An HBT-based fluorescent dye with enhanced quantum yield in water system and its application for constructing NQO1...

A novel HBT-based fluorescent dye HBTM, which exhibited long wavelength emission (~600 nm) and large Stokes shift (~203 nm) due to the intrinsic mechanism of ESIPT coupled ICT process, was reasonably designed and synthesized by conjugating neutral pyrimidine moiety as the electron acceptor to 2-(benzo[d]thiazol-2-yl)-4-methylphenol scaffold. Fluorescence emission of HBTM showed less significant spectral dependency on solvents nature, delivering excellent anti-hypochromatic properties, and notably enhanced quantum yield (Φ = 25.5%) in water system was obtained. Furthermore, a "Turn-On" fluorescent probe HBTMP was developed for the detection of NQO1 by masking the hydroxyl group of HBTM with quinone propionic acid (QPA) as the sensing group. Probe HBTMP displayed a highly sensitive and selective response to NQO1 with a linear relationship in the range of 60-180 ng/mL and low detection limit of 1.6 ng/mL, and was successfully applied in detecting endogenous NQO1 in living cancer cells.