A fluorescence off–on reporter for real time monitoring of gemcitabine delivery to the cancer cells

We present the design, synthesis, optical properties and in vitro biological assessments of the theranostic prodrug 6 in which a near IR fluorophore is conjugated with a cancer cell-directing biotin unit; further it is linked with the anti-cancer drug gemcitabine via a self-immolative spacer, a disulfide bond. The prodrug 6 is able to monitor drug delivery and cellular imaging.