Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationschannels flowing over a substrate surface. Cells were then trapped by irradiation ofthe channels with UV light through a photomask which resulted in cross-linking ofthe hydrogel. Subsequent removal of the microfluidic assembly left a patterned arrayof a multi-phenotype cell array. This system was able to sustain cell separation ofmurine fibroblast, murine hepatocytes and murine macrophages, keeping differentcell types apart down to micron-size separation distances.Patel et al., [74] produced a patterned culture of BAEc and pheochromocytoma(PC12) using microfluidics. A PDMS mould was formed containing grooves whichformed microchannels when put in contact with a substrate. This enabled the spatialcontrol of solvent flow over the surface. The substrate used was a film of PLA-PEGblock copolymer modified with biotin. Flow of avidin over the film through themicrochannels produced spatially activated regions on the substrate. Biotinylatedpeptides containing the RGD peptide or a laminin fragment were subsequentlyflowed through the microchannels to produce a surface conducive to cell attachment.Removal of the PDMS mould and seeding of the cells on the activated surfaceresulted in preferential attachment of the cells to the modified regions.Takayama et al., [75] developed a method of cell patterning using combinedlaminar flows through capillary networks. In one experiment Escherichia coli (Ecoli)was patterned to a surface by prepatterning a surface with a mannose containingprotein (Figure 1.4A). Mannose was chosen because the cell membrane of E-coli isdecorated with mannose-binding proteins. Subsequent incubation of E-coli with thepatterned surface caused the adsorption of E-coli to the mannose-coated regions(Figure 1.4B). This technique also enabled the surface patterning of eukaryotic cellsand proteins.1-25