Dextran is labeled with both biotin and fluorescein, Ex/Em wavelength 494/518 nm. Purity: >95% lyophilized powder. Degree of substitution: 1 mol % substitution for each dye and at least one biotin and one fluorescein molecule per polymer. Literature: 1) Improved fluorescent compounds for tracing cell lineage. Dev Biol. 1985 Jun; 109(2):509-14.