Patterned and switchable surfaces for biomaterial applications

Chapter 5 – Surface plasmon resonance imaging of polymer microarraysinhomogeneous refractive index. A method was, therefore, devised to comparablyand simultaneously conduct SPR measurements of a polymer microarray, containingspots of varied thickness and refractive index. This approach was used to investigatethe kinetics and thermodynamics of bovine serum albumin (BSA), fibronectin (FN)and collagen (CN) type I adsorption on the polymer microarray spots. In addition,cell attachment to the polymer spots was also investigated.5.2. Theory behind surface plasmon resonance imagingSPR reflectivity measurements enable the determination of the thickness orrefractive index (η) of a thin organic or biopolymer film in real-time with a highdegree of surface sensitivity [247, 248]. This has allowed for measurements inchanges in the refractive index or thickness of the film, which in turn has permittedthe monitoring of biological interactions such as antibody-antigen binding, DNAhybridisation and protein-DNA interactions [248]. A typical SPR experiment isconducted by illuminating a noble metal coating (silver, gold or copper) by p-polarised light (electric field vector oscillating parallel to the plane of incidence) toexcite surface plasmons (charge-density waves that propagate parallel to aninterface) when the sign of the real part of the dielectric constant of the two materialsat the interface is opposite, for instance, a metal and a dielectric [248-250]. Theexcitation of surface plasmons results in a loss of energy from the incident beam anda decrease in the intensity of the reflected light, which can be monitored [247].5-158