Immunosensor For Detection Of Aflatoxin B1 Research Articles

Nafion-Immobilized Functionalized MWCNT-based Electrochemical Immunosensor for Aflatoxin B1 Detection.

The ubiquitous aflatoxin B1 (AFB1) contamination in foods and other complex matrices has brought great challenges for onsite monitoring. In this study, an ultrasensitive Nafion-immobilized functionalized multiwalled carbon nanotube (MWCNT)-based electrochemical (EC) immunosensor was developed for trace AFB1 detection. The introduced Nafion film could steadily stabilize functionalized MWCNTs with uniform distribution and tiling on the surface of a Au electrode. Functionalized MWCNTs with a large specific surface area, numerous active sites to couple with abundant anti-AFB1 monoclonal antibodies (mAbs), and high conductivity served as the signal amplifier for remarkably enhancing the sensing performance of the immunosensor. In the presence of AFB1, it was specifically captured by mAbs to reduce the amplified current signals, which were recorded by differential pulse voltammetry for the accurate quantitation of AFB1. Because of the synergistic effects of Nafion on the stabilization of functionalized MWCNTs as signal enhancers, the developed EC immunosensor exhibited an extremely high selectivity, excellent sensitivity with a limit of detection as low as 0.021 ng/mL, and a wide dynamic range of 0.05-100 ng/mL, besides fascinating merits of easy construction, low cost, good stability in 7 days, and good reusability. The anti-interference ability of the immunosensor was verified against three other mycotoxins, and the practicability and accuracy were confirmed by measuring AFB1 in fortified malt, lotus seed, and hirudo samples with a satisfactory recovery of 92.08-104.62%. This novel immunosensing platform could be extended to detect more mycotoxins in complex matrices to ensure food safety.

Label-free photoelectrochemical immunosensor for aflatoxin B1 detection based on the Z-scheme heterojunction of g-C3N4/Au/WO3

Aflatoxin B1 (AFB1) is the most toxic mycotoxin, is widely found in foods and animal feeds, and can pose a serious threat to our lives. A label-free photoelectrochemical (PEC) immunosensor was fabricated for the sensitive detection of AFB1. A Z-scheme heterojunction of gold nanoparticles (Au NPs) loaded on graphitic carbon nitride sheet and tungsten trioxide sphere composite (g-C3N4/Au/WO3) acted as the highly sensitive platform. The g-C3N4/Au/WO3 is capable, not only of immobilizing antibodies via Au NPs, but also enhancing the separation of electron-hole pairs due to its good energy band matching efficiency. The mechanism of photo-generated electron/hole transfer on g-C3N4/Au/WO3 was explored using scavengers to eliminate active components. On this basis, an electron transfer pathway for the immunosensor was deduced. The PEC immunosensor displayed a linear concentration range from 1.0 pg mL−1 to 100 ng mL−1 and a low detection limit of 0.33 pg mL−1 (S/N = 3) for AFB1. Good reproducibility, stability, and specificity provide a solid foundation for the practical application of this immunosensor.

Ultrasensitive Immunosensor for Aflatoxin B1 Detection Based on Screen-Printed Carbon Electrode Modified by Ferrocene @Multi-Walled Carbon Nanotubes

Ultrasensitive Immunosensor for Aflatoxin B1 Detection Based on Screen-Printed Carbon Electrode Modified by Ferrocene @Multi-Walled Carbon Nanotubes

A competitive-type photoelectrochemical immunosensor for aflatoxin B1 detection based on flower-like WO3 as matrix and Ag2S-enhanced BiVO4 for signal amplification

A competitive photoelectrochemical (PEC) immunosensor was successfully utilized for quantitative detection of aflatoxin B1 (AFB1). The flower-like tungsten oxide (WO3) hierarchical architectures with large specific surface areas and porous nanostructure was prepared as a matrix material for immobilizing of BSA-AFB1. The Ag ions-modified bismuth vanadate nano-polyhedron (BiVO4@Ag+) was utilized as labels for immobilization anti-AFB1 through affinity specific binding. The Ag2S was prepared in-situ growth by immediately deposition the S2− onto the BiVO4@Ag+. The high photocurrent intensity was generated by the obtained BiVO4@Ag2S under visible-light irradiation. Moreover, excellent sensitivity was achieved by using the WO3 as the matrix and BiVO4@Ag2S as labels to enhance photocurrent response and improve the photocurrent conversion efficiency. Under optimal conditions, the competitive PEC immunosensor showed wide linear range from 1.0 pg mL−1 to 120 ng mL−1 with limit detection of 0.28 pg mL−1 for AFB1. The biosensor was performed with good reproducibility, acceptable stability, and high specificity, which indicated potential application in the detection of other toxic small molecules.

A novel electrochemical piezoelectric label free immunosensor for aflatoxin B1 detection in groundnut

An electrochemical quartz crystal microbalance (EQCM) based label-free immunosensor has been developed for the quantitative detection of aflatoxin B1 (AFB1) in groundnut. The gold (Au) coated quartz crystal (6 MHz) functionalized with self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) has been utilized to immobilize anti-aflatoxin antibodies (aAFB1). The quartz crystal microbalance QCM frequency and EQCM cyclic voltammetry measurements have been used to optimize the deposition of SAM layer on Au electrode (4-ATP/Au), antibody immobilization (aAFB1/4-ATP/Au), bovin serum albumin (BSA) adsorption (BSA/aAFB1/4-ATP/Au) and immuno interaction (AFB1/BSA/aAFB1/4-ATP/Au). Interestingly, the EQCM studies conducted on this immunoelectrode provide wider linear range of 0.1–4.0 ng mL−1 and higher sensitivity than those obtained using under identical condition. The high association constant of 9.4 × 10−2 ng mL−1 of the EQCM immunosensor can be attributed to molecularly oriented self assembled monolayer of 4-ATP on QCM gold electrode that acts as a nanowire between aAFB1 and electrode through amide linkage formed by the NH2 group of 4-ATP and COOH group of Fc part of aAFB1. This linkage also helps to project paratope part of aAFB1 to interact with AFB1. The developed label free EQCM based immunosensor was tested for the AFB1 detection in the extract of contaminated groundnut and the results were compared with Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The comparative results demonstrate the suitability of this sensor for routine screening of groundnut and the percent error is found to be ±12%.