A dual-enzyme self-powered biosensor utilizing bimodal 3D DNA nanomachines and gold nanoparticle (AuNPs)/carbon/disulfide molybdenum hollow nanorods bioconjugates is developed for the electrochemical and visual detection of the tumor biomarker let-7a. DNA probes are immobilized on a flexible electrode substrate of AuNPs/graphdiyne/carbon cloth to improve probe loading capacity and electron transfer efficiency. The presence of let-7a initiates the work of dual-enzyme 3D DNA nanomachine, and the output DNA single strand cleaved by Nb.BbvCI is served as a bridge to connect glucose oxidase (GOD)-DNA conjugate. The GOD coordinates with the cathodic enzyme bilirubin oxidase and produces an increased open circuit voltage signal, which is attributed to the hexaammine ruthenium in the double-stranded adsorption system of the biocathode. By utilizing the HO generated during the oxidation process of GOD, a linear relationship between the color of 3,3′,5,5′-tetramethylbenzidine and the concentration of let-7a is established, enhancing the reliability of the detection results through the independent signal conversion mechanisms of electrochemical/colorimetric modes. The results demonstrate a wide dynamic range of 0.0001–0.1 pM with detection limits of 31.04 aM (=3) in electrochemical mode and 59.99 aM (=3) in the colorimetric mode. This dual-mode biosensing strategy can be expanded to detect additional nucleic acid biomarkers, providing a promising support and reference for biological analysis and medical diagnosis.

中文翻译：

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双峰 3D DNA 纳米机器与生物共轭物耦合，为 Let-7a 提供电化学和视觉驱动的双酶级联传感

开发了一种双酶自供电生物传感器，利用双峰 3D DNA 纳米机器和金纳米颗粒 (AuNP)/碳/二硫化钼空心纳米棒生物结合物，用于肿瘤生物标志物 let-7a 的电化学和视觉检测。 DNA 探针固定在 AuNPs/石墨二炔/碳布的柔性电极基底上，以提高探针负载能力和电子转移效率。 let-7a的存在启动了双酶3D DNA纳米机器的工作，并且由Nb.BbvCI切割的输出DNA单链充当连接葡萄糖氧化酶（GOD）-DNA缀合物的桥梁。 GOD与阴极酶胆红素氧化酶配合，产生增加的开路电压信号，这归因于生物阴极双链吸附系统中的六氨合钌。利用GOD氧化过程中产生的H2O，建立了3,3',5,5'-四甲基联苯胺的颜色与let-7a浓度之间的线性关系，通过独立的检测增强了检测结果的可靠性。电化学/比色模式的信号转换机制。结果表明，动态范围较宽，为 0.0001–0.1 pM，电化学模式下的检测限为 31.04 aM (=3)，比色模式下的检测限为 59.99 aM (=3)。这种双模式生物传感策略可以扩展到检测其他核酸生物标志物，为生物分析和医学诊断提供有希望的支持和参考。