AbstractThe authors describe a method for enhancing the hybridization chain reaction (HCR) by using gold nanoparticles (AuNPs). This can considerably improve the sensitivity of electrochemical immunoassays as demonstrated for the carbohydrate antigen 125 (CA125), a biomarker for ovarian cancer. Compared to previous HCR based assays, the DNA acting as fuel strands were immobilized onto AuNPs, so that dendrimeric like chains were formed on the electrode after HCR. The improved signal is due to the reaction of DNA on the electrode. Specifically, the reaction of the phosphate groups of DNA with molybdate forms redox-active molybdophosphate, and this generates a strong electrochemical current. The immunosensor was prepared by sequential capturing, on the electrode, (a) antibody against CA125, (b) analyte (CA125), and (c) an aptamer against CA125 to form a sandwich structure. The primer on the aptamer sequence initiates HCR by annealing to one strand of DNA on the AuNPs and to another DNA in solution. The increased loading of DNA molecules onto the electrode increases the amount of phosphate groups and subsequently increases the electrical signal. The sensitivity of the assay is found to be significantly improved compared to assays without HCR and when using conventional HCR. The immunosensor was successfully applied to the determination of CA125 in human serum samples. The detection limit (based on an S/N ratio of 3) is 50 μU.mL−1. This indicates that this signal amplification strategy has a large potential in terms of clinical applications. It may be modified such that it also can be applied to the determination of other analytes for which proper aptamers are available. Graphical abstractGold nanoparticle (AuNP) enhanced hybridization chain reaction is reported to improve the sensitivity of electrochemical immunosensor. Hybridization chain reaction is carried out by annealing of H1 DNA strand immobilized on AuNP to the sticky end primer sequence of the aptamer and H2 strand to the complementary sequence of H1.

中文翻译：

---

金纳米粒子增强杂交链反应作为信号放大的方法。卵巢癌生物标志物碳水化合物抗原125在电化学免疫检测中的应用

摘要作者描述了一种使用金纳米粒子 (AuNPs) 增强杂交链反应 (HCR) 的方法。这可以显着提高电化学免疫测定的灵敏度，正如碳水化合物抗原 125 (CA125) 所证明的那样，这是一种卵巢癌的生物标志物。与之前基于 HCR 的分析相比，作为燃料链的 DNA 被固定在 AuNP 上，因此在 HCR 后在电极上形成树枝状链。改善的信号是由于 DNA 在电极上的反应。具体来说，DNA 的磷酸基团与钼酸盐反应形成具有氧化还原活性的钼磷酸盐，这会产生强大的电化学电流。通过在电极上依次捕获（a）针对 CA125 的抗体，（b）分析物（CA125），(c) 针对 CA125 的适体形成夹心结构。适体序列上的引物通过与 AuNP 上的一条 DNA 链和溶液中的另一条 DNA 退火来启动 HCR。DNA 分子在电极上的负载增加会增加磷酸基团的数量，随后会增加电信号。与没有 HCR 的测定和使用传统 HCR 时的测定相比，发现该测定的灵敏度显着提高。该免疫传感器成功应用于人血清样品中CA125的测定。检测限（基于 3 的信噪比）为 50 μU.mL-1。这表明这种信号放大策略在临床应用方面具有很大的潜力。可以对其进行修改，使其也可用于测定其他可用适体的分析物。据报道，图形摘要金纳米颗粒 (AuNP) 增强的杂交链反应可提高电化学免疫传感器的灵敏度。杂交链反应是通过将固定在 AuNP 上的 H1 DNA 链与适体的粘性末端引物序列和 H2 链与 H1 的互补序列退火来进行的。