DNA methylation plays an important role in a variety of human diseases. Thus, accurately analyze 5-methylcytosine in different DNA segments is of great significance. Herein, we proposed a novel 3D matrixed DNA self-nanocatalyzer via gold nanoparticles (AuNPs) supporting DNA self-hybridization with hemin as biomimetic enzyme and methylene blue (MB) as electrochemical mediator, which was employed as an efficient electrochemical sensitizer for the ultrasensitive bioassay of DNA 5-methylcytosine. Meanwhile, the AuNPs, graphitic carbon nitride (g-C3N4) and reduced graphene oxide (rGO) was prepared as AuNPs/g-C3N4@rGO nanocomposites to coat on the electrode surface to immobilize the capture hairpin DNA (CH). In the presence of target DNA with 5-methylcytosine, the target DNA could hybridize with CH via the hyperstable triple-helix formation. Based on the specific biorecognition between biotin and streptavidin and immune recognition between anti-5-methylcytosine antibodies and 5-methylcytosine sites on the target DNA, the 3D matrixed DNA self-nanocatalyzer could be captured onto the electrode surface to generate an amplified electrochemical signal related to the concentration of 5-methylcytosine. Under the optimal conditions, the proposed strategy performed a linear range from 10-17 M to 10-8 M with a detection limit of 8.6 aM. Remarkably, this strategy could be expanded easily to various biomarkers, including protein, DNA, phosphorylation and glycosylation, providing a promising strategy for clinical diagnosis and mechanism investigation of various diseases.

中文翻译：

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3D 基质 DNA 自纳米催化剂作为电化学敏化剂，用于 DNA 5-甲基胞嘧啶的超灵敏研究

DNA甲基化在多种人类疾病中起着重要作用。因此，准确分析不同DNA片段中的5-甲基胞嘧啶具有重要意义。在此，我们提出了一种新型 3D 基质 DNA 自纳米催化剂，通过金纳米粒子 (AuNPs) 支持 DNA 自杂交，血红素作为仿生酶，亚甲蓝 (MB) 作为电化学介质，用作超灵敏生物测定的有效电化学敏化剂DNA 5-甲基胞嘧啶。同时，将AuNPs、石墨氮化碳（g-C3N4）和还原氧化石墨烯（rGO）制备成AuNPs/g-C3N4@rGO纳米复合材料涂覆在电极表面以固定捕获发夹DNA（CH）。在目标 DNA 与 5-甲基胞嘧啶存在的情况下，目标 DNA 可以通过超稳定三螺旋形成与 CH 杂交。基于生物素和链霉亲和素之间的特异性生物识别以及抗 5-甲基胞嘧啶抗体与目标 DNA 上的 5-甲基胞嘧啶位点之间的免疫识别，3D 基质 DNA 自纳米催化剂可以被捕获到电极表面，产生放大的电化学信号。 5-甲基胞嘧啶的浓度。在最佳条件下，所提出的策略在 10-17 M 到 10-8 M 的线性范围内执行，检测限为 8.6 aM。值得注意的是，该策略可以轻松扩展到各种生物标志物，包括蛋白质、DNA、磷酸化和糖基化，为各种疾病的临床诊断和机制研究提供了一种有前景的策略。