In this study, a novel modification-free electrochemical sensing approach for thrombin that utilizes both electrically assisted bond and bisferrocene to enhance the signal output in a homogeneous solution was reported. First, the selected aptamer probe with a stem–loop structure was labeled with bisferrocene and thiol at the 3′ and 5′ terminals, respectively, and the closed–loop structure of the probe prevented thiol from reaching the electrode surface. However, the stem–loop structure opened after treatment with the target thrombin protein; hence, the thiol can rapidly attach to the electrode to form a Au–S self-assembly by potential-assisted, followed by the measurement of the bisferrocene electrochemical signal. Binding was directly performed in the solution, and it did not require the probe to be fixed in advance; meanwhile, necessary electrode modification was prevented. This modification-free homogeneous strategy exhibited a detection limit as low as 0.8 × 10⁻¹² M of thrombin. Moreover, advanced specificity against common interfering proteins was observed.

在这项研究中，报道了一种新颖的凝血酶免修饰电化学传感方法，该方法利用电辅助键和双二茂铁两者来增强均质溶液中的信号输出。首先，选定的具有茎环结构的适体探针在3'和5'末端分别用双二茂铁和硫醇标记，并且探针的闭环结构阻止了硫醇到达电极表面。然而，在用目标凝血酶蛋白处理后，茎环结构打开了。因此，硫醇可以通过电势辅助快速附着在电极上，形成Au-S自组装，然后测量双二茂铁的电化学信号。结合直接在溶液中进行，不需要预先固定探针。与此同时，防止了必要的电极修饰。这种无修饰的均质策略显示的检出限低至0.8×10^-12 M的凝血酶。此外，观察到了对常见干扰蛋白的高级特异性。