Although DABCYL has been used to develop a variety of FRET applications, its low quenching efficiency of longer wavelength dyes (such as fluoresceins, rhodamines and cyanines) has limited its use in the development of sensitive fluorogenic FRET probes. Additionally, the absorption spectrum of DABCYL is environment-sensitive. AAT Bioquest has developed the robust Tide Quencher™ acceptor dyes for the development of longer wavelength FRET probes. These Tide Quencher™ dark FRET acceptors (such as TQ1, TQ2, TQ3, TQ4, TQ5, TQ6 and TQ7) are optimized to pair with our Tide Fluor™ dyes and the classic fluorophores (such as AMCA, EDANS, FAM, TAMRA, HEX, JOE, TET, ROX, Cy3, Cy5 and Cy7). Like our Tide Fluor™ donor dyes, our Tide Quencher™ acceptor dyes are much more cost-effective with comparable or even better performance for your desired biological applications than other similar products on the market.

Besides their broad applications in the development of Molecular Beacon probes, our Tide Quencher™ dyes have also been used to develop various protease substrates such as HIV protease, MMPs and secretases. In some cases, they have demonstrated greatly improved enzyme performance. This may be partly due to the red-shifted absorption spectrum that overlaps better with the emission spectrum of fluoresceins, rhodamines and cyanines. Tide Quencher™ dyes are a great choice for you to eliminate the limitations of classic quenchers. Tide Quencher™ dyes are excellent dark quenchers that are individually optimized to pair with all the popular fluorescent dyes such as fluoresceins, rhodamines and cyanines. Our Tide Quencher™ series of nonfluorescent dyes cover the full visible spectrum with unusually high efficiency. TQ2 has absorption maximum perfectly matching the emission of FAM while TQ3, TQ5 and TQ7 are proven to be the best quencher for Cy3, Cy5 and Cy7.

FRET can be detected either by the appearance of sensitized fluorescence of the acceptor, by the intensity ratio change of donor/acceptor (if the acceptor is fluorescent), or by the fluorescence decrease of the donor. In the later case, acceptor can be either fluorescent or non-fluorescent. Table 4.1. summarizes our Tide Quencher™ FRET building blocks designed to develop FRET probes for the demanding applications. Based on our in-house research and experience, it is recommended to use the FRET pairs marked in green. The pairs marked in light blue are OK to use, but less efficient. We have proved that these recommended FRET pairs have demonstrated high sensitivity and low background in our protease and nucleic acid detection assays. There are also other factors that you need to consider besides the FRET efficiency, such as pH, multiplexing and buffer interference, etc.