Streptavidin-R-Phycoerythrin (R-PE) is used to label biotin-conjugated (biotinylated) molecules and biotin derivatized surfaces in a wide variety of immunofluorescence applications such as immunochemistry and histochemistry. Streptavidin-R-Phycoerythrin may be used in the development of bioassay devices such as Lab-on-a-chip (LoC) systems and microarrays.