Sensitive detection of Bacillus thuringiensis Cry1B toxin based on camel single‐domain antibodies

Bt Cry1B toxin, a residue in insect‐resistant transgenic plants, has been identified to be harmful to human health. Therefore, it is urgent to detect the Cry1B toxin level in each kind of transgenic plant. Nbs, with prominently unique physiochemical properties, are becoming more and more promising tools in the detection of target antigens. In this study, an immune phage display library that was of high quality was successfully constructed for the screening of Cry1B‐specific Nbs with excellent specificity, affinity, and thermostable. Subsequently, a novel sandwich ELISA for Cry1B detection was established, which was based on the biotin–streptavidin system using these aforementioned Nbs. This established detection system presented a linear working range from 5 to 1000 ng ml(−1) and a low detection limit of 3.46 ng ml(−1). The recoveries from spiked samples were in the range of 82.51%–113.56% with a relative standard deviation (RSD) lower than 5.00%. Taken together, the proposed sandwich ELISA would be a potential method for the detection of Cry1B toxin in transgenic Bt plants specifically and sensitively.