Semi-automatized processing of AFM force-spectroscopy data

Atomic force microscopy operated in the force-spectroscopy mode is now a wi despread technique, often used to investigate ligand-receptor interactions with the goal of measuring forces at the individual molecule level. However , in an experiment, the simultaneous interaction of several ligand/receptor pairs cannot he excluded. This may product complicated force curves, altho ugh unambiguous ruptures are sometimes observed. In the case of the non-spe cific adhesion of molecules. such as fibrinogen. to a surface, it is usuall y difficult to identify the real events on the force curves. This can rende r the application of fixed rules uneasy and in addition can introduce some degree of arbitrariness if the analysis has to be performed by hand. In the present paper a computer algorithm, aimed at speeding up the processing, a nd at applying selection rules in a reproducible manner, is proposed. It is applied to force recordings performed at various retraction velocities. th us various loading rates. The influence on the evaluation of the rupture fo rces of the different parameters that can be set by the operator is discuss ed. (C) 2001 Elsevier Science B.V. All rights reserved.