An ultrasensitive electrochemical immunosensor for Cry1Ab based on phage displayed peptides

• Published in: Talanta (Oxford) 2018-03, Vol.179, p.646-651
• Main Authors: Lu, Xin, Jiang, Dong-jian, Yan, Jia-xiang, Ma, Zhen-e, Luo, Xiu-er, Wei, Tai-long, Xu, Yang, He, Qing-hua
• Format: Article
• Language: English
• Subjects: amino acid sequences; animals; Antibodies, Monoclonal - chemistry; Bacillus thuringiensis; Bacillus thuringiensis - chemistry; Bacillus thuringiensis - genetics; Bacillus thuringiensis - metabolism; bacterial proteins; Bacterial Proteins - analysis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; bacteriophages; Biological Variation, Individual; Biosensing Techniques; corn; crops; Crops, Agricultural - chemistry; Crops, Agricultural - genetics; Crops, Agricultural - metabolism; cross reaction; Cry1Ab protein; Electrochemical immunosensor; Electrochemical Techniques; electrochemistry; Electrodes; Endotoxins - analysis; Endotoxins - genetics; Endotoxins - metabolism; food safety; Gene Expression; Gold - chemistry; Hemolysin Proteins - analysis; Hemolysin Proteins - genetics; Hemolysin Proteins - metabolism; immunization; Immunoassay; immunosensors; Insecticides - analysis; Insecticides - chemistry; Insecticides - metabolism; Limit of Detection; Metal Nanoparticles - chemistry; nanogold; Peptide Library; peptides; Phage displayed peptide; Plants, Genetically Modified; Protein Isoforms - analysis; Protein Isoforms - genetics; Protein Isoforms - metabolism; risk assessment; sequence homology; Transgenes; transgenic plants; wheat; Zea mays - chemistry; Zea mays - genetics; Zea mays - metabolism
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2017.11.032

The rapid and widespread adoption of Bacillus thuringiensis (Bt) proteins in genetically modified (GM) crops has raised concerns about the impact of GM crops on environment and food safety. A sensitive and specific method for detecting Bt proteins in GM crops is of great significance for environment and food risk assessment. In this study, using Cry1Ab as a model Bt protein, an ultrasensitive electrochemical immunosensor for Cry1Ab protein has been developed based on phage displayed peptide. Phage displayed peptides against Cry1Ab protein were obtained from a phage displayed peptide library without animal immunization process through biopanning-elution strategy. After modification of electrode with gold nanoparticles, selected phage displayed peptide was applied to electrochemical immunosensor for Cry1Ab. Under the optimized conditions, the peptide-based immunosensor showed a dynamic range of 0.01–100ng/mL and a limit detection of 7pg/mL. Specific measurement of this established method was conducted by testing cross-reactivity of Cry1Ac (88% amino acid sequence homology to Cry1Ab protein), and the result showed that peptide-based immunosensor has negligible cross-reactivity with analogue. In addition, the accuracy and reproducibility of this established immunosensor was evaluated by testing the recovery of spiked samples and assay coefficients of variation, respectively. The results showed that the average recovery of corn and wheat sample was 90–120% and 86.7–120%, respectively; the intra-assay coefficient of variation was 7.4% (n = 6), and the inter-assay coefficient of variation was 6.9% (n = 6) at 1ng/mL Cry1Ab solution. Furthermore, the novel concept of peptide-based immunosensor may provide a potential application in general method for the ultrasensitive detection of various Bt proteins. [Display omitted] •Phage displayed peptide replaced traditional IgG antibody for Cry1Ab detection.•An electrochemical immunosensor based on phage displayed peptides was developed.•The immunosensor showed wide linear range from 10pg/mL to 100ng/mL with LOD of 7pg/mL.•The principles of Cry1Ab assays are applicable to detection other Bt proteins.