A highly selective ratiometric fluorescent probe for butyrylcholinesterase: Applications in quantification, residue screening, and toxicological studies of organophosphorus pesticides

This study presents a ratiometric fluorescent probe, DEDD, designed for selective detection of butyrylcholinesterase (BChE) and accurate quantification of organophosphorus pesticides (OPPs). DEDD combines a 4-hydroxy-1,8-naphthalimide fluorophore with a cyclopropanecarboxylate recognition group, enabling an intramolecular charge transfer-based dual-wavelength response. This design mitigates issues associated with conventional single-wavelength probes, such as photobleaching and environmental interference. The probe achieved a limit of detection (LOD) of 0.59 mU/mL for BChE, with a linear range extending up to 0.16 U/mL, and demonstrated remarkable selectivity over acetylcholinesterase and other biomolecules. By leveraging the inhibitory effects of OPPs on BChE, DEDD quantified paraoxon with an LOD of 2.49 ng/mL and exhibited high accuracy in foods, achieving spiked recoveries of 92.04-103.02 %. In addition, a dual-mode test strip was developed, integrating colorimetric and fluorescence detection to eliminate food matrix interference. Furthermore, DEDD showed low cytotoxicity and cell membrane permeability, enabling imaging of OPP-induced BChE inhibition in cells.