Data analysis of interaction forces measured with the atomic force microscope

The force-distance cycle mode of the atomic force microscope (AFM) allows f or detection of interaction forces between the AFM-tip and a substrate (pro be). This can either be a direct tip-sample interaction or an interaction b etween molecules coupled to the tip and probe, respectively. The interactio n forces are typically in the range of a few pN to some hundred pN. In this article we describe algorithms for the analysis of force-distance cycles, to quantify interaction forces between tip and probe. Both, the direct tip- probe interaction as well as the interaction between specifically bound mol ecules are analyzed. The molecules bound to tip and probe have to be either long and flexible or have to be bound via a flexible cross linker. The alg orithms are exemplified on direct tip-probe interactions and on unbinding e vents of cadherins which are bound via PEG-spacers to the AFM-tip and to th e probe. (C) 2000 Elsevier Science B.V. All rights reserved.