DNA imaged on a HOPG electrode surface by AFM with controlled potential

Area of Science:

• Biophysics
• Surface Science
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is crucial for nanoscale imaging.
• Understanding DNA behavior on conductive surfaces is vital for biosensor development.
• Self-assembly of DNA onto substrates presents imaging challenges.

Purpose of the Study:

• To investigate single-molecule DNA imaging on highly oriented pyrolytic graphite (HOPG).
• To explore the effect of electrode potential on DNA adsorption and stability.
• To enhance AFM imaging capabilities for DNA on conducting substrates.

Main Methods:

• Single-molecule Atomic Force Microscopy (AFM) imaging.
• Self-assembly of single-stranded and double-stranded DNA onto HOPG.
• Control of electrode potential applied to the HOPG substrate.
• Analysis of topographical and phase images.

Main Results:

• DNA molecules aggregated and interacted upon adsorption onto the hydrophobic HOPG surface.
• Applying a +300 mV potential to HOPG enhanced DNA molecule stability and robustness.
• Increased electrostatic interaction between the positively charged electrode and DNA backbone was observed.
• Phase images confirmed topographical characterization, aiding in correct imaging.

Conclusions:

• Electrode potential control significantly improves AFM imaging of DNA on conducting substrates.
• Enhanced DNA stability allows for more detailed topographical characterization.
• This method expands AFM's utility for studying immobilized DNA on conductive materials like HOPG.