Adhesive forces between ligand and receptor measured by AFM

Author :Vincent T. Moy, Ernst-Ludwig Florin, Hermann E. Gaub
Publication :Colloids and Surfaces
Volume :93
Pages :343-348
Year :1994

Since its invention, the atomic force microscope (AFM) has been used to image a wide range of samples, including
soft biological materials. Although various imaging modes have been developed in recent years, the images obtained
by these techniques are primarily derived from the mechanical interactions between AFM tip and sample. An imaging
mode based on the specific recognition of defined functional groups on the sample by receptor molecules attached to
the AFM tip may prove to be beneficial. especially in complex specimens such as the cell membrane. A prerequisite
towards this goal is the development of AFM tips functionalized with ligand-specific receptors. Here we report the
fabrication of tips functionalized with either avidin or antibodies. These functionalized tips were characterized by force
scan measurements on ligands cross-linked to agnrose beads. The specificity of the observed adhesion between tip and
sample was confirmed by specitic blocking of the ligands or the receptors.