Aflatoxin B1 removal by multifunctional membrane based on polydopamine intermediate layer

Simultaneous monitoring of multiple prohibited drugs in various aquatic products

Both sedative and antipathogenic drugs are often found to be illegally used in aquaculture, but there is a lack of simultaneous monitoring methods. A method for simultaneously monitoring multiple prohibited drugs in various aquatic product samples was developed in this work, including fish, shrimp, crab, and shellfish. Sulfonic acid-functionalized magnetic graphitic carbon nitride (S-MGCN) was synthesized and validated to efficiently co-extract all targets (adsorption efficiency over 90.07%) through various adsorption mechanisms such as electrostatic interaction, hydrogen bonding, and π-π interaction while demonstrating good sample matrix purification ability (matrix effect below 13.60%). A new magnetic solid-phase extraction method based on S-MGCN was subsequently established. Coupled with UPLC-MS/MS, the detection limits were 0.030.075 μg /kg, and the recoveries ranged from 88.76% to 111.74% with the RSDs lower than 14.60%, indicating that the developed method has good sensitivity, accuracy, and precision. Further validation of its practicality was achieved through actual sample analysis.

Development of a mesoporous polypyrrole nanofiber mat for simultaneous detection of multiple mycotoxins in various foods

Due to health hazards and co-contamination of mycotoxins, efficient separation and detection of multiple mycotoxins in food is highly desirable yet challenging. In this study, we prepared a novel mesoporous polypyrrole nanofiber mat (M-PPy NFM) for extracting multiple mycotoxins from food. The mesoporous effects and multifunctional PPy contribute to higher recovery and purification efficiency of M-PPy NFM for mycotoxins by facilitating hydrogen bonding and π-π interaction. Under optimized conditions, a simple, eco-friendly solid phase extraction (SPE) method coupled with high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) was developed for mycotoxin detection. This innovative method demonstrates good linearity (0.9991-0.9999), low detection limits (0.03-0.33 μg kg-1), satisfactory recoveries (92.0 %-108.0 %) and precision (0.3 %-11.7 %). Notably, it significantly reduces organic solvent consumption to 3.1 mL while minimizing adsorbent usage to 5.0 mg. Moreover, M-PPy NFM could be reused ten times. This study confirms the huge potential of M-PPy NFM for efficient applications in mycotoxin extraction and determination.

Simultaneously Selective Separation of Zearalenone and Four Aflatoxins From Rice Samples Using Co-Pseudo-Template Imprinted Polymers With MIL-101(Cr)-NH2 as Core

A novel approach for the simultaneous separation of zearalenone (ZEN) and four types of aflatoxins (AFB1, AFB2, AFG1 and AFG2) from rice samples was presented. This approach utilized modified MIL-101(Cr)-NH2 as core, with molecularly imprinted polymers (MIPs) serving as the shell. The MIL-101(Cr)-NH2 was prepared via ring-opening reaction, while the imprinted polymers were synthesized using warfarin and 4-methylumbelliferyl acetate as co-pseudo template, ethylene glycol dimethacrylate as the cross-linker and azobisisobutyronitrile as initiator. The resulting co-pseudo-template-MIPs (CPT-MIPs) were thoroughly characterized and evaluated. Adsorption studies demonstrate that the adsorption process of CPT-MIPs follows a chemical monolayer adsorption mechanism, with imprinted factors ranging from 1.24 to 1.52 and selective factors ranging from 1.29 to 1.52. Self-made columns were prepared, and the method for separation was developed and validated. The limit of detections ranged from 0.12 to 2.09 μg/kg, and the limit of qualifications ranged from 1.2 to 6.25 μg/kg. To assess the reliability of the method, ZEN and AFs were spiked at three different levels, and the recoveries ranged from 79.53 to 94.58%, with relative standard deviations of 2.90-5.78%.

Relevant mycotoxins in oil crops, vegetable oils, de-oiled cake and meals: Occurrence, control, and recent advances in elimination

Mycotoxins in agricultural commodities have always been a concern due to their negative impacts on human and livestock health. Issues associated with quality control, hot and humid climate, improper storage, and inappropriate production can support the development of fungus, causing oil crops to suffer from mycotoxin contamination, which in turn migrates to the resulting oil, de-oiled cake and meals during the oil processing. Related research which supports the development of multi-mycotoxin prevention programs has resulted in satisfactory mitigation effects, mainly in the pre-harvest stage. Nevertheless, preventive actions are unlikely to avoid the occurrence of mycotoxins completely, so removal strategies may still be necessary to protect consumers. Elimination of mycotoxin has been achieved broadly through the physical, biological, or chemical course. In view of the steadily increasing volume of scientific literature regarding mycotoxins, there is a need for ongoing integrated knowledge systems. This work revisited the knowledge of mycotoxins affecting oilseeds, food oils, cake, and meals, focusing more on their varieties, toxicity, and preventive strategies, including the methods adopted in the decontamination, which supplement the available information.

Simultaneous determination of multiple mycotoxins in corn and wheat by high efficiency extraction and purification based on polydopamine and ionic liquid bifunctional nanofiber mat

Due to the universality and harmfulness of mycotoxin co-contamination in cereals, it is of great significance to simultaneously monitor various mycotoxins co-polluted to ensure food safety and public health. In this work, a nanofiber mat modified by polydopamine and ionic liquid (PDA-IL-NFsM) was prepared and utilized as a solid-phase extraction (SPE) adsorbent for the simultaneous quantitative detection of multiple mycotoxins in corn and wheat. The PDA-IL-NFsM can form multiple retention mechanisms with the targets through hydrogen bond, π-π interaction, electrostatic or hydrophobic interaction, it shows favorable simultaneous adsorption performance (adsorption efficiency mostly higher than 88.27%) for fifteen mycotoxins in seven classes. Moreover, it can significantly reduce the matrix effect (lower than -13.69%), showing a good purification effect on the sample matrix. Based on the superior performance of PDA-IL-NFsM, a simple sample preparation method was established. The sample extract is simply diluted with water for SPE, and the eluent can be directly collected for ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analysis. The detection limit can reach 0.04-4.21 μg kg^-1, the recovery was 80.09%-113.01%, and the relative standard deviations of intra-day and inter-day precision were 2.80%-14.81% and 0.68%-13.80% respectively. The results show that the proposed method has good sensitivity, accuracy and precision, and has practical application potential.

Occurrence of aflatoxins in water and decontamination strategies: A review

Aflatoxins are highly carcinogenic metabolites produced by some Aspergillus species and are the most prevalent mycotoxins. Although aflatoxins are commonly synthesized during fungal colonization in preharvest maize, cereals, and nuts, they can be transported by rainfall to surface water and are a common toxin found in wastewater from some food industries. Here, the occurrence of aflatoxins in bodies of water is reviewed for the first time, along with the decontamination methods. Aflatoxins have been detected in surface, wastewater and drinking water, including tap and bottled water. The specific sources of water contamination remain unclear, which is an important gap that must be addressed in future research. Two main kinds of decontamination methods have been reported, including degradation and adsorption. The best degradation rates were observed using gamma and UV irradiations, oxidoreductases and ozone, while the best adsorption abilities were observed with minerals, polyvinyl alcohol, durian peel and activated carbon. Synthetic polymers could be used as membranes in pipes to remove aflatoxins in water flows. Although most decontamination methods were screened using AFB₁, the other commonly found aflatoxins were not used in the screenings. Overall, the occurrence of aflatoxins in water could be a significant emerging public health concern largely ignored by local and international legislation. Numerous advances have been reported for the decontamination of aflatoxins in water; however, there is still a long way to go to put them into practice.

Enhancement of AFB1 Removal Efficiency via Adsorption/Photocatalysis Synergy Using Surface-Modified Electrospun PCL-g-C3N4/CQDs Membranes

Aflatoxin B₁ (AFB₁) is a highly toxic mycotoxin produced by aspergillus species under specific conditions as secondary metabolites. In this study, types of PCL (Polycaprolactone) membranes anchored (or not) to g-C₃N₄/CQDs composites were prepared using electrospinning technology with (or without) the following surface modification treatment to remove AFB₁. These membranes and g-C₃N₄/CQDs composites were characterized by SEM, TEM, UV-vis, XRD, XPS and FTIR to analyze their physical and chemical properties. Among them, the modified PCL-g-C₃N₄/CQDs electrospun membranes exhibited an excellent ability to degrade AFB₁ via synergistic effects of adsorption and photocatalysis, and the degradation rate of 0.5 μg/mL AFB₁ solution was observed to be up to 96.88% in 30 min under visible light irradiation. Moreover, the modified PCL-g-C₃N₄/CQDs electrospun membranes could be removed directly after the reaction process without centrifugal or magnetic separation, and the regeneration was a green approach synchronized with the reaction under visible light avoiding physical or chemical treatment. The mechanism of adsorption by electrostatic attraction and hydrogen bonding interaction was revealed and the mechanism of photodegradation of AFB₁ was also proposed based on active species trapping experiments. This study illuminated the highly synergic adsorption and photocatalytic AFB₁ removal efficiency without side effects from the modified PCL-g-C₃N₄/CQDs electrospun membranes, thereby offering a continual and green solution to AFB₁ removal in practical application.

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.

Electrospun Membranes Anchored with g-C3N4/MoS2 for Highly Efficient Photocatalytic Degradation of Aflatoxin B1 under Visible Light

The degradation of aflatoxin (AF) is a topic that always exists along with the food and feed industry. Photocatalytic degradation as an advanced oxidation technology has many benefits, including complete inorganic degradation, no secondary contamination, ease of activity under moderate conditions, and low cost compared with traditional physical, chemical, and biological strategies. However, photocatalysts are usually dispersed during photocatalytic reactions, resulting in energy and time consumption in the separation process. There is even a potential secondary pollution problem from the perspective of food safety. In this regard, three electrospun membranes anchored with g-C₃N₄/MoS₂ composites were prepared for highly efficient photocatalytic degradation of aflatoxin B₁ (AFB₁) under visible light. These photocatalytic membranes were characterized by XRD, SEM, TEM, FTIR, and XPS. The factors influencing the degradation efficiency of AFB₁, including pH values and initial concentrations, were also probed. The three kinds of photocatalytic membranes all exhibited excellent ability to degrade AFB₁. Among them, the photocatalytic degradation efficiency of the photocatalytic membranes prepared by the coaxial methods reached 96.8%. The experiment is with an initial concentration of 0.5 μg/mL (500 PPb) after 60 min under visible light irradiation. The mechanism of degradation of AFB₁ was also proposed based on active species trapping experiments. Moreover, the prepared photocatalytic membranes exhibited excellent photocatalytic activity even after five-fold use in the degradation of AFB₁. These studies showed that electrospun membranes anchored with g-C₃N₄/MoS₂ composites have a high photocatalytic ability which is easily removed from the reacted medium for reuse. Thereby, our study offers a highly effective, economical, and green solution for AFB₁ degradation in the foodstuff for practical application.

Enhancing the degradation of Aflatoxin B1 by co-cultivation of two fungi strains with the improved production of detoxifying enzymes

After the co-culture of Aspergillus niger and Pleurotus ostreatus, the obtained extracellular crude enzymes solution was employed to aflatoxin B₁ (AFB₁) degradation. The maximum AFB₁ degradation with co-culture reached 93.4%, which increased by 65.9% and 37.6%, respectively, compared with those of the mono-culture of Pleurotus ostreatus and Aspergillus niger. The molecular weight of the key detoxifying enzymes isolated by ultrafiltration was 58 and 63 kDa by SDS-PAGE analysis. The purified detoxifying enzymes had a high detoxification effect on AFB₁ with the degradation rate of 94.7%. It was found that the co-culture of Pleurotus ostreatus and Aspergillus niger promoted the production of 58 and 63 kDa detoxifying enzymes to enhance the AFB₁ degradation. The chemical structure of major degradation products of AFB₁ by the mixed cultures were preliminarily identified by LC-Triple TOF MS. Two pathways of AFB₁ degradation were inferred with the high potential of fungal co-cultivations for AFB₁ detoxification applications.

Efficient and simple simultaneous adsorption removal of multiple aflatoxins from various liquid foods

In this study, a polydopamine modified nanofibers membrane (PDA-PS NFsM) was prepared and evaluated as the adsorbent for simultaneous removal of a variety of aflatoxins in various liquid foods, including edible oil, soy sauce and milk, rice vinegar and liquor. The removal efficiency for every single aflatoxin from all samples involved above was more than 76.5% within 1 h at 25 °C, except the liquors with higher ethanol content, for which the efficiency was lower. Moreover, PDA-PS NFsM can be removed directly after the adsorption process without any subsequent separation. The results suggested that the adsorption mechanism of the aflatoxins onto PDA-PS NFsM was chemisorption-based spontaneous endothermic reaction and aflatoxins were adsorbed by electrostatic interaction, hydrogen bonding and π-π interaction. This study confirmed that the PDA-PS NFsM has a good practical application potential in the simultaneous removal of a variety of aflatoxins from various liquid foods.

Biocatalytic membrane: Go far beyond enzyme immobilization

Biocatalytic membrane takes advantages of reaction-separation integration as well as enzyme immobilization, which has attracted increasing attentions in online detection and biomanufacturing. However, the high preparation cost, inferior comprehensive performance, and low stability limit its applications. Thus, besides enzyme immobilization, more efforts should be made in biocatalytic membrane configuration design for a specific application to enhance the synergistic effect of reaction and separation and improve its operating stability. This review summarized the recent progress on biocatalytic membrane preparation, discussed different membrane configurations for various applications, finally proposed several challenges and possible solutions, which provided directions and guides for the development and industrialization of biocatalytic membrane.

Enzymes for Detoxification of Various Mycotoxins: Origins and Mechanisms of Catalytic Action

Mycotoxins are highly dangerous natural compounds produced by various fungi. Enzymatic transformation seems to be the most promising method for detoxification of mycotoxins. This review summarizes current information on enzymes of different classes to convert various mycotoxins. An in-depth analysis of 11 key enzyme mechanisms towards dozens of major mycotoxins was realized. Additionally, molecular docking of mycotoxins to enzymes' active centers was carried out to clarify some of these catalytic mechanisms. Analyzing protein homologues from various organisms (plants, animals, fungi, and bacteria), the prevalence and availability of natural sources of active biocatalysts with a high practical potential is discussed. The importance of multifunctional enzyme combinations for detoxification of mycotoxins is posed.

Aflatoxin in foodstuffs: Occurrence and recent advances in decontamination

Aflatoxins are highly toxic compounds produced as secondary metabolites by some Aspergillus species, whose occurrence have been reported predominantly in several types of foods of low moisture content, while aflatoxin biotransformation products have been reported mainly in milk and milk products. This review deals with the occurrence of aflatoxins in some of the major food products in the last 5 years including regulatory aspects, and recent advances in detoxification strategies for contaminated foods. Aflatoxin contamination in cereals including corn and peanut is still a public health problem for some populations, especially in African countries. Despite that most of physical and chemical methods for aflatoxin detoxification may affect the nutritional properties of food, or are not safe for human consumption, gamma-radiation and ozone applications have demonstrated great potential for detoxification of aflatoxins in some food matrices. Biological methods based on removal or degradation of aflatoxins by bacterial and yeast have good perspectives, although further studies are needed to clarify the detoxification mechanisms by microorganisms and determine practical aspects of the use of these methods in food products, especially their potential effects on sensory characteristics of foods.