Intraduplex DNA-mediated electrochemistry of covalently tethered redox-active reporters.

Intraduplex DNA-mediated reduction is established as a general mechanism for the reduction of distally bound stacked redox-active species covalently tethered to DNA through flexible alkane linkages. Methylene Blue (MB), Nile Blue (NB), and Anthraquinone (AQ) were covalently tethered to DNA with three different covalent linkages. Using these reporters DNA electrochemistry was shown to be both DNA-mediated and intra-, rather than inter-, duplex. Significantly, the charge transport pathway occurring through the DNA π-stack is established by using an intervening AC mismatch to break this path. The fact that the DNA-mediated reduction of MB occurs primarily via intraduplex intercalation is established through varying the proximity and integrity of the neighboring duplex DNA.