Innovative detection mechanism for deltamethrin based on a dual-emitting Fluoroprobe and its application in a smartphone-based photoelectric conversion device.

Pyrethroids are widely used insecticides worldwide, while their on-site and rapid detection still faces technological challenges. Herein, an innovative detection mechanism was designed for deltamethrin, a typical kind of type II pyrethroids, based on a dual-emitting fluoroprobe consisting of NH-SiQDs and Eu. Deltamethrin can rapidly hydrolyze into 3-phenoxybenzaldehyde (3-PBD) and react specifically with fluoroprobe, causing fluorescence quenching of SiQDs while maintaining the fluorescent stability of Eu. Building upon the above fluorescence-responsive principle, SiQDs@Eu provided satisfactorily dual-emitting signals, realizing the highly-selective and sensitive detection of deltamethrin. Correlation between the surface structure of SiQDs and their absorption spectra was in-depth unraveled by TD-DFT calculation and FT-IR analysis. As for the analytical performance, the recovery and LOD of deltamethrin in lettuce, provided by SiQDs@Eu, were comparable or even superior over conventional chromatographic analysis. Meanwhile, an innovative smartphone-based optical device was developed, which greatly decreased errors caused by the previously reported smartphone-based fluorescence detection.