Detection of antigen-antibody binding events with the atomic force microscope

Area of Science:

• Biophysics
• Immunology
• Nanotechnology

Background:

• Immunoassays are crucial for detecting specific molecular interactions.
• Directly observing molecular binding forces in biosensors remains challenging.
• Atomic Force Microscopy (AFM) offers high-resolution surface analysis capabilities.

Purpose of the Study:

• To directly monitor specific antibody-antigen interactions using AFM.
• To investigate the forces involved in molecular binding within an immunoassay context.
• To assess the potential of AFM as an analytical tool for biosensor development.

Main Methods:

• Utilized AFM probes functionalized with ferritin.
• Measured adhesive forces between ferritin-functionalized probes and anti-ferritin antibody-coated substrates.
• Analyzed force distribution data to identify force quantization.

Main Results:

• Observed quantized adhesive forces during antibody-antigen interactions.
• Identified a force quantization period of 49 +/- 10 pN.
• Attributed the quantized forces to single antigen-antibody unbinding events.

Conclusions:

• AFM can directly monitor molecular interactions in immunoassay systems.
• Quantized forces provide insights into single molecular binding events.
• AFM is a promising analytical tool for studying biosensor molecular interactions.