INVESTIGATING MAMMALIAN CELL NANOMECHANICS WITH SIMULTANEOUS OPTICAL AND ATOMIC FORCE MICROSCOPY - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 385

Figure 18.10. A luorescence image of a C2C12 rat myoblast expressing Actin-GFP on
a GXG substrate with embedded 200 nm red luorescent beads (scale bar = 10 μ m).

Dishes were mounted on the stage of a simultaneous AFM-luorescence
microscope and phase-contrast/luorescence images of the cell and
associated stressed and relaxed bead positions were captured automatically
with a deep cooled CCD camera for TFM analysis. Experiments were designed
to incorporate a built-in control for every cell measured. In the “control”
experiment, a cell was chosen and a phase-contrast image was acquired
followed by a series of luorescent images of the surface beads every 30
seconds for 2 minutes. This was followed by the “stress” experiment by
positioning of the AFM tip above the nucleus of the same cell and repeating
the aforementioned procedure. The AFM tip was lowered onto the cell
immediately after the = 0 second image of the surface beads. In both

“control” and “stress” experiments, the

t

= 0 second luorescence image was
treated as the “null” image and subsequent images were treated as “stressed”
images. Therefore, each cell measured has a built-in control measurement
which provides us with the natural cellular traction force dynamics and the
perturbed dynamics in response to mechanical stimulation. We performed

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