Figure 1: Structure-conductance modulation in 11-mer (NH₂-5′-CCCGCGCGCCC-3′-NH₂) dsDNA.

Schemes showing (a) B-form (blue) and (b) A-form (green) dsDNA bound to Au electrodes. The linkers to the electrodes (either amines or thiols) are shown in orange. (c) Representative current versus distance curves measured during electrode separation in buffer (blue) and 80% ethanol (green) solutions containing dsDNA, and in the absence of the molecule (grey) (curves offset horizontally for clarity). (d) Logarithmic conductance histograms obtained from thousands of current versus distance traces for B-form DNA in buffer (blue), A-form DNA in ethanol (green) and a control experiment without DNA present (grey), the control histogram is increased by 20 times for clarity. Dashed lines are Gaussian fittings. G₀ is the quantum conductance. (e) Circular dichroism spectra (differential absorbance versus wavelength) for dsDNA in solution in the same conditions described in b, demonstrating a clear change from B-form to A-form. Inset shows a titration of the intensity at 210 nm versus increasing concentrations of ethanol in the solution.