Molecular Recognition of Proteins through Quantitative Force Maps at Single Molecule Level

Area of Science:

• Biophysics
• Surface Science
• Nanotechnology

Background:

• Atomic force microscopy (AFM) is a high-resolution surface imaging technique.
• Force spectroscopy in AFM measures interactions between the tip and sample.
• Distinguishing similar molecules like avidin and streptavidin is challenging.

Purpose of the Study:

• To refine the intermittent jumping force mode of AFM for molecular recognition.
• To apply this refined mode for differentiating between avidin and streptavidin proteins.
• To establish a method for quantitative molecular mapping using specific rupture forces.

Main Methods:

• Utilized intermittent jumping force mode in a repulsive regime with very low forces.
• Scanned hybrid samples containing avidin and streptavidin with biotinylated probes.
• Analyzed adhesion images to identify specific tip-sample rupture events and forces.

Main Results:

• Adhesion images revealed specific rupture events, acting as molecular recognition maps.
• Avidin molecules were identified with rupture forces of 40-80 pN.
• Streptavidin molecules were identified with rupture forces of 120-170 pN.

Conclusions:

• Repulsive jumping force mode with low forces enables biomolecule identification via specific complex rupture forces.
• This method allows for qualitative and quantitative molecular recognition at fast rates.
• The technique shows potential for identifying membrane receptors and designing ultrasensitive detection technologies.