Novel fluorescence-based and portable detection platforms using nitrogen-doped carbon dots for environmental monitoring of dichloran fungicide

Abstract

A novel fluorescence sensor utilizing label-free nitrogen self-doped carbon dots (NCDs) was developed for the sensitive, selective, and rapid determination of dichloran fungicide, popularly used in agricultural and horticultural fields. The NCDs were prepared from maleic anhydride and diethylenetriamine via a one-step pyrolysis process. They demonstrated strong blue fluorescence emission with a quantum yield of 12 %. With the addition of dichloran, the fluorescence emission of NCDs was quenched, attributed to the inner filter effect and dynamic quenching. They demonstrated outstanding sensitivity to dichloran with a linear range between 1.0 and 50.0 µM and a remarkably low detection limit of 7.6 nM, the best reported date. The sensing process could be repeatedly and rapidly generated within 30 s. Additionally, the NCDs exhibited selectivity towards dichloran amidst interferences, including common metal ions, organic chemicals, and other fungicides. The detection of dichloran in carrots, grapes, and drinking water was successfully accomplished using NCDs, yielding satisfactory recovery results ranging between 95.1 and 108.7 %. Moreover, a paper-based sensor based on NCDs as sensing probes was demonstrated to observe the fluorescence quenching towards dichloran, with a detection limit of 4.24 µM. It also showed high efficacy in distinguishing and selectively detecting dichloran against interferences. Therefore, this work contributes to the development of efficient and portable detection platforms with applications in environmental monitoring and agricultural fields.