A Quinoline-Benzimidazole Probe for Efficient Detection of Imidacloprid: Mechanisms and Applications

To explore an alternative detection approach for the pesticide imidacloprid (IMI), this study repurposed the quinoline-benzimidazole fluorescent probe DQBM-B—previously developed for Co2+ recognition—and investigated its detection performance and interaction mechanism toward IMI in the aggregated state. The optimal working conditions of the probe were determined by optimizing key detection parameters, and the sensing performance and matrix compatibility were evaluated through selectivity tests and proof-of-concept spiked cucumber extract analysis. The DQBM-B aggregates interact with IMI synergistically through intermolecular hydrogen bonding and π–π stacking, which enrich IMI at the aggregate surface to create a local enrichment layer. The observed fluorescence quenching arises from the synergistic contribution of static quenching (due to ground-state complex formation) and the inner filter effect (IFE). Under the optimal conditions, the system exhibited a detection limit of 0.75 μmol L−1 for IMI with favorable anti-interference ability. The matrix effect evaluation in cucumber extract demonstrated good recovery and precision, demonstrating the feasibility of the aggregation-regulated IFE strategy in complex food matrices. This study expands the application scope of the DQBM-B probe from metal-ion sensing to pesticide detection and provides a metal-free, aggregation-regulated strategy for the fluorescence detection of neonicotinoid pesticides.