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RuLabels

phosphorescent ruthenium probes for polarization assays

Active Motif Chromeon RuLabels are phosphorescent ruthenium probes that emit strongly polarized light with a long decay time (between 400 ns and 5 µs). These properties make possible a wide range of detection methods including intensity, decay time (lifetime) and FRET-based measurements.

Anisotropy measures the degree of polarization of emitted light from a molecule after it has been excited by polarized light. Small molecules, and those that are freely rotating in a solution, have low anisotropy compared to larger molecules, or to molecules that are bound. Thus, anisotropy can be used to deduce information about a labeled molecule's microenvironment. The differences in anisotropy between a bound and a free molecule can be used to develop a variety of useful assays that measure this change in physical state. Measuring anisotropy is also advantageous in assays that have high background because it provides a simple way to exclude the background noise from the "real" data. The strong polarized light and long decay time of Active Motif Chromeon RuLabels enable you to develop a variety of immunoassays that measure the anisotropy of molecules, such as the binding of antibodies or proteins to their target molecule.

Active Motif Chromeon RuLabels can serve as precursors for membrane probes, especially those obtained by reactions with phospholipids, amino modified cholesterols or amino modified long alkyl chains. These membrane probes have been shown to be useful tools for the determination of membrane viscosity, membrane phase transitions and cholesterol dependent membrane phase transitions via fluorescence polarization.

Active Motif Chromeon offers a full line of chemically activated ruthenium probes for conjugation to a variety of biomolecules:

Active Motif Chromeon RuLabels are soluble in water, ethanol and methanol, and are moderately soluble in chloroform. The absorption maximum is 458 nm, while the emission maximum is 622 nm.

Figure 1: Structure and spectral properties of Active Motif Chromeon RuLabels.

RuLabel Advantages

• Long decay times
• Large Stokes shifts
• Flexibility of conjugation to biomolecules
• Various solubilities for use in different solvents

Contents & Storage

All Dyes are supplied lyophilized and are available as a reactive NHS-Ester or a carboxylic acid. Guaranteed stable for 6 months when stored in the dark at 4°C.