Merck, FD500S-5G, Fluorescein isothiocyanate–dextran

Dextran is a polymer of anhydroglucose. It is composed of approximately 95% alpha-D-(166) linkages. The remaining (163) linkages account for the branching of dextran. Conflicting data on the branch lengths implies that the average branch length is less than three glucose units. However, other methods indicate branches of greater than 50 glucose units exist. Native dextran has been found to have a molecular weight (MW) in the range of 9 million to 500 million. Lower MW dextrans will exhibit slightly less branching and have a more narrow range of MW distribution. Dextrans with MW greater than 10,000 behave as if they are highly branched. As the MW increases, dextran molecules attain greater symmetry. Dextrans with MW of 2,000 to 10,000, exhibit the properties of an expandable coil. At MW below 2,000, dextran is more rod-like. The MW of dextran is measured by one or more of the following methods: low angle laser light scattering, size exclusion chromatography, copper-complexation and anthrone reagent colorometric reducing-end sugar determination and viscosity.