Figure 7.

E-DNA signal suppression is eliminated at low ACV frequencies. This presumably occurs when the ACV frequency falls below the rate at which the redox moiety of the probe—target duplex collides with the electrode; under these conditions, electron transfer is efficient from both free and bound probes. As the ACV frequency increases, it presumably surpasses the collision rate of the bound probe, reducing transfer efficiency and producing a large, hybridization-linked reduction in the sensing current. Consistent with this argument, the frequency at which this transition occurs is higher for lower density sensors, presumably because reduced probe densities lead to higher collision rates for the probe—target duplex. Shown are the signal suppressions achieved at 200 nM of the target ST-25.