A peptide Epitope − Synthetic hydrogel polymer conjugate that mimics insecticidal protein Receptors. Application in environmental and biological analysis

[Display omitted] •An epitope is identified for broad-spectrum recognition of Bt Cry protein variants.•A robust epitope–polymer conjugate library was created.•Screening identified a candidate for environmental and biological analysis.•An extraction protocol is established for Bt proteins in environmental samples.•A biotinylated conjugate is integrated into an ELISA assay for GMO identification. Monitoring transgenic crops (GMOs) is essential to track cross-breeding and ensure regulatory compliance but multiple protein variants now engineered into important crops challenges conventional antibody detection. Analysis of Bacillus thuringiensis (Bt) Cry protein − insect receptor complexes identified a peptide epitope, NITIHITDTNNK, with high sequence similarity to cadherin-like receptors across a family of Bt Cry proteins for broad-spectrum recognition. The peptide lacks the necessary physical, mechanical and chemical properties for practical applications. Conjugation of the peptide to a synthetic polymer creates a hybrid material that imparts robustness, adhesion, processability and polyvalence to the epitope. An epitope − hydrogel polymer conjugate library is created and screened for Bt Cry protein binding. A candidate with high adsorption capacity (∼995 mg g−1), fast adsorption kinetics (within 2 min), broad-spectrum specificity, and pH-responsive catch-and-release is identified as a selective sequestrant for extraction and isolation of Bt Cry variants from water and soil samples. An enrichment factor of 9.0 ∼ 12.5 and a linear range of 0.09 ∼ 0.45 µg g−1 was obtained for soil samples. The biotinylated epitope − polymer conjugate, a recognition element entirely different from an antibody, is integrated into an enzyme-linked immunosorbent assay (ELISA) for identification of cotton and rice crops transgenic with a variety of Bt Cry variants. The established ELISA assay exhibits wide linear range (0 ∼ 50 ng mL−1) and high accuracy (95.4 ∼ 108 %) for GMO cotton leaves. However, to distinguish GMO rice from non-GMO ones, background interference still needs to be overcome. We are now working for a more effective diagnostic for GMO rice.