Patterned and switchable surfaces for biomaterial applications

Chapter 5 – Surface plasmon resonance imaging of polymer microarraysthickness or refractive index at a particular surface. This feature of SPRi allows therapid, parallel SPR analysis of the adsorption of a particular biomolecule to an arrayof microscale spots under identical environmental conditions. The lateral resolutionof SPRi is limited by the propagation length of the excited surface plasmons, whichis dependent on ε m , η s and w 0 [244]. Under optimised conditions a resolution less than2 m can be achieved [249]. SPRi has been used to monitor many different patternedsurfaces and analyte behaviour including DNA hybridisation [254-256], proteinmaterialinteractions [257], protein-DNA interactions [258], avidin-biotin binding[259], self-assembled monolayer (SAM) formation [242], protein-carbohydrateinteractions [260], antibody-antigen interactions [261, 262], electropolymerisation oforganic films [263] and small molecule-protein interactions [245]. However,presently SPRi is limited to imaging uniform surface coatings [245, 246].5.3. Materials and methods5.3.1. Substrate preparationSPR chips (SPR-1000-050, GWC Technologies) with a gold coating of 45 nm onSF10 glass were used as received.Poly(ethylene glycol) (PEG) coatings were prepared as follows. Initially, SPRchips or glass slides were coated by plasma polymerisation in a custom-built reactordescribed elsewhere [182]. In short, the plasma reactor consisted of two circularelectrodes separated by 12.5 cm in a cylindrical reactor being 35 cm high with adiameter of 17 cm. Allylamine (Aldrich, 98% purity) was used as a monomer.Allylamine plasma polymer (ALAPP) deposition conditions used were a frequencyof 200 kHz, a power of 20 W and an initial monomer pressure of 0.200 mbar. The5-162