Description
6-FAM-SE: High-Performance NHS Ester for Reliable Biomolecule Labeling
6-Carboxyfluorescein NHS Ester (6-FAM-SE) is a single-isomer amine-reactive dye designed for efficient fluorescent labeling of proteins and alkylamino-modified nucleic acids. Its excitation maximum closely matches the 488 nm line of argon-ion lasers, making it a popular choice for confocal laser scanning microscopy and flow cytometry applications. 6-FAM-SE offers high absorptivity, strong quantum yield, and excellent water solubility, enabling bright and stable fluorescence without compromising biomolecule solubility.
Performance Highlights
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Strong excitation at 498 nm and emission at 514 nm
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High absorptivity (ε > 81,000 M⁻¹·cm⁻¹) for intense signal output
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Reacts with primary amines via NHS chemistry to form stable amide linkages
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Excellent quantum yield and good water solubility
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Low tendency to precipitate when conjugated to proteins
Properties
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Molecular Weight: 473.9
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Empirical Formula: C₂₅H₁₅NO₉
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Absorption [λmax]: 492 ± 3 nm
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Excitation [λmax]: 498 nm
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Emission [λmax]: 514 ± 3 nm
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Extinction Coefficient (ε): >81,000 M⁻¹·cm⁻¹
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Reactive Moiety: NHS ester (reacts with 1° amines to form stable amide linkage)
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Solubility: Acetonitrile, DMF, DMSO
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Buffer for Fluorescence Readings: PBS, pH 7.4
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Appearance (form/color): Orange solid (powder)
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Storage: −20 °C. Keep dry and protect from light, especially in solution
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CAS Number: 92557-81-8
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Name: 2-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)-terephthalic acid 4-(2,5-dioxo-pyrrolidin-1-yl) ester
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Trade Names: 6-Carboxyfluorescein-NHS-ester, 6-FAM-SE, 6-carboxyfluorescein succinimidyl ester (single isomer)
Applications
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Bioconjugation of proteins and nucleic acids
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Flow cytometry (FACS)
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Confocal laser scanning microscopy
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Fluorescence-based detection and tracking
