Molecular tripods showing fluorescence enhancement upon binding to streptavidin

We introduce a new approach to biotin-streptavidin assays based on a molecular tripod which consists of biotin, a fluorophore, and a quencher. The interaction between streptavidin and molecular tripods perturbs the ground-state quencher-fluorophore dimeric conformation in the absence of streptavidin and diminishes the intrinsic self-quenching of a quencher-fluorophore pair. The emission intensity of the molecular tripods plus streptavidin is 3.5-5.2 times that of molecular tripods in the absence of streptavidin.