BIOLOGICAL CRYO ATOMIC-FORCE MICROSCOPY - A BRIEF REVIEW

Despite many successes, atomic force microscopy (AFM) of biological sp ecimens at room temperature is still severely limited by at least two factors: the softness and the thermal motion of flexible multi-domain/ subunit molecules. Both problems can be overcome by imaging biological structures at cryogenic temperatures. Even though the instrumentation is considerably more complex and earlier attempts were largely unsucc essful, cryo-AFM has recently been demonstrated on a number of biologi cal specimens, using an AFM operated in liquid nitrogen vapor under am bient pressure. In this brief review, both the method of instrumentati on and the latest biological applications are discussed. Not only has the cryo-AFM attained high resolution on those specimens that could no t be well imaged at room temperature, but it has also produced potenti ally important information on several specimens. These results firmly establish the cryo-AFM as a useful and versatile structural probe in b iology with its own unique capabilities.