IN-SITU HIGH-RESOLUTION ATOMIC-FORCE MICROSCOPE IMAGING OF BIOLOGICALSURFACES

In situ high-resolution atomic force microscope imaging of biological surfaces was performed on cells with relatively rigid surfaces (e.g., bacteria). The surface of Lactobacillus helveticus (a rod-shaped bacte rium) was investigated before and after exposure to LiCl, a denaturant . Image details were stable both at variant force loads and under diff erent scan directions. From images of the oblique lattice structure (i .e., S layer of L. helveticus), it was estimated that the lateral reso lution of the images was up to 2 nm. This resolution can be explained by assuming that there is an apex with a curvature of radius of simila r to 10 nm near the end of the tip. Modelling of this geometry indicat es that such a tip configuration is particularly suitable for in situ high-resolution imaging of relatively soft objects covered by a rigid shell (membrane). (C) 1996 American Vacuum Society.