Abstract
A reusable sandwiched electrochemical piezoelectric immunosensor has been developed for aflatoxin B1 (AFB1) detection using gold coated iron oxide core-shell (Au-Fe3O4) nanostructure. The monoclonal anti-aflatoxin antibody (aAFB1) was immobilized on self-assembled monolayer of 4-aminothiophenol on gold coated quartz crystal to fabricate immunoelectrode (BSA/aAFB1/4-ATP/Au). In addition, secondary rabbit-immunoglobulin antibodies (r-IgGs) functionalized with Au-Fe3O4NPs via cysteamine (r-IgG-Cys-Au-Fe3O4) were allowed to interact with AFB1. Both competitive and noncompetitive strategies were employed and a competition between coated AFB1 and free AFB1 was carried out. The competitive mode shows higher linear range (0.05 to 5 ng mL−1) than the noncompetitive one (0.5 to 5 ng mL−1), high sensitivity 335.7 µA ng−1 mL cm−2, and LOD 0.07 ng mL−1. The fabricated immunosensor has been tested using cereal samples spiked with different concentrations of AFB1. The developed competitive immunoelectrode displays good reproducibility, and storage stability and regenerated with negligible loss in activity through removal of the r-IgG-Cys-Au-Fe3O4conjugate using a strong external magnet.
Highlights
Aflatoxin B1 (AFB1), which is a low molecular mass compound mainly produced by the moulds Aspergillus flavus and Aspergillus parasiticus, can contaminate several important crops under favorable environmental conditions [1, 2]
Among the signal detection techniques, quartz crystal microbalance (QCM) based detection systems are considered to be the most promising for immunointeraction owing to their affordable cost and real-time and label-free compatibility with miniaturization, portability, and high sensitivity [23,24,25]
Monoclonal anti-aflatoxin B1 antibodies, aflatoxin B1 (AFB1), bovine serum albumin (BSA), polyclonal IgG antibodies from rabbit (r-IgG), 4-aminothiophenol (4-ATP), N-ethyl-N-(3-dimethylaminopropyl) carbodiimide (EDC), N-hydroxysuccinimide (NHS), ferrous chloride hexahydrate (FeCl2⋅6H2O), ferric chloride tetrahydrate (FeCl3⋅4H2O), sodium hydroxide (NaOH), and chloroauric acid (HAuCl4⋅H2O) were procured from SigmaAldrich
Summary
Aflatoxin B1 (AFB1), which is a low molecular mass compound mainly produced by the moulds Aspergillus flavus and Aspergillus parasiticus, can contaminate several important crops (e.g., corn, sorghum, peanuts, fruits, dried fruits, cocoa, and spices) under favorable environmental conditions [1, 2]. Owing to high toxicity and carcinogenicity, AFB1 is of major concern for food producers, the food processing industry, and consumers [3]. Some of the biosensing techniques used for AFB1 detection include electrochemical biosensors [15, 16], surface plasmon resonance [17, 18], fluorescent biosensors [19, 20], and quartz crystal (piezoelectric) microbalance based sensors [21, 22]. Among the signal detection techniques, quartz crystal microbalance (QCM) based detection systems are considered to be the most promising for immunointeraction owing to their affordable cost and real-time and label-free compatibility with miniaturization, portability, and high sensitivity [23,24,25]
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