Biomedical Engineering Reference
In-Depth Information
d n 4 t 3 n g | 0
Figure 2.12 A representative longitudinal image of green, fluorescently labeled
oligopeptide channels constructed from a series of XY cross-section
micrographs taken at 20 mm intervals over a depth of 0.5mm (contrast
adjusted to clearly view the isolated regions).
(Reprinted by kind permission of the Institute of Physics Publishing.)
n 3 .
and primary rat hippocampal neurons adhered to areas patterned with biotin-
conjugated proteins. Fluorescence and bright-field modes of microscopy were
used to measure cell morphology on modeled surfaces. LRM55 cells were
found to attach to protein-stamped regions of the hydrogel only.
There have been a number of other studies of ECM proteins attached to
polymers of various types, but particularly hydrogels, and these are reviewed in
ref. 41.
A more orchestrated approach to look at cell attachment to ECM proteins
and peptides has been the use of spatially modified substrates such as glass and
silicon (the field being beautifully reviewed in ref. 42). The idea that the surface
spacing of ECM-based RGD peptides is important in terms of cell adhesion
dates back to the 1990s. 43 In this early work the synthetic peptide
Gly-Arg-Gly-Asp-Tyr (GRGDY) was attached to a glass surface with different
concentration of peptide being employed to purportedly 'space out' the
molecules on the surface. Using fibroblasts it was shown spreading of cells
occurred at a minimum spacing of 440 nm, whereas focal contact formation
occurred at 140 nm. Although these results on a two-dimensional (2D)
substrate indicated the importance of peptide spacing, it should be emphasized
that little or no surface characterization was included in the experiments. 43
Much later, a more rigorous experiment was published in which nano-
patterning of RGD peptides was employed to study cell spreading. 44
Copolymers in micellar structural form contained gold nanoparticles which
were then deposited on glass slides. The polymer was removed for this system
 
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