Patterned and switchable surfaces for biomaterial applications
Patterned and switchable surfaces for biomaterial applications
Patterned and switchable surfaces for biomaterial applications
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Andrew Hook – <strong>Patterned</strong> <strong>and</strong> <strong>switchable</strong> <strong>surfaces</strong> <strong>for</strong> <strong>biomaterial</strong> <strong>applications</strong>Otsuka et al., [80] developed a plat<strong>for</strong>m <strong>for</strong> spatially controlled cell growth by<strong>for</strong>mation of a PEG/PLA block copolymer layer by spin coating on glass silanisedwith [3-(methacryloyl-oxy)-propyl]trimethoxysilane. Etching through a photomaskwith a nitrogen <strong>and</strong> hydrogen plasma removed the PEG/PLA layer <strong>and</strong> exposed thesilanised glass. On this plat<strong>for</strong>m, Otsuka et al., [80] were able to demonstrate spatialcontrol of bovine aortic endothelial cells (BAEc), which grew on the exposed glassregions that readily adsorbed proteins including ECM proteins, but not on thePEG/PLA regions where the PEG blocks were effective in resisting proteinadsorption. Interestingly, rat primary hepatocytes were able to grow on both thePEG/PLA <strong>and</strong> the glass regions. Upon prior seeding <strong>and</strong> attachment of BAEc, spatialcontrol of hepatocytes was achieved <strong>and</strong> hepatocyte spheroids grew on the etchedregions carrying an underlying endothelial cell monolayer. A minimum centre-tocentrespacing between etched regions of 200 m was also determined as sufficientto prevent bridging between colonies.Spatially directed cell attachment has also been achieved using a vitronectinmediated, photolithographically <strong>for</strong>med, patterned N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (EDS) <strong>and</strong> dimethyldichlorosilane (DMS) substrate.Spatially directed cell attachment was driven by the preferential adsorption ofvitronectin to the EDS over the DMS [53]. The vitronectin acted as a promoter ofcell growth in the regions it was adsorbed upon. This system sustained cell viability<strong>and</strong> attachment <strong>for</strong> at least 2 hr using human bone-derived cells.Another application of photolithography is <strong>for</strong> on-chip DNA synthesis on DNAmicroarrays. In this technique a light source passes through a mask to direct lightonto localised areas cleaving a photo-labile group <strong>and</strong> activating the site <strong>for</strong> thegrafting of the next DNA nucleotide building block. By changing the photomask <strong>and</strong>1-19
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