Bionanoelectronics Platform with DNA Molecular Wires Attached to High Aspect-Ratio 3D Metal Microelectrodes

In this study, the investigation of attachment of DNA molecular wires and ropes to high aspect-ratio three-dimensional (3D) metal microelectrodes and their subsequent electrical characterization as part of a bionanoelectronics platform is reported. The 3-D microelectrode architecture consists of mainly high aspect-ratio microelectrode structures (75 μm height and above) patterned from relatively thick layers of negative tone photoresist and covered by sputtered gold on their top surface. DNA attachments on 3-D microelectrode structures was demonstrated using oligonucleotide-DNA self-assembly and thiol-gold covalent bonding. Further, DC and AC electrical characterization of double-stranded λ-DNA molecular wires in a dry environment and suspended between high aspect-ratio 3D microelectrodes 75 μm away from the substrate (to heights unprecedented so far in the literature which thereby eliminate interference of substrate) is presented. Electrical characterizations based on I-V and AC impedance analysis of several repeatable data points of attachment with varying λ-DNA concentration (500 ng/μL to 1.5 ng/μL) showed measurable and significant conductivity of λ-DNA molecular wires with some band-gap; thereby establishing it as semi-conductor at low-frequencies (