Topographic effects on adhesive force mapping of stretched DNA molecules by pulsed-force-mode atomic force microscopy

Area of Science:

• Surface science
• Nanotechnology
• Biophysics

Background:

• Adhesive forces between surfaces are complex, influenced by topography, elasticity, and surface chemistry.
• Understanding these forces is crucial for nanoscale manipulation and material interactions.
• Pulsed-force-mode atomic force microscopy (PFM-AFM) is a powerful tool for probing these interactions at the microscopic level.

Purpose of the Study:

• To investigate the influence of surface topography on adhesive interactions at the nanoscale.
• To specifically examine the topographic effects on the adhesive force of stretched DNA molecules.
• To establish reproducible methods for mapping adhesive forces influenced by topography.

Main Methods:

• Utilized pulsed-force-mode atomic force microscopy (PFM-AFM) to measure pull-off forces.
• Employed low relative humidity (RH) and alkanethiol-modified tips to minimize water capillary forces.
• Stretched DNA molecules using dynamic molecular combing on hydrophobic surfaces with specific surface modifications for enhanced adsorption.

Main Results:

• Demonstrated that surface topography significantly impacts adhesive force measurements.
• Showcased the successful measurement of adhesive forces on stretched DNA molecules, considering their smaller radius of curvature.
• Confirmed the reproducibility of adhesive force mapping under controlled experimental conditions.

Conclusions:

• Surface topography is a critical factor influencing nanoscale adhesive interactions.
• The experimental approach effectively isolated and quantified topographic effects on adhesive forces.
• This research provides a foundation for precise control and understanding of molecular-level adhesion.