Manipulation of Fibrin
Fiber is broken off the surface, stretched, then ruptured, using an AFM tip.
It appears that a small piece of the fiber was detached when the fiber
ruptured. These images were produced by the NanoManipulator program, by adding a
colormap and rulergrid to the standard height-field view.
Notice the correspondence between the force peaks in the graph and the size
of the fiber after the manipulation. The first peak is attributed to detaching
the fiber from the substrate, and the second peak shows the force increasing as
the fiber is stretched tight, then decreasing when the fiber ruptures. The
NanoManipulator captures lateral-force data like this by default. These
manipulations were performed using a the poly-line tool, in which the user plans
the path of the manipulation by using the Phantom to feel the shape of the
sample, and places markers to designate the path. Then the NanoManipulator moves
the tip automatically, and the smooth motion produces reliable lateral-force
data.
This graph shows the behavior of all the fibers measured, and the best fit
shows behavior similar to an inhomogeneous cylinder.
Fiber 2: After rupture, the fiber moves back towards it's original position
when the AFM tip is removed. This elastic behavior was observed several times.
More details can be found in these two references:
1. Guthold, M., Falvo, M. R., Matthews, W. G., Paulson, S., Washburn, S., Erie, D., Superfine, R., Brooks,
F. P. & Taylor, R. M. (2000). Controlled Manipulation of Molecular Samples with the nanoManipulator.IEEE/ASME Transactions on
Mechatronics. 5, 189-198
2. Guthold, M., Falvo, M., Matthews, W. G., Paulson, S., Mullin, J., Lord, S., Erie, D., Washburn, S.,
Superfine, R., Brooks, F. P. & Taylor, R. M. (1999). Investigation and Modification of Molecular Structures Using the NanoManipulator. J Mol. Graphics Mod. 17,
187-197
All images and scientific content are courtesy of Martin Guthold and
the University of North Carolina at Chapel Hill.
