Determination Of Aflatoxin B1 Research Articles

Phycocyanin-based rapid fluorometric immunoassay for the determination of aflatoxin B1, deoxynivalenol, and zearalenone in food and feed matrices

This study presents a new multiplex lateral flow immunoassay (LFIA) for the detection of aflatoxin B1 (AFB1), deoxynivalenol (DON), and zearalenone (ZEN). The multi-LFIA utilized phycocyanin (PC), a protein with excellent photophysical properties, as a fluorescent indicator for quantifying the three mycotoxins on a lateral flow strip platform. PC and monoclonal antibodies (mAbs) against AFB1, DON, and ZEN were immobilized onto carboxylated latex nanospheres (LNS) through a one-step coupling process. The resulting conjugates with strong red fluorescence were then used for multiplex sensing of AFB1, DON, and ZEN in wheat, corn, and animal feed. The visual results of the assay were obtained using LED UV lights coupled with a smartphone in less than 25 min. Under the optimal conditions, the new multi-LFIA achieved minimum detection limits of 1.04, 1.6, and 2.08 ng/mL for AFB1, 2.2, 6.45, and 2.9 ng/mL for DON, and 1.74, 1.67, and 2.11 ng/mL for ZEN in wheat, corn, and feed, respectively. The proposed method demonstrated high selectivity for AFB1, DON, and ZEN and showed strong correlation with LC-MS/MS results in spiked samples. In summary, the proposed method is feasible, rapid, and could serve as a highly sensitive platform for detecting AFB1, DON, and ZEN and other analytes in a single format.

Enhanced sensitivity for Aflatoxin B1 detection in food through a h-Zn1Cd5S-based photoelectrochemical aptasensor

Designing photoelectrochemical sensors for detecting ultra-trace amounts of Aflatoxin B1 (AFB1) in complex samples poses a significant challenge. In pursuit of this objective, we engineered hollow-structured ZnCdS (denoted as h-Zn1Cd5S) material and applied an electrodeposition method to introduce Au nanoparticles (AuNPs) on the surface. This approach resulted in a significant enhancement of the photocurrent response of the photoelectrode, attributed to the synergistic effects of the hollow structure and surface plasmon resonance, thereby underscoring its potential for advanced applications. Utilizing density functional theory, we computed the transfer route and energy band formation of photogenerated electrons. Subsequently, we developed an AFB1 photoelectrochemical (PEC) aptasensor based on the competition mechanism, coupled with aptamer probe technology. This aptasensor allows for the ultra-trace determination of AFB1, exhibiting a remarkable detection limit as low as 1.32 fg/mL and a linear range from 1.0 × 10−2 to 100.0 pg/mL. The PEC aptasensor for AFB1 demonstrates excellent sensitivity and selectivity. When applied to the detection of AFB1 in Tsaoko, wheat, and corn samples, its performance aligns closely with high-performance liquid chromatography (HPLC) results, validating its applicability for analyzing real-world samples.

Determination and risk assessment of aflatoxin B1 in the kernel of imported raw hazelnuts from Eastern Azerbaijan Province of Iran

Aflatoxin B1 (AFB1) is widespread and seriously threatens public health worldwide. This study aimed to investigate AFB1 in imported hazelnut samples in northwest of Iran (Eastern Azerbaijan Province) using High-Performance Liquid Chromatography with a Fluorescent Detector (HPLC-FLD). In all tested samples AFB1 was detected. The mean concentration of AFB1 was 4.20 μg/kg and ranged from 3.145 to 8.13 μg/kg. All samples contained AFB1 levels within the maximum acceptable limit except for one sample. Furthermore, the human health risk assessment of AFB1 from consuming imported hazelnuts by Iranian children and adults was evaluated based on the margin of exposure (MoE) and quantitative liver cancer risk approaches. The MoE mean for children was 2529.76, while for adults, it was 8854.16, indicating a public health concern. The present study found that the risk of developing liver cancer among Iranian children was 0.11100736 per 100,000 people, and in the Iranian adult population was 0.0314496 cancers per 100,000 people. Since environmental conditions potentially affect aflatoxin levels in nuts, countries are advised to monitor aflatoxin contents in imported nuts, especially from countries with a conducive climate for mold growth.

Determination of Aflatoxin B1 in Grains by Aptamer Affinity Column Enrichment and Purification Coupled with High Performance Liquid Chromatography Detection.

Aflatoxin B1 (AFB1) is a highly teratogenic and carcinogenic secondary metabolite produced by Aspergillus. It is commonly detected in agricultural products such as cereals, peanuts, corn, and feed. Grains have a complex composition. These complex components severely interfere with the effective extraction and separation of AFB1, and also cause problems such as matrix interference and instrument damage, thus posing a great challenge in the accurate analysis of AFB1. In this study, an aptamer affinity column for AFB1 analysis (AFB1-AAC) was prepared for the enrichment and purification of AFB1 from grain samples. AFB1-AAC with an AFB1-specific aptamer as the recognition element exhibited high affinity and specificity for AFB1. Grain samples were enriched and purified by AFB1-AAC, and subsequently analyzed by high performance liquid chromatography with post-column photochemical derivatization-fluorescence detection (HPLC-PCD-FLD). The average recoveries of AFB1 ranged from 88.7% to 99.1%, with relative standard deviations (RSDs) of 1.4-5.6% (n = 3) at the spiked levels of 5.0-20.0 μg kg-1. The limit of detection (LOD) for AFB1 (0.02 μg kg-1) was much below the maximum residue limits (MRLs) for AFB1. This novel method can be applied to the determination of AFB1 residues in peanut, corn, and rice.

Polycarboxyl ionic liquid functionalized Yb-MOFs nanoballs based dual-wavelength responsive photoelectrochemical aptasensor for the simultaneous determination of AFB1 and OTA

Developing an accurate and precise approach for the simultaneous detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1) is significant for food safety surveillance. Herein, a photoelectrochemical sensing platform was constructed based on polycarboxylic ionic liquid functionalized metal-organic framework integrated with gold nanoparticles (Yb-MOFs@AuNPs). Sulfhydryl functionalized hairpin DNA (hDNA) was immobilized on a Yb-MOFs@AuNPs modified glassy carbon electrode (GCE) surface through Au-S bond. After blocking residual active binding sites with BSA, gold nanoparticles-labeled AFB1 aptamer (AuNPs-Apt 1) and gold nanorods-labeled OTA aptamer (AuNRs-Apt 2) were introduced to construct a photoelectrochemical aptasensor for the simultaneous determination of AFB1 and OTA. Due to the surface plasmon resonance effect and the nanometer size effect of gold nanomaterials, the photoelectrochemical aptasensor can output photocurrent responses as being excited with different wavelengths at 520 nm and 808 nm, respectively. When the AFB1 and OTA concentration in the range of 0.001–50.0 ng mL−1, a good linear relationship between the photocurrent difference (ΔI) before and after recognizing targets and the logarithm of AFB1 or OTA concentration was obtained. The detection limits for AFB1 and OTA were 0.40 pg mL−1 and 0.19 pg mL−1, respectively. AFB1 and OTA in corn samples were detected simultaneously by the photoelectrochemical aptasensor.

A dual-signal aptasensor based on cascade amplification for ultrasensitive detection of aflatoxin B1

Aflatoxin B1 (AFB1) is considered as a serious carcinogenic mycotoxin that was widely detected in grains and foods, and its sensitive analysis is of key importance to avoid the health threats for consumers. In this study, a dual-signal aptasensor based on cascade of entropy-driven strand displacement reaction (ESDR) and linear rolling circle amplification (LRCA) was fabricated for ultrasensitive determination of AFB1. At the sensing system, the complementary strand would be released after the aptamer combined with AFB1, which will bring about the functional domains exposed, triggering the subsequent ESDR. Meanwhile, the two strands that were outputted by ESDR would incur the downstream LRCA reaction to produce a pair of long strands to assist in the generation of fluorescence and absorbance signals. Under the optimized conditions, the proposed aptasensor could achieve excellent sensitivity (limit of detection, 0.427 pg/mL) with satisfactory accuracy (recoveries, 92.8–107.9 %; RSD, 2.4–5.0 %), mainly ascribed to the cascade amplification. Importantly, owing to the flexibility design of nucleic acid primer, this analytical method can be applied in monitoring various hazardous substances according to the specific requirements. Our strategy provides some novel insights at signal amplification for rapid detection of AFB1 and other targets.

Quantitative Determination of Aflatoxin B1 in Maize and Feed by ELISA and Time-Resolved Fluorescent Immunoassay Based on Monoclonal Antibodies.

In this study, a highly sensitive monoclonal antibody (mAb) was developed for the detection of aflatoxin B1 (AFB1) in maize and feed. Additionally, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluorescence immunoassay assay (TRFICA) were established. Firstly, the hapten AFB1-CMO was synthesized and conjugated with carrier proteins to prepare the immunogen for mouse immunization. Subsequently, mAb was generated using the classical hybridoma technique. The lowest half-maximal inhibitory concentration (IC50) of ic-ELISA was 38.6 ng/kg with a linear range of 6.25-100 ng/kg. The limits of detections (LODs) were 6.58 ng/kg and 5.54 ng/kg in maize and feed, respectively, with the recoveries ranging from 72% to 94%. The TRFICA was developed with a significantly reduced detection time of only 21 min, from sample processing to reading. Additionally, the limits of detection (LODs) for maize and feed were determined to be 62.7 ng/kg and 121 ng/kg, respectively. The linear ranges were 100-4000 ng/kg, with the recoveries ranging from 90% to 98%. In conclusion, the development of AFB1 mAb and the establishment of ic-ELISA for high-throughput sample detection, as well as TRFICA for rapid detection presented robust tools for versatile AFB1 detection in different scenarios.

Development of a label-free, sensitive gold nanoparticles-poly(adenine) aptasensing platform for colorimetric determination of aflatoxin B1 in corn.

In this work, a sensitive colorimetric bioassay method based on a poly(adenine) aptamer (polyA apt) and gold nanoparticles (AuNPs) was developed for the determination of aflatoxin B1 (AFB1). The polyA apt, adsorbed on the AuNPs, especially can bind to the analyte while deterring non-specific interactions. This nano aptasensor uses cationic polymer poly(diallyl dimethyl ammonium chloride) (PDDA), as an aggregating agent, to aggregate gold nanoparticles. PolyA apt-decorated gold nanoparticles (AuNPs/polyA apt) show resistance to PDDA-induced aggregation and maintains their dispersed state (red color) with the optical absorbance signal at λ = 520 nm. However, in the presence of AFB1 in the assay solution, the specific aptamer reacts with high affinity and folds into its three-dimensional form. Aggregation of AuNPs induced by PDDA caused their optical signal shift to λ = 620 nm (blue color). AFB1 concentration in the bioassay solution determines the amount of optical signal shift. Therefore, optical density ratio in two wavelengths (A620/520) can be used as a sturdy colorimetric signal to detect the concentration of aflatoxin B1. AFB1 was linearly detected between 0.5 and 20 ng mL-1, with a detection limit of 0.09 ng mL-1 (S/N = 3). The fabricated aptasensor was applied to the detection of AFB1 in real corn samples.

Europium nanospheres based ultrasensitive fluorescence immunosensor for aflatoxin B1 determination in feed

In this work, a new competitive immunosensor for aflatoxin B1 (AFB1) detection was developed using europium (Eu) fluorescent nanospheres and magnetic beads. Firstly, Eu nanospheres were synthesized through two steps including carboxylated polystyrene nanospheres and Eu-doped polystyrene nanospheres preparation. Then Eu nanospheres were covalently tagged to anti-AFB1 monoclonal antibody (anti-AFB1 mAb) through an EDC coupling method. Carboxylated Fe3O4 magnetic beads were conjugated to AFB1-BSA through EDC/NHS crosslinking to obtain AFB1-BSA-Fe3O4. In the absence of AFB1, Eu-anti-AFB1 mAb were incubated with AFB1-BSA-Fe3O4 to form Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 in PBS buffer. However, in the presence of AFB1, the competitive interaction of AFB1 and AFB1-BSA-Fe3O4 to bind with Eu-anti-AFB1 mAb occurred. With the increasing concentration of AFB1, less Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 formed. So the fluorescence intensity of Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 was gradually decreased after magnetic separation. The degree of fluorescence decrease was linear with respect to the logarithm of AFB1 concentration in the range of 0.01–2 ng/mL in both buffer solution and feed samples and the detection limit was 0.003 ng/mL. What's more, the immunosensor showed excellent specificity for AFB1 without being interfered by other mycotoxins. In consideration of the excellent performance of this immunosensor, we can speculate that the proposed method could be widely used in detecting food contaminants.

A versatile CuCo@PDA nanozyme-based aptamer-mediated lateral flow assay for highly sensitive, on-site and dual-readout detection of Aflatoxin B1

Mycotoxin contaminations in food and environment seriously harms human health. Constructing sensitive and point-of-test early-warning tools for mycotoxin determination is in high demand. In this study, a CuCo@PDA nanozyme-based aptamer-mediated lateral flow assay (Apt-LFA) has been elaborately designed for on-site and sensitive determination of mycotoxin Aflatoxin B1 (AFB1). Benefiting from the rich functional groups and excellent peroxidase-like activity, the CuCo@PDA with original dark color can be conjugated with the specific recognition probe (i.e., aptamer), generating colorimetric signal on the test lines of Apt-LFA via a competitive sensing strategy. The signal can further be amplified in-situ by catalytic chromogenic reaction. Therefore, a visual and dual-readout detection of AFB1 has been realized. The developed Apt-LFA provides a flexible detection mode for qualitative and quantitative analysis of AFB1 by naked-eyes observation or smartphone readout. The smartphone-based LFA platform shows a reliable and ultrasensitive determination of AFB1 with the limit of detection (LOD) of 2.2 pg/mL. The recoveries in the real samples are in the range of 95.11–113.77% with coefficients of variations less than 9.84%. This study provides a new approach to realize point-of-test and sensitive detection of mycotoxins in food and environment using nanozyme-based Apt-LFAs.

Development of isotope dilution-ultrahigh-performance liquid chromatography-tandem mass spectrometry for the accurate determination of aflatoxins in grains

A method for the accurate determination of aflatoxin B1, B2, G1, and G2 in grains was established using isotope dilution-ultrahigh-performance liquid chromatography-tandem mass spectrometry (ID-UHPLCMS/MS). 13C- labeled aflatoxins (AFs) were used as internal standards. AFs were extracted with a mixture of methanol/water (60/40; v/v) and purified using an immunoaffinity column (IAC) for adequate elimination of matrix interferences. The method showed excellent analytical performance over the studied range (0.5–4 µg/kg). The limits of detection (0.002–0.005 µg/kg) and quantification (0.007–0.011 µg/kg) were substantially lower than the maximum level fixed by the European Union for grain cereals. The accuracy values ranged from 97 % to 103 % for all AFs, with intraday and interday precisions ranging from 1.8 % to 3.0 % and 0.3–3.8 % relative standard deviation (RSD), respectively. The measurement uncertainty was less than 4.20 %. The developed method shows high-order metrological quality with superior performance over the existing analytical methods. The practical applicability of the method was demonstrated by the measurement of AFs in different grain samples.

A Label-Free Aptasensor for Turn-On Fluorescent Detection of Aflatoxin B1 Based on an Aggregation-Induced-Emission-Active Probe and Single-Walled Carbon Nanohorns.

The determination of the aflatoxin B1 (AFB1) content has received widespread attention in the context of food safety, which is a global public health issue. Accordingly, a label-free and turn-on fluorescent AFB1 determination method is developed herein with an ss-DNA aptamer as the recognition element, 4, 4-(1E,1E)-2, 2-(anthracene-9, 10-diyl) bis(ethene-2, 1-diyl) bis(N, N, N-trimethylbenzenaminium iodide) (DSAI) as the aggregation-induced emission (AIE) fluorescent probe, and single-walled carbon nanohorns (SWCNHs) as the selective part with a fluorescence quenching effect. In the presence of AFB1, the AFB1-specific aptamer undergoes a structural transformation and switches from being a random helix to a folded structure. DSAI's fluorescence is protected as a result of the resistance of the transformed aptamer adsorbed on the SWCNHs' surface. Because DSAI's fluorescence is not quenchable, the fluorescence intensity is calculated as a function of the AFB1 concentration. By simply mixing DSAI, aptamer, AFB1 samples, and SWCNHs, the method can be carried out in 2 h, with a limit of detection (LOD) of 1.83 ng/mL. It has a high selectivity in the presence of other mycotoxins, and its performance is confirmed in soybean sauce with a known concentration of AFB1. The LOD was 1.92 ng/mL in the soy sauce samples and the recovery ranged from 95 to 106%, implying that the presented aptasensor has great potential for food analysis.

UiOL@AIEgens-assisted lateral flow immunosensor for the ultrasensitive dual-modal point-of-care detection of aflatoxin B1

Aflatoxin B1 (AFB1) contamination in food has attracted worldwide attention. The sensitive detection of AFB1 is vital for ensuring food quality and safety. This study developed an ultrasensitive signal-enhanced lateral flow immunosensor (LFIS) based on the functionalized zirconium metal-organic framework (MOF) of a UiO linker enriched with abundant aggregation-induced emission luminogen (UiOL@AIEgens) probes for the rapid dual-modal point-of-care (POC) determination of AFB1. Using UiO MOFs with numerous active sites as the carrier facilitated abundant AIEgens enrichment on the surface. After coupling with enough anti-AFB1 monoclonal antibodies (mAbs), the green-emissive UiOL@AIEgens-mAbs probes with high specificity and remarkably-enhanced fluorescence responses were obtained to competitively capture target AFB1 in the standard or sample solution and AFB1 antigen immobilized on the test (T) line of the POC LFIS. Under optimum conditions, the LFIS was capable of visual qualitative and smartphone-assisted dual-modal determination of target AFB1 within 7 min. Detection occurred in a range of 0.01–5 ng/mL at an ultra-low detection limit of 0.003 ng/mL, which was 300- and 600-fold lower than traditional immunoassays and the maximum limit set by the European Union, respectively. Moreover, the feasibility and robustness of the LFIS platform were assessed by detecting AFB1 in maize and lotus seed samples with average recoveries of 94.3–109.0%. The developed UiOL@AIEgens-based POC LFIS can be used for ultrasensitive, reliable, on-site detection in food. This study provides a new method for the real-time monitoring of AFB1 and other harmful contaminants in food and more complex matrices.

A triple-signal strategy separated aptasensor for sensitive determination of aflatoxin B1 in peanut based on electrochemical and fluorescent dual-mode

It is necessary to develop accurate and sensitive AFB1 detection method due to its high toxicity of pathogenicity and carcinogenicity. The results of traditional single-mode AFB1 detection methods are easily affected by the test environment and human operation. Herein, an electrochemical and fluorescent dual-mode separated aptasensor was developed for detecting AFB1 with triple-signal readout. The AFB1 aptasensor was constructed by combining the Fc-labeled AFB1 aptamer with its complementary DNA (cDNA). Subsequently, the methylene blue (MB) was incorporated into dsDNA as another signal tag. In the presence of AFB1, the Fc tag approached to electrode surface, both of the cDNA and MB molecule released due to the interaction between AFB1 and its aptamer, resulting in “signal-on” and “signal-off” dual-signal strategy. There was a good linear relationship between the SWV electrochemical response signal and the logarithm of AFB1 concentration at 0.01–200 ng/mL (LOD 2.5 pg/mL, S/N = 3). Meanwhile, the released cDNA was designed to trigger hybridization chain reaction (HCR), and the HCR product was served as template for the formation of fluorescent copper nanoparticles (CuNPs). There was a good linear relationship between the fluorescent intensity of CuNPs and the logarithm of AFB1 concentration at 0.001–200 ng/mL (LOD 0.28 pg/mL, S/N = 3). The separated fluorescent method showed broadened linear range and lower LOD compared with SWV method, both up to 10-folds, which improved the detection sensitivity. The constructed dual-mode AFB1 aptasensor showed satisfactory selectivity, stability and reproducibility, and the good recoveries of real peanut samples indicated its practical application in food detection.

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.