Development and comparative study of chemosynthesized antigen and mimotope-based immunoassays for class-specific analysis of O,O-dimethyl organophosphorus pesticides

Abstract

The multi-residue determination of organophosphorus pesticides (OPs) is an important task due to the wide application and high toxicity of OPs. However, there is no promising immunoassay to monitor the multi-residue of O,O-dimethyl OPs. In this study, a monoclonal antibody (mAb) against a generic hapten of O,O-dimethyl OPs (O,O-dimethyl O-(3-carboxyphenyl)phosphorothioate) was prepared. To develop an effective class-specific immunoassay, two strategies were performed to select the appropriate coating antigen or competing antigen. On the one hand, a total of 20 haptens were chemosynthesized, attached to ovalbumin for use as coating antigen candidates, and selected by direct competitive ELISA (dcELISA). As a second strategy, mimotopes of the mAb were selected from a random phage-display peptide library by panning, and the optimum mimotope was expressed as a fusion protein and biotinylated in vitro. Based on the selected chemosynthesized coating antigen and the biotinylated mimotope fusion protein, two sensitive broad-specificity dcELISAs were developed. The sensitivity, selectivity and practicability of the two immunoassays were compared. The results demonstrated that both methods showed similar selectivity and sensitivity and were reliable for O,O-dimethyl OP residues screening. However, the screening operation of mimotopes was much simpler and safer compared to the preparation of chemosynthesized coating antigens.

Monitoring of the Organophosphate Pesticide Chlorpyrifos in Vegetable Samples from Local Markets in Northern Thailand by Developed Immunoassay

“…The concentrations of chlorpyrifos residues in vegetables were calculated against the standard curve ( Figure 2) and reported in µg/kg of vegetable sample. The results of the immunoassay were usually validated with the gold standard technique, i.e., a chromatographic technique [34,40,48]. [40,[49][50][51].…”

Progress of the discovery, application, and control technologies of chemical pesticides in China

“…Zhao et al (2016) used monoclonal antibodies and organic phosphorus pesticide-specific antibodies to establish a highly efficient and specific immunoassay method for 18 types of organophosphorus pesticides. The detection limit of this method was 0.3-52.4 μg L -1 , showing good selectivity and sensitivity (Zhao et al 2016). However, most of the existing electrochemical enzyme sensors can respond only to the pesticides in a single component.…”

Homogeneous Quenching Immunoassay for Fumonisin B1 Based on Gold Nanoparticles and an Epitope-Mimicking Yellow Fluorescent Protein

“…29,30 As they bind to the same antibody paratope as the antigen and elicit a similar antibody response, epitope mimics can be used as the competitor instead of the labeled antigen in applications where the conjugation of the target to a carrier molecule is challenging, or it can cause toxicity to the user. Several mimotopes have been selected from phage-displayed peptide libraries for the detection of low molecular weight targets such as pesticides, 31 neurotoxins, 32 cancer drugs, 33 mycotoxins, 34−36 and other chemicals. 37 Phage-borne peptides have shown great potential for the development of small-molecule immunoassays, but considering the large size and the biologically active nature of phages these methods are not always ideal for immunoassay development.…”

“…The exceptional ability of epitope-mimicking peptides, or mimotopes, to imitate the epitope of an antigen and thus bind to same antibody paratope, has been witnessed in several fields including immunotherapy, epitope mapping, and allergy treatment. , Furthermore, epitope-mimicking peptides and antibodies are an intriguing option to overcome some of the limitations of competitive immunoassays. , As they bind to the same antibody paratope as the antigen and elicit a similar antibody response, epitope mimics can be used as the competitor instead of the labeled antigen in applications where the conjugation of the target to a carrier molecule is challenging, or it can cause toxicity to the user. Several mimotopes have been selected from phage-displayed peptide libraries for the detection of low molecular weight targets such as pesticides, neurotoxins, cancer drugs, mycotoxins, − and other chemicals . Phage-borne peptides have shown great potential for the development of small-molecule immunoassays, but considering the large size and the biologically active nature of phages these methods are not always ideal for immunoassay development. , As an alternative, the synthetic counterparts of the phage-borne mimotopes − or recombinant peptide–protein fusions − have been suggested as phage-free options.…”