Quantitative Detection Of Aflatoxin B1 Research Articles

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.

Quantum dot nanobead-based multiplexed immunochromatographic assay for simultaneous detection of aflatoxin B1 and zearalenone

Immunochromatographic assay (ICA) is a promising technology for on-site detection. Nonetheless, the wide-scale application of ICA is hindered by several disadvantages, such as poor reproducibility, low sensitivity, and single-target detection. Thus, a novel quantum dot nanobead (QB)-based multiplexed ICA (QB-ICA) with multiple test lines was developed in this study for the simultaneous quantitative detection of aflatoxin B1 (AFB1) and zearalenone (ZEN), where QBs with high luminescence were used as labels to enhance the analytical sensitivity of the ICA. Moreover, a streptavidin (SA)-biotin system, which was undisturbed by the target mycotoxins, was introduced as the signal output for the control line. Consequently, stable and reliable T/C values (ratios of signals on the test line to that of the control line) were obtained as quantitative signals. The proposed QB-ICA demonstrated high sensitivity for the simultaneous detection of AFB1 and ZEN, of which the half-maximal inhibitory concentrations reached as low as 38.98 pg mL−1 and 1.23 ng mL−1, respectively. At 10% competitive inhibition concentration, the limit detections (LOD) were 1.65 and 59.15 pg mL−1 for AFB1 and ZEN, respectively. The average recoveries of the intra- and inter-assays ranged from 81.77% to 119.70% and from 94.18% to 111.4% for AFB1 and ZEN quantification, respectively, and the variation coefficients were less than 12%, thereby indicating that the proposed method is highly accurate and robust. These findings suggest that QB-ICA using SA-biotin system as the signal output of control line is an excellent point-of-care platform for the rapid screening of mycotoxins.

Development and evaluation of the magnetic particle-based chemiluminescence immunoassay for rapid and quantitative detection of Aflatoxin B1 in foodstuff

ABSTRACT Herein, a simple and cost-effective chemiluminescence immunoassay combined with the magnetic particles (MPCLIA) is presented for the rapid detection and analysis of Aflatoxin B1, which is a potent carcinogen found in the environment. Several physicochemical factors that potentially influence the assay performance of the proposed method were investigated in detail, including concentrations of FITC-labelled antibody, AFB1-alkaline phosphatase and magnetic particles concentration. Under the optimized experiment condition, the method showed: (i) a low limit detection of 0.05 ng/mL; (ii) satisfactory recoveries in real grain and oil samples ranging from 78% to 109%, which was well within the requirement of residue analysis, and (iii) excellent sensitivity, wide dynamic range and easy to separate in the washing process, which was superior to enzyme-linked immunosorbent assay (ELISA) method. In addition, the device used is of low cost. Moreover, the MPCLIA results for the real samples were in good agreement with that obtained by the high-performance liquid chromatography. These results suggest that the proposed MPCLIA method has potential application for screening other toxic mycotoxins occur in the food industry or other applied fields.

Fabrication and Modeling of an Ultrasensitive Label Free Impedimetric Immunosensor for Aflatoxin B1 based on Protein A Self-assembly Modified Gold 3D Nanotube Electrode ensembles

A novel label-free impedimetric immunosensor for the quantitative detection of aflatoxin B1 (AFB1) was developed based on orientated staphylococcus protein A (SPA) modified gold three dimensional nanotube ensembles (3DTNEEs) which consisted of gold nanotubes fabricated by combining the technologies of template synthesis and controlled chemical etching of track-etched polycarbonate membrane. The structure and morphology of 3DTNEEs were evaluated by scanning electron microscopy. The diffusion characteristic and local current distribution on 3DTNEEs were simulated via the COMSOL Multiphysics 4.4 simulative software. The SPA self-assembly modified 3DTNEEs (SPA/3DTNEEs) was assessed by X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy was employed to characterize the fabrication process and optimize working conditions. The model of the molecular recognition interface was constructed and analyzed. The detection limit of AFB1 was 1.0×10−12gmL−1 (S/N=3) with a linear AFB1 concentration range of 4.0×10−12 to 6.0×10−9gmL−1. The AFB1 recovery test in corn samples demonstrated one potential application of the immunosensor.

Development and evaluation of an up-converting phosphor technology-based lateral flow assay for rapid and quantitative detection of aflatoxin B1 in crops

Contamination of grains and other crops by aflatoxin B1 (AFB1), a highly toxic aflatoxin produced by Aspergillus flavus and Aspergillus parasiticus, poses a serious threat to human health and is an important food safety issue. In this study, a competitive up-converting phosphor technology-based lateral flow (AFB1-UPT-LF) assay was developed for rapid detection of AFB1. Detection sensitivity of the proposed assay can reach 0.03ngmL−1 for standard AFB1 solutions, with the coefficients of variation (CV) less than 10% (from 1.0 to 9.4%). A good linearity (r=0.9889) was observed for quantification of AFB1 from 0.03 to 1000ngmL−1. Except for aflatoxin M1, no cross-reactivity was found with the abrin, ricin, ochratoxin A, botulinum toxin, shiga toxin 1, shiga toxin 2, and staphylococcal enterotoxin B, even at high concentrations of 100 or 1000ngmL−1. After optimizing the extraction of AFB1, the assay showed good tolerance to various crop samples, with the detection limit (from 0.1 to 5ngg−1) lower than the corresponding maximum residue level (MRL) set in China. The AFB1-UPT-LF assay provides a promising tool for rapid on-site detection of AFB1 because of its high sensitivity, specificity, and sample tolerance.

Detection of aflatoxin B1 with immunochromatographic test strips: Enhanced signal sensitivity using gold nanoflowers

Immunochromatographic test strips (ICTS) are commonly limited to higher concentrations of analytes. This limitation stems from the relatively low sensitivity of conventional gold nanospheres (AuNSs with a diameter of 20nm) to emit detectable brightness values. The larger multi-branched gold nanoflowers (AuNFs) with a higher optical brightness as well as good colloidal stability exhibit significant improvements over conventional AuNSs for enhanced sensitivity of ICTS. In this study, blue AuNFs with an average diameter of 75±5nm were synthetized and employed as a signal amplification probe for ultrasensitive and quantitative detection of aflatoxin B1 (AFB1) in rice. A portable optical strip reader was used to record the optical densities of test and control lines of the strip. Under the optimal conditions, the AuNF based ICTS system accurately detected AFB1 linearly and dynamically over the range of 0.5–25pg/mL with a half maximal inhibitory concentration at 4.17pg/mL. The inhibitory concentration was achieved 10 times lower than that of the traditional AuNS based ICTS systems (41.25pg/mL). The limit of detection for AFB1 in rice extract was achieved at 0.32pg/mL. In summary, AuNFs are a novel probe that exhibited excellent sensitivity in the ICTS system and could be used for ultrasensitive detection of other analytes in food safety monitoring, and even medical diagnostics.

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%.

Rapid and Quantitative Detection of aflatoxin B1 in Plant grain and oilseeds products Using Colloid Golden Immuno-chromatographic Method

Rapid and Quantitative Detection of aflatoxin B1 in Plant grain and oilseeds products Using Colloid Golden Immuno-chromatographic Method

Development of antibody-based microarray assay for quantitative detection of aflatoxin B1

BACKGROUND: Aflatoxin B1 (AFB1) is a toxic metaboliteproduced by Aspergillus species that contaminates a wide range ofagricultural products. OBJECTIVES: This study was designed todevelop a rapid and highly sensitive immunoassay method inmicroarray format for quantitative detection of AFB1 to evaluatethe potential of microarray platform for high-throughput screening,which can be beneficial in food and feed industry. METHODS:Following successful optimization, using an indirect competitiveimmunoassay in dot blot format, AFB1-bovine serum albumin(AFB1-BSA) conjugate was contact-printed onto 16 isolated subarrayson multi-pad nitrocellulose coated slides; subsequently usedin competitive binding assays. RESULTS: Using the aforementionedassay, AFB1 was determined from 15 pg/g to 3.04 ng/g workingrange with detection limit (LOD) of 1 pg/g. To evaluate assayperformance in real food matrices, the authors spiked wheatsamples with different concentration of AFB1. After extraction,working ranges of 0.11-4.15 ng/g with detection limit of 30pg/g wasdetermined. Good recoveries (94±9%) were obtained, demonstratingaccurate detection of AFB1 concentrations in wheat samples.Assay procedure completed in 3 hours. CONCLUSIONS: The resultsindicated that the proposed developed assay in microarray formatcould be used for rapid and sensitive detection of AFB1in wheatsamples.

Toxin detection by Si photosensitive biosensors with a new measurement scheme

We propose a new type of photosensitive biosensor with a CMOS compatible Si photodiode integrated circuit, for the high-sensitive detection of small mycotoxin molecules requiring competitive assay approach. In this work, a photodiode is connected to the gate of a field effect transistor (FET) so that the open circuit voltage (VOC) of the illuminated photodiode is transferred into the drain/source current (IDS) of the FET. The sensing scheme employs competitive binding of toxin molecules (within the sample solution) and toxin–BSA conjugates (immobilized on the photodiode surface) with Au-nanoparticle-labeled antibodies, followed by silver enhancement to generate opaque structures on the photodiode surface. By utilizing the non-linear dependence of the VOC on the light intensity, we can maintain a sufficiently high signal resolution at low toxin concentrations (with most of the incident light blocked) for the competitive assay. By monitoring the IDS of the FET whose gate is driven by the VOC, quantitative detection of Aflatoxin B1 has been achieved in the range of 0–15ppb.

Detection of Small Toxin Molecules by Si Photovoltaic Integrated Circuit

We propose a new type of photosensitive biosensor with a CMOS compatible Si photovoltaic integrated circuit, for the high-sensitive detection of small mycotoxin molecules requiring competitive assay approach. In this work, a photodiode is connected to the gate of a field effect transistor (FET) so that the open circuit voltage (VOC) of the illuminated photodiode is transferred into the drain/source current of the FET. The sensing scheme employs competitive binding of toxin molecules (within the sample solution) and toxin-BSA conjugates (immobilized on the photodiode surface) with Au-nanoparticle-labeled antibodies, followed by silver enhancement to generate opaque structures on the photodiode surface. As the amount of toxin increases, less opaque becomes the photodiode surface resulting in a higher VOC. By monitoring the channel current of the FET whose gate is driven by the VOC, quantitative detection of Aflatoxin B1 has been achieved in the range of 0∼15 ppb.

Qualitative and quantitative detection of aflatoxin B1 in poultry sera by enzyme-linked immunosorbent assay

An indirect competitive inhibition type enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of aflatoxin B1, in poultry sera. Preincubation of aflatoxin B1, samples with the antibody prior to competition yielded better results in terms of higher sensitivity. After competition, amount of antibody bound to solid phase was measured by incubation with anti-rabbit immunoglobulins coupled with horse raddish peroxidase. Intensity of colour decreased as the amount of free aflatoxin B1, increased. Final detection of aflatoxin B1, was made by (i) visual comparison with standard aflatoxin B1 using dot-ELISA (qualitative) and (ii) by plate-ELISA, where optical density was measured at 492 nm (quantitative). Plate-ELISA was more sensitive than dot-ELISA, with sensitivity limits being 100 fg and 1 pg per 10 μl, respectively. However, due to ease and speed of performance, dot-ELISA has greater potential as a test for the diagnosis of mycotoxicosis at the field level.