Patterned and switchable surfaces for biomaterial applications

Chapter 4 – Formation of a chemically patterned substrate for cell microarray applicationsto the underlying surface. Another study arrayed monomers of interest with aninitiator that upon UV irradiation instigates the in situ polymerisation of polymermaterial to form rigid polymer spots cross-linked to the substrate surface [145, 146].This polymer microarray has been utilised to study the influence of surface chemistryon transfection [219]. However, this approach is limited to the formation of highlycrosslinked, randomly ordered polymer networks, the structure of which may bedifficult to characterise and replicate at a larger scale.Cell microarrays have also been widely utilised for the formation of transfectedcell microarrays (TCM), which utilise reverse transfection to form locally transfectedcells within a lawn of cells seeded onto a microarray of DNA vectors of interest [1,8]. Typically, a TCM is formed by firstly forming an array of DNA or RNA vectorsof interest. Cells are then seeded onto the array for the formation of a lawn of cellssuch that cells attached onto arrayed spots will take up the arrayed vectors andexpress or silence the genes of interest. Recently, use of recombinant adenovirusbased transfection systems allows for the use of primary cells with TCMs [169]. Asignificant challenge for this type of cell array is the prevention of crosscontaminationbetween the spots and the outgrowth of cells from spots of interest.Therefore, researchers desire cell attachment to be limited to the arrayed spots, whilstthe area in between the spots prevents cell attachment. This can only be achieved bysurface patterning, introducing cell adhesive regions within a background thatprevents protein adsorption and concurrently cell attachment, termed ‘low fouling’[67]. A chemical or physical pattern regulating the growth of cells can be generatedusing a range of lithographic techniques including photolithography, softlithography, microfluidics and microelectronics (see section 1.2) [66]. However, allof these techniques require microfabrication tools that are not always readily4-130