DRAQ7 has many applications and is highly compatible with existing protocols across a wide range of instrumentation platforms.
- Rapid staining of dsDNA/nuclei of dead or permeabilized cells
- Combination with live cell dyes for dead/live discrimination
- Easy to use - no wash, no RNase needed
- Ideal for use with GFP & FITC labels - DRAQ7 fluoresces in the far-red region
- DRAQ7 is an ideal far-red DNA counterstain for IF/IHC, high content screening and cell-based assays
- Fluorescence emission from 665 nm into the low infra-red
- Suggested optimal emission filters include 695LP, 715LP or 780 LP
- Optically compatible with benchtop flow & laser scanning cytometers and epifluorescent & non-UV confocal microscopes
- Useful excitation at sub-optimal wavelengths from the 488 nm, 568 nm and 633 nm lines, plus optimal 647 nm excitation. No UV excitation, unlike propidium iodide.
- No compensation needed with common FITC/GFP + PE combinations in flow cytometry. Can be combined with many live cell dyes.
- Allows multi-line imaging/cytometry when combined with UV & vis. range fluorochromes
- No apparent fluorescence enhancement upon binding to DNA
- Photobleaching not normally observed
The graphs below show standard absorbance and fluorescence emission spectra for DRAQ7 in aqueous solution for a range of different excitation wavelengths. As can be seen, DRAQ7 can be effectively excited by 488nm systems. In these circumstances, we recommend that a long band pass filter be used - to capture as many emitted photons as possible.
- 633 & 647 nm line optimal (Exλmax 599/644 nm)
- 488, 514 and 568 lines, sub-optimal (only by flow cytometry)
- >665 nm to infra-red >800 nm (Emλmax 678 nm / 694 nm intercalated with dsDNA)
- Minimal overlap with visible range e.g. GFP and FITC
- Emission filters may include 695LP, 715LP, 725 BP 20 or 780 LP
DRAQ7 enters and labels only membrane-compromised cells.
The flow cytometric data below shows apoptosis (compromised membranes permitting entry of DRAQ7) of human Jurkat cells exposed to 0.1 - 2.0 µM staurosporine for 24h compared to negative controls.
DRAQ7 can be used in flow cytometric analysis to mark membrane-compromised cells, in combined with reagents such as Annexin V, mitochondrial membrane probes and other reporters of cell health. Live, intact cell impermeant DNA dyes are commonly combined with Annexin V (which reports membrane inversion) to give information about the progression of apoptosis. As shown in the figure below, DRAQ7 (top & middle series) performs in an equivalent manner to propidium iodide (PI, bottom series), to report the onset of membrane leakiness caused by increasing doses of VP-16. Plus, DRAQ7 offers new possibilities as a far-red, non-enhancing DNA binding dye. Using both log and linear displays, further discrete sub-populations can be identified. Also, unlike PI, DRAQ7 will permit several fluorescent parameters to be measured in parallel; 4 with blue laser excitation.
DRAQ7 can be used in apoptosis assays, cytotoxicity assays, cytolytic antibody testing, cell health assays.
Due to its far-red emission signal, DRAQ7 can be easily combined with multiple other fluorophores; up to 4 using the single 488 nm excitation source (argon-ion laser).