Development of robust, environmental, immunoassay formats for the quantification of pesticides in soil

The use of antibodies, or more specifically recombinant antibody fragments (scAbs), for the immunodetection of pesticides, could provide a rapid, reliable, and robust method of environmental analysis. The inherent instability of some antibody structures in nonphysiological conditions, however, limits the utility of this approach. We have developed a generic strategy for the stabilization of scAbs in polar and nonpolar solvents, and in a range of other denaturing environments, by the introduction of an interdomain disulfide bond, generating stabilized antibody fragments or stAbs. StAbs specific for the phenoxyacid herbicide mecoprop and the phenylurea herbicide diuron were fully functional when compared to their equivalent unmodified scAbs but significantly more stable in nonphysiological conditions associated with the extraction of organics from environmental samples. Antiatrazine, mecoprop, diuron, and paraquat stAbs were successfully used to accurately identify and quantify pesticides present in solvent and aqueous extracted soil samples. Immunoassay data were validated by HPLC. Recombinant stAbs can be produced readily, cost-effectively, and in quantity from Escherichia coli expression systems and provide robust reagents for immunoassay detection of pollutants present in complex environmental matrices.