Biomedical Engineering Reference
In-Depth Information
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Figure 2.11
Average number of dorsal rat ganglia cells adhered on various peptide-
modified surfaces using a base hydrogel. The two columns to the left
represent values for pure polymers whereas those to the right are for
peptide modified hydrogels.
(Reprinted by kind permission of Elsevier, BV.)
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standard surface ethyl(dimethylaminopropyl) carbodiimide-N-hydroxysuccin-
imide (EDC-NHS) activation chemistry. (The chemistry behind the latter is
outlined in Chapter 1.) NMR spectroscopy was employed to ascertain the
composition of the resulting hydrogel. Following exposure to ultraviolet (UV)
light in order to create cylindrical channels, GRGDS oligopeptides could be
attached and concentrated within the channels; the latter are shown in
Figure 2.12. The next step was to allow the UV/peptide-modified hydrogel to
interact with neural cells derived from rat dorsal root ganglia, the idea being to
examine the possibility for peptide-guided neurite growth following cell
migration within the channel volumes. The remarkable result was obtained that
the GRGDS gradient across the x-y plane of the biochemical channels affected
neurite outgrowth such that neurites extended preferentially up the concen-
tration gradient towards the central core of the peptide channel. The authors
pointed out that the result constituted the first time that guided neurite in such
a fashion had been achieved.
A similar approach was used by Hynd and co-workers
40
with respect, also, to
directed cell growth on a hydrogel. In this case the hydrogel was based on
photo-polymerized acrylamide. The attachment of biotin-tagged ECM proteins
to the hydrogel was achieved by co-polymerization of the polymer with
streptavidin. Micro-contact printing was used to pattern the proteins such as
laminin on the hydrogel surface. It was observed that both LRM55 astroglioma
