A ratiometric and rapid-response fluorescent nanoprobe based on modification of carbon quantum dots by naphthalimide for HClO bioimaging in living cells and mice

A ratiometric and rapid-response fluorescent nanoprobe (NA-CQDs) for the detection of hypochlorous acid based on naphthalimide (NA) modified carbon quantum dots (CQDs) has been prepared. The nanoprobe NA-CQDs showed blue fluorescence with a unique yellow fluorescence in the presence of HClO, accompanying the emission wavelength change from 457 nm to 538 nm. The fluorescence detection limit for HClO was 99 nM with a linear range from 0.1 to 32 μM. The nanoprobe exhibited a rapid response to HClO within 20 s. The sensing mechanism might be attributed to the oxidation and cleavage of p -aminophenylether group on the nanoprobe NA-CQDs, leading to the FRET process from the CQDs to the NA due to enhanced ICT of the NA portion. A series of real applications were conducted including spiked real water samples, test paper strips, and fluorescence bioimaging in RAW 264.7 and HepG2 cells and nude mice, highlighting the potential application of NA-CQDs for future environmental sensing and biosensing in living things.