Aflatoxin B1 Molecules Research Articles

A disposable microfluidic aptasensor for one-step and real-time detection of sub-femtomolar-level aflatoxin B1 in food

Aflatoxin B1 (AFB1) is a highly toxic substance found in food, necessitating rapid and sensitive detection methods. Combining interfacial capacitive sensing with AC electrothermal (ACET) enrichment, an aptasensor based on a PCB electrode array is developed for real-time detection of trace AFB1. Owing to the sensitive solid–liquid capacitance with a pF-level resolution, AFB1 detection at sub-femtomolar level is achieved. The induced ACET flows enrich AFB1 molecules towards the electrode surface during capacitance measurement, enabling a one-step detection containing target enrichment, with an overall time of 20 s without any extra concentrating devices or processes. This sensor has a low detection limit of 620 aM, a selectivity of 2262:1 against interferences, and a wide semi-log linear range from 1 fM to 10 pM. It is with a cost below 1 US dollar for disposable detection and a convenient operation for on-site application. The detection of AFB1 in three types of quality control samples demonstrates a good feasibility for food safety inspection.

Achieving improved efficiency for removal of aflatoxin B1 by combination use of cold atmospheric-pressure plasma and plasma-activated water

A novel approach was employed to remove aflatoxin B1 (AFB1), a very toxic metabolite from Aspergillus flavus (A. flavus), by using cold atmospheric-pressure plasma (CAP) and plasma-activated water (PAW) in combination. The results showed that CAP could efficiently degrade AFB1, while the PAW produced by CAP could further remove AFB1 with a relatively long treatment time. During the CAP processing, hydroxyl radical (·OH) was one of the dominant reactive species, which caused the hydroxylation at furan ring of AFB1, while in PAW treatment, singlet oxygen (1O2) was the major reactive agent for AFB1 degradation, which caused the destruction of the methyl group on the benzene side chain and oxidized the double bond of the terminal furan ring in the AFB1 molecule. This study therefore provides new guidance for the application of plasma technology in the treatment of fungal mycotoxins for food safety.

Removal of Aflatoxin B1 and Zearalenone in Mixed Aqueous Solution by Palygorskite-Montmorillonite Materials In Situ Prepared from Palygorskite Mineral.

In view of the animal feeds inevitably contaminated by multiple mycotoxins, eco-friendly and efficient palygorskite-montmorillonite (Pal-Mt) materials were prepared to remove polar aflatoxin B1 (AFB1) and weak polar zearalenone (ZEN) from mixed mycotoxins aqueous solution. The adsorption properties and bonding mechanisms between Pal-Mt materials and mycotoxins (AFB1 and ZEN) were investigated systematically. The as-prepared Pal-Mt showed excellent adsorption capacity for AFB1 and ZEN in single- and binary-mycotoxin systems, indicating the effectiveness of Pal-Mt acting as multiple mycotoxin adsorbents. The kinetics of adsorption for ZEN was fast due to the adsorption on the external surface (film and intraparticle diffusion), while AFB1 molecules permeated into mesopores after the external adsorption for the more planar structure. Adsorption isotherms demonstrated that heterogeneous surface adsorption appeared between Pal-Mt and AFB1, and monolayer adsorption occurred on Pal-Mt and ZEN for different polarities of mycotoxins. Thermodynamic parameters illustrated that the adsorption process of both AFB1 and ZEN onto Pal-Mt was spontaneous and endothermic. The adsorption mechanism studies suggested that hydrogen bonding, electrostatic attraction, calcium bridging linkage, and ion-dipole played fundamental roles in the interaction between Pal-Mt and these two mycotoxins.

Computational Studies of Aflatoxin B1 (AFB1): A Review.

Aflatoxin B1 (AFB1) exhibits the most potent mutagenic and carcinogenic activity among aflatoxins. For this reason, AFB1 is recognized as a human group 1 carcinogen by the International Agency of Research on Cancer. Consequently, it is essential to determine its properties and behavior in different chemical systems. The chemical properties of AFB1 can be explored using computational chemistry, which has been employed complementarily to experimental investigations. The present review includes in silico studies (semiempirical, Hartree-Fock, DFT, molecular docking, and molecular dynamics) conducted from the first computational study in 1974 to the present (2022). This work was performed, considering the following groups: (a) molecular properties of AFB1 (structural, energy, solvent effects, ground and the excited state, atomic charges, among others); (b) theoretical investigations of AFB1 (degradation, quantification, reactivity, among others); (c) molecular interactions with inorganic compounds (Ag+, Zn2+, and Mg2+); (d) molecular interactions with environmentally compounds (clays); and (e) molecular interactions with biological compounds (DNA, enzymes, cyclodextrins, glucans, among others). Accordingly, in this work, we provide to the stakeholder the knowledge of toxicity of types of AFB1-derivatives, the structure-activity relationships manifested by the bonds between AFB1 and DNA or proteins, and the types of strategies that have been employed to quantify, detect, and eliminate the AFB1 molecule.

Aflatoxin Adsorption by Natural and Heated Sepiolite and Palygorskite in Comparison with Adsorption by Smectite

Abstract Smectites are effective binders of aflatoxin in aqueous solutions. Unfortunately, their efficacy is reduced in guts because of interference by biomolecules and essential nutrients within the gut. Tunnel structures in palygorskite and sepiolite may function as molecular sieves and may, therefore, serve as alternatives or complements to smectites in binding aflatoxins but not larger biological compounds. The objective of the current work was to determine the effect of heat treatment on aflatoxin B1 (AfB1) adsorption and selectivity for biomolecules by two palygorskites (Plg_PK and Plg_CN), sepiolite (Sep), and a palygorskite-smectite mixture (Plg-Sm) in comparison with a smectite (Sm-37GR). The clays were heated at 250, 400, 500, and 600°C while phase and structural changes were characterized by X-ray diffraction and infrared spectroscopy. Comparative AfB1 adsorption was determined in aqueous and in simulated gastric fluids. The clay structures collapsed irreversibly in Sm-37GR and folded in fibrous clays with heating at 400°C or more. Sm-37GR adsorbed more AfB1 than all of the other clays; the estimated adsorption capacity followed the trend Sm-37GR (44 g kg–1) > Plg_PK (18.12 g kg–1) > Sep (12.7 g kg–1) > Plg_CN (11.4 g kg–1) > Plg-Sm (9.0 g kg–1). This trend appeared to be correlated with the abundance of smectite in the clays. Sepiolite had greater binding strength for AfB1 than the other clays. With intact clay structures, heating induced a negligible effect on AfB1 adsorption by the fibrous clays while in Sm-37GR and Plg-Sm, adsorption increased with heating at 250°C. Tunnel folding and structural collapse that had occurred at 400°C caused an abrupt decline in AfB1 adsorption irrespective of the clay type. The sepiolite clay adsorbed the least pepsin (370 g kg–1) while smectite adsorbed the most (1430 g kg–1). Consequently, in the simulated gastric fluid, adsorption declined by 25–30% in sepiolite, 52–60% in smectite, and remained unaffected in the palygorskites. Aflatoxin B1 adsorption probably occurred through H-bonding at the surface with the silanol group in palygorskite and sepiolite. No evidence that AfB1 molecules occupied the tunnels of the natural or heated palygorskite or sepiolite was observed in the present study. Palygorskite and sepiolite had a much smaller adsorption capacity for AfB1 than the smectite but also adsorbed less pepsin; therefore, both may be effective aflatoxin binders in gastrointestinal systems.

Graphene Quantum Dot-Based Optical Sensing Platform for Aflatoxin B1 Detection via the Resonance Energy Transfer Phenomenon.

An optical sensing platform for the detection of an important mycotoxin, aflatoxin B1 (AFB1), in the absence of a bioactive environment is explored. In this work, a fluorescence-based sensing technique was designed by combining graphene quantum dots (GQDs) and AFB1 via fluorescence quenching, where AFB1 acts as the quencher of GQD fluorescence. GQDs were synthesized through a single-step hydrothermal reaction from the leaves of "curry tree" (Murraya Koenigii) at 200 °C. The fluorescent GQDs were quenched by AFB1 (quencher), which itself is detecting the analyte. Hence, this study reports the direct sensing of the mycotoxin AFB1 without the involvement of inhibitors or biological entities. The possible mode of quenching is the nonradiative resonance energy transfer between the GQDs and the AFB1 molecules. This innovative sensor could detect AFB1 in the range from 5 to 800 ng mL-1 with a detection limit of 0.158 ng mL-1. The interferent study was also carried out in the presence of different mycotoxins and carbohydrates (d-fructose, cellulose, and starch), which demonstrated the high selectivity and robustness of the sensor in the complex sample matrix. The recovery percentage of the spiked samples was also calculated to be up to 106.8%. Thus, this study reports the first GQD based optical sensor for AFB1.

High‐Performance Functional Fe‐MOF for Removing Aflatoxin B1 and Other Organic Pollutants

AbstractOrganic pollutants, including mycotoxins, organic dyes, and pesticide residues, are the most critical threats to the global environment. In particular, efficient adsorption based on synthetic nanomaterials is considered a versatile and green approach to control mycotoxins. This work systematically investigates the aflatoxin B1 (AFB1) removal capacity of MIL‐101(Fe), a typical type of metal‐organic framework (MOF) synthesized by solvothermal methods and possesses super‐high porosity and excellent dispersion in liquid. The experimental results demonstrate that as‐prepared MIL‐101(Fe) exhibits a much higher saturated loading capacity (30.58 mg g−1) toward AFB1 than other adsorbents described in the literature. Subsequently, the adsorption process is studied via isothermal and kinetic analyses. This work also evaluates the removal effect of MIL‐101(Fe) on organic dyes and pesticides compared to the other five MOFs; the results reveal that MIL‐101(Fe) possesses a diversity of pollutant adsorption. The molecular docking and interaction region indicator analysis is applied to reflect the interactions between AFB1 molecules and MIL‐101(Fe). This work will provide a simple and effective approach for AFB1 treatment and adsorption in wastewaters and offer new insights and perspectives to the practical applications of synthetic nanomaterials, MOFs in environmental management.

Potential of Kale and Lettuce Residues as Natural Adsorbents of the Carcinogen Aflatoxin B1 in a Dynamic Gastrointestinal Tract-Simulated Model.

Adsorption of the carcinogen aflatoxin B1 (AFB1) onto agro-waste-based materials is a promising alternative over conventional inorganic binders. In the current study, two unmodified adsorbents were eco-friendly prepared from kale and lettuce agro-wastes. A dynamic gastrointestinal tract-simulated model was utilized to evaluate the removal efficiency of the sorptive materials (0.5%, w/w) when added to an AFB1-contaminated diet (100 µg AFB1/kg). Different characterization methodologies were employed to understand the interaction mechanisms between the AFB1 molecule and the biosorbents. Based on adsorption results, the biosorbent prepared from kale was the best; its maximum adsorption capacity was 93.6%, which was significantly higher than that of the lettuce biosorbent (83.7%). Characterization results indicate that different mechanisms may act simultaneously during adsorption. Non-electrostatic (hydrophobic interactions, dipole-dipole interactions, and hydrogen bonding) and electrostatic interactions (ionic attractions) together with the formation of AFB1-chlorophyll complexes appear to be the major influencing factors driving AFB1 biosorption.

(Invited) Cold Plasma As a Tool for a Removal of the Harmful Contaminants

Cold atmospheric pressure plasmas (CAP) represent an emerging technology that shows an enormous potential in removal of different hazardous contaminants relevant in the fields such as food and environmental technology and medicine [1]. In principle, plasma is the fourth state of matter; it can be created by applying the gas into a strong electrical field, which leads to the ionisation, dissociation and excitation of gaseous molecules. CAP generated using only air and electricity is a strongly non-equilibrium system, exhibiting striking physical and chemical characteristics; electron temperatures exceed 30,000 K, while the temperature of neutrals remains close to room temperature [2]. As a mixture of highly reactive particles, it represents a very promising, low-cost and eco-friendly method for decontamination with negligible effect on the treated substrate.To demonstrate its potential, we present a case study based on decontamination of mycotoxins using surface barrier discharge (SBD) CAP system, working at ambient air. Mycotoxins, the secondary metabolites produced by filamentous fungi, are toxic compounds that are found on over 70 % of global food and feed crop. Although many preventive measures are carried out, the trend of mycotoxin contamination is growing and affecting the health of more than a half of the human population [3]. Therefore, the development of a new and more effective method is necessary.We demonstrated that CAP was able to reach more than 90 % reduction of the treated mycotoxins. In comparison to commercially used UV irradiation, decontamination rate of CAP was a magnitude higher [4]. Furthermore, a detailed analysis based on CAP treatment of most potent mycotoxin aflatoxin B1 (AFB1) was performed, revealing that CAP induced degradation started at C8-C9 site of AFB1 molecule, which is also responsible for its toxicity. Further degradation led to the formation of 4 most important degradation products. Toxicity tests demonstrated that CAP induced complete removal of AFB1 toxicity [5]. According to these encouraging results, it can be concluded that CAP technology can be applied as a new efficient tool for decontamination of mycotoxins and also other emerging contaminants such as pesticides, pharmaceuticals, bisphenols etc.[1] M. Moreau, N. Orange, J.-L. Brisset, Ozone: Science and Engineering 2005, 27, 469-473.[2] A. Dickenson, Y. Morabit, M. I. Hasan, J. L. Walsh, Scientific Reports 2017, 7, 14003.[3] M. Eskola, G. Kos, C. T. Elliott, J. Hajšlová, S. Mayar, R. Krska, Critical Reviews in Food Science and Nutrition 2019, 1-17.[4] N. Hojnik, M. Modic, G. Tavčar-Kalcher, J. Babič, J. L. Walsh, U. Cvelbar, Toxins 2019, 11, 219.[5] N. Hojnik, M. Modic, J. L. Walsh, D. Žigon, U. Javornik, J. Plavec, B. Žegura, M. Filipič, U. Cvelbar, Journal of Hazardous Materials 2021, 403, 123593.

In-situ preparation of palygorskite-montmorillonite materials from palygorskite mineral via hydrothermal process for high-efficient adsorption of aflatoxin B1

Due to the threats of mycotoxin-contaminated animal feeds to livestock farming, food safety and human health, Palygorskite-Montmorillonite (Pal-Mt) materials with different functional groups and microstructures have been studied as an effective mycotoxin adsorbent. In this study, Pal-Mt materials were controllably regulated from Pal mineral via hydrothermal process by adjusting the hydrothermal temperature. Along with the increase of hydrothermal temperature, the microstructure of Pal showed a gradual transformation from fiber to layer, which led to a fiber-layered structure. Batch aflatoxin B1 (AFB1) adsorption experiments were conducted at different conversion rates of Pal. The optimized Pal-Mt with 50% conversion of Pal exhibited satisfactory adsorption capacity of 13.17 mg/g and removal rate of 95.65% and 91.33% (only 33.09% and 26.27% for Pal) from 2 mg/L of AFB1 phosphate buffer solution at pH 3.5 and 6.5, respectively. The increasing adsorption capacity was mainly attributed to the synergistic effect of cations in the interlayer of Mt and the high specific area of Pal, resulting in a larger proportion of available adsorption sites (e.g., Ca2+, –OH), which favored bonding with AFB1 molecules. This work provides a new material regulated from abundant Pal mineral, which is effective and promising for adsorption of AFB1.

Smartphone-based technology for nanomolecular detection of aflatoxin B1 by aptamer-conjugated magnetic nanoparticles

The need for a healthy market in the rapid and accurate screening of a variety of pathogenic agents and toxins in the environment and food has led to an increase in the development of new biosensors, which have ideal characteristics, such as high sensitivity and specificity with rapid detection and simple preparation of the sample. Among the food contaminants, mycotoxins have been identified as a major challenge for the food industry, and rapid and accurate detection has attracted the attention of food inspection and monitoring organisations. In this study, a nanomolecular detection method is described using aflatoxin B1 (AFB1)-specific aptamers attached to streptavidin-coated magnetic nanoparticles. A prominent feature of the AFB1-specific aptamers is a guanine-rich (G-rich) sequence with a G-quadruplex structure after capturing AFB1 molecules and mimicking peroxidase activity. The enzymatic reaction evaluated in the presence of chromogenic substrate and measurement is done by a smartphone-specific application for colorimetric measurement. The results indicated that the assay could measure AFB1 in rice, flour, seed, maize, and pistachio. In addition, the application of hybrid nanomaterial technology resulting from the binding of biotin-labelled aptamers to the surface of streptavidin-coated magnetic nanoparticles minimises preparation and treatment of samples, improves results, and consequently reduces false negative and positive responses in the detection field. This study may eventually lead to the design and development of a fast, sensitive, specific, and on-site AFB1-based nanomolecular colorimetric detection system via a smartphone-based application that can be readily accessible to all applicants, from professionals to manufacturers of foodstuffs.

Photoluminescence label-free immunosensor for the detection of Aflatoxin B1 using polyacrylonitrile/zinc oxide nanofibers.

The precise and rapid detection of hazardous molecules, microorganisms, pollutants, and toxins currently remains a global challenge. Aflatoxin B1 (AFB1) is a toxic and dangerous product of fungi that considered as cancerogenic, mutagenic, and immunosuppressive for humans and animals. Therefore, the screening of AFB1 in food and beverages plays an important role in preventing foodborne illnesses. In this study, AFB1 molecules were detected in a microfluidic device with integrated polyacrylonitrile/zinc oxide (PAN/ZnO) nanofibers fabricated via a combination of the electrospinning, and atomic layer deposition (ALD) techniques. The structural and optical analyses of PAN/ZnO nanofibers were performed and samples with the most suitable properties were utilized for AFB1 detection. In order to obtain the biorecognition layer towards AFB1, PAN/ZnO samples were modified by (3-Aminopropyl) triethoxysilane (APTES), and glutaraldehyde (GA), bovine serum albumin (BSA) and monoclonal antibodies (Anti-AFB1). Subsequently, photoluminescence (PL)-based immunosensor was integrated into a microfluidic cell and tested for AFB1 detection. The mechanism of PL changes caused by AFB1 & Anti-AFB1 complex formation was analyzed and developed. The proposed approach enables the detection of AFB1 with the lowest concentration (LOD) of about 39pg/ml, while the sensitivity range was evaluated as 0.1-20ng/ml. The obtained values of LOD and sensitivity, as well as the simplicity of the detection method, make this approach a prospect for further application.

A Theoretical Study of the Adsorption Process of B-aflatoxins Using Pyracanthakoidzumii (Hayata) Rehder Biomasses.

Employing theoretical calculations with density functional theory (DFT) using the B3LYP/6-311++G(d,p) functional and basis set, the interaction of the aflatoxin B1 (AFB1) molecule and the functional groups present in the Pyracantha koidzumii biosorbent was investigated. Dissociation free energy and acidity equilibrium constant values were obtained theoretically both in solution (water) and gas phases. Additionally, the molecular electrostatic potential for the protonated molecules was calculated to verify the reactivity. Thus, methanol (hydroxyl group), methylammonium ion (amino group), acetate ion (carboxyl group), and acetone (carbonyl group), were used as representatives of the substrates present in the biomass; these references were considered using the corresponding protonated or unprotonated forms at a pH value of 5. The experimental infrared spectrophotometric data suggested the participation of these functional groups in the AFB1 biosorption process, indicating that the mechanism was dominated by electrostatic interactions between the charged functional groups and the positively charged AFB1 molecule. The theoretical determination indicated that the carboxylate ion provided the highest interaction energy with the AFB1 molecule. Consequently, an enriched biosorbent with compounds containing carboxyl groups could improve the yield of the AFB1 adsorption when using in vitro and in vivo trials.

Boron-doped diamond electrochemical aptasensors for trace aflatoxin B1 detection

An electrochemical aptasensor for detecting trace aflatoxin B1 (AFB1) is designed and fabricated consisting of aptamers and gold nanoparticles on conductive boron-doped diamond (BDD) electrode. By examining the relative impedance shift from electrochemical impedance spectroscopy as a function of AFB1 concentration, the low detection limit (wide linear relationship range) of the aptasensor is realized to be 5.5 × 10−14 mol L−1 (1.0 × 10−13‒1.0 × 10−8 mol L−1). The variation in impedance property of the aptasensor is determined by the specific adsorption of AFB1 molecules to the aptamer at a certain concentration covering the electrode. By means of multiple characteristic processes, it is demonstrated that the constructed aptasensor is favorable for testing the trace AFB1 with high specificity, sensitivity, stability, repeatability, and reusability, which lead to a possibility to achieve high performance biosensor for practical application to quantitatively detract trace AFB1 in environments.

Quantum bead-based fluorescence-linked immunosorbent assay for ultrasensitive detection of aflatoxin M1 in pasteurized milk, yogurt, and milk powder

Herein, we reported a novel direct competitive fluorescence-linked immunosorbent assay (dcFLISA) for the ultrasensitive detection of aflatoxin M1 (AFM1) in pasteurized milk, yogurt, and milk powder using 150-nm quantum dot beads (QB) as the carrier of competing antigen. Large QB were applied to decrease the binding affinity of the competing antigen to antibody and enhance the fluorescent signal intensity. The aflatoxin B1 molecule was used as the surrogate of AFM1 to label with BSA on the surface of QB because of its 63% cross reaction to anti-AFM1 mAb. The binding affinity of the competing antigen to mAb was tuned by changing the labeled molar ratios of aflatoxin B1 to BSA. Through combining the advantages of QB as the carrier of the competing antigen, including low binding affinity to mAb and highly fluorescent signal output, the proposed dcFLISA exhibited an ultrahigh sensitivity for AFM1 detection, with a half-maximal inhibitory concentration of 3.15 pg/mL in 0.01 M phosphate-buffered saline solution (pH 7.4), which is substantially lower than that of the traditional horseradish peroxidase-based ELISA. The proposed method also exhibited very low detection limitations of 0.5, 0.6, and 0.72 pg/mL for real pasteurized milk, yogurt, and milk powder, respectively. These values are considerably below the maximum permissible level of the European Commission standard for AFM1 in dairy products. In summary, the proposed dcFLISA offers a novel strategy with an ultrahigh sensitivity for the routine monitoring of AFM1 in various dairy products.

Cytotoxicity of gamma irradiated aflatoxin B1 and ochratoxin A

Toxicity of gamma irradiated mycotoxins aflatoxin B1 (AFB1) and ochratoxin A (OTA) was investigated in vitro. AFB1 and OTA stock solutions (50 mM, in methanol) were gamma irradiated (5 and 10 kGy) and non-irradiated and irradiated mycotoxins solutions were tested for cytotoxicity on Pk15, HepG2 and SH-SY5Y cell lines (MTT assay, 1–500 μM concentration range; 24 h exposure). Degradation of mycotoxin molecules was examined by liquid chromatography tandem mass spectrometry (HPLC-MS/MS). AFB1 and OTA radiolytic products were less toxic than the parent mycotoxins to all of the tested cell lines. Gamma irradiation even at 5 kGy had effect on AFB1 and OTA molecules however, this effect was dependent on chemical structure of mycotoxin. Since gamma irradiation at low dose reduced initial level of both mycotoxins, and gamma irradiated mycotoxins had lower toxicity in comparison to non-irradiated mycotoxins, it can be concluded that gamma irradiation could be used as decontamination method.

Adsorption behaviors of aflatoxin B1 and zearalenone by organo-rectorite modified with quaternary ammonium salts

Organo-rectorites (ORts) modified with different quaternary ammonium salts were prepared to remove polar mycotoxin aflatoxin B1 (AFB1) and weak polar, hydrophobic mycotoxin zearalenone (ZER). The structural and surface properties of the prepared ORts were studied. The intercalation of organic cationic surfactants expanded the interlayer of rectorite and increased the hydrophobicity. In vitro adsorption experiments were carried out to simulate the in vivo conditions of gastrointestinal tract of animals by a batch mode. The prepared ORts showed super enhanced adsorption capacities towards AFB1 and ZER compared with raw rectorite, indicating the effectiveness of the prepared ORts as mycotoxins adsorbents. The ORts modified with longer chain surfactant molecules possessed a higher adsorption capacity towards mycotoxins. In addition, with increasing the modifier dosage, the adsorption capacity increased first and then decreased. The best adsorption capacity was achieved when the dosage of the modifier increased to 2.0CEC. The adsorption of both AFB1 and ZER onto ORts could be well described by Langmuir model. In the binary-contaminant system, the existence of AFB1 would bring negative effect to the adsorption of ZER. On the other hand, the adsorption of ZER was in favor of the adsorption of AFB1 molecules. The solution pH had negligible influence on the adsorption process of ORts both in single system and binary system, indicating no desorption occurred when the adsorbents pass through from stomach to intestine as animal feed. This study demonstrates that the received ORts could be a promising adsorbent for detoxication of different mycotoxins in real application.

On-Site Detection of Aflatoxin B1 in Grains by a Palm-Sized Surface Plasmon Resonance Sensor.

Aflatoxins (AFs) are highly toxic compounds that can cause both acute and chronic toxicity in humans. Aflatoxin B1 (AFB1) is considered the most toxic of AFs. Therefore, the rapid and on-site detection of AFB1 is critical for food safety management. Here, we report the on-site detection of AFB1 in grains by a portable surface plasmon resonance (SPR) sensor. For the detection of AFB1, the surface of an SPR Au chip was sequentially modified by cysteine-protein G, AFB1 antibody, and bovine serum albumin (BSA). Then, the sample solution and AFB1-BSA conjugate were flowed onto the Au chip in serial order. In the absence of AFB1, the SPR response greatly increased due to the binding of AFB1-BSA on the Au chip. In the presence of AFB1, the SPR response showed little change because the small AFB1 molecule binds on the Au chip instead of the large AFB1-BSA molecule. By using this portable SPR-based competitive immunoassay, the sensor showed low limits of detection (2.51 ppb) and quantification (16.32 ppb). Furthermore, we successfully detected AFB1 in rice, peanut, and almond samples, which suggests that the proposed sensing method can potentially be applied to the on-site monitoring of mycotoxins in food.

SERS detection of aflatoxin B1 in edible oil based on Au core-poly acrylamide shell nanoparticles

The core-shell nanoparticles, which took gold nanoparticle as core and molecular imprinted polymer as shell, were prepared by covering the polyacrylamide aflatoxin B1 molecular imprinted polymer around the gold nanoparticles.The aflatoxin B1 molecules could be captured by the specificity holes in polyacrylamide shell, then got into the effective range of plasma resonance magnetic field of gold nanoparticles to achieve the SERS detection of aflatoxin B1.The linear range of detection varies from 3 × 10-11 to 3 × 10-4mol/L, the correlation coefficient R2 was 0.982, and the limit of detection reaches up to 3 ×10-11mol/L. This method could be applied into the detection of aflatoxin B1 in edible oil samples.The content of aflatoxin B1 was between 4.65 × 10-9mol/L and 4.98 × 10-5mol/L, the recovery rate of sample varies from 89.84% to 101.24%, and the relative standard deviation was from 4.51% to 13.11%. The results showed that this method is rapid and accurate and convenient, as well as can be used for the rapid detection of aflatoxin B1 in edible oil.

Development of a cellular biosensor for the detection of aflatoxin B1, based on the interaction of membrane engineered Vero cells with anti-AFB1 antibodies on the surface of gold nanoparticle screen printed electrodes

The development of methods for the detection of aflatoxin B1 (AFB1) in foods is a very important practice for ensuring food quality and safety. Most tests of AFB1 are still conducted with conventional methods (i.e. antibody-based ELISA tests, high performance liquid chromatography – HPLC); however biosensor methods are being developed to date as screening tools for field analysis. Compared to immunology/ELISA-like tests or chromatography methods, biosensors are able to provide rapid, sensitive, robust and cost effective quantitative methods for on-site testing. In this work we propose a cellular biosensor based on Vero cells, membrane engineered with anti-AFB1 antibody as the biological recognition element reacting with AFB1 molecules on gold nanoparticle/screen printed electrodes (SPEs) (three electrode system). In order to culture the cells on the SPEs surfaces the working electrodes were coated with poly-l-lysine to facilitate cell adhesion. The SPEs were connected to a potentiostat device through a transducer and chronoamperometric (CA) and cyclic voltammetric (CV) measurements were performed. Quantitative results obtained using the cellular biosensor method for AFB1 were compared to those obtained using the HPLC method in pistachio samples spiked with AFB1. The method displayed good sensitivity (r2 = 0.87) and detection limit (0.5 ng/mL).