DAPI
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IUPAC name
2-(4-Amidinophenyl)-1H-indole-6-carboxamidine
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Other names
4′,6-Diamidino-2-phenylindole
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Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChEMBL | |
ChemSpider | |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C16H15N5 | |
Molar mass | 277.331 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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DAPI (pronounced 'DAPPY', /ˈdæpiː/), or 4′,6-diamidino-2-phenylindole, is a
History
DAPI was first synthesised in 1971 in the laboratory of Otto Dann as part of a search for drugs to treat
Strong fluorescence when bound to DNA led to the rapid adoption of DAPI for fluorescent staining of DNA for
Fluorescence properties
When bound to double-stranded DNA, DAPI has an absorption maximum at a wavelength of 358 nm (ultraviolet) and its emission maximum is at 461 nm (blue). Therefore, for fluorescence microscopy, DAPI is excited with ultraviolet light and is detected through a blue/cyan filter. The emission peak is fairly broad.[2] DAPI will also bind to RNA, though it is not as strongly fluorescent. Its emission shifts to around 500 nm when bound to RNA.[3][4]
DAPI's blue emission is convenient for microscopists who wish to use multiple fluorescent stains in a single sample. There is some fluorescence overlap between DAPI and green-fluorescent molecules like fluorescein and green fluorescent protein (GFP) but the effect of this is small. Use of spectral unmixing can account for this effect if extremely precise image analysis is required.
Outside of analytical fluorescence light microscopy DAPI is also popular for labeling of
Modelling of absorption and fluorescence properties
This DNA fluorescent probe has been effectively modeled[6] using the time-dependent density functional theory, coupled with the IEF version of the polarizable continuum model. This quantum-mechanical modeling has rationalized the absorption and fluorescence behavior given by minor groove binding and intercalation in the DNA pocket, in term of a reduced structural flexibility and polarization.
Live cells and toxicity
DAPI can be used for fixed cell staining. The concentration of DAPI needed for live cell staining is generally very high; it is rarely used for live cells.
Alternatives
The Hoechst stains are similar to DAPI in that they are also blue-fluorescent DNA stains which are compatible with both live- and fixed-cell applications, as well as visible using the same equipment filter settings as for DAPI.
References
- ^ PMID 8580206.
- ^ a b Invitrogen, DAPI Nucleic Acid Stain Archived 2009-03-06 at the Wayback Machine. accessed 2009-12-08.
- ^ Scott Prahl, DAPI. accessed 2009-12-08.
- PMID 1696951.
- S2CID 25224870.
- PMID 23423468.
- PMID 12543070.
- ^ DAPI MATERIAL SAFETY DATA SHEET. kpl.com
- PMID 11377248.
See also
- DNA binding ligand
- Hoechst stain
- Lexitropsin
- Netropsin
- Pentamidine