Abstract:
A dual mechanistic FRET and PET paired ratiometric fluorescence sensor probe has been prepared
using carbon dots and naphthalimide fluorophores. The carbon dots are covalently joined with a
naphthalimide moiety to develop the FRET phenomenon, which emits at two different wavelengths
(i.e., lmax = 440 and 540 nm). However, on catalytic reaction of tyrosinase, the fluorescence emission
intensity of the acceptor unit at 540 nm is quenched gradually, owing to the switching on of the PET
mechanism; while emission of the donor unit remains significantly unaffected. The probe exhibits high
selectivity and specificity towards tyrosinase in complex biological medium with a detection limit of
1.2 U mL 1. Moreover, endogenous images of tyrosinase in B16 cells have been observed under a
confocal laser-scanning microscope.
