The labelling of polymers with fluorescein via its FITC derivative is a long-established method for obtaining fluorescent-labelled polymers for studies of, inter alia, permeability. For convenience, the products are designated as FITC-derivatives. (Reference; A.N.de Belder and K.Granath, Carbohydr. Res., 1973, 30, 375)
The fluorescein moiety is bound by thiocarbamoyl-linkage which displays good stability in-vitro and in-vivo. FITC-labelled polymers have now been used for more than 30 years, largely for real-time studies of permeability, distribution and diffusion. The fluorescein moiety is excited at 493 nm and emission is measured at 518 nm. Maximum fluorescence is recorded in the pH range 6-8.
In this section we described various FITC-labelled polymers (dextran, inulin, Polysucrose) and also FITC-derivatives with polycationic and polyanionic character.