ABSTRACT
Scanning probe microscopy (SPM) was developed in the 1980s, first
with the invention of the scanning tunnelling microscope, usable
on electrically conductive samples, and subsequently with the
introduction of the atomic force microscope, which broadened the
scope for work using SPM to be extended to nonconductive samples,
hence opening the prospect of the adoption of the technique by
biologists. There were attractions in this because the new ultrahigh-
resolution techniques showed promise for the resolution of the
structures of biological macromolecules at a level until then not
achievable, and the tantalizing prospect also existed that atomic
force microscopy (AFM) experiments could be conducted in fluid,
thus allowing high-resolution imaging of biological specimens under
near-physiological conditions-an impossibility with the then pre-
vailing high-resolution imaging technique of electron microscopy.
Some of the excitement of these early days is captured in a review
of AFM imaging in biology, written by Helen Hansma and Jan Hoh
in 1994 [1], in which they describe the excitement generated by
early scanning tunnelling microscopy images of deoxyribonucleic
acid (DNA), published by Binnig and Rohrer as early as 1984 [2].
