PROBE MICROSCOPIES - FEELING THEIR WAY

The invention of the scanning tunnelling microscope (STM) in the early 1980s revolutionized the field of microscopy. The STM is the first of a growing family of probe microscopes which image surfaces by scannin g them with a sharp probe, measuring some form of interaction between the probe and the surface. The invention of the STM was closely follow ed by the development of the scanning force microscope (SFM). Since th eir inception, scanning probe microscopes have had an obvious appeal t o biologists and biophysicists. Both techniques are capable, under app ropriate conditions, of obtaining atomic resolution images of suitable surfaces. Images can be obtained under gaseous or liquid environments , offering the prospect for studying biological systems under 'native' or 'physiological' conditions. Because of its detection mechanism the STM is largely restricted to the study of interfaces or individual bi opolymers and their interactions. However, the potential magnification range achievable with the SFM spans the ranges covered by both light and electron microscopes. Examples of the use of scanning probe micros copes will be given in areas relevant to food and agriculture, and pot ential applications of the microscopes will be discussed.