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

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 mu g g-1 was obtained for soil samples. The biotinylated epitope -polymer conjugate, a recognition element entirely different from an anti-body, 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.

Automated summary

Monitoring transgenic crops is essential, but conventional antibody detection faces challenges with multiple protein variants engineered into important crops. A peptide epitope with high sequence similarity to certain proteins is identified, but lacks the necessary properties for practical applications. Conjugation of the peptide to a synthetic polymer creates a hybrid material that can be used for extraction and detection of transgenic protein variants from water and soil samples.