Quantum Dot Products

Quantum Dot Corporation (QDC) announces two additions to its nanocrystal-based family of fluorescent labels: the Qtracker 655 Kit for loading Qdot nanocrystals into live cells and the Qdot 705 streptavidin conjugate for ultra-bright, near-infrared bio-detection.

Qtracker 655 Kit

The Qtracker 655 Kit is the first in a new line of labeling reagents designed for introducing Qdot nanocrystal-based fluorochromes into live cells. The Qtracker kit utilizes custom-targeting peptides to deliver the extremely bright Qdot nanocrystals to the cytoplasm. Once inside the cells, the Qdot nanocrystals provide highly photostable fluorescence that doesn't bleach over time or under extensive, continuous illumination and observation.

"The Qtracker 655 Kit is an excellent tool for long-term studies of migration, motility, morphology and many other characteristics where the cell must be observed over time, even through several generations of cell division," explains Charlie Hotz, QDC's director of labels R&D.

QDC says Qtracker quantum dots are easy to use in powerful experimental designs because they do not add unwanted autofluorescence, are not transferred to adjacent cells in the population and display excellent retention properties. Qdot nanocrystals are inert and nontoxic to all tested cell types. They may be still observed in cells a week or more after transfection.

Qdot 705 Streptavidin Conjugate

QDC also introduces the Qdot 705 Streptavidin Conjugate, the brightest near-infrared fluorophore available by far. This new conjugate is ideal for applications requiring visualization in turbid, opaque or otherwise scattering media such as in vivo experiments.

The Qdot 705 Streptavidin conjugate is useful in a wide range of applications, including: immunohistochemistry, in vivo labeling, western blots, solid-phase immunosorbent assays and flow cytometry.

Far-red and near-infrared light penetrates much more deeply into samples such as tissues, gels and animals than typical visible light, and also escapes from a greater depth. Additionally, autofluorescent background is significantly diminished in this spectral region, particularly when excitation is in the blue or UV range. Emission is well beyond the spectral range of typical sample autofluorescence. Also, scattering and other optical effects which reduce resolution are minimized in the red. These qualities are now coupled with the exceptional brightness and stability enabled by Qdot nanotechnology.

The Qdot 705 Streptavidin conjugate can be used with other colors of Qdot conjugates for multicolor analysis. It is orders of magnitude more photostable than Cy5 streptavidin conjugates and can be excited at many different wavelengths including 633nm, 532, and 405nm -- common sources in an array of existing instrument platforms.

"At last year's cell biology meeting, we launched our company's first product. Since then, the product portfolio has been expanded significantly to include 6 Qdot colors and a range of different biomolecules including antibodies, streptavidin, protein A, and biotin. We are also beginning to see our customers publish landmark scientific papers, enabled by our Qdot products," said Carol Lou, QDC's president.

Quantum dots are nanoscale crystals of semiconductor material that glow, or fluoresce brightly when excited by a light source such as a laser. They are used by life-science researchers as tiny beacons, or markers, allowing them to easily see individual genes, nucleic acids, proteins or small molecules. Qdot conjugates work by seeking out and bonding with target materials. Once bound to a target, each individual Qdot particle emits light. Depending on their size, they can glow in a variety of colors and are up to 1,000 times brighter than fluorescent dyes.