SINGLEMOLECULE FORCE SPECTROSCOPY OF MICROBIAL CELL ENVELOPE PROTEINS - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 315

Figure 15.1. AFM force spectroscopy of the NTA-His 6 bond. Force histogram and
typical force curve obtained between a NTA tip and a His 6 support in the presence of
Ni 2+ . Left: surface chemistry used to modify tip and support.
15.2.3 Cell Immobilizaon
For cell experiments, another crucial issue is to attach the cells on a solid
support using non-destructive methods. 26 Unlike animal cells, microbes have
a well-deined shape and have no tendency to spread on surfaces. As a result,
the contact area between a cell and a support is very small, often leading
to cell detachment by the scanning tip. Therefore, several approaches have
been developed to promote cell attachment. A convenient method makes use
of porous polymer membranes. 26,27 This approach allows us to image single
bacterial, yeast and fungal cells under aqueous conditions while minimizing
denaturation of the surface molecules ( Fig. 15.2 ) .
Figure 15.2. Microbial cell imaging by AFM requires attaching the cells irmly onto
an appropriate support, which can be achieved by trapping the cells into a porous
polymer membrane. Shown here is a single living yeast cell of ~5 μm diameter,
decorated with a bud scar.