Signal Transduction through Dye-Labeled M-DNA Y-Branched Junctions:  Switching Modulated by Chemical Reduction of Anthraquinone

Metal-DNA (M-DNA) is a complex formed between duplex DNA and divalent metal ions which facilitates electron transfer. In this study, 90 base-pair DNA Y-branched junctions were prepared with the electron donor fluorescein attached to one arm and electron acceptors, rhodamine or anthraquinone, to the other arms. Upon formation of M-DNA, the fluorescence of fluorescein was quenched by the electron acceptors, demonstrating that electron transfer could occur through the junction. As well, the quenching was modulated by chemical reduction of anthraquinone, mimicking a chemical switch. Base-pairing defects at the point of the junction were observed to have only a small impact on the quenching, demonstrating the robust nature of electron transfer in M-DNA. Therefore, M-DNA may have extraordinary potential for the development of nanoelectronic devices.