A novel label-free and enzyme-free detection strategy has been developed for the fluorescent detection of isocarbophos (ICP) using multi-walled carbon nanotubes (MWCNTs) and G-quadruplex as the signal transducers. In this work, the split ICP aptamer were attached to a G-quadruplex motif at their respective terminals. In the presence of ICP, the split aptamers could undergo conformational change into a sandwiched-like ternary complex, which prevent them from adsorbing to the MWCNTs due to the increased steric hindrance. As a result, the fluorescence signal of the G-quadruplex probes N-methyl mesoporphyrin IX (NMM) was enhanced significantly. In the absence of ICP, the split aptamer only existed in the form of single-stranded DNA, which could be easily adsorbed by MWCNTs and resulted in a quenched fluorescence signal of NMM. The proposed strategy could selectively and sensitively detect ICP with a detection limit of 10 nM. Furthermore, we have also demonstrated the capability of this strategy in the detection of ICP in real samples from vegetable extract, indicating the potential application of this strategy in food safety issues.

已经开发了一种新颖的无标记和无酶检测策略，该方法使用多壁碳纳米管（MWCNT）和G-四链体作为信号传感器进行荧光检测ICP（ICP）。在这项工作中，分裂的ICP适体在其各自的末端连接到G-四链体基序。在存在ICP的情况下，分裂的适体可能发生构象变化，变成三明治状的三元复合物，从而由于空间位阻的增加而阻止它们吸附到MWCNTs上。结果，G-四链体探针N-甲基中卟啉IX（NMM）的荧光信号显着增强。在没有ICP的情况下，分裂的适体仅以单链DNA的形式存在，它很容易被MWCNT吸附，并导致NMM的荧光信号淬灭。所提出的策略可以选择性且灵敏地检测ICP，检测限为10 nM。此外，我们还证明了该策略在检测蔬菜提取物中真实样品中ICP中的能力，表明该策略在食品安全问题中的潜在应用。