Signal changes for dye-complexed biomolecular interactions on waveguide-sensor chips

We have previously made several modifications to the sensing chips of waveguide-mode sensors to permit detection of the interactions of several biomolecules at the 50-nM level. We further improved the sensitivity of this sensor by preparing a complex of a colored material with the target biomolecule. By using this strategy, we achieved a detection limit equivalent to 1 nM for the interactions of aptamers with proteins in the presence of Coomassie Brilliant Blue; this corresponds to an approximately fiftyfold increase in sensitivity. For comparison, we also evaluated the sensitivity of our system to another fluorescent dye, Hoechst 33258. These studies delineated the suitability of our color-sensitive sensor chips for the detection of interactions of biomolecules at low concentrations.