Qtracker™ 705 Cell Labeling Kit

Qtracker cell labeling reagents are taken up by the cell through endocytosis and sequestered in endosomes. This gives the label a punctate or vesicular appearance. This is normal. There is nothing that can be done to make it appear uniform throughout the cytoplasm.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Quantum dots can be excited by wavelengths of light ranging from 250 nm to 40 nm below the emission peak wavelength. For example, Qtracker 655 non-targeted quantum dots can be excited from 250 -615 nm. The wavelength in the product name refers to the emission peak, not the excitation peak. Since quantum dots have an exponential curve to their absorbance, the lower the wavelength at which they are excited, the more efficiently they will absorb, so you will want to use your lowest available laser line or excitation wavelength.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

This is not recommended. When these stains bind to DNA and RNA, they may affect the normal function of the nucleic acids, disrupting transcription, as well as replication. Other reagents, such as CellTracker dyes or Qtracker reagents are more optimized for tracking without disrupting normal activity. If a nuclear label is still desired, though, and the cells are mammalian and non-hematopoietic, CellLight nuclear reagents can transiently transfect cells to express GFP or RFP on a nuclear-expressing protein for up to several days without affecting function.

Find additional tips, troubleshooting help, and resources within our Cell Tracing and Tracking Support Center.

Please see this Web link (http://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-tracing-tracking-and-morphology/cell-tracking.html) to help you choose the right option for your application. Start by planning how long you want to track your cells, then consider the mechanism of binding. Calcein dyes are very uniform in label and are good for short-term cell migration, but may be rapidly effluxed from some cell types. Lipophilic cyanine dyes, such as DiI, DiO, and similar dyes label cell membranes, don’t disrupt function, and can last longer, but have the potential to cross to other cells if membranes fuse. They are also lost upon permeabilization. CellTracker dyes are better for longer-term labeling, as they possess a mildly reactive chloromethyl moiety that allows covalent binding to cellular components. CFDA SE also covalently binds to cellular components. With all the reagents, their retention within cells is dependent upon the rate of cell division and the inherent properties of the cell (active efflux, membrane and protein turnover rates, etc.) and reagents that allow for covalent attachment exhibit longer retention than those that do not.

The longest-lasting and brightest options are the Qtracker reagents, which are taken up through endocytosis. These are so bright individual quantum dots can be detected, and are also robust enough to survive not only fixation and permeabilization, but even the heat and solvents used in paraffin processing.

Find additional tips, troubleshooting help, and resources within our Cell Tracing and Tracking Support Center.