School of Pharmacy, Shandong University, 250012 Jinan, PR China.
Biosens Bioelectron. 2013 May 15;43:84-7. doi: 10.1016/j.bios.2012.12.008. Epub 2012 Dec 11.
This work reports a novel signal amplification method for Hg(2+) detection based on quantum dots (QDs) and nicking endonuclease (NEase). In this assay, streptavidin-coated QDs were conjugated to biotinylated hairpin-shaped probe A which was modified with a quencher BHQ-2. The fluorescence of the QDs was quenched by BHQ-2 through FRET quenching. In the presence of Hg(2+), probe B hybridized with the loop of probe A due to specific binding between thymine-thymine mismatches and Hg(2+), thus probe A was opened. Then NEase recognized specific nucleotide sequences and cleaved probe A. After the dissociation of probe A fragments, the distance between QDs and BHQ-2 increased, which led to increase of QDs fluorescence. The released Hg(2+) and probe B could hybridize with another probe A to start a new cycle, therefore a remarkable signal amplification was achieved. Under optimal conditions, the detection limit of this assay was 8.0×10(-10)mol L(-1).
这项工作报道了一种基于量子点（QDs）和切口内切酶（NEase）的新型 Hg(2+)检测信号放大方法。在该测定法中，链霉亲和素包被的 QDs 与生物素化发夹形探针 A 缀合，探针 A 修饰有淬灭剂 BHQ-2。QDs 的荧光通过 FRET 猝灭被 BHQ-2 猝灭。在存在 Hg(2+)的情况下，由于胸腺嘧啶-胸腺嘧啶错配与 Hg(2+)之间的特异性结合，探针 B 与探针 A 的环杂交，从而打开探针 A。然后，NEase 识别特定的核苷酸序列并切割探针 A。探针 A 片段解离后，QDs 和 BHQ-2 之间的距离增加，导致 QDs 荧光增强。释放的 Hg(2+)和探针 B 可以与另一个探针 A 杂交以开始新的循环，从而实现显著的信号放大。在最佳条件下，该测定法的检测限为 8.0×10(-10)mol L(-1)。
