W. Richard Bowen and Nidal Hilal 4

Slow (μm)
40
20
7.3 AFM IN CELL MEASUREMENT 213
(a) (b)
0
0 20
Slow (μm)
(e)
Fast (μm)
(c) (d)
8
6
4
2
0
40
0 2 4 6 8
Fast (μm)
645.5 nm
0 nm
183.3 nm
0 nm
under the tip, and the height contours of some are so steep as to prove
difficult for the AFM tip to follow topographically. Thus, there are many
considerations to take into account when designing experiments using
live cell imaging, such as operation modes, loading force, choice of tip
Slow (μm)
Slow (μm)
(f)
40
20
8
6
4
2
0
0
0 20
Fast (μm)
0 2 4 6 8
Fast (μm)
129.7 mV
0 mV
309.1 nm
FIgurE 7.8 Simultaneous AFM and optical imaging of functional cell structures on a
nanostructured substrate. Fluorescence images show an overview of the F-actin stress fibres
(light colour in (a)) and tubulin (light colour in (b)) cytoskeleton protein distributed on a protrusion
region (a and b). AFM height (c) and error images (d) revealing the detailed subcellular
structures of the same region. The Directoverlay TM feature (JPK instrument Ltd) was
employed for image overlay and positioning of the AFM tip, permitting precise location of a
zoomed in region (identified in d). AFM images (e and f) of the zoomed in region, revealing
the filopodial interacting with the underlying nanopatterned structures. AFM imaging was
carried out in contact mode using a silicon nitride cantilever with spring constant 0.01 N m �1 .
40
0 mV