Development of a phage chemiluminescent enzyme immunoassay with high sensitivity for the determination of imidaclothiz in agricultural and environmental samples.

In this study, we isolated six phage-displayed peptides by biopanning phage-displayed peptide libraries on an immobilized anti-imidaclothiz monoclonal antibody. After analyzing the relative sensitivity of the individual phage-displayed peptides, we subsequently developed and optimized both a phage enzyme immunoassay (P-ELISA) and a phage chemiluminescent enzyme immunoassay (P-CLEIA) to improve the sensitivity and linear range of imidaclothiz assays. The P-CLEIA (50% inhibition concentration (IC50) of 0.86ngmL-1, linear range of 0.13-5.84ngmL-1) was more sensitive and had a wider linear range compared to the P-ELISA (IC50 of 1.45ngmL-1, linear range of 0.55-3.82ngmL-1). Besides, the sensitivities of the P-ELISA and P-CLEIA were increased by >4-fold and 8-fold, respectively as compared to homologous immunoassays developed using the same monoclonal antibody. Neither method had significant cross-reactivity with the analogues of imidaclothiz except for imidacloprid. Recoveries of the P-ELISA and P-CLEIA for imidaclothiz in paddy water, soil, cabbage, rice, apple, pakchoi, pear and tomato samples were 72.3-101.3% and 73.9-102.6%, respectively. The P-ELISA and P-CLEIA detected imidaclothiz in the authentic samples, and showed good correlation with results obtained from high-performance liquid chromatography (HPLC).