SY-9 (QSY®-9 equivalent) is a more hydrophilic version of the popular SY-7 dark quencher (QSY®-7 equivalent). This nonfluorescent acceptor dye is often used for the preparation of peptide FRET probes. A broad and intense quenching range from 500-600 nm makes it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications in conjunction with dyes emitting at 500 nm to 600 nm, such as Fluorescein, Oregon Green, Carboxyrhodamine 110 (Rhodamine Green), Alexa Fluor® 488, 532, 546, 555, 568, Cy3, TAMRA and ROX dyes.
SY-9 Azide can be reacted with terminal alkynes via a copper-catalyzed click reaction (CuAAC). It also reacts with strained cyclooctyne via a copper-free “click chemistry” reaction to form a stable triazole and does not require Cu-catalyst or elevated temperatures.
QSY®-9 is registered trademarks of ThermoFisher Scientific.