The present invention relates to novel fluorophores and their use in combination with novel nucleic acid molecules, called aptamers, that bind specifically to the fluorophore and thereby enhance the fluorescence signal of the fluorophore upon exposure to radiation of suitable wavelength. Molecular complexes formed between the novel fluorophores, novel nucleic acid molecules, and their target molecules are described, and the use of multivalent aptamer constructs as fluorescent sensors for target molecules of interest are also described.
