Figure 3. Mismatch detection on DNA-modified electrodes.

Comparison of the electrochemical properties of a well-matched DNA monolayer assembled on gold electrodes to that of a monolayer containing a single base pair mismatch. A distally bound, covalent redox probe such as Nile blue can stack with the DNA bases and report on the integrity of the DNA. Cyclic voltammogram (CV) traces demonstrate that current flows from the electrode surface to the redox probe at different applied potentials in physiological buffer. Charge can flow efficiently through well-matched DNA, but when the π-stacking of the bases is disrupted by a single base pair mismatch or lesion, DNA CT is attenuated and current does not flow effectively to the redox probe.