Highly efficient detection of imidacloprid in agricultural samples based on ZIF-8-derived carbon particles-modulated fluorescence polarization immunoassay

Imidacloprid (IMI) has potential hazards to human health and honeybees. Herein, we developed a highly sensitive fluorescence polarization immunoassay (FPIA) based on ZIF-8-derived carbon particles (ZIF-8-C) for the detection of IMI in agricultural samples, and studied the effect of different sizes of ZIF-8-derived carbon-antibody conjugates (ZIF-8-C-PDA-mAb) and fluorescence lifetime on the detection sensitivity. The results found that the detection sensitivity of FPIA was related to the particle sizes of ZIF-8-C-PDA-mAb. Under optimized conditions, 220 nm ZIF-8-C-PDA-mAb-based FPIA showed the best limit of detection of 0.46 μg/L, which was 47-fold lower than that of the traditional mAb-based FPIA. The recoveries ranged from 86.75 to 111.75%, with a relative standard deviation below 8.44%. Additionally, FPIA results correlated well with HPLC, with a correlation coefficient of 0.998. This strategy provides a great potential FPIA method for rapid and high-sensitivity detection of pesticides and other small molecule pollutants in environmental and agricultural samples.