Labeled dextran is the hydrophilic polysaccharide most commonly used in microscopy studies to monitor cell division and track living cells. Move and report the hydrodynamic properties of the cytoplasmic matrix. Labeled dextran is typically introduced into cells via microinjection.

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Dextran Specifications:
< br>•Marking (Ex/Em): SNARF™-1 (563/639)
• Specification: 70,000 MW
• Charge: Anionic
• Fixable: Unfixable

High production standards of Molecular Probes™ dextran
We are producing Over 50 fluorescent and biotinylated dextran conjugates are available across a range of molecular weights. Dextran is a hydrophilic polysaccharide characterized by medium to high molecular weight, good water solubility, and low toxicity. They also generally exhibit low immunogenicity. Glucans are biologically inert due to their less common poly-(α-D-1,6-glucose) linkages, which render them resistant to cleavage by most endogenous cellular glycosidases.

In most cases, Molecular Probes™ fluorescent dextran is brighter and more negatively charged than dextran from other sources. In addition, we use stringent methods to remove as much unconjugated dye as possible and then measure the dextran conjugates by thin layer chromatography analysis to ensure the absence of low molecular weight contaminants.

Wide range of substituents and molecular weight options
Molecular Probes™ dextran conjugated to biotin or a variety of fluorophores, including our 7 Alexa Fluor™ Dyes (Molecular Probes Dextran Conjugates – Table 14.4), offering the following nominal molecular weights (MW) for selection: 3,000; 10,000; 40,000; 70,000; 500,000; 2,000,000 daltons.

Dextran Net Charge and Immobilization Capacity
We utilize succinimide coupling of dyes to dextran molecules, which in most cases results in neutral or anionic dextran. Reactions used to produce Rhodamine Green™ and Alexa Fluor™ 488 dextran can produce neutral, anionic or cationic end products. Alexa Fluor™, Cascade Blue™, Lucifer Yellow, Fluorescein, and Oregon Green™ Dextran are anionic in nature, but most Dextran labeled with the zwitterionic rhodamine B, tetramethylrhodamine, and Texas Red™ dyes is essentially neutral. To create more highly anionic dextran, we use a patented process to add negatively charged groups to the dextran carrier; these products are designated "polyanionic" dextran.

Some applications require treatment of dextran tracers with formaldehyde or glutaraldehyde for subsequent analysis. For these applications, we offer “lysine-fixable” versions of most fluorophores or biotin-dextran conjugates. These dextrans possess covalently bound lysine residues, allowing the dextran tracer to bind to surrounding biomolecules via aldehyde-mediated fixation for subsequent detection by immunohistochemistry and ultrastructural techniques. We have also demonstrated that all of our 10,000 MW Alexa Fluor™ dextran conjugates can be fixed with aldehyde fixatives.

Key applications using labeled dextran
There is a series of citations describing the use of labeled dextran. Some of the most common uses include:

•Neuronal tracing in living cells (anterograde and retrograde)
• Tracing of cell lineages in living cells
• Neuroanatomical tracing
• Examining intercellular communication (e.g., in gap junctions, during wound healing, and during embryonic development)
• Study vascular permeability and blood-brain barrier integrity
• Track endocytosis
• Monitor acidification (some dextral Dye conjugates are pH sensitive)
• Study the hydrodynamic properties of cytoplasmic matrices

Research use only. Not for use in the treatment or diagnosis of any animal or human being.