06-0097 Cyanine and Mercocyanine Dyes with Improved Photostability

Cyanine and mercocyanine dyes have found widespread use as fluorescent labels for biomolecules. The appeal of these fluorophores derives from their straightforward syntheses, large range of available wavelengths, large molar extinction coefficients and high quantum yields. The cyanine dyes are commonly used for labeling of proteins or antibodies for histochemical studies or in immune-basedassays. Because of the sensitivity of fluorescence intensity and wavelength of mercocyanine dyes to solvent polarity and other aspects of the environment, the mercocyanine dyes are commonly used as sensors of protein activation, protein-protein binding and protein conformational changes.

One major problem encountered by these and any organic fluorophoreis its tendency to undergo photobleaching. Cyanine and mercocyanine dye photobleaching arises from the dye’s reaction with singletoxygen. Dr. Klaus Hahn and colleagues at UNC Chapel Hill have discovered that a substitution in the double chain of mercocyanine or cyanine dyes with a cyano-group or fluorine atom results in a substantial increase in photostability. This increase in photostability is the result of lower reactivity of the substituted dyes towards singlet oxygen.


  • Significantly decreased photobleaching of organic fluorescent dyes
  • Increased capacity for use of dyes in basic research and drug screening

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