Li Yubin, Yuan Jiaming, Xu Zexi
School of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China.
School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK.
J Anal Methods Chem. 2019 Mar 3;2019:3712032. doi: 10.1155/2019/3712032. eCollection 2019.
A C-Ag-C structure-based fluorescence biosensor with novel combination design of exonuclease III (Exo III) dual-recycling amplification is proposed for the application of silver ions (Ag) detection. Since oligo-1 involves C-C mismatches, the presence of Ag can be captured to form C-Ag-C base pairs, which results in a double-helix structure with a blunt terminus. The double-helix structure can be cleaved by EXO III to release short mononucleotide fragments (trigger DNA) and Ag. Released Ag can form new bindings with oligo-1, and other trigger DNA can be produced in the digestion cycles. Hybridization with the signal DNA (oligo-2) transforms a trigger DNA into double-stranded DNA with blunt terminus which can be cleaved by Exo III to reproduce the trigger DNA and form guanine- (G-) quadruplex DNA. The trigger DNA returns free to the solution and hybridizes with another signal DNA, which realizes the dual-recycling amplification. The G-quadruplex DNA can be reported by -methylmesoporphyrin IX (NMM), a specific G-quadruplex DNA fluorochrome. This method allows Ag to be determined in the 5 to 1500 pmol/L concentration range, with a 2 pmol/L detection limit, and it has been successfully applied to the detection of Ag in real samples.
本文提出了一种基于C-Ag-C结构的荧光生物传感器，该传感器采用了新型的核酸外切酶III（Exo III）双循环扩增组合设计，用于银离子（Ag）检测。由于寡核苷酸1存在C-C错配，Ag的存在可被捕获形成C-Ag-C碱基对，从而产生具有平端的双螺旋结构。该双螺旋结构可被EXO III切割，释放出短的单核苷酸片段（触发DNA）和Ag。释放出的Ag可与寡核苷酸1形成新的结合，并且在消化循环中可产生其他触发DNA。与信号DNA（寡核苷酸2）杂交可将触发DNA转化为具有平端的双链DNA，该双链DNA可被Exo III切割以再生触发DNA并形成鸟嘌呤-（G-）四链体DNA。触发DNA重新游离到溶液中并与另一个信号DNA杂交，从而实现双循环扩增。G-四链体DNA可通过特异性G-四链体DNA荧光染料-甲基中卟啉IX（NMM）进行检测。该方法可在5至1500 pmol/L的浓度范围内测定Ag，检测限为2 pmol/L，并且已成功应用于实际样品中Ag的检测。
