Electrical characterization of self-assembled single- and double-stranded DNA monolayers using conductive AFM

Area of Science:

• Molecular electronics
• Nanotechnology
• Biophysics

Background:

• Previous studies reported electrical transport through double-stranded DNA (dsDNA) molecules.
• dsDNA was embedded in a single-stranded DNA (ssDNA) monolayer and connected to a metal substrate and gold nanoparticle (GNP).

Purpose of the Study:

• Compare electrical transport through ssDNA monolayers and dsDNA monolayers.
• Investigate the role of thiol end-groups in dsDNA electrical transport.
• Evaluate charge injection efficiency in DNA molecules.

Main Methods:

• Conductive atomic force microscopy (AFM) was employed for measurements.
• Electrical transport was measured through ssDNA monolayers, dsDNA monolayers with and without thiol end-groups, and GNP-connected dsDNA.
• Various AFM techniques were utilized.

Main Results:

• ssDNA monolayers showed no current transport, acting as an effective insulator.
• dsDNA monolayers without upper thiol end-groups exhibited rare, low current transport.
• dsDNA monolayers with thiols on both ends showed significant current but with lower reliability and reproducibility compared to GNP-connected dsDNA.
• GNP-connected dsDNA achieved 220 nA at 2 V.

Conclusions:

• dsDNA can conduct electrical current under specific conditions.
• ssDNA monolayers serve as efficient insulating layers.
• Efficient charge injection via covalent bonding is crucial for electrical transport in single dsDNA molecules.