Manipulating DNA conformation using intertwined conducting polymer chains

In the field of inherently conducting polymers,polyaniline (Pani) has elici ted tremendous interest due to its promising electrical properties and uniq ue redox tunability. Synthetic routes involving the use of polyelectrolytes have significantly improved the processability of polyaniline. Recently,a template guided synthesis catalyzed by an enzyme, horseradish peroxidase (H RP), has provided a means of polymerizing aniline under milder pH condition s (pH 4.3) and subsequently widened the. choice of templates to more delica te biological macromolecules. Here we report a strategy that exploits the i nherent molecular order as well as the polyelectrolyte behavior of DNA to e nzymatically synthesize and biologically assemble conducting polyaniline. T his "wrapping" of polyaniline on DNA has been. found to induce reversible c hanges in the secondary structure of DNA, leading to the formation of an ov er-wound polymorph. The polyaniline synthesized on the DNA also exhibited a template-induced macroasymmetry. This unique polyaniline/DNA intertwined c omplex has been used to "probe" and control the conformation of the DNA dou ble helix.