Qdot® Nanocrystals in Flow Cytometry

What are Qdot® Nanocrystals?
Qdot® nanocrystals are nanometer-scale semiconductor particles with unique fluorescence properties that differ from those of typical dye molecules. The color of light that the Qdot® nanocrystal emits is strongly dependent on the particle size, creating a common platform of labels from green to red, all manufactured from the same underlying semiconductor material (Figure 1).

Qdot® nanocrystals have broad absorbance spectra that increase dramatically at shorter excitation wavelengths. Their emission peaks are narrow and symmetrical, and do not change with variations in the excitation source (Figure 2).  Qdot® nanocrystals are optimally excited by a UV or violet (405–407 nm) laser, although sufficient excitation can also be obtained with other sources as discussed below.

Take Your Flow Cytometry to the Next Level
Qdot® nanocrystal conjugates are increasingly used in multispectral flow cytometry.  The use of these nanocrystal conjugates will allow the addition of one to six colors, all excited from the violet laser. Qdot® nanocrystals provide the additional advantages of brightness and photostability.

Because of their physical properties, Qdot® nanocrystals are brighter than most organic fluorophores when compared to conventional dyes; Qdot® conjugates remain fluorescent under constant illumination, while conventional dyes photobleach to varying degrees. The fluorescence stability of a Qdot® nanocrystal translates to better stability of the reagent, and consequently of the stained sample, and also permits additional analysis steps after sorting.

• See All Qdot® Nanocrystal Primary Antibody and Streptavidin Conjugates

Figure 1. Nanocrystals absorb light and then re-emit the light in a different color; the size of the nanocrystal determines the color. Seven different nanocrystal solutions are shown excited with the same long-wavelength UV lamp.