A fluorometric and colorimetric dual-readout nanoprobe based on Cl and N co-doped carbon quantum dots with large stokes shift for sequential detection of morin and zinc ion.

A novel visual nanoprobe was developed for the sequential detection of morin and zinc ion (Zn) based on Cl and N co-doped carbon quantum dots (ClNCQDs) via a fluorometric and colorimetric dual-readout mode. The yellow fluorescence ClNCQDs was synthesized by the one-step hydrothermal treatment of o-chlorobenzoic acid and p-phenylenediamine. The most distinctive property of the ClNCQDs is the large stokes shift (177 nm), which is significantly higher than other reported CQDs. The fluorescence of the ClNCQDs can be effectively quenched by morin based on the synergistic effect of IFE, electrostatic interaction, and dynamic quenching process, and recovered upon the addition of Zn due to strong interaction between morin and Zn. The nanoprobe exhibited favorable selectivity and sensitivity toward morin and Zn with detection limits of 0.09 µM and 0.17 µM, respectively. Simultaneously, the color of the ClNCQDs solution was changed (light-pink → faint-yellow → dark-yellow) along with the variation of the fluorescence signal of the ClNCQDs. This proposed nanoprobe was successfully applied for morin and Zn analyses in actual samples and live cells with high accuracy. The results of this study demonstrate the great application prospects of the ClNCQDs for morin and Zn detection in complex actual samples and biosystems.