Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsremove any unbound polymer, the resultant surface pattern was available forsubsequent formation of an additional microarray deposited on top of the polymerspots or for the seeding of cells that readily attach to the regions modified with aminefunctional polymers, while cell attachment on the underlying PEG coating isprevented. This technique is not limited exclusively to amine functional polymers.By choice of suitable photoreactive crosslinkers, microarrays containing a widevariety of synthetic polymers with diverse chemistries could be formed.4.3.3. Polymer microarray characterisationInitial experiments were aimed at demonstrating that amine functional polymersreacted with NSANB can indeed be covalently bound to the PEG coating in the formof an array of polymer spots. A polymer array set of PAA, PEI, PLL and PVP wasinitially incubated with NSANB at a concentration of 2, 1, 0.5 and 0 mg/ml for 10min. As a negative control, PAA and PVP were also included. The phenylazidederivatised polymers was arrayed onto the PEG coating and subsequently irradiatedwith UV. The array was then subjected to overnight washing in 0.05% Tween20solution at 37 °C with constant stirring to remove unbound polymer. Fluorescencemicroscopy images were taken of the array before and after washing and are shownin Figure 1. The polymer spots are approximately 400 µm in diameter due to the useof a 375 µm diameter spotting pin. Here the fact that these polymers showautofluorescence is utilised [227]. PEI shows strong autofluorescence whilst PAAshowed only weak fluorescence (Figure 4.4A). After washing, the PAA and PVParrays were removed, judging by the absence of fluorescence (Figure 4.4C). This wasexpected as NSANB was not able to react with these polymers due to the absence ofamine groups, thus preventing the formation of covalent linkages between polymers4-143