A polycytosine DNA-based immunosensor for electrochemical detection was developed and tested for detection of human epidermal growth factor receptor 2 (HER2), a breast cancer biomarker. We utilized gold nanoparticles (AuNPs) as supporting matrix to immobilize polycytosine DNA sequence (dC₂₀) for electrochemical current generation and anti-HER2 antibodies. In the presence of target HER2, a sandwiched immunocomplex forms between a peptide specific to HER2 immobilized on the gold electrode and the anti-HER2 antibodies on the AuNPs. The HER2 captured by the sensor is detected because of the reaction of the dC₂₀ phosphate backbone with molybdate, forming redox molybdophosphate precipitate that generates an electrochemical current on the surface of the electrode. The assay is sensitive: the calculated limit of detection of HER2 was as low as 0.5 pg/mL and the detection was linear to HER2 from 1 pg/mL to 1 ng/mL. The sensor’s specificity is high, and there is no cross reactivity with several potential interferents, such as human IgG, human IgA, p53, carcinoembryonic antigen, and protein kinase. The sensor’s performance with HER2 in clinical serum samples is similar to the performance of commercial ELISA assays. The configuration of polycytosine DNA as electrochemical current generating label and anti-HER2 antibodies on AuNPs is versatile and can be reconfigured to detect low levels of different analytes, or made more sensitive by amplifying the DNA to produce more phosphate to react with Na₂MoO_4.

中文翻译：

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电化学检测人表皮生长因子受体2（HER2）的多胞嘧啶DNA电流免疫传感器。

开发了一种用于电化学检测的基于多胞嘧啶DNA的免疫传感器，并经过测试可检测出人类表皮生长因子受体2（HER2）（一种乳腺癌生物标记物）。我们利用金纳米颗粒（AuNPs）作为支持基质来固定多胞嘧啶DNA序列（dC ₂₀），用于电化学电流产生和抗HER2抗体。在靶HER2的存在下，夹在中间的免疫复合物在固定于金电极上的HER2特异性肽与AuNPs上的抗HER2抗体之间形成。由于dC ₂₀的反应，检测到传感器捕获的HER2磷骨架与钼酸盐形成氧化还原钼磷酸盐沉淀，在电极表面产生电化学电流。该测定法很灵敏：计算得出的HER2检出限低至0.5 pg / mL，并且与HER2呈线性关系，从1 pg / mL到1 ng / mL。该传感器的特异性很高，并且与几种潜在的干扰物（例如人IgG，人IgA，p53，癌胚抗原和蛋白激酶）没有交叉反应。HER2在临床血清样品中的传感器性能类似于商业ELISA分析的性能。在AuNPs上，多胞嘧啶DNA作为电化学电流产生标记和抗HER2抗体的配置具有多种用途，可以重新配置以检测低含量的不同分析物，₂ MoO _4。