Patterned and switchable surfaces for biomaterial applications

Chapter 4 – Formation of a chemically patterned substrate for cell microarray applicationsmicroarray. Such an approach was demonstrated, as illustrated in Figure 4.1, andallows the facile patterning of almost any base surface chemistry with a large varietyof different polymer chemistries.In this chapter, polymers of interest were modified with a crosslinker containing aphotoactivatable phenylazide group. The modified polymers were then arrayed ontoa low fouling coating and UV irradiated to crosslink the arrayed polymers to theunderlying surface coating (Figure 4.1). The low fouling background was formed byinitially coating a glass substrate with a thin plasma polymer film utilising allylamineas a monomer to introduce amine functionality that could subsequently be used tograft a high density poly(ethylene glycol) (PEG) brush to the surface. In the case ofend-point grafted PEG, it has been found that the PEG coating provides an interfacialbarrier that prevents proteins from interacting with the underlying substrate, which isconcomitant with resistance to cell attachment. Therefore, the molecular weight andinterfacial graft density of PEG chains are important parameters to enable lowfouling properties of the coating [66, 67]. The resultant PEG coatings have beenshown to resist protein adsorption, DNA adsorption and cell attachment [84, 188,197].Specifically, this approach enables the formation of a surface pattern consisting ofislands, where cell attachment is promoted, on a low fouling background surface.This method further allows the formation of a library of polymers in an array format.Moreover, since patterning is readily achieved using a robotic spotting device, thesurface patterns formed can be used for the subsequent deposition of biomoleculearrays, thus, enabling chip-based, high density cell assays.4-132