A sensitive homogenous aptasensor based on tetraferrocene labeling for thrombin detection

In this work, a novel homogeneous electrochemical aptasensor based on electrically assisted bond and tetraferrocene signal amplification was constructed for thrombin detection. Importantly, modification of the electrode is not necessary for this sensor, requiring only the construction of a simple and efficient probe. In addition, a brand new signal marker-tetraferrocene, containing four ferrocene molecules, was employed as a label to the terminal position of the probe. Compared with a single ferrocene moiety, tetraferrocene possesses a larger amplification signal for rapid detection of thrombin. In the detection of thrombin, the selected aptamer probe with a stem-loop structure was labeled with tetraferrocene at the 30 terminal and thiol at the 5' terminal, respectively. Confinement of the thiol to the stem-loop structure of the probe, the ability of thiol to reach the surface of electrode lossed even with the aid of the applied potential. However, upon treatment with the target protein of thrombin the stem-loop structure opened, promoting rapid attachment of the thiol group to the electrode interface generating Au-S self-assembly with the action of potential-assistance. The electrochemical signal of tetraferrocene could be measured by differential pulse voltammetry (DPV), which was subsequently used for target quantitative detection. This strategy displayed a detection limit as low as 0.126 pM, and an inherently high specificity for the detection of a single mismatch. Moreover, it exhibited advanced specificity against common interfering proteins. (C) 2020 Published by Elsevier B.V.