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Cyanagen produces RUTHENIUM COMPLEXES for fluorescence polarization assays and fluorescence lifetime imaging applications.
The labels obtained from these complexes are remarkably stable both chemically and photochemically.
They can be used in fluorescence polarization assays, time-resolved immunoassays, ECL immunoassays and to label amines on biomolecules under mild conditions.



  • Chemical and fotochemical stability
  • High fluorescence duration
  • Large Stokes shifts

Cyanagen is the leading manufacturer of ruthenium complexes for fluorescence polarization assays and fluorescence lifetime imaging applications.
d6 Metal ions such as Ru2+, Os2+, Re+ form highly fluorescent complexes with chelating ligands such as bipyridines and phenanthrolines. Additional ligands such as phosphines, nitriles, CO or pyridines can be used to fine-tune their properties and/or for labelling purposes.

The labels obtained from these compounds are remarkably stable both chemically and photochemically and possess unique properties, such as long fluorescence lifetimes (from hundreds of nanoseconds to several microseconds) and very large Stokes shifts. The long-lived fluorescence signal of these labels can be easily distinguished from the short-lived emission from cells and biomolecules, while minimizing dye self-absorption. In addition, for some of these fluorophores, it is possible to use electricity rather than light to elicit a fluorescent signal. This phenomenon, known as ECL (ElectroChemiLuminescence) can be exploited to achieve extremely high signal-to-noise ratios. These probes can be used in fluorescence polarization assays, time-resolved immunoassays, ECL immunoassays and imaging applications.

Longer lifetimes enable both time gated as well as time-dependent measurement. Another important aspect is their utility for polarization assays with high-molecular weight antigens. They can also be used to label amines on biomolecules under mild conditions.

Absorption and emission spectra 

Absorption and Emission Spectra of [(bathophenanthrolinedisulfonate)3Ru(II)]4- ion



Classical labeling methodologies used in immunoassay are based on chemiluminescent or fluorescent molecules, enzymes and radioactive isotopes. An electrochemiluminescence assays (ECL) is an antibody-based test designed to detect the presence of a biological threat agent. In an ECL assay, the presence of an agent of interest creates a complex with two antibodies: one antibody is attached to a magnetic particle, the other antibody, in solution, is modified with a reporter molecule. In the instrument, the antigen/antibody complex is exposed to an electrode, which simultaneously attracts the magnetic bead and stimulates the detection molecule to emit light. The measurement of light is correlated with the presence of the specific antigen.

Metal Complexes 

Analytical methods based on ECL allow today the detection of drugs and biomolecules in a wide range of molecular weights. Through ECL the concentration or the presence of specific proteins and DNA sequences can be accurately monitored. Another area of application has been the tracking of enzymes activity inside living cells. For its advantages over photoluminescence, ECL has been extensively used for immunoassay and DNA analysis.

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