Description
DAPI Aqueous Solution – Classic Fixed-Cell Nuclear Stain
DAPI aqueous solution (1 mg/mL) is a high-purity nuclear counterstain specifically developed for fixed-cell fluorescence microscopy and cellular imaging. This UV-excitable dye selectively binds to the minor groove of double-stranded DNA, dramatically increasing its fluorescence intensity (~20-fold), making it ideal for high-contrast staining of nuclei in fixed cells and tissues.
DAPI (4′,6-Diamidino-2-phenylindole) is widely used in immunofluorescence applications and high-content screening workflows requiring accurate DNA content quantification. While DAPI is not suitable for live-cell imaging, it offers strong and specific nuclear fluorescence and is compatible with fluorescein- and rhodamine-labeled antibodies for multiplex staining setups.
Performance Highlights
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Blue fluorescent emission at 452 nm (458 nm with dsDNA) upon excitation at 341 nm (360 nm with dsDNA)
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Approximately 20-fold increase in fluorescence upon DNA binding
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High specificity for DNA and low background from cytoplasmic staining
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Ideal for nuclear counterstaining in fixed-cell imaging
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Compatible with common fluorophores such as fluorescein and rhodamine
Properties
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CAS Number: 28718-90-3
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Molecular Weight: 350.25
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Empirical Formula: C₁₆H₁₇N₅Cl₂
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Absorption [nm]: 343 ± 3
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Emission [nm]: 444 ± 3
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ε [M⁻¹ cm⁻¹]: >30,000
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Excitation (free dye): 341 nm
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Excitation (with dsDNA): 360 nm
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Emission (free dye): 452 nm
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Emission (with dsDNA): 458 nm
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Buffer System for Fluorescence Readings: H₂O
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Solubility: H₂O
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Appearance (colour): yellow
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Appearance (form): solution
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Storage: +2 to +8 °C. Protect from light!
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Trade Name: 4′,6-Diamidino-2-phenylindole dihydrochloride; DAPI, Dihydrochloride
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Reactive Moiety: –
Application
Fluorescence microscopy of fixed cells and tissues. Ideal for use in immunofluorescence protocols and DNA content analysis. For live-cell nuclear staining, use Hoechst 33342 instead.
