Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, China.
College of Food Science and Technology, Henan University of Technology, Zhengzhou, 450001, China.
Mikrochim Acta. 2018 Oct 3;185(10):494. doi: 10.1007/s00604-018-3036-7.
The authors describe a fluorometric method for improving the determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG). A nicking endonuclease (NEase)-powered 3-D DNA nanomachine was constructed by assembling hundreds of carboxyfluorescein-labeled single strand oligonucleotides (acting as signal reporter) and tens of swing arms (acting as single-foot DNA walkers) on a gold nanoparticle (AuNP). The activity of this DNA nanomachine was controlled by introducing the protecting oligonucleotides. In the presence of aptamer against 8-OHdG, the protecting oligonucleotides are removed from the swing arms by toehold-mediated strand displacement reaction. In the next step, detached DNA walker hybridizes to the labelled DNA so that the DNA nanomachine becomes activated. Special sequences of signal reporter in the formed duplex can be recognized and cleaved by NEase. As a result, the DNA walker autonomously and progressively moves along the surface of the AuNP, thereby releasing hundreds of signal reporters and causing a rapid increase in green fluorescence. This 3-D nanomachine is highly efficient because one aptamer can release hundreds of signal reporters. These unique properties allowed for the construction of a DNA nanomachine-based method for sensitively detecting 8-OHdG in concentrations as low as 4 pM. This is three orders of magnitude lower compared to previously reported methods. Graphical abstract Schematic of a fluorometric method for determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine. A nicking endonuclease powered 3D-DNA nanomachine was used to improve the sensitivity. Limit of detection is three orders of magnitude lower than reported methods.
作者描述了一种荧光法来改进癌症生物标志物 8-羟基-2'-脱氧鸟苷（8-OHdG）的测定。通过将数百个羧基荧光素标记的单链寡核苷酸（作为信号报告器）和数十个摆动臂（作为单足 DNA 行走器）组装在金纳米颗粒（AuNP）上，构建了一种切口内切酶（NEase）驱动的 3D DNA 纳米机器。该 DNA 纳米机器的活性受引入保护寡核苷酸的控制。在存在针对 8-OHdG 的适体的情况下，通过 toehold 介导的链置换反应，保护寡核苷酸从摆动臂上被去除。在下一步中，分离的 DNA 行走器与标记的 DNA 杂交，从而使 DNA 纳米机器被激活。形成的双链体中的信号报告器的特殊序列可以被 NEase 识别和切割。结果，DNA 行走器自主且逐步地沿 AuNP 的表面移动，从而释放数百个信号报告器并导致绿色荧光迅速增加。这种 3D 纳米机器效率非常高，因为一个适体可以释放数百个信号报告器。这些独特的特性使得能够构建一种基于 DNA 纳米机器的方法，用于灵敏地检测低至 4 pM 的 8-OHdG。与之前报道的方法相比，这降低了三个数量级。
