Authors: R.D. Boyd, R. Avci, M. Schweitzer, J. Wittmeyer, B. Spangler and K.M. Thieltges
Affilation: Cranfield University, United Kingdom
Pages: 558 - 561
Keywords: AFM, force measuremnt, antibody-antigen, imaging
Measuring ligand receptor forces using the atomic force microscope as a force-sensing instrument has been well documented. For example in the detection of antibody-antigen interactions with the antibody attached to the AFM tip with a spacer molecule in-between. The vast majority of these studies use idealized systems, such as individual antibodies adsorbed onto a well-defined substrate. Little work has been done on the investigations on biological systems more representative of actual ‘real-life’ situations. It has been demonstrated that antibody – antigen interactions can be detected on collagen tendons with an unbinding force of 90 - 120 pN. In addition, by moving the AFM tip laterally the spatial distribution of the interactions could be determined a resolution of a hundred nanometers showing a non-uniform distribution of events across the tendon. The analysis was complicated by signals arising from not only from antibody-antigen interactions but also from the pulling of the collagen fibrils by the AFM tip. It has been demonstrated that modifying the structure of the spacer molecule so that more area of the AFM tip is passivated helps to reduce the number of non-specific events.