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Qdot 705 probe is an excellent near-IR–fluorescent label with outstanding brightness and photostability for imaging and flow cytometry applications. With an emission maximum of ~705 nm, Qdot 705 probe can be excited using a laser line from 350 nm up to 633 nm or a standard Cy5.5 filter. Optimum imaging results with brighter signals are achieved with a Qdot 705 filter or light cube.
Made from nanocrystals of semiconductor material, Qdot probes are broadly compatible with standard fluorescence techniques, but there are some novel aspects to their use that can be optimized to obtain the best possible results. In general they have an extremely broad excitation range and narrow emission with a large Stokes shift. Optimal brightness is generally achieved using a specific Qdot filter.
Organic fluorophores and Qdot probes can be readily combined in multiplexed flow cytometry or imaging studies. Longer-wavelength Qdot probes are also ideal for multiplexed western blots.
Initial brightness | For best results use a Qdot-optimized filter and PBS or a mounting medium without antifade.
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Photostability in buffer |
18 | 350 or 633 | Cy5.5 | UV | 705 |
Stain index | Laser line | Common filter set | Excitation max | Emission max |
The exceptional brightness and photostability of Qdot probes make it easier to detect low-abundance targets. With narrow and symmetric emission spectra, Qdot probes are also ideal for multiplexed fluorescence detection using a combination of Qdot probes and organic dyes.
Histogram overlay of human leukocytes labeled with CD10 Mouse Anti-Human (clone MEM-78) Qdot 705 Conjugate.
The black line represents cells from the granulocyte gate and the grey line represents cells from the lymphocyte gate. Sample was acquired and analyzed using 405 nm excitation and a 695/40 band pass emission filter using the Attune Acoustic Cytometer Blue/Violet option.
We’ve developed functionalized versions of the Qdot 705 label for the preparation of custom conjugates of proteins and other biomolecules. The first—a carboxyl-derivatized form—can be coupled to amine groups of proteins and modified oligonucleotides. The second—an amine-derivatized PEG form—can be coupled to isothiocyanates and succinimidyl esters (or with native carboxylic acids using water-soluble carbodiimides).
Amine | Aldehyde-, ketone, carboxylate or phosphate |
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Qdot Probes are made from nanocrystals of semiconductor material and are broadly compatible with standard fluorescence techniques, but there are some novel aspects to their use that can be optimized to obtain the best possible results.