The Qdot® 565 goat anti-fluorescein conjugate efficiently binds and quenches the fluorescence of fluorescein and Oregon Green® dyes and enables the use of the extremely bright and photostable Qdot® 565 nanocrystal. This antibody enables the use of fluorescein or Oregon Green® dyes as haptens instead of biotin. Unlike biotin, which is an endogenous ligand in mitochondria, dye-based haptens permit background-free staining of cells and tissues and a sensitive alternative to biotin-streptavidin methods.