Scanning electron microscopy studies of protein-functionalized atomic force microscopy cantilever tips

Area of Science:

• Biophysics
• Materials Science
• Surface Science

Background:

• Atomic force microscopy (AFM) is a powerful tool for studying single molecular interactions.
• Protein functionalization of AFM tips enables the investigation of specific ligand-receptor binding events.
• Understanding the stability and morphology of protein coatings on AFM tips is crucial for reliable measurements.

Purpose of the Study:

• To characterize the surface morphology of protein-coated AFM cantilever tips using scanning electron microscopy (SEM).
• To assess the stability and potential degradation of protein coatings on AFM tips during force measurements.

Main Methods:

• Scanning electron microscopy (SEM) was employed to visualize the surface of protein-functionalized AFM tips.
• Bovine serum albumin (BSA) was used to create initial protein coatings on silicon nitride cantilevers.
• Avidin-functionalized tips were subjected to force measurements using biotinylated agarose beads.

Main Results:

• SEM imaging demonstrated spontaneous adsorption of bovine serum albumin (BSA), forming a uniform protein layer on AFM cantilevers.
• Further protein deposition did not significantly alter the surface morphology of the BSA-coated tips.
• Avidin-functionalized tips exhibited debris contamination after force measurements with biotinylated agarose beads, suggesting material transfer.

Conclusions:

• Protein coatings, such as BSA, can form stable and uniform layers on AFM tips.
• Avidin-functionalized AFM tips may be susceptible to contamination and functional deterioration when interacting with certain substrates like agarose beads.
• These findings highlight the importance of considering tip stability and potential contamination in AFM-based single-molecule force spectroscopy experiments.