RESUMO
The multianalyte immunoassay (MIA) has attracted increasing attention due to its high sample throughput, short assay time, low sample consumption, and reduced overall cost. However, up to now, the reported MIA methods commonly require multiple antibodies since each antibody can recognize only one antigen. Herein, a novel bispecific monoclonal antibody (BsMcAb) that could bind methyl parathion and imidacloprid simultaneously was produced by a hybrid hybridomas strategy. A chemiluminescence (CL) reaction kinetics-resolved strategy was designed for MIA of methyl parathion and imidacloprid using the BsMcAb as the unique recognition reagent. Horseradish peroxidase (HRP) and alkaline phosphatase (ALP) were adopted as the signal probes to tag the haptens of the two pesticides due to their very different CL kinetic characteristics. After competitive immunoreactions, the HRP-tagged methyl parathion hapten and the ALP-tagged imidacloprid hapten were simultaneously bound to the BsMcAb since there were two different antigen-binding sites in it. Then, two CL reactions were simultaneously triggered by adding the CL coreactants, and the signals for methyl parathion and imidacloprid detections were collected at 0.6 and 1000 s, respectively. The linear ranges for methyl parathion and imidacloprid were both 1.0-500 ng/mL, with detection limits of 0.33 ng/mL (S/N = 3). The proposed method was successfully used to detect pesticides spiked in ginseng and American ginseng with acceptable recoveries of 80-118%. This proof-of-principle work demonstrated the feasibility of MIA using only one antibody.