Cyanine fluorophore derivatives with enhanced photostability

Conjugation of triplet-state quenchers to the small organic cyanine fluorophore, Cy5, increases photostability without affecting its spectral characteristics. This allows longer fluorescence imaging with a concomitant reduction in blinking both in vitro and in living cells. Fluorescence applications requiring high photostability often depend on the use of solution additives to enhance fluorophore performance. Here we demonstrate that the direct or proximal conjugation of cyclooctatetraene (COT), 4-nitrobenzyl alcohol (NBA) or Trolox to the cyanine fluorophore Cy5 dramatically enhanced fluorophore photostability without otherwise affecting its native spectral characteristics. Such conjugation is a powerful means of improving the robustness of fluorescence-based applications demanding long-lived, nonblinking fluorescence emission.