Fluorescent Quenchers
Fluorescent quenchers efficiently absorb the emission energy of nearby fluorophores. Qihe Biotech offers a full-spectrum quencher portfolio for qPCR probes, molecular beacons, FRET assays, and more.
Quenching Mechanisms
FRET (Förster Resonance Energy Transfer)
The donor fluorophore transfers energy to an adjacent quencher via long-range dipole–dipole interactions. Effective distance: 10–100 Å; depends on spectral overlap and separation distance.
Static Quenching
The fluorophore and quencher form a non-fluorescent ground-state complex, directly suppressing fluorescence emission without dependence on molecular diffusion.
Contact Quenching
At very close range (<10 Å) the fluorophore and quencher quench via electron transfer or proton coupling — more efficient than FRET.
Quencher Types
Black Hole Quencher (BHQ)
Broad-spectrum absorber with no intrinsic fluorescence; covers 480–730 nm; widely used in qPCR probes.
Dabcyl
Classical azo quencher; absorption maximum ~453 nm; suitable for blue/green fluorophores (EDANS/FAM).
TAMRA
Tetramethylrhodamine quencher with intrinsic fluorescence; absorption maximum ~565 nm; classic molecular beacon quencher.
QSY Series
Long-wavelength dark quenchers covering 500–750 nm; compatible with Cy3/Cy5/Alexa Fluor series.
Selection Guide
| Quencher | Absorption range (nm) | Matched fluorophore(s) | Recommended application |
|---|---|---|---|
| BHQ-1 | 480–580 | FAM, TET, JOE | qPCR probes |
| BHQ-2 | 550–650 | HEX, TAMRA, ROX | Multiplex qPCR |
| BHQ-3 | 620–730 | Cy5, Alexa 647 | Near-infrared probes |
| Dabcyl | 400–500 | EDANS, FAM | FRET substrates |
| TAMRA | 530–590 | FAM, TET | Molecular beacons |
| QSY-7/QSY-9 | 500–600 | Cy3, Alexa 555 | Immunofluorescence |