In contrast to RIfS, the interference spectroscopy under total reflectance (TRIS) employs a light source that illuminates the transducer and its sensitive layer not vertically, but under an angle of total reflectance. Using this setup, a maximum of reflectivity is gained at the interface (bio)polymer/solvent (or air). However, the formation of an interference spectrum requires the existence of a second reflective layer at the interface glass/(bio)polymer. Therefore, the glass transducer is coated with an additional layer of a few nanometers of chromium. The advantage of TRIS with regard to RIfS is the much higher intensity of the detected light, as all the irradiated light is reflected and can be used to detect the measuring signal.
The currently developed setup is optimized for measurements on a lying drop (stop flow). Therefore, the observed kinetics only depends on the diffusion processes of the analyte molecules within the liquid drop and the interaction between the analyte and the sensitive layer, in an ideal case. Several optimizations of the setup, especially optimizations of the composition of the reflective layers, have been undertaken. With the optimized setup, the adsorption processes of proteins to polystyrene layers have been observed in a time-resolved manner.
Literature
- Kerstin Nötzold et al., Anal. Bioanal. Chem. 2008, 391(5), 1739-1749
