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Sytox Red

Sytox Red (Ex-Max 639 nm/Em-Max 655 nm)

Sytox Red from Thermo Fisher Scientific is a cell-impermeant, fluorogenic nucleic acid stain that can be used as a viability dye for use in flow cytometry and as a nuclear counterstain in fluorescence microscopy. It has an excitation peak at 639 nm an emission peak at 655 nm, similar to To-Pro-3.

Excitation & emission spectra

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Key facts

Excitation maximum
639 nm
Emission maximum
655 nm
Optimal laser line
628-640
Optimal filter
660/20

Sytox Red has an excitation maximum at 639 nm and an emission maximum at 655 nm, a Stokes shift of 16 nm. It is optimally excited by the 628-640 laser line.

Frequently asked questions

What is Sytox Red?
Sytox Red from Thermo Fisher Scientific is a cell-impermeant, fluorogenic nucleic acid stain that can be used as a viability dye for use in flow cytometry and as a nuclear counterstain in fluorescence microscopy. It has an excitation peak at 639 nm an emission peak at 655 nm, similar to To-Pro-3.
What laser excites Sytox Red?
Sytox Red is optimally excited by the 628-640 laser line. Its excitation maximum is 639 nm.
What filter should I use to detect Sytox Red?
A 660/20 filter captures the peak of the Sytox Red emission near 655 nm with minimal spillover.