Characterization of the adhesion force between avidin-functionalized AFM tips and biotinylated agarose beads

Author :Markus Ludwig, Vincent T. Moy, Matthias Rief, Ernst-Ludwig Florin and Hermann E. Gaub
Publication :Microscopy, Microanalysis, Microstructures
Volume :5
Pages :321-328
Year :1994

With AFM related techniques we investigated the specific interaction between avidin
and biotin. The contact rupture force (adhesion) between avidin functionalized tips and biotin, which
was covalently linked to agarose beads, was measured and characterized. A comprehensive study of
the physical properties of the receptor-functionalized tips and the biotin-labeled agarose bead was
carried out. The functional stability of the avidin coated tip persisted for several hundred force scan
measurements. The strength of the interaction between the tip and the bead was found to depend on
the force applied by the AFM tip on the polymer beads. By regulating the contact via indentation,
the interaction can vary from one to as much as 100 biotin-avidin pairs. When surface interaction
is minimized, quantized interaction between avidin and biotin was observed. This approach induces
minimal stress on the interacting molecules.