A Redox-Reversible Switch of DNA Bonding and Structure

A controlled interface with nanotechnology is key to progressing interests in adhesion, photonics, electronics, energy harvesting and storage, sensing, and thermal management. Electrically reconfigurable biological materials open pathways for advancing these broad interests and enhancing current efforts to leverage biological self-organization to generate novel materials with designer medical, mechanical, optical, and electrical properties. We have identified DNA base surrogates with redox-reconfigurable hydrogen bonding behavior based on alloxazine, the redox-active moiety of the biological flavin cofactors. Alloxazine DNA base surrogates were synthesized and incorporated into DNA duplexes as surrogate bases that function as a redox-active switch of hydrogen bonding. Circular dichroism revealed that 24-mer DNA duplexes incorporating one or two alloxazines exhibited spectra and melting transitions like DNA with only canonical bases, indicating the constructs adopt a conventional B-form conformation. Thiolated DNA duplexes incorporating alloxazines were self-assembled onto multiplexed gold electrodes and probed electrochemically. Square wave voltammetry revealed a redox peak near −0.27 V versus a Ag/AgCl reference, consistent with the reduction of the alloxazine moiety. Furthermore, alternating between alloxazine oxidizing and reducing conditions modulated the redox peak consistent with the formation and loss of hydrogen bonding, which disrupts the base pair stacking and charge transport efficiency. These alternating signals support the assertion that alloxazine can function as a redox-active switch of hydrogen bonding, useful in controlling DNA and bioinspired assemblies.