Figure 1. Indirect Fluorescent Immunoassay using Surface Plasmon coupled emission (SPCE).

In this SPCE assay diagram, capture antibodies have been printed on a gold sensor chip which has a holographic diffraction grating. Analyte capture was detected by recirculating an analyte-specific biotinylated secondary antibody and streptavidin-Alexa Fluor 647 over the chip. Fluorophores on the chip were then excited using an LED light source, and a CCD camera detected the resulting fluorescence. In addition to the standard fluorescent excitation shown above, the interaction of the surface plasmon increases the directional fluorescent emission which amplifies this fluorescent signal ~80-fold.