TUD

DNA is considered as one of the attractive candidates for molecular electronics due to the high density of its components, its accurate synthesis and its double-strand recognition properties that suggest self-assembly. DNA was studied in many ways including: electrical transport, atomic force microscope (AFM) and scanning tunneling microscope (STM). It seems that the results of the various measurements of charge transport in DNA are not consistent.
We have now developed a method to attach short (26 bp) DNA molecules to a gold surface at one end and to a gold nanoparticle on the other end. Upon approaching and contacting the gold particle with a conductive AFM tip with a controlled applied force, we can measure current-voltage curves through the double-stranded DNA molecule. Preliminary measurements show relatively high currents. We report also control experiments that are performed on the insulating surrounding layer.
We also report the production and characterization of novel DNA-based molecules that may have better conduction properties.
If time allows we will report results of topography contrast inversion that is observed in STM imaging of DNA molecules (the DNA appears above the surface in parts of the image and under it in other parts). This contrast is induced either spontaneously or in a controlled way. The results are interpreted and simulated theoretically as well.

FIGURE: Schematic of the experiment (a) and a topography image of gold nanoparticles connected through double-stranded DNA to an underlying gold surface surrounded by a single-stranded DNA monolayer.