Outlined for the first time in 1942, FITC (Fluorescein-5,6-isothiocyanate, Figure 1) is a fluorescein derivative consisting of a fluorescein core and an amine-reactive isothiocyanate moiety. It is a very widely used bright green fluorophore in biological research due to its broad fluorescence emission spectrum, high absorption capacity, superior fluorescence quantum yield and good solubility in water. However, it is subject to rapid photobleaching unless an anti-fading agent is used, and is susceptible to pH changes and fluorescence quenching following conjugation with biopolymers.
Figure 1. Structure of 5'-Fluorescein-5,6-isothiocyanate (R = sequence).
metabion offers the FITC modification in its DNA and RNA portfolio: