Comprehensive Investigation of a Hand-Held Fluorescence-Based Rapid Detection Scheme for Total Pyrethroids’ Residues Based on Transition of Aggregation: Mechanism, Application, and Toxicological Assessment

Developing facile, on-site, and hand-held devices remains challenging for pyrethroids' residual detection in environmental waters and crops. Herein, we synthesized a fluorescent molecule, DTC, to determine pyrethroids via intermolecular interactions. Trifluoromethyl groups in DTC reduced water solubility and promoted dimer formation, and simultaneously diethylamino groups induced a stable twisted intramolecular charge transfer (TICT) state to quench DTC's intrinsic fluorescence. Specific binding between DTC and pyrethroids facilitated the transition from TICT to intramolecular charge transfer (ICT) states, disrupting dimers and recovering quenched fluorescence. Leveraging this, a dual-emitting fluoroprobe combining DTC with a water-soluble Eu-ICP was developed, enabling broad-spectrum and rapid quantification of six pyrethroids (15 s reaction time and detection limits of ∼61 nM). To minimize errors from hardware variations and smartphone-based operations, a fluorescence-visual transverter (FVT) was applied to enable hand-held rapid detection in the field and remote areas. Meanwhile, the environmental friendliness of the detection protocol was confirmed by studying the behavior and morphology of embryonic-larval zebrafish and performing an oxidative damage assessment. Thus, this satisfies the technological requirement for modern "green" analysis in routine environmental and food monitoring.