High Throughput Techniques for the Investigation of Cell–Material Interactions - Biointerfaces: Where Material Meets Biology - page 297

d n 3 r 4 n g | 7

Figure 10.18 (A) Schematic for the fabrication of silane concentration gradients

using a confined channel diffusion method; (B) surface chemistry to
generate gradients of RGD and OGD; (C) two-step sequential depos-
ition: following the first silane deposition, the sample was rotated 901,
and then a second silane was deposited.
Figure adapted from Ma et al. 167

substrate and a knife was used to spread the polymer solution over the
substrate by flow coating (Figure 10.19C and D). An annealing temperature
gradient was prepared orthogonal to the polymer composition gradient
through the use of a gradient temperature heat block (Figure 10.19E).
Osteoblast attachment turned out to be greatest near the boundaries of the
polymer islands and at annealing temperatures of

.

110 1C.
Yang et al. 151 prepared a 2D gradient in groove width and surface chem-
istry (from amine to hydrocarbon) (Figure 10.20). The groove width topo-
graphy gradient was prepared by hot embossing, pressing a silicon master
(prepared by reactive-ion etching) into a thin PMMA substrate. A chemical
gradient was prepared by plasma polymerisation orthogonal to the topo-
graphy. 7 Contact angles measured from

B

951
at the hydrocarbon end. Whilst there was little difference in cell attachment
after 1 and 2 days, after 3 days in culture a hot spot was observed for a
contact angle of

B 551 at the amine-rich end to B

50 mm. There was little cell
attachment on the extreme hydrophilic and hydrophobic ends of the gra-
dient regardless of the groove width, suggesting the cells were more sensitive
to changes in the surface chemistry/charge than topography. Another point
to note is that the groove width appeared to influence the alignment of cells
regardless of the surface chemistry for all 1-3 days of culture. The findings
here further highlight the importance of 2D gradient surfaces when in-
vestigating influences on cellular response.
2D gradient samples combining topography and peptide density gradients
were prepared by combining a pSi topography gradient orthogonal to a

B 731 and groove width of B