Determination Of Aflatoxin B1 Research Articles

A novel highly active AgMOF-based silver single-atom catalyst and its application to the aptamer SERS/RRS for the determination of aflatoxin B1

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl4–H2Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (AptAFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to AptAFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005–0.225 μg/L and a detection limit of 0.002 μg/L.

A novel Recjf Exo signal amplification strategy based on bioinformatics-assisted truncated aptamer for efficient fluorescence detection of AFB1

Aflatoxin B1 (AFB1) is a typical mycotoxin that signifacntly endangers public health and economy. In this study, we systematically studied the interaction of aptamers with AFB1 using circular dichroism, molecular dynamics, molecular docking, and fluorescence analysis. The truncated sequence aptamers were screened using molecular docking. We successfully obtained the AFB1 aptamer with higher affinity and its truncated form was enhanced by 5.2-fold compared to the initial AFB1 aptamer. In addition, for rapid detection of AFB1, we designed a fluorescent nano-adaptor sensing platform using RecJf exonuclease signal amplification strategy based on the optimal aptamer. The aptasensor showed satisfactory sensitivity towards AFB1 with a linear detection range of 1–400 ng/mL and a detection limit of 0.57 ng/mL. The aptasensor was successfully applied to the determination of AFB1 in soybean oil and corn oil with recoveries of 91.02 %–106.59 % and 87.39 %–110.61 %, respectively. The successful application of the AFB1 aptasensor, developed through bioinformatics truncation of the aptamer, provides a novel approach to creating a cost-effective, eco-friendly, and rapid aptamer sensing platform.

Fe-N-C single-atom nanozyme-linked immunosorbent assay for quantitative detection of aflatoxin B1

Aflatoxin B1 (AFB1) is a prominent food contaminant known for its high toxicity. Rapid, low-cost, and sensitive detection of AFB1 is an urgent demand for food safety risk control. In the traditional enzyme-linked immunosorbent assay (ELISA) method for AFB1 detection, horseradish peroxide (HRP) is high-cost and possesses poor environmental stability. In this study, a direct competitive single-atom nanozymes (SAzymes) -linked immunosorbent assay was developed based on Fe-N-C SAzymes. The proposed methods exhibited excellent sensitivity, rapid detection, fabrication, and low cost. Under the optimal conditions, the limit of detection of the new assay was 3.3 pg mL−1, with a quantitative relationship between 0.0084 and 0.358 ng mL−1. In addition, the developed method presented good recoveries in spiked samples, ranging from 84.50% and 103.75%, with coefficients of variation below 10%. Furthermore, the developed detection method showed good consistency (R2 = 0.9852) with the reference method, liquid chromatography/mass spectrometry (LC-MS/MS). To our knowledge, this is the first report about single-atom nanozymes-based ELISA for AFB1 determination. This work provides a feasible strategy for the rapid and sensitive detection of food contaminants using SAzymes.

Mycotoxin Occurrence in Milk and Durum Wheat Samples from Tunisia Using Dispersive Liquid-Liquid Microextraction and Liquid Chromatography with Fluorescence Detection.

Food and feed contamination with mycotoxins is a major public health concern. Humans and animals are exposed to these toxins by consuming contaminated products throughout their lives. In this study, a method based on dispersive liquid-liquid microextraction (DLLME), followed by liquid chromatography with fluorescence detection (LC-FLD), was validated for the determination of aflatoxins (AFs) M1, B1, B2, G1, G2, zearalenone (ZEN), and ochratoxin A (OTA). The method was applied to 150 raw cow milk samples and 90 market durum wheat samples from two Tunisian climatic regions: the littoral region (Mahdia) and the continental region (Béja). This work was carried out to obtain more surveillance data to support rapid initiatives to assure safe foods and protect consumer health and to estimate the daily exposure of the Tunisian population consuming those products. AFG2 and OTA were found in wheat with incidences of 54.4 and 11.1%, respectively. On the other side, milk samples were contaminated by AFG2, AFB1, and AFB2 with incidences of 8.7%, 2.0%, and 0.67%, respectively. Some of the samples showed OTA concentrations above the maximum limit allowed by the European Union, which represents a health risk for consumers in Tunisia, where no legislation exists about the maximum content of mycotoxins in food.

MnO2 nanoflowers based colorimetric and fluorescent dual-mode aptasensor for sensitive detection of aflatoxin B1 in milk

Aflatoxin B1 (AFB1) with tremendous toxic effects has caused a serious threat to food security. Accurate quantification of AFB1 in food can effectively prevent the risk of human intake of AFB1. Herein, a colorimetric and fluorescent dual-mode aptasensor for accurate and sensitive detection of AFB1 has been developed based on MnO2 nanoflowers (MnO2NFs) for the first time. MnO2NFs could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxidation product (TMBox) by H2O2, which would be used for visible detection of AFB1. Simultaneously, MnO2NFs can be served as a signal amplifier and reduced by ascorbic acid to generate lots of Mn2+ which would quench the fluorescence of calcein for fluorescent detection of AFB1. Both colorimetric and fluorescent methods have been successfully applied for determination of AFB1 in milk samples with satisfactory results. The proposed dual-mode detection method with high detection sensitivity and accuracy showed great promise for monitoring AFB1 in food.

In situ synthesized eRAFT polymers for highly sensitive electrochemical determination of AFB1 in foods and herbs.

An electrochemical sensor based on environmentally friendly eRAFT polymerization was developed for the detection of aflatoxin B1 (AFB1) in food and herbal medicine. Two biological probes, aptamer (Ap) and antibody (Ab), were used to specifically recognize AFB1, and a large number of ferrocene polymers were grafted on the electrode surface by eRAFT polymerization, which greatly improved the specificity and sensitivity of the sensor. The detection limit of AFB1 was 37.34fg/mL. In addition, the recovery rate was 95.69% to 107.65% and the RSD was 0.84% to 4.92% by detecting 9 spiked samples. The delighted reliability of this method was verified by HPLC-FL.

Multiplex bio-barcode based fluorometric immunoassay for simultaneous determination of zearalenone, fumonisin B1, ochratoxin A, and aflatoxin B1 in cereals

Multiplex bio-barcode based fluorometric immunoassay for simultaneous determination of zearalenone, fumonisin B1, ochratoxin A, and aflatoxin B1 in cereals

A novel fluorescent sensing platform based on nitrogen-doped carbon quantum dots for rapid and sensitive detection of aflatoxin B1 in corn flour

Aflatoxin B1 (AFB1) contamination in cereals and their products seriously concerns food safety and human health. Herein, a nitrogen-doped carbon quantum dots (N-CQDs)-based fluorescent sensing platform was successfully developed for the sensitive and rapid detection of AFB1 in corn flour. In this work, using sodium citrate and urea as precursors, hydrophilic N-CQDs were synthesized by the one-step hydrothermal method with good biocompatibility and high fluorescence stability. The as-prepared N-CQDs exhibited excitation wavelength-independent fluorescence in the 300–370 nm range, and had bright blue emission at 448 nm upon 360 nm excitation. Via fluorescence quenching of the N-CQDs in the presence of increasing AFB1 concentrations, the proposed fluorescent sensor had an excellent selectivity for AFB1 detection with a low limit of detection (0.13 ng/mL) in the linear range of 0.5–100 ng/mL. Under optimized sensing conditions, the rapid AFB1 determination in real corn flour samples was realized with good recoveries (95.3–105.7%). In summary, present results indicated the promising potential of this novel N-CQDs-based fluorescent sensor for rapid and effective AFB1 detection in agricultural products.

Development of an ultrasensitive SERS aptasensor for determination of aflatoxin B1 by modifying magnetic beads with UiO-66-NH2 for enhanced signal probe capturing

A versatile Surface-enhanced Raman Spectroscopy (SERS) aptasensor was fabricated for ultrasensitive and stable aflatoxin B1 (AFB1) detection using complementary DNA strands (cDNA) modified Fe3O4@UiO-66-NH2 as capture probe and aptamer modified Au@ 4-MBA@AgNPs as signal probe. The surface of the Fe3O4 beads was functionalized with UiO-66-NH2 to improve the surface area and content of reactive amino groups for stable immobilization of cDNA and capture of more signal probes. Raman tag (4-mercaptobenzoic acid, 4-MBA) embedded Au@AgNPs nanoparticles (Au@4-MBA@AgNPs) was used as signal probes to achieve strong SERS intensity and protect the tag molecules from external interference. When no AFB1 existed, a strong SERS intensity of the signal probe was observed due to the DNA hybridization reaction between the capture and signal probe. While, the addition of AFB1 led to the dissociation of signal probes from the capture probes, leading to a decreased Raman intensity. As a result, a low limit of detection of 1.47 × 10−7 ng/mL and wide linear range from 10−6 to 102 ng/mL were obtained for determination of AFB1 based on the fabricated aptasensor. Moreover, an excellent selectivity and desirable recoveries from 94.3 % to 103.3 % in real maize samples were obtained, demonstrating the fabricated SERS aptasensor is promising in practical applications.

Determination of Aflatoxins B1, B2, G1, and G2 and Ochratoxin A in Dry Fermented Sausages Using a Dilute and Shoot Method and LC–MS/MS

Determination of Aflatoxins B1, B2, G1, and G2 and Ochratoxin A in Dry Fermented Sausages Using a Dilute and Shoot Method and LC–MS/MS

Label-Free Electrochemical Aptasensor Based on the Vertically-Aligned Mesoporous Silica Films for Determination of Aflatoxin B1.

Herein we report a highly specific electrochemical aptasenseor for AFB1 determination based on AFB1-controlled diffusion of redox probe (Ru(NH3)63+) through nanochannels of AFB1-specific aptamer functionalized VMSF. A high density of silanol groups on the inner surface confers VMSF with cationic permselectivity, enabling electrostatic preconcentration of Ru(NH3)63+ and producing amplified electrochemical signals. Upon the addition of AFB1, the specific interaction between the aptamer and AFB1 occurs and generates steric hindrance effect on the access of Ru(NH3)63+, finally resulting in the reduced electrochemical responses and allowing the quantitative determination of AFB1. The proposed electrochemical aptasensor shows excellent detection performance in the range of 3 pg/mL to 3 μg/mL with a low detection limit of 2.3 pg/mL for AFB1 detection. Practical analysis of AFB1 in peanut and corn samples is also accomplished with satisfactory results by our fabricated electrochemical aptasensor.

A flexible, highly adaptive, self-standing photoelectrochemical aptasensor based on 3D pinecone-like structure BiOBr/TiO2 hierarchical nanofiber membranes

Here, we designed a flexible, highly adaptive, self-Standing photoelectrochemical (PEC) aptasensor for Aflatoxin B1 (AFB1) detection based on BiOBr/TiO2 hierarchical nanofiber membranes (NFM) with a 3D pinecone-like structure by integrating sol-gel electrospinning with the successive ionic layer adsorption and reaction (SILAR) method. The uniformly deposited BiOBr nanosheets could not only enlarge the surface area but also expand the light absorption range of TiO2 NFM. Owing to the pinecone-like and hierarchical structure, the photo-generated carriers of BiOBr/TiO2 NFM could be separated quickly and efficiently, which was contributed to obtain a larger and more stable photocurrent intensity. The photocurrent intensity of 6-BiOBr/TiO2 NFM was 12.1 times of pristine TiO2 NFM and 3.4 times of pure BiOBr, respectively. The constructed flexible and self-Standing PEC aptasensor has achieved AFB1 detection in tomato samples with good repeatability, specificity and sensitivity. Under the optimized conditions, a wide linear range (0.001–400 ng mL−1) and a detection limit of 0.12 pg mL−1 (S/N = 3) were obtained for AFB1 determination. This design principle provided a neo-idea for development of flexible and self-Standing PEC aptasensor.

Au@SiO2 SERS nanotags based lateral flow immunoassay for simultaneous detection of aflatoxin B1 and ochratoxin A.

Agricultural products are frequently contaminated by mycotoxins. Multiplex, ultrasensitive, and rapid determination of mycotoxins is still a challenging problem, which is of great significance to food safety and public health. Herein, a surface-enhanced Raman scattering (SERS) based lateral flow immunoassay (LFA) for the simultaneous on-site determination of aflatoxin B1 (AFB1) and ochratoxin A (OTA) on the same test line (T line) was developed, in this study. In practice, two kinds of Raman reporters 4-mercaptobenzoic acid (4-MBA), and 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) encoded silica-encapsulated gold nanotags (Au4-MBA@SiO2 and AuDNTB@SiO2) were used as detection markers to identify the two different mycotoxins. Through systematic optimization of the experimental conditions, this biosensor has high sensitivity and multiplexing with the limits of detection (LODs) at 0.24pgmL-1 for AFB1 and 0.37pgmL-1 for OTA. These are far below the regulatory limits set by the European Commission, in which the minimum LODs for AFB1 and OTA are 2.0 and 3.0μgkg-1. In the spiked experiment, the food matrix are corn, rice, and wheat, and the mean recoveries of the two mycotoxins ranged from 91.0%±6.3%-104.8%±5.6% for AFB1 and 87.0%±4.2%-112.0%±3.3% for OTA. These results demonstrate that the developed immunoassay has good stability, selectivity, and reliability, which can be used for routine monitoring of mycotoxin contamination.

A novel immunosensor based on cobalt oxide nanocomposite modified single walled carbon nanohorns for the selective detection of aflatoxin B1.

We developed a novel, sensitive, and selective platform for the specific determination of aflatoxin B1 (AFB1). Single-walled carbon nanohorns decorated by a cobalt oxide composite and gold nanoparticles were created to provide facile electron transfer and improve the sensor's sensitivity. In addition, we attributed the selectivity of the proposed sensor to the specific binding property of the anti-aflatoxin B1 antibody. We clarified the specific interaction of the proposed immunosensor to AFB1 using homology modeling combined with molecular docking. In the presence of AFB1, the current signal of the modified electrode reduced; this involved specific antibody-antigen binding, including hydrophobic hydrogen bonding and pi-pi stack interactions. The new AFB1 sensor platform showed two linearity ranges of 0.01-1ngmL-1 and 1-100ngmL-1, with the limit of detection at 0.0019ngmL-1. We investigated the proposed immunosensor in real samples, including peanuts, certified reference material of a peanut sample (labeled 206μgkg-1 AFB1), corn, and chicken feed. The sensor's accuracy was 86.1-104.4% recovery, which agrees with the reference HPLC technique using paired t-test analysis. The present work shows excellent performance for AFB1 detection and could be applied for food quality control or modified to detect other mycotoxins.

Nanoassemblies Based on a Cationic Perylene Diimide Derivative and Sodium Dodecyl Sulfate: A Simple Fluorescent Platform for Efficient Analysis of Aflatoxin B1.

Aflatoxin B1 (AFB1) is a kind of potently carcinogenic fungal metabolite in food threatening human health, and it is crucial and challenging to develop advanced nonimmune approaches for AFB1 determination. Addressing this challenge, we successfully constructed a nanoassembly (PdE-PDI/SDS) by noncovalently coupling a cationic perylene diimide derivative (PdE-PDI) and sodium dodecyl sulfate (SDS), exhibiting high-density charges and a specific surface area for rapid sensing of AFB1. The large electronic conjugate structure and rigid plane of PdE-PDI enable it to form more stable σ-π, π-π coordination, and hydrogen bonds with AFB1. Additionally, the introduction of SDS significantly amplifies noncovalent interactions and enhances the quenching efficiency of PdE-PDI toward AFB1. The proposed PdE-PDI/SDS exhibited excellent specificity to AFB1 and showed dosage-sensitive detection with detection limit as low as 0.74 ng mL-1. Finally, the PdE-PDI/SDS was successfully applied in cereal samples with good recoveries from 94.61 to 109.92%. To our knowledge, this is the first time a fluorescent strategy from the point of self-assembly for AFB1 determination is reported, which holds great promise for wide applications of perylene diimide derivative in food safety.

An electrochemical sensor based on curcumin-encapsulated zeolitic imidazolate framework-8 for the sensitive determination of aflatoxin B1 in grain products

A sensitive voltammetric electrochemical immunosensor was developed for the detection of aflatoxin B1 (AFB1) using anti-mouse immunoglobulin IgG labeled with curcumin@zeolitic imidazolate framework-8/polydopamine (CCM@ZIF-8/PDA/IgG) as a signal probe. ZIF-8 exhibited strong adsorption properties due to its large specific surface area, which greatly improved the encapsulation of CCM in the signal probe. CCM with remarkably electrochemical properties, PDA with good conductivity and ZIF-8 cooperated to enhance the analytical performance. Under optimum conditions, the peak current of the modified electrode decreased with the increment of AFB1 within a linear range of 0.5 pg mL−1 to 10 ng mL−1 and detection limit of was 0.11 pg mL−1. The immunosensor also presented outstanding selectivity and long − term stability. In addition, it was well employed to detect AFB1 in spiked rice and wheat samples with acceptable recoveries (86.65–105.20%), and was well verified by HPLC.

An aptamer-functionalized photonic crystal sensor for ultrasensitive and label-free detection of aflatoxin B1

As a novel optical responsive material, photonic crystal is a promising sensing material in the recognition and detection of small molecules. Herein, a label-free composite sensor for aflatoxin B1 (AFB1) based on aptamer-functionalized photonic crystal arrays was successfully developed. Three-dimensional photonic crystals (3D PhCs) with a controllable number of layers were produced by a layer-by-layer (LBL) approach, and the introduction of gold nanoparticles (AuNPs) facilitated the immobilization procedure of recognition element aptamers, thus creating the AFB1 sensing detection system (AFB1-Apt 3D PhCs). The sensing system AFB1-Apt 3D PhCs exhibited a good linearity in the wide range of 1 pg mL−1-100 ng mL−1 AFB1 with a limit of detection (LOD) of 0.28 pg mL−1. Furthermore AFB1-Apt 3D PhC was successfully applied in the determination of AFB1 in the millet and beer samples with good recovery. The sensing system performed ultrasensitive and label-free detection to the target, which could be further applied in the fields of food safety, clinical diagnosis or environmental monitoring, establishing an efficient and rapid universal detection platform.

Cover Picture: Determination of aflatoxin B1 by biomass derived porous carbon modified electrode with molecularly imprinted polymer (Electroanalysis 5/2023)

The cover image is based on the Short Communication Determination of aflatoxin B1 by biomass derived porous carbon modified electrode with molecularly imprinted polymer by Longyi Chen et al., DOI: 10.1002/elan.202200371.

Impedimetric Polyaniline-Based Aptasensor for Aflatoxin B1 Determination in Agricultural Products.

An impedimetric aptasensor based on a polyaniline (PAni) support matrix is developed through the surface modification of a screen-printed carbon electrode (SPE) for aflatoxin B1 (AFB1) detection in foodstuffs and feedstuffs for food safety. The PAni is synthesized with the chemical oxidation method and characterized with potentiostat/galvanostat, FTIR, and UV-vis spectroscopy techniques. The stepwise fabrication procedure of the PAni-based aptasensor is characterized by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The impedimetric aptasensor is optimized using the EIS technique, and its feasibility of detecting AFB1 in real sample matrices is evaluated via a recovery study in spiked foodstuffs and feedstuffs, such as pistachio nuts, cinnamons, cloves, corn, and soybeans, with a good recovery percentage, ranging from 87.9% to 94.7%. The charge transfer resistance (RCT) at the aptasensor interface increases linearly with the AFB1 concentration in the range of 3 × 10-2 nM to 8 × 10-2 nM, with a regression coefficient (R2) value of 0.9991 and detection limit of 0.01 nM. The proposed aptasensor is highly selective towards AFB1 and partially selective to AFB2 and ochratoxin A (OTA) due to their similar structures that differ only at the carbon-carbon double bond located at C8 and C9 and the large molecule size of OTA.

Optimization and Validation of Dispersive Liquid-Liquid Microextraction for Simultaneous Determination of Aflatoxins B1, B2, G1, and G2 in Senna Leaves and Pods Using HPLC-FLD with Pre-Column Derivatization.

Dispersive liquid-liquid microextraction (DLLME) was optimized for the simultaneous extraction of aflatoxins (AFB1, AFB2, AFG1, and AFG2) from powdered senna leaves and pods. Detection was performed using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and pre-column derivatization. The parameters affecting the DLLME extraction efficiency were evaluated. Chloroform (200 µL) was used as an extraction solvent, 500 µL of distilled water was used as a dispersive solvent, and the extraction was performed at pH 5.6 with no salt added. The optimized method was validated using leaves and pods according to the European Commission guidelines. The linear range for all aflatoxins was 2-50 µg/kg, with values for regression coefficients of determination exceeding 0.995. The recoveries of spiked senna leaves and pods were in the ranges of 91.77-108.71% and 83.50-102.73%, respectively. The RSD values for intra-day and inter-day precisions were in the ranges of 2.30-7.93% and 3.13-10.59%, respectively. The limits of detection and quantification varied in the ranges of 0.70-1.27 µg/kg and 2.13-3.84 µg/kg, respectively. The validated method was successfully applied for the quantification of aflatoxins in 60 real samples of dried senna leaves and pods.