Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsAPPENDIX 2.AFM FORCE CURVES OF CROSS-LINKEDPOLYMER ARRAYS9.10.A2.1. IntroductionSurface modification has become of increasing importance for a wide range ofapplications. Techniques to modify the outer surface of a material whilst notcompromising the materials bulk properties or integrity are of interest. Of particularinterest are patterned surfaces that are able to offer spatial control over the behaviourof biomolecules at a particular surface. Surface patterning may incorporate bothchemical and topographical features, and can be achieved by a wide range ofapproaches including photolithography, soft lithography, robotic printing,microfluidics and microelectronics [66, 74-77, 79, 133, 197, 214]. A significantoutcome of the development of microfabrication is microarrays. DNA and proteinmicroarrays have revolutionised genomic studies and continue to bring considerableinsight ubiquitously in medical science [98, 127, 135, 309]. Development ofpatterned surface chemistry that precisely match the surface patterns of microarrayscould increase microarray capabilities by allowing higher densities by minimisingthe required separation between adjacent spots, and higher signal to noise ratios byincorporating low-fouling surfaces that minimise non-specific binding. This is ofparticular interest for microarrays containing living cells [1, 45].The formation of a patterned surface, as described in CHAPTER 4, is of particularsuitability for DNA microarray applications. Initially a polycationic polymer havingbioactive properties is functionalised with a phenylazide cross-linker then arrayedonto a low-fouling surface and UV cross-linked to form a covalently linked polymerC