Description

Fluorescein Maleimide is a high-purity, bifunctional labeling reagent that combines the reactive maleimide group with the fluorescent properties of fluorescein. This compound is essential for site-specific conjugation to thiol groups (-SH) in proteins, peptides, and other biomolecules, enabling sensitive detection and analysis. It is a critical tool for researchers and manufacturers in bioconjugation, proteomics, diagnostic assay development, and fluorescence-based cellular imaging.

Application

• Bioconjugation and Protein Labeling: Site-specific fluorescent labeling of cysteine residues in antibodies, enzymes, and other proteins for assay development.
• Diagnostic Kit Manufacturing: Production of fluorescent probes and tracers used in lateral flow assays (LFAs), ELISA, and other immunoassays.
• Proteomics & Biomolecular Research: Tagging and tracking of biomolecules in gel electrophoresis, fluorescence microscopy, and flow cytometry studies.
• Cellular Imaging: Conjugation to cell-penetrating peptides or antibodies for visualizing intracellular targets and processes.
• Drug Delivery & Biotherapeutics: Development of fluorescently tagged drug conjugates or nanocarriers for pharmacokinetic and biodistribution studies.
• Material Science: Functionalization of surfaces and nanoparticles with fluorescent markers for sensor development.

Basic Information

Product Name	Fluorescein Maleimide
CAS No.	2228857-33-6
Molecular Formula	C24H15NO7
Molecular Weight	429.38 g/mol
Synonyms	5-((2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)-2-(3-hydroxy-6-oxoxanthen-9-yl)benzoic acid; Fluorescein-5-maleimide; 5-FAM Maleimide; 5-Fluorescein Maleimide; 5-FM; Fluorescein Maleimide, Isomer I; Fluorescein-5-isothiocyanate analog; Thiol-reactive fluorescein derivative
EINECS	Contact for details

Quality Control

Our Fluorescein Maleimide is manufactured under strict quality management systems. Each batch undergoes comprehensive analytical testing, including HPLC for purity and identity confirmation, to ensure it meets the high standards required for sensitive life science applications. A detailed Certificate of Analysis (COA) documenting purity, absorbance/fluorescence properties, and other critical parameters is provided with every shipment.

Storage

Preserve in a tightly closed container, protected from light. Store in a freezer at -20°C or below under desiccant. This product is hygroscopic (moisture-sensitive) and light-sensitive. Allow the vial to equilibrate to room temperature in a dry environment before opening to minimize moisture uptake.

Specification

Item	Specification
Appearance	Orange to red solid
Identification (HPLC/UV)	Conforms
Purity (HPLC)	≥ 95.0%
Absorption Maximum (λmax)	~492 nm
Emission Maximum	~518 nm
Solubility	Soluble in DMSO, DMF
Water Content (KF)	≤ 1.0%

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.