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

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.