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Multiple-mycotoxin contamination has been frequently found in the agro-food monitoring due to the coexistence of fungi. However, many determination methods focused on a single mycotoxin, highlighting the demand for on-site determination of multiple mycotoxins in a single run. We develop a multicolor-based immunochromatographic strip (ICS) for simultaneous determination of aflatoxin B1 (AFB1), zearalenone (ZEN) and T-2 toxin in maize- and cereal-based animal feeds. The nanoparticles with different colors are conjugated with three monoclonal antibodies, which serve as the immunoassay probes. The decrease in color intensity is observed by the naked eyes, providing simultaneous quantification of three mycotoxins. The visible limits of detection for AFB1, ZEN and T-2 are estimated to be 0.5, 2, and 30 ng/mL, respectively. The cut-off values are 1, 10, and 50 ng/mL, respectively. Considerable specificity and stability are found using real samples. The results are in excellent agreement with those from high-performance liquid chromatography/tandem mass spectrometry. The multi-color ICS boasts sensitive and rapid visual differentiation and simultaneous semi-quantification of aflatoxin B1, zearalenone and T-2 toxin in maize- and cereal-based feed samples within 20 min. [ABSTRACT FROM AUTHOR]

Mycotoxins usually found in agricultural products such as peanut, corn, and wheat, are a serious threat to human health and their detection requires multiplexed and sensitive analysis methods. Herein, a simultaneous determination for aflatoxin B1, B2, G1, G2, ochratoxin A, zearalanone and T-2 toxin was investigated using high performance liquid chromatography coupled with tandem mass spectrometry in a single run via a home-made multiple immunoaffinity column. Four monoclonal antibodies were produced in our lab against aflatoxins, ochratoxin A, zearalanone and T-2 toxin, respectively, then combined as a pool and bound to Sepharose-4B for affinity chromatography. Seven mycotoxins were effectively extracted from the agricultural product samples by using acetonitrile/water/acetic acid (80:19:1, v/v/v) Then, the extraction was cleanup by multiple immunoaffinity column. This method demonstrated a considerable linear range of 0.30–25, 0.12–20, 0.30–20, 0.12–20, 0.60–30, 0.30–25, and 1.2–40 μg kg −1 and lower limits of detection at 0.1, 0.04, 0.1, 0.04, 0.2, 0.1 and 0.4 μg kg −1 for AFB1, AFB2, AFG1, AFG2, OTA, ZEN and T-2, respectively, in comparison with previously reported methods, as well as excellent recoveries. The mIAC capacity for AFB1, AFB2, AFG1, AFG2, OTA, ZEN, and T-2 were 187, 181, 153, 151, 105, 130, 88 ng, respectively. It was found that all of the 7 mycotoxins were present in 90 agricultural product samples. The proposed method meets the requirements for rapid sample preparation and highly sensitive identification of multiple mycotoxins in agricultural product and food safety. This method provides a promising alternative with high throughput and high sensitivity for rapid analysis of seven mycotoxins in the monitoring of food safety. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 poses grave threats to food and feed safety due to its strong carcinogenesis and toxicity, thus requiring ultrasensitive rapid on-site determination. Herein, a portable immunosensor based on chromatographic time-resolved fluoroimmunoassay was developed for sensitive and on-site determination of aflatoxin B1 in food and feed samples. Chromatographic time-resolved fluoroimmunoassay offered a magnified positive signal and low signal-to-noise ratio in time-resolved mode due to the absence of noise interference caused by excitation light sources. Compared with the immunosensing performance in previous studies, this platform demonstrated a wider dynamic range of 0.2-60 μg/kg, lower limit of detection from 0.06 to 0.12 µg/kg, and considerable recovery from 80.5% to 116.7% for different food and feed sample matrices. It was found to be little cross-reactivity with other aflatoxins (B2, G1, G2, and M1). In the case of determination of aflatoxin B1 in peanuts, corn, soy sauce, vegetable oil, and mouse feed, excellent agreement was found when compared with aflatoxin B1 determination via the conversational high-performance liquid chromatography method. The chromatographic time-resolved fluoroimmunoassay affords a powerful alternative for rapid on-site determination of aflatoxin B1 and holds a promise for food safety in consideration of practical food safety and environmental monitoring. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel direct competitive fluorescence-linked immunosorbent assay was developed. [•] The quantum dots were successfully linked to the monoclonal antibody. [•] This method was simple and sensitive for detection of aflatoxin B1 in peanuts. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fungal mycelia@graphene oxide@Fe 3 O 4 (FM@GO@Fe 3 O 4) nanoarchitecture was assembled. • FM@GO@Fe 3 O 4 is an effective adsorbent for both aflatoxin B 1 and zearalenone. • π–π stacking, hydrogen-bond, electrostatic and hydrophobic interactions all exist. • FM@GO@Fe 3 O 4 has good biological safety, magnetic manipulability and stability. • Detoxification treatments by FM@GO@Fe 3 O 4 has little effect on oil quality. Physical adsorbents for detoxification are widely used in vegetable oil industry. So far, the high-efficiency and low-cost adsorbents have not been well explored. Here, a hierarchical fungal mycelia@graphene oxide@Fe 3 O 4 (FM@GO@Fe 3 O 4) was fabricated as an efficient adsorbent for simultaneous removal of aflatoxin B 1 (AFB 1) and zearalenone (ZEN). The morphological, functional and structural characteristics of the prepared adsorbents were systematic investigated. Batch adsorption experiments in both single and binary systems were conducted, and the adsorption behaviours and mechanism were explored. The results indicated that the adsorption process occurred spontaneously and the mycotoxin adsorption could be described as physisorption through hydrogen bonding, π–π stacking, electrostatic and hydrophobic interactions. Due to good biological safety, magnetic manipulability, scalability, recyclability and easy regeneration, FM@GO@Fe 3 O 4 performance is suitable for application as a detoxification adsorbent in vegetable oil industry. Our study addresses a novel green strategy for removing multiple mycotoxins by integrating the toxigenic isolates with advanced nanomaterials. [ABSTRACT FROM AUTHOR]

A sensitive and specific immunoaffinity column to clean up and isolate multiple mycotoxins was developed along with a rapid one-step sample preparation procedure for ultra-performance liquid chromatography-tandem mass spectrometry analysis. Monoclonal antibodies against aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, zearalenone, ochratoxin A, sterigmatocystin, and T-2 toxin were coupled to microbeads for mycotoxin purification. We optimized a homogenization and extraction procedure as well as column loading and elution conditions to maximize recoveries from complex feed matrices. This method allowed rapid, simple, and simultaneous determination of mycotoxins in feeds with a single chromatographic run. Detection limits for these toxins ranged from 0.006 to 0.12 ng mL, and quantitation limits ranged from 0.06 to 0.75 ng mL. Concentration curves were linear from 0.12 to 40 μg kg with correlation coefficients of R > 0.99. Intra-assay and inter-assay comparisons indicated excellent repeatability and reproducibility of the multiple immunoaffinity columns. As a proof of principle, 80 feed samples were tested and several contained multiple mycotoxins. This method is sensitive, rapid, and durable enough for multiple mycotoxin determinations that fulfill European Union and Chinese testing criteria. [ABSTRACT FROM AUTHOR]

Aflatoxin B 1 (AFB 1) is a prominent food contaminant known for its high toxicity. Rapid, low-cost, and sensitive detection of AFB 1 is an urgent demand for food safety risk control. In the traditional enzyme-linked immunosorbent assay (ELISA) method for AFB 1 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 AFB 1 determination. This work provides a feasible strategy for the rapid and sensitive detection of food contaminants using SAzymes. • A Fe-N-C single-atom nanozyme-linked immunosorbent assay was developed. • Aflatoxin B 1 (AFB 1) could be detected within 50 min. • The results are reliable and sensitive. • The method was successfully applied to quantification of AFB 1 in peanut samples. [ABSTRACT FROM AUTHOR]

Multi-class chemical contaminants, such as pesticides and mycotoxins, are recognized as the major risk factors in agro products. It is thus necessary to develop rapid and simple sensing methods to fulfill the on-site monitoring of multi-class chemical contaminants with different physicochemical properties. Herein, a lateral flow immunoassay via time-resolved fluorescence was developed for the rapid, on-site, simultaneous, and quantitative sensing aflatoxin B1 (AFB1), zearalenone (ZEA), and chlorothalonil (CTN) in maize and peanut. The sample preparation was optimized to a single step, combining the grinding and extraction. Under optimal conditions, the sensing method lowered the limits of detection (LOD) to 0.16, 0.52, and 1.21 µg/kg in maize and 0.18, 0.57, and 1.47 µg/kg in peanut with an analytical range of 0.48–20, 1.56–200, and 3.63–300 µg/kg for AFB1, ZEA and CTN, respectively. The protocol could be completed within 15 min, including sample preparation and lateral flow immunoassay. The recovery range was 83.24–110.80%. An excellent correlation was observed between this approach and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for mycotoxins and gas chromatography-tandem mass spectrometry (GC-MS/MS) for pesticide in maize and peanut. This work could be applied in on-site multi-class sensing for food safety. [ABSTRACT FROM AUTHOR]

[Display omitted] • Develop Au nanopartics decorated urchin-like Bi2S3 on graphene wrapped carbon fiber. • Fabricate electrochemical immunosensor based on nanohybird microelectrode. • Excellent electrochemical sensing performances for aflatoxin B1 detection. Aflatoxin in food is a significant concern that threatens human health and life and causes a heavy burden on international trade and healthcare. In this work, we developed a new type of label-free electrochemical immunosensor for the high-sensitivity determination of aflatoxin B1 (AFB1) based on Au nanoparticles decorated urchin-like Bi 2 S 3 (Au/Bi 2 S 3) anchored on electrochemically reduced graphene oxide (ERGO) modified carbon fiber (CF) microelectrode (Au/Bi 2 S 3 /ERGO/CF). The morphology and characterization of the modified microelectrode were investigated using scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Under the optimum conditions, the label-free electrochemical immunosensor detected AFB1 within the linear range of 10 pg mL−1 to 20 ng mL−1, with a low detection limit of 8 pg mL−1 and high sensitivity (0.48 μA/ng mL). The immunosensor showed high selectivity, good reproducibility, and acceptable stability. The immunosensor was applied to detecting AFB1 in cornflour samples, offering excellent reliability and accuracy compared with typical detection methods. Finally, this platform provides a superior prospect for the development of a nanohybrid immunosensor. [ABSTRACT FROM AUTHOR]

Designing a photoelectrochemical (PEC) biosensor with preponderant sensitivity and anti-interference is a challenge for detecting small molecules in real samples with complex matrices. To this end, the Bi 2 O 3 /CuBi 2 O 4 was synthesized in one step to enhance visible light's absorption ability, transferring the interfacial carrier's efficiency, a high-active Z-scheme heterojunction, and a photocathode biosensor was proposed. For the first time, we used the density functional theory to verify a Z-scheme transfer pathway of photogenerated electrons in Bi 2 O 3 /CuBi 2 O 4 and the energy band structure of Bi 2 O 3 and CuBi 2 O 4 , respectively. Bi 2 O 3 /CuBi 2 O 4 -based PEC biosensor was developed for competive immunoassay of small molecular, aflatoxin B1 (AFB1) as an example, resulting in a low detection limit of 297.4 fg/mL and a linear range of 1.4 pg/mL-280 ng/mL in urine, water, peanut, and wheat samples. Using spiked experiments, the satisfied repeatability, reproducibility, stability, and specificity of the Bi 2 O 3 /CuBi 2 O 4 -based PEC biosensor indicated a promise for application in health care, the environment, and food. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel nanozyme-based LFIA was fabricated for AFB 1 screening. • MnO 2 nanosheets (MnO 2 NSs) behave as both oxidase mimics and nanolabels for LFIA. • MnO 2 NSs-TMB chromogenic system was applied to the LFIA for the first time. • The LFIA simultaneously exhibits high sensitivity and an ultrawide linear range. • The LFIA offers seven detection ranges to meet the different testing needs of different allowable limits. Lateral flow immunoassay (LFIA) is the most effective real-time detection method for aflatoxin B 1 (AFB 1). Here, we constructed a nanozyme-strip based on MnO 2 nanosheets (MnO 2 NSs) as a catalytic label for detection of AFB 1. By taking advantage of the MnO 2 -TMB catalytic amplified system, the new test achieves rapid detection with high sensitivity and ultrawide range. The limit of detection of the assay was 15 pg mL−1, which was over 100-fold lower than the maximum limit set by the European Union (EU) of AFB 1 in foods. In addition, the strip test could offer 7 dynamic detection ranges, spanning 4 orders of magnitude, which could cater to the varieties of limits on AFB 1 residues in foods and feeds set by different countries. The estimated recoveries were in the range of 85.67%-106.38% with coefficients of variations (CVs) less than 9.68%. Overall, the developed approach is a rapid, reliable, sensitive and widely available tool for on-site detection of AFB 1. [ABSTRACT FROM AUTHOR]

Abstract: Mycotoxins are highly toxic contaminants and have induced health threat to human and animals. Aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) commonly occur in food and feed. A multi-component immunochromatographic assay (ICA) was developed for rapid and simultaneous determination of these three mycotoxins in agro-food. The strategy was performed based on the competitive immunoreactions between antibody-colloidal gold nanoparticle conjugate probes and mycotoxins or mycotixin antigens. Each monoclonal antibody specially recognize its corresponding mycotoxin and antigen, and there was no cross reactivity in the assay. Three mycotixin antigens were immobilized as three test lines in the nitrocellulose membrane reaction zone, which enable the simultaneous detection in one single test. The visible ICA results were obtained in 20min. The visual detection limits of this strip test for the AFB1, OTA and ZEA were 0.25ng/mL, 0.5ng/mL and 1ng/mL, respectively. The assay was evaluated using spiked and naturally contaminated peanuts, maize and rice samples. The results were in accordance with those obtained using enzyme-linked immunosorbent assay. In summary, this developed ICA could provide an effective and rapid approach for onsite detection of multi-mycotoxin in agro-food samples without any expensive instrument. [Copyright &y& Elsevier]

Food safety is currently a significant issue for human life and health. Various fluorescent nanomaterials have been applied in the point-of-care test (POCT) for food safety as labeling materials. However, previous fluorescent nanomaterials can cause aggregation-caused quenching (ACQ), thus reducing the detection sensitivity. Conversely, aggregation-induced emission luminogens (AIEgens) are promising candidates for POCT in the food safety field because they can enhance detection sensitivity and throughput. Mycotoxins, such as aflatoxin B 1 (AFB 1) and cyclopiazonic acid (CPA), are a primary threat to human life and health and a significant food safety issue, and their on-site detection from farm to table is needed. Herein, an ultrasensitive point-of-care test was developed based on TPE-Br, a blue-emissive tetraphenylethylene derivative AIEgen. Under optimal conditions, this AIEgen-based lateral-flow biosensor (ALFB) allowed for a rapid response of 8 min toward AFB 1 and CPA detection, with considerable sensitivities of 0.003 and 0.01 ng/mL in peanut matrices, respectively. In peanut matrices, the recoveries were 90.3%–110.0% for both mycotoxins, with relative standard deviations (RSDs) below 6%. The ALFB was further validated via UPLC-MS/MS using spiked peanut samples. AIEgens open an avenue for on-site, ultrasensitive, high-throughput detection methods and can be extensively used in point-of-care tests in food safety. [Display omitted] • Developed a lateral flow biosensor for multiple mycotoxin detection using TPE-Br. • Designed a specific portable reader for quantitative detection of multiple mycotoxins. • Sensitivity for AFB 1 and CPA detection was enhanced up to 196- and 600-fold. • Novel sensing platform for multiple-toxins monitoring for food safety is proposed. [ABSTRACT FROM AUTHOR]

Sensitive and point-of-care detection of small toxic molecules plays a key role in food safety. Aflatoxin, a typical small toxic molecule, can cause serious healthcare and economic issues, thereby promoting the development of sensitive and point-of-care detection. Although ELISA is one of the official detection methods, it cannot fill the gap between sensitivity and point-of-care application because it requires a large-scale microplate reader. To employ portable readers in food safety, Pt-catalysis has attracted increasing attention due to its portability and reliability. In this study, we developed a sensitive point-of-care aflatoxin detection (POCAD) method via a portable handheld barometer. We synthesized and characterized Au@PtNPs and Au@PtNPs conjugated with a second antibody (Au@PtNPs-IgG). A competitive immunoassay was established based on the homemade monoclonal antibody against aflatoxins. Au@PtNPs-IgG was used to catalyze the production of O2 from H2O2 in a sealed vessel. The pressure of O2 was then recorded by a handheld barometer. The aflatoxin concentration was inversely proportional to the pressure recorded via the barometer reading. After optimization, a limit of detection of 0.03 ng/mL and a linear range from 0.09 to 16.0 ng/mL were achieved. Recovery was recorded as 83.1%–112.0% along with satisfactory results regarding inner- and inter-assay precision (relative standard deviation, RSD < 6.4%). Little cross-reaction was observed. Additionally, the POCAD was validated by high-performance liquid chromatography (HPLC) by using peanut and corn samples. The portable POCAD exhibits strong potential for applications in the on-site detection of small toxic molecules to ensure food safety. [ABSTRACT FROM AUTHOR]