A homogenous electrochemical sensing DNA sensor by using bare Au electrode based on potential-assisted chemisorption technique

A novel electrochemical DNA sensing strategy based on potential-assisted Au-S deposition was presented in this article. Specifically, the 3′ terminal of double hairpin DNA probe was used to modify ferrocene (Fc), while the 5′ terminal was employed to modify thiol. The loop probe could prevent thiol from arriving on the surface of bare gold electrode under the action of an applied potential, without hybridization with the target DNA. In comparison, the stem-loop structure of probe would be opened after hybridization with the target DNA, which would lead to the formation of a hairpin DNA structure. This had facilitated the contact of thiol with electrode, resulting in potential-assisted Au-S self-assembly. Additionally, electrochemical signals of Fc were measured by differential pulse voltammetry (DPV), which were subsequently used for target quantitative detection. Such strategy has established a detection limit of down to 3.4 pM and an inherently high specificity in detecting even for a single-base mismatch.