The Engineered Synthesis and Enhancement of Nitrogen and Chlorine Co-Doped Fluorescent Carbon Dots for the Sensitive Detection of Quercetin.

Flavonoid alcohols, particularly quercetin, as emerging antioxidants, demand advanced detection methodologies to comprehensively explore and evaluate their potential environmental and health risks. In this study, nitrogen-chlorine co-doped carbon dots (N, Cl-CDs), featuring an extended wavelength emission at 625 nm, were synthesized via the reaction of 4-chloro-1,2-phenylenediamine with polyethyleneimine. The engineered N, Cl-CDs exhibit superior photostability, exceptional aqueous dispersibility, and anti-interference capability in complex matrices. Leveraging static electron transfer mechanisms, the N, Cl-CDs demonstrate selective fluorescence quenching toward quercetin with an ultralow detection limit of 60.42 nM. Validation through rigorous spiked recovery assays in apple peel and red wine has been proficiently performed with satisfactory accuracy, highlighting the significant prospect of the constructed N, Cl-CDs for quercetin identification in real samples. This study provides valuable insights into the analytical determination of flavonoid compounds in complex environmental matrices, highlighting the potential of N, Cl-CDs for environmental and food safety monitoring.