By coupling a new aptamer proximity recognition-dependent strand translocation strategy with catalytic hairpin assembly (CHA) signal amplification, we have developed a simple and sensitive method for detecting thrombin in human serums. Simultaneous binding of two engineered aptamer probes to the thrombin target significantly increases the local concentrations of the two probes and facilitates the translocation of a ssDNA strand from one of the probes to the other through toehold mediated strand displacement. Such a strand translocation leads to the generation of a ssDNA tail in the aptamer sequence for subsequent initiation of the assembly of two fluorescently quenched hairpins into many DNA duplexes via CHA. The formation of the DNA duplexes thus results in significant fluorescence recovery for amplified detection of thrombin down to 8.3 pM. The developed method is highly selective to the thrombin target against other interference proteins due to the dual recognition mode, and can be employed to monitor thrombin in human serum samples. With the advantage of simplicity, sensitivity and selectivity, this method can be a universal non-enzymatic and nanomaterial-free amplified sensing platform for detecting different protein molecules.

中文翻译：

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适体邻近识别依赖性链易位，通过催化发夹组装对凝血酶进行无酶和扩增荧光检测

通过将新的适体邻近识别依赖链易位策略与催化发夹组装 (CHA) 信号放大相结合，我们开发了一种简单而灵敏的方法来检测人血清中的凝血酶。两个工程适体探针与凝血酶靶标的同时结合显着增加了两个探针的局部浓度，并通过立足点介导的链置换促进了 ssDNA 链从一个探针到另一个探针的易位。这种链易位导致在适体序列中产生 ssDNA 尾，用于随后通过 CHA 将两个荧光淬灭的发夹组装成许多 DNA 双链体。因此，DNA 双链体的形成导致显着的荧光恢复，用于低至 8.3 pM 的凝血酶的扩增检测。由于采用双重识别模式，所开发的方法对凝血酶靶标对其他干扰蛋白具有高度选择性，可用于监测人血清样品中的凝血酶。该方法具有简单、灵敏和选择性的优点，可以成为一种通用的非酶促和无纳米材料的放大传感平台，用于检测不同的蛋白质分子。