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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 23: Electronic and Optical Properties

CPP 23.6: Vortrag

Mittwoch, 25. März 2009, 15:30–15:45, ZEU 114

New thiol-gold binding protocol for improving the conductance of double-stranded DNA — •Shoupeng Liu¹, Benjamin Bornemann², Andreas Marx², Elke Scheer², and Artur Erbe¹ — ¹Physics Department, University of Konstanz, D-78457 Konstanz, Germany — ²Chemistry Department, University of Konstanz, D-78457 Konstanz, Germany

Thiol-functionality at 5' ends DNA are normally used to allow its binding to gold electrodes for measuring its conductance. However, poor overlap of the electronic orbitals of the thiols with the Pi-system leads to low conductance of DNA. In this contribution, new oligonucleotides are synthesized that bear short thioalkyl functions at the nucleobases rather than at the phosphor-sugar backbone. We investigated the electronic transport properties of double-stranded DNA ended with these new oligonucleotides by mechanically controllable break junctions (MCBJ). From the measured current-voltage characteristics we deduce a semiconductor-like electronic band-structure. The results suggest a comparatively high conductance with a current of 700 nA in 0.25V, which is higher than in most of the former reports. The improved conductance is suggested to be caused by the thioalkyl group which facilitates charge transfer into the Pi-system of the nucleobases.