In this paper, a rationally designed aptasensing platform based on Hybridization Chain Reaction (HCR) and G-quadruplex DNAzyme for the fluorescence detection of Carcinoembryonic Antigen (CEA) has been developed. In the presence of target CEA, the aptamer sequence in Aptamer Probe (AP) specifically bound to CEA, resulting in the AP conformation change and thus releasing initiator, which triggered the autonomous cross-opening of Hairpin 1 (H1) and Hairpin 2 (H2) that yielded extended nicked double-stranded DNA via HCR. Upon the addition of hemin, G-rich segments at the end of H1 and H2 self-assembled into the peroxidase-mimicking hemin/G-quadruplex DNAzymes, which catalyzed the hydrogen peroxide-mediated oxidation of thiamine to achieve fluorescence detection of CEA. The HCR product, and the formation and catalytic performance of DNAzyme were characterized by agarose gel electrophoresis, UV–vis spectroscopy and fluorescence spectroscopy, respectively. Under optimal conditions, the fluorescent aptasensor showed a linear relationship ranging from 0.25 to 1.5 nM toward CEA with a detection limit of 0.2 nM. In addition, this aptasensor exhibited high selectivity for CEA without being affected by other interfering proteins, such as IgG, AFP and PSA. Furthermore, this proposed aptasensor was successfully applied to CEA analysis in diluted human serum samples. It is believed that this strategy has a promising potential in biochemical analysis and clinic application.

本文开发了一种基于杂交链反应（HCR）和G-四链体DNA酶的合理设计的适体平台，用于荧光检测癌胚抗原（CEA）。在存在目标CEA的情况下，适体探针（AP）中的适体序列与CEA特异性结合，导致AP构象变化并因此释放引发剂，从而触发发夹1（H1）和发夹2（H2）的自主交叉开放）通过HCR产生延伸的刻痕双链DNA。加入血红素后，H1和H2末端的富G片段自组装为模仿过氧化物酶的血红素/ G-四链体DNA酶，该酶催化过氧化氢介导的硫胺素氧化，从而实现CEA的荧光检测。HCR产品，琼脂糖凝胶电泳，紫外可见光谱和荧光光谱分别表征了DNAzyme的形成和催化性能。在最佳条件下，荧光适体传感器向CEA的线性关系为0.25至1.5 nM，检测极限为0.2 nM。另外，该适体传感器对CEA表现出高选择性，而不受其他干扰蛋白如IgG，AFP和PSA的影响。此外，该拟议的适体传感器已成功应用于稀释的人血清样品中的CEA分析。相信该策略在生化分析和临床应用中具有前途的潜力。荧光适体传感器向CEA的线性关系在0.25至1.5 nM之间，检出限为0.2 nM。另外，该适体传感器对CEA表现出高选择性，而不受其他干扰蛋白如IgG，AFP和PSA的影响。此外，该拟议的适体传感器已成功应用于稀释的人血清样品中的CEA分析。相信该策略在生化分析和临床应用中具有前途的潜力。荧光适体传感器向CEA的线性关系在0.25至1.5 nM之间，检出限为0.2 nM。另外，该适体传感器对CEA表现出高选择性，而不受其他干扰蛋白如IgG，AFP和PSA的影响。此外，该拟议的适体传感器已成功应用于稀释的人血清样品中的CEA分析。相信该策略在生化分析和临床应用中具有前途的潜力。