High Throughput Techniques for the Investigation of Cell–Material Interactions - Biointerfaces: Where Material Meets Biology - page 299

c(RGDfK) density gradient on the same substrate were created by Clements
et al. 108 The orthogonal gradient platform revealed that rMSCs respond more
favourably to changes in c(RGDfK) density than to changes in pore size. In
these experiments, since the same apparatus is used for the preparation of
both gradient surfaces, generation of 2D gradients is arguably more straight-
forward than other reported 2D gradient methods. The 2D format illustrates
that surface-bound gradients are useful for the combinatorial screening of
cell-material surface interactions where one can optimise the effects of vary-
ing two surface properties in regard to the cellular response on a single sample
and in a single experiment. Additionally, this study highlights the importance
of screening multiple factors that influence cellular response simultaneously.

d n 3 r 4 n g | 7

10.2.6 Two-dimensional Topography Gradients
Recently, several groups have developed 2D topography gradients. 238-240
Zink et al. 238 developed micro-roughness and particle nano-roughness
density gradients (Figure 10.21A). Roughness gradients were prepared via

.

Figure 10.21 Examples of two topography vs. topography gradients: (A) micro-
roughness versus nanoparticle nano-roughness (i) schematic of 2D
gradient, (ii) graph showing osteopontin expression (indicator for
osteogenesis); (B) groove pitch vs. depth, (i) schematic of 2D gradient,
(ii) cell response of fibroblasts, epithelial cells and endothelial cells
with heat maps (d, h, l) showing optimum surface properties on 2D
gradients for epithelial and endothelial cells.
Figure adapted from Reynolds et al. 239 and Zink et al. 238