AbstractThe 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 abstractSchematic 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.

中文翻译：

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使用 3D DNA 纳米机器改进癌症生物标志物 8-羟基-2'-脱氧鸟苷的荧光测定

摘要作者描述了一种用于改进癌症生物标志物 8-羟基-2'-脱氧鸟苷 (8-OHdG) 测定的荧光法。通过在金纳米颗粒上组装数百个羧基荧光素标记的单链寡核苷酸（充当信号报告器）和数十个摆臂（充当单脚 DNA 助行器），构建了一种由切口核酸内切酶 (NEase) 驱动的 3-D DNA 纳米机器（纳米金）。这种 DNA 纳米机器的活性是通过引入保护性寡核苷酸来控制的。在存在针对 8-OHdG 的适配体的情况下，保护性寡核苷酸通过立足点介导的链置换反应从摆臂上移除。在下一步中，分离的 DNA 助行器与标记的 DNA 杂交，从而激活 DNA 纳米机器。形成的双链体中信号报告基因的特殊序列可以被NEase识别和切割。结果，DNA 步行者自主并逐渐沿着 AuNP 表面移动，从而释放数百个信号报告分子并导致绿色荧光快速增加。这种 3-D 纳米机器非常高效，因为一个适配体可以释放数百个信号报告基因。这些独特的特性允许构建一种基于 DNA 纳米机器的方法，用于灵敏地检测浓度低至 4 pM 的 8-OHdG。与之前报道的方法相比，这降低了三个数量级。用于测定癌症生物标志物 8-羟基-2'-脱氧鸟苷的荧光法的图形摘要示意图。使用切口核酸内切酶驱动的 3D-DNA 纳米机器来提高灵敏度。