FITC-Dextran (MW 4000)

FITC-Dextran (MW 4000) (CAS No.: 60842-46-8) is a fluorescein-labeled polysaccharide probe widely employed in biomedical research to investigate membrane integrity, microvascular transport, and barrier permeability. Derived from dextran conjugated with fluorescein isothiocyanate, this compound exhibits characteristic fluorescence with excitation and emission maxima around 495 nm and 525 nm, enabling sensitive detection in fluorescence-based assays. Its defined molecular size makes it particularly suitable for evaluating size-dependent permeability across biological barriers, including the blood-brain barrier, as well as for assessing capillary leakage, cellular uptake, and paracellular transport processes. Mechanistically, FITC-Dextran functions as an inert tracer that does not bind specific molecular targets but instead passively distributes according to barrier integrity and pore size, thereby providing quantitative insight into solute diffusion and junctional disruption under physiological and stress conditions such as heat shock or apoptosis. It has been broadly applied in in vitro cell culture systems and in vivo animal models to monitor early and late stages of cell damage, endothelial dysfunction, and tissue permeability changes, as well as in plant biology to study cell wall porosity. As a non-bioactive probe, it does not exhibit classical pharmacological activity such as receptor binding or enzyme inhibition, and thus no IC50 or EC50 values are typically defined; instead, experimental concentrations are selected based on detection sensitivity and model system requirements. This reagent is commonly integrated into drug discovery workflows to evaluate compound effects on barrier function and cellular integrity, with dosing and assay conditions tailored to specific experimental objectives.