DNA building blocks for AFM tip functionalization: An easy, fast and stable strategy

Area of Science:

• Nanotechnology
• Biophysics
• Biochemistry

Background:

• Biosensing atomic force microscopy (AFM) enables single-molecule analysis of biomolecular interactions and nanoscale mapping.
• Current AFM tip functionalization methods, often using poly(ethylene glycol) linkers, are time-consuming and yield broad rupture length distributions, limiting automation and accuracy.

Purpose of the Study:

• To develop a stable, fast, and efficient method for AFM tip functionalization using DNA tetrahedra.
• To improve the accuracy and automation potential of single-molecule force spectroscopy by achieving a sharp distribution of rupture lengths.

Main Methods:

• A novel functionalization strategy employing tetra-functional DNA tetrahedra was developed.
• DNA tetrahedra with disulfide legs were used for site-directed coupling to gold-coated AFM tips.
• The method was validated using the avidin-biotin system and applied to thrombin detection with DNA aptamers.

Main Results:

• The DNA tetrahedron approach provides fast and low-effort tip functionalization with a high success rate.
• A sharp, defined distribution of rupture length was achieved, improving measurement accuracy.
• The method demonstrated successful application in detecting human thrombin using DNA aptamers.

Conclusions:

• Tetra-functional DNA tetrahedra offer a superior alternative for AFM tip functionalization compared to traditional methods.
• This technique enhances the precision and automation capabilities of single-molecule biosensing.
• The DNA tetrahedron approach holds significant promise for advancing nanoscale molecular interaction studies.