With excitation and emission maxima of 640 and 663 nm, respectively, Qnuclear™ Deep Red stain can be visualized with standard fluorescence microscopy filter sets (Figure 1) and is completely compatible with Qdot® 525, 565, 585, 605, and 625 nanocrystals. This counterstain can also be used with Qdot® 655 nanocrystals and its conjugates, though care must be taken to use appropriate excitation and filter sets given the fluorescence emission overlap. The fluorescent signal from Qnuclear™ Deep Red stain is well-maintained when mounted in the recommended Qmount™ Qdot® mounting media (Figure 2). Qnuclear™ Deep Red stain is provided as a convenient, concentrated dimethyl sulfoxide (DMSO) solution.
Figure 1—Absorption and fluorescence emission spectra for Qnuclear™ Deep Red stain.
Figure 2—Comparison of human carcinoma (HeLa) cells labeled with Qnuclear™ Deep Red stain and mounted in Qmount™ Qdot® mounting media. Samples were imaged 1 day, 13 days, and 8 months after mounting. Qmount™ Qdot® mounting media provided excellent signal preservation both initially and when stored over time, as measured by fluorescence intensity in the nuclear regions.