Downy Serviceberry – Amelanchier arborea

7-Aminoactinomycin D (7-AAD) is a fluorescent chemical compound with a strong affinity for DNA. It is used as a fluorescent marker for DNA in fluorescence microscopy and flow cytometry. It intercalates in double-stranded DNA, with a high affinity for GC-rich regions,^[2] making it useful for chromosome banding studies.^[3]

Applications

With an absorption maximum at 546 nm, 7-AAD is efficiently excited using a 543 nm helium–neon laser; it can also be excited with somewhat lower efficiency using a 488 nm or 514 nm argon laser lines. Its emission has a very large Stokes shift with a maximum in the deep red: 647 nm. 7-AAD is therefore compatible with most blue and green fluorophores – and even many red fluorophores – in multicolour applications.

7-AAD does not readily pass through intact cell membranes; if it is to be used as a stain for imaging DNA fluorescence, the cell membrane must be permeabilized or disrupted. This method can be used in combination with formaldehyde fixation of samples.

7-AAD is also used as a cell viability stain. Cells with compromised membranes will stain with 7-AAD, while live cells with intact cell membranes will remain dark. Viability of the cells in flow cytometry should be around 95% but not less than 90%.^[4]

Actinomycin D

The related compound actinomycin D is nonfluorescent, but binds DNA in the same way as 7-AAD. Its absorbance changes when bound to DNA, and it can be used as a stain in conventional transmission microscopy.

References

^ 7-Aminoactinomycin D at Interchim
^ Liu X; Chen H; Patel D (1991). "Solution structure of actinomycin-DNA complexes: drug intercalation at isolated G-C sites". J Biomol NMR. 1 (4): 323–47. doi:10.1007/BF02192858. PMID 1841703. S2CID 40569430.
^ Latt S (1977). "Fluorescent probes of chromosome structure and replication". Can J Genet Cytol. 19 (4): 603–23. doi:10.1139/g77-065. PMID 76502.
^ "Flow cytometry (FACS) staining protocol (Cell surface staining)". Yale School of Medicine - Yale Flow Cytometry. Retrieved 2023-10-17.

Gallery

Absorptions

External links

Structure from Invitrogen
MSDS Archived 2014-08-06 at the Wayback Machine

[ref-1] 7-Aminoactinomycin D at Interchim

[2] Liu X; Chen H; Patel D (1991). "Solution structure of actinomycin-DNA complexes: drug intercalation at isolated G-C sites". J Biomol NMR. 1 (4): 323–47. doi:10.1007/BF02192858. PMID 1841703. S2CID 40569430.

[3] Latt S (1977). "Fluorescent probes of chromosome structure and replication". Can J Genet Cytol. 19 (4): 603–23. doi:10.1139/g77-065. PMID 76502.

[4] "Flow cytometry (FACS) staining protocol (Cell surface staining)". Yale School of Medicine - Yale Flow Cytometry. Retrieved 2023-10-17.

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