Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applications(A)(B)(C)Figure 5.1. (A) The Kretschmann configuration for SPR measurements. Light iscoupled at a specific angle of incidence into a glass prism, which has oneface coated by a metal. The evanescent light wave produced at the totalinternal reflectance event excites surface plasmons at the metal/dielectricinterface. This event can be detected by measuring changes in the intensityof the reflected light. Changes in the dielectric properties of the dielectricmaterial in contact with the metal surface, such as the adsorption ordesorption of a biomolecule, alter the excitation of the surface plasmonsproducing a change in the intensity of the reflected light. Conducted at afixed angle over time, this allows the measurement of biomolecularadsorption in real-time, producing a sensorgram of reflectivity over time asshown in (B). Here a biomolecular adsorption event resulted in a shift inreflectivity from I to II. If reflectivity measurements were taken for variedangle of incidence before and after the adsorption event a shift in theresonance angle, at which reflectivity is minimised, would be observed, asshown in (C) with a shift in the reflectivity versus angle of incidence curvefrom I to II.5-159