A Sensitive Thrombin Aptasensor Based on Target Circulation Strategy.

A convenient homogeneous electrochemical thrombin sensor based on potential-assisted Au-S deposition and a dual signal amplification strategy was established in this study. Potential-assisted Au-S deposition does not require the modification of the gold electrode, thus eliminating the tedious pre-modification of the electrode. To better amplify the output signal, both ends of the signal hairpin probes were modified with a new electroactive substance, tetraferrocene, which was synthesized by the authors. Thrombin was immediately hybridized with a thiol-modified probe to open the stem-loop structure. After chain hybridization, thrombin was replaced and participated in the next round of the reaction; thus, the cascade amplification of the signal was realized. The hybrid chain formed an Au-S deposition under potential assistance, and the electrochemical signal of tetraferrocene could then be measured through differential pulse voltammetry (DPV) and consequently used for the quantitative detection of target thrombin. In addition, the detection limit of thrombin was as low as 0.06 pmol/L, and the detection of common interfering proteins was highly specific.