Non-Contact Measurement of Adsorbed Cytochrome c with Optical Waveguide Spectrometry; The Effect of Distance between Waveguide and Protein on the Spectral Sensitivity

Optical waveguide spectrometry with non-contact conditions was performed with the aim of widening the choice of substrate material. The visible absorption spectrum of cytochrome c (cyt.c) adsorbed on a quartz glass or gold surface was detected with the evanescent wave from a co-faced waveguide. A clear correlation was observed between absorbance of cyt.c and the gap between the waveguide surface and the protein.