Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applications5.4.4. Assessment of cell attachment to polymer arraysFurther to the SPRi analysis of biomolecular adsorption to a polymer microarray,PAAc, PEIc and PLLc arrays on the HDI PEG coated surface were subjected to cellattachment assays. SK-N-SH neuroblastoma cells were seeded onto the polymerarray and after 24 hr were stained using Hoechst 33342 and observed by fluorescencemicroscopy. This cell line was used as they are known to be highly adhesive to manydifferent surfaces, thus, presenting a good model for studying cell adhesiveproperties [228]. The resultant cell patterns are shown as Figure 5.17. Cellattachment was observed on PEIc and PLLc as determined by the large number ofcells aligning with the underlying polymer array as compared with the low cellnumbers on the PEG background (Figure 5.17B and C). Thus, PEIc and PLLcpromoted neuroblastoma cell attachment. PEG is well known in its ability to resistcell attachment and protein adsorption, thus, low cell attachment on this layer wasexpected [65, 67, 84], whilst, the presence of amine groups has previously beenshown to promote cell attachment, particularly with neuronal cells [299]. Conversely,cell attachment was poor on the PAAc (Figure 5.17A). Interestingly, an even lowercell density was observed on these polymer spots as compared with the underlyingPEG coating. Cell attachment inhibition by PAA has been previously reported for anumber of different cell types [300-303]. This contrasts with the low-density graftingof PAA, which on some substrate surfaces is able to improve cell attachment bytuning the surface wettability to be more suitable for cell attachment [304, 305].However, in the present case, PAA surface density is sufficiently high to repel cellattachment by electrostatic repulsion with the negative charge on the cell membrane[300-303].5-203