Qdot® 800 probe is an excellent near-IR–fluorescent label with outstanding brightness and photostability for imaging and flow cytometry applications. With an emission maximum of ~800 nm, Qdot® 800 probe can be excited using any laser line from 350 nm up to 633 nm or a standard Cy®5.5 filter. Optimum imaging results with brighter signals are achieved with a Qdot® 800 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.

Qdot® 800 Probe dashboard

Initial brightness



For best results use a Qdot®-optimized filter and PBS or a mounting medium without antifade.



Photostability in buffer


  633 Cy®5.5 UV 800  
Laser line

Common filter set

Excitation max

Emission max

Qdot® 800 Products

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 (gated) of human monocytes with CD38 Mouse Anti-Human mAb (clone HIT2) Qdot® 800 Conjugate.

Histogram overlay plot of gated human monocytes, the black line represents cells labeled with CD38 Mouse Anti-Human mAb (clone HIT2) Qdot® 800 Conjugate and the gray line represents unstained cells. Samples were acquired and analyzed using 405 nm excitation and a 780/60 band pass emission filter using the Attune® Acoustic Cytometer Blue/Violet option.

Qdot® 800 Conjugation Kits

We’ve developed functionalized versions of the Qdot® 800 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

Qdot® Probes and Accessories

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. Learn more about Qdot® Probes:


Molecular Probes® Handbook

Molecular Probes HandbookThe significantly revised 11th Edition is the most complete fluorescence labeling and detection reference available. The Molecular Probes® Handbook can help you achieve the best experimental results for your fluorescence labeling and detection experiments. View the handbook online or order your own copy.


Antifades and mounting media

Antifade reagentsHigh-performance antifade reagents like ProLong® Gold and SlowFade® Gold will inhibit the photobleaching of organic dyes but suppress the fluorescence of Qdot® probes. A better solution for imaging Qdot® probes is simply PBS or a clear, colorless toluene-based mounting medium formulated from acrylic resins without the addition of antifade components.


Cell stain tool

Cell stain toolStain your own cell by using our simulation tool to develop reproducible results with many of our signature fluorescent dyes. Develop your multiplexing strategy for antibody probes, reactive dyes, and counterstains to create your perfectly labeled fluorescent cell.


Fluorescence SpectraViewer

Fluorescence SpectraviewerPlot and compare spectra and check the spectral compatibility for common fluorophores including all the Molecular Probes® fluorescent probes. The Fluorescence SpectraViewer tool is formatted for both microscope imaging and flow cytometry applications.