Introduction
Ligand molecules for a particular
receptor can be attached to the tip
of an AFM probe, transforming the
probe into a sensitive, chemically
selective biosensor for that recep-
tor [Riener et al. 2003]. Molecular
recognition force microscopy
(MRFM) is a single-molecule AFM-
based technique that relies heavily
on nanoscale surface chemistry,
nanoscale biochemical immobiliza-
tion chemistry, and bioconjugation
chemistry. In MRFM, single-mole-
cule unbinding interactions
between AFM probe-bound ligands
and substrate-bound receptor
pairs are observed and quantified
one by one as the AFM cantilever
approaches and then is subse-
quently withdrawn from the sur-
face many times. The nanoNewton-
scale molecular unbinding events
are generally detected by measur-
ing the optical deflection of the
flexible AFM cantilever. These
force spectroscopy (FS) experi-
ments can provide valuable infor-
mation about the structure and
dynamics of molecular unbinding
events at the single-molecule level
[Noy et al. 1997]. In addition to