Methods of Synthesis and Characterization of Conductive DNA Nanowires Based on Metal Ion-Mediated Base Pairing for Single-Molecule Electronics

Abstract

Advances in the field of molecular electronics have made possible the directmeasurement of charge transport across single molecules. In particular, workon DNA oligomers has demonstrated that this weakly-conducting biomoleculecan be functionalized through metal-mediated nucleobase pairing in order tosignificantly increase electron mobility across the molecule. The introductionof interacting stacks of single metal ions inside the DNA helix is an attractiveplatform for assay and optimization; for this reason we present a protocolfor the production and processing of nanowires with a metal base pair forsingle-molecule applications. In particular, we describe the construction of DNA duplex wires with a cytosine-Ag+-cytosine base pair (dC:Ag+:dC).A thorough investigation of buffer components suggests the use of divalentmagnesium counterions to stabilize highly mismatched oligonucleotides insolution. We further analyse cleaning and processing of thin gold films forbatch-fabrication of conductive imaging substrates for use in conductivescanning probe assays of single-molecule conductivity. With a clear path toelectrical assays, we suggest that the C:Ag+:C orthogonal nucleotide pair andother similar chemistries may provide a foundation for molecular electroniccomponents in integrated devices