News from the Bench

Discover what’s going on at CST, receive our latest application notes and tips, read our science features, and learn about our products.


To Purchase # 4082S

4082S 25 mg $60.00.0


Find answers on our FAQs page.


PhosphoSitePlus® Resource

  • Additional protein information
  • Analytical tools



Immunofluorescence (Immunocytochemistry)

Immunofluorescent analysis of HeLa cells using α-Tubulin (DM1A) Mouse mAb #3873 (red) and Phospho-Histone H3 (Ser10) (D2C8) XP® Rabbit mAb #3377 (green). Blue pseudocolor = Hoechst 33342 (fluorescent DNA dye).

Learn more about how we get our images

Product Description

Hoechst 33342 (bisBenzimide H33342 trihydrochloride) is supplied as a lyophilized powder in 25 mg units. It can be used to examine cellular DNA in most fluorescent applications.

Molecular Formula:

C27H28N6O 3(HCl) 3(H2O)

Fluorescent Properties

  • Free dye excitation maximum = 340 nm
  • Free dye emission maximum = 510 nm
  • DNA complex excitation maximum = 355 nm
  • DNA complex emission maximum = 465 nm

Product Usage Information

This product is soluble up to 50 mg/ml in deionized water or dimethylformamide yielding a clear yellow solution. Heating and/or sonication may be required. For standard fluorescence based assays, Hoechst 33342 stock solutions should be diluted in phosphate-buffered saline or mounting medium to a final working concentration of 1 μg/ml.

Storage: The lyophilized powder is stable for 1 year if kept below 0°C with desiccant. Aqueous solutions are stable for at least 1 month if kept in the dark between 2-8°C.

Hoechst 33342 and Hoechst 33258 are specific fluorescent DNA stains that bind within the minor groove of double-stranded AT-rich regions. These stains can be used on both live and fixed cells (1). Replicating or dividing chromosomes will not stain with Hoechst 33342 DNA dye.

1.  Portugal, J. and Waring, M.J. (1988) Biochim Biophys Acta 949, 158-68.

For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology is a trademark of Cell Signaling Technology, Inc.

Hoechst 33342