DETECTION OF ANTIGEN-ANTIBODY BINDING EVENTS WITH THE ATOMIC-FORCE MICROSCOPE

An atomic force microscope (AFM) has been used to directly monitor spe cific interactions between antibodies and antigens employed in an immu noassay system. Results were achieved using AFM probes functionalized with ferritin, and monitoring the adhesive forces between the probe an d anti-ferritin antibody-coated substrates. Analysis of the force dist ribution data suggests a quantization of the forces, with a period of 49 +/- 10 pN. This periodic force may be attributed to single unbindin g events between individual antigen and antibody molecules. These resu lts demonstrate that the AFM could be employed as an analytical tool t o study the interactions between the molecules involved in biosensor s ystems. The potential of the technique to provide information relating to the manner in which the antibody molecule binds to its specific an tigen is also discussed.