，荧光恢复。所提出的生物传感器的荧光强度与 Hg 浓度在 0-250 nM 范围内呈正相关（R = 0.9955），检测限（3σ）计算值为 3.93 nM。它成功地应用于池塘水的实际样品中进行 Hg 检测，回收率为 99.6%至 101.1%。
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