iFluor® 405–dextran conjugate (average molecular weight ~150,000 Da) is a high molecular weight, water-soluble fluorescent tracer consisting of a 150 kDa dextran polymer covalently labeled with iFluor® 405, a bright blue-fluorescent dye with excitation/emission maxima at ~403/427 nm. The large dextran size significantly restricts cellular internalization, making it highly effective for applications that require exclusion from intracellular compartments. This includes detailed analyses of vascular permeability, paracellular transport, and extracellular diffusion in both in vitro and in vivo systems.

The iFluor® 405 dye is spectrally analogous to Pacific Blue® and is optimized for use with standard 405 nm laser excitation in flow cytometry and fluorescence microscopy systems. It offers excellent photostability, high fluorescence quantum yield, and minimal background signal, ensuring robust performance during extended imaging sessions or repeated excitation cycles. The conjugate is supplied as a lyophilized powder and reconstitutes readily in aqueous buffers, allowing for straightforward integration into experimental workflows that demand reliable extracellular fluorescent tracers with minimal nonspecific interaction.