FIGURE 1.

Schematic illustration of dynamic AFM force spectroscopy: a single chemical bond, e.g., in a ligand-receptor complex, is connected via two flexible linker molecules with the tip of an AFM cantilever and a piezoelectric element. The latter pulls down the attached linker molecule at some constant velocity υ. The resulting elastic reaction force of the cantilever can be determined from the deflection of a laser beam. The main quantity of interest is the force value at the moment when the bond dissociates.