Fig. 1.

Here we demonstrate a method for monitoring protein–small molecule interactions. Our approach employs a DNA probe, one end of which is chemi-adsorbed to an interrogating electrode and the other end of which is modified with a recognition element and with a redox reporter. The binding of a protein to the recognition element reduces the efficiency with which the redox reporter approaches the electrode, minimizing the observed faradaic current. The addition of a small molecule that disrupts protein binding reverses this effect. (Inset) Shown are representative square wave voltammograms illustrating the competitive detection of TNT via this approach.