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. 2021 Dec 7:9:770584.
doi: 10.3389/fchem.2021.770584. eCollection 2021.

A Label-Free Immunosensor Based on Gold Nanoparticles/Thionine for Sensitive Detection of PAT Protein in Genetically Modified Crops

Qianwen Yang  1   2 , Yu Wang  1   2 , Xiaofeng Liu  2 , Hua Liu  1   3 , Huifang Bao  4 , Jinbin Wang  1   3 , Haijuan Zeng  1   3
Affiliations

A Label-Free Immunosensor Based on Gold Nanoparticles/Thionine for Sensitive Detection of PAT Protein in Genetically Modified Crops

Qianwen Yang et al. Front Chem. .

Abstract

Genetically modified (GM) crops containing phosphinothricin acetyltransferase (PAT) protein has been widely planted worldwide. The development of a rapid method for detecting PAT protein is of great importance to food supervision. In this study, a simple label-free electrochemical immunosensor for the ultrasensitive detection of PAT protein was constructed using thionine (Thi)/gold nanoparticles (AuNPs) as signal amplification molecules and electrochemically active substances. Under optimum conditions, the limits of detection of the sensor for soybean A2704-12 and maize BT-176 were 0.02% and 0.03%, respectively. The sensor could detect crops containing PAT protein and had no cross-reaction with other proteins. After storage at 4°C for 33 days, the sensor still retained 82.5% of the original signal, with a relative standard deviation (RSD) of 0.92%. The recoveries of the sensor for soybean A2704-12 and maize BT-176 were 85%-108% and 98%-113%, respectively. The developed PAT-target immunosensor with high sensitivity, specificity, and satisfactory reproducibility and accuracy will be a useful tool in the trace screening of GM crops. Moreover, this design concept can be extended to other proteins by simply changing the antibody.

Keywords: genetically modified crops; gold nanoparticles; immunosensor; label free; thionine.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Scheme 1
Scheme 1
Schematic diagram of the electrochemical immunosensor based on gold nanoparticles (AuNPs)/thionine (Thi) for the sensitive and rapid detection of phosphinothricin acetyltransferase (PAT) protein in genetically modified (GM) crops.
FIGURE 1
FIGURE 1
Characterization of the electrochemical immunosensor. (A) The stepwise assembly process of the immunosensor was detected by cyclic voltammeter measurements. (B) The scanning electron microscope (SEM) image of gold nanoparticles (AuNPs) deposited on the electrode surface.
FIGURE 2
FIGURE 2
Condition optimization of Thi. (A) Optimization of time. (B) Optimization of Thi concentration.
FIGURE 3
FIGURE 3
Sensitivity of the immunosensor. (A) Differential pulse voltammetry (DPV) peak current for different concentrations of soybean A2704-12. (B) DPV peak current for different concentrations of maize BT-176. (C) Calibration curve of the immunosensor toward soybean A2704-12 (n = 3). (D) Calibration curve of the immunosensor toward maize BT-176 (n = 3).
FIGURE 4
FIGURE 4
Specificity and stability of the developed immunosensor. (A) The specificity of the sensors. (B) The stability of the sensors by cyclic voltammeter (CV) measurements.
See this image and copyright information in PMC

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