A novel competitive aptasensor for thrombin detection is developed by using a tetrahedral DNA (T-DNA) probe and hybridization chain reaction (HCR) signal amplification. Sulfur and nitrogen co-doped reduced graphene oxide (SN-rGO) is firstly prepared by a simple reflux method and used for supporting substrate of biosensor. Then, T-DNA probe is modified on the electrode by Au-S bond and a competition is happened between target thrombin and the complementary DNA (cDNA) of aptamer. The aptamer binding to thrombin forms an aptamer-target conjugate and make the cDNA remained, and subsequently hybridizes with the vertical domain of T-DNA. Finally, the cDNAs trigger HCR, which results in a great current response by the catalysis of horseradish peroxidase to the hydrogen peroxide + hydroquinone system. For thrombin detection, the proposed biosensor shows a wide linearity range of 10^–13–10⁻⁸ M and a low detection limit of 11.6 fM (S/N = 3), which is hopeful to apply in biotechnology and clinical diagnosis.

通过使用四面体DNA（T-DNA）探针和杂交链反应（HCR）信号放大，开发了一种新颖的竞争性凝血酶适体传感器。硫氮共掺杂还原氧化石墨烯（SN-rGO）是通过简单的回流方法制备的，用于支撑生物传感器的基质。然后，通过Au-S键在电极上修饰T-DNA探针，靶凝血酶与适体的互补DNA（cDNA）之间发生竞争。与凝血酶结合的适体形成适体-靶标缀合物并保留cDNA，然后与T-DNA的垂直结构域杂交。最后，cDNA触发HCR，通过辣根过氧化物酶催化过氧化氢+对苯二酚系统，产生很大的电流响应。对于凝血酶检测，^–13 –10 ^-8  M，低检测限11.6 fM（S / N = 3），有望应用于生物技术和临床诊断。