Single molecule labeling of an atomic force microscope cantilever tip

Area of Science:

• Nanoscience and Nanotechnology
• Biophysics
• Materials Science

Background:

• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale imaging and force measurements.
• Precise control over the number of molecules on an AFM cantilever is crucial for accurate force spectroscopy and interaction mapping.
• Current methods often result in multiple molecule attachments, leading to noisy or unreliable data.

Purpose of the Study:

• To develop a reliable method for functionalizing AFM cantilevers with a single or very few molecules.
• To improve the signal-to-noise ratio in force spectroscopy and interaction mapping experiments.
• To provide a broadly applicable technique for scanning probe microscopy requiring minimal molecular functionalization.

Main Methods:

• Covalent attachment of single molecules to the apex of an AFM cantilever.
• Utilizing a paper substrate wetted with a quantum dot solution.
• Leveraging capillary action (wicking) of the paper to control molecule deposition onto the hydrophilic cantilever tip.

Main Results:

• Successfully achieved covalent attachment of single or a few molecules to the AFM cantilever apex.
• Demonstrated a method to minimize spurious measurements by controlling molecular density.
• The technique proved effective for functionalizing the cantilever tip with quantum dots.

Conclusions:

• The developed method offers a simple yet effective way to achieve precise molecular functionalization of AFM cantilevers.
• This technique is suitable for applications requiring a low density of molecules on the probe tip.
• Broad applicability in scanning probe microscopy for enhanced measurement accuracy.