Detection and localization of antibody–antigen interactions with high spatial resolution on collagen tendons

The use of the atomic force microscope to measure antibody and antigen interactions is not new and, in theory, allows the detection of single antibody–antigen interactions with nanometre resolution. However the application of this technique has been limited to ‘ideal’ situations and not been applied as a general laboratory technique. Previous studies on more realistic samples have been hampered by non-specific interactions. The technique has been modified with a double attachment spacer molecule between tip and antibody in order to successfully reduce the number of non-specific events seen and improving the sensitivity of the technique. This technique has been applied to an identical sample used for immunofluorencese and electron microcopy investigations. Antibody–antigen interactions were readily detected on the sample with a resolution of 50–100 nm. The presence of specific interactions was confirmed by blocking using excess antibodies.