Impact of the sequence of base pairs onto the electrical transport through single DNA molecules

Abstract

We studied short single-DNA molecules, using the mechanically controllable break junction technique (MCBJ). We measured two different sequences. The first resulted in a single-DNA conductance of 1.6 ' 2.0 10-4 G0 in high-vacuum (with G0 the quantum of conductance). The other sequence with an induced bulge, an unpaired nucleotide on one strand, was measured in aqueous as well as in high-vacuum conditions. To broaden our measurement range to ultralow conductance, a method was developed to reduce the ionic conduction of the buffer. The measurements resulted in a conductance value for a single-DNA molecule of 10-5 G0. We can conclude that we were able to measure the electric transport through single-DNA molecules using a MCBJ setup in different conditions, for different sequences. It is clear that environmental factors play a huge role in determining the conductance, and that the understanding of a complex system like DNA is challenging.