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Classic Dark Quenchers
Classic dark quenchers—including DABCYL, DNP, QXY, and AzoDye families—are non-fluorescent acceptor molecules that suppress donor fluorescence through energy transfer and/or contact quenching mechanisms without emitting light themselves. These established chemistries were some of the earliest available for FRET-based assays, offering well-tested, though sometimes limited, performance for molecular beacons, TaqMan® probes, and protease substrates.
AAT Bioquest offers a comprehensive selection of classic quenchers in versatile reactive forms (NHS esters and maleimides) as well as bioorthogonal azide and alkyne derivatives, and as FMOC-protected amino acid building blocks for solid-phase peptide synthesis. We also offer a family of dark quenchers, known as Tide Quenchers™, that are designed to provide improved water solubility, quenching efficiency and spectral versatility compared to many classic quencher chemistries.
Quencher | Abs Max | Best Donor Fluorophores | Key Features | Applications |
|---|---|---|---|---|
DNP | ~360 nm | Trp, Tyr | Dual-function: quencher + hapten tag recognized by anti-DNP antibodies | Hapten tagging, immunoassays |
DABSYL | ~460 nm | Lucifer Yellow | Sulfonyl chloride reactive group; highly stable derivatives | Amino acid labeling, protease substrates |
DABCYL | ~470 nm | EDANS, coumarin, blue fluorophores | Most widely used classic quencher; gold standard EDANS/DABCYL FRET pair | FRET peptides, molecular beacons |
AzoDye-1 | ~534 nm | FAM, HEX, TET, NED, JOE | BHQ-1 equivalent; superior quenching vs DABCYL for green dyes | qPCR probes, molecular beacons (green) |
QXY7 | ~550 nm | Cy3, TAMRA, Alexa Fluor 555, iFluor 555 | QSY-7 equivalent; no detectable fluorescence | FRET probes with orange/yellow donors |
AzoDye-2 | ~580 nm | TAMRA, ROX, Cy3, Cy3.5 | BHQ-2 equivalent; broader quenching range than AzoDye-1 | qPCR probes, multiplex assays |
QXY21 | ~661 nm | Cy5, Alexa Fluor 647, iFluor 647 | QSY-21 equivalent; no detectable fluorescence | Molecular beacons (red), NIR FRET |
AzoDye-3 | ~670 nm | Cy5, Cy5.5, DyLight 647, Alexa Fluor 647, iFluor 647 | BHQ-3 equivalent; far-red/NIR quenching | Molecular beacons (red), NIR FRET |
Available Classic Dark Quenchers
This document (01.0197.251203r1) was last updated on Thu Feb 12 2026. All trademarks and registered trademarks mentioned herein are the property of their respective owners.
Classic Dark Quenchers