by TdB Labs
FITC-dextrans are synthesised by coupling fluoresceinyl isothiocyanate (5-isomer) to selected dextran fractions. All batches are checked for molecular weight, degree of substitution, loss on drying and free FITC. TdB Labs produce FITC-dextrans from 4 kDa to 2000 kDa. FITC-dextrans are supplied as a yellow to orange powder.
Structure
Dextran is a branched polysaccharide elaborated by the bacteria Leuconostoc mesenteroides B512F. Dextran is essentially a linear glucose chain linked by α-D-(1 – 6) linkages. The degree of branching is about 5 %. The fluorescein moiety is attached by a stable thiocarbamoyl linkage and the labelling procedure does not lead to any depolymerization of the dextran. FITC-dextrans have from 0.002-0.008 mol FITC per glucose unit. These low levels of substitution confer minimal charges to dextran, which is an essential requirement for permeability studies.
Spectral data
FITC-dextran has an excitation maximum of 493 nm and an emission maximum of 518 nm. Maximal intensity is observed at pH >8.
Storage and stability
FITC-dextran is stable for more than 6 years when stored dry in well-sealed containers at ambient temperature. Studies at 37°C in rabbit plasma, muscle homogenate, liver homogenate and urine established that FITC-dextran is stable for at least 3 days. No changes in the molecular weight and no release of fluorescein moieties was noted (1).
Solubility
FITC-dextran dissolves readily in water.
Application
FITC-dextran is mainly used for studying permeability and microcirculation. It can also be used as a molecular size marker, for studies of drug delivery and more.
Technical information
Specifications
