Solid-phase extraction of aflatoxins using a nanosorbent consisting of a magnetized nanoporous carbon core coated with a molecularly imprinted polymer

Fabrication of a magnetic functionalized chitosan hydrogel for effective extraction of aflatoxins from cereals

A magnetic adsorbent was synthesized by coupling magnetic nanoparticles, UiO-66-NH2 and 1-butyl-trimethylimidazole bromide ([BMIM][Br]) to chitosan (CS)-based composite conveniently. A series of modern characterizations were employed to assess its properties. The results showed that UiO-66-NH2 was uniformly distributed within the composite via in-situ growth, which can enhance the porosity obviously. The introduction of various ligands enables the composite to exhibit excellent extraction performance for four aflatoxins (AFs) through multiple interactions. The adsorption mechanism was elucidated and the main factors affecting extraction efficiency were evaluated. Under optimal conditions, the limits of detection (LODs) ranged from 0.08 to 0.56 μg/kg. The established method was successfully utilized to determine AFs from cereal samples (rice, glutinous rice, wheat, soybean, paddy, and corn) with satisfactory recovery of 77% ∼ 119% with relative standard deviations (RSDs) of 1.0% ∼ 11.7% (n = 5). The adsorbent demonstrated sufficient robustness for repeated use at least six times without obvious damage of extraction property.

Mycotoxins-Imprinted Polymers: A State-of-the-Art Review

Mycotoxins are toxic metabolites of molds which can contaminate food and beverages. Because of their acute and chronic toxicity, they can have harmful effects when ingested or inhaled, posing severe risks to human health. Contemporary analytical methods have the sensitivity required for contamination detection and quantification, but the direct application of these methods on real samples is not straightforward because of matrix complexity, and clean-up and preconcentration steps are needed, more and more requiring the application of highly selective solid-phase extraction materials. Molecularly imprinted polymers (MIPs) are artificial receptors mimicking the natural antibodies that are increasingly being used as a solid phase in extraction methods where selectivity towards target analytes is mandatory. In this review, the state-of-the-art about molecularly imprinted polymers as solid-phase extraction materials in mycotoxin contamination analysis will be discussed, with particular attention paid to the use of mimic molecules in the synthesis of mycotoxin-imprinted materials, to the application of these materials to food real samples, and to the development of advanced extraction methods involving molecular imprinting technology.

Strategies to control mycotoxins and toxigenic fungi contamination by nano-semiconductor in food and agro-food: a review

Mycotoxins are toxic secondary metabolites generated from toxigenic fungi in the contaminated food and agro-food, which have been regarded as a serious threat to the food safety and human health. Therefore, the control of mycotoxins and toxigenic fungi contamination is of great significance and has attracted the increasing attention of researchers. As we know, nano-semiconductors have many unique properties such as large surface area, structural stability, good biocompatibility, excellent photoelectrical properties, and low cost, which have been developed and applied in many research fields. Recently, nano-semiconductors have also been promisingly applied in mitigating or controlling mycotoxins and toxigenic fungi contaminations in food and agro-food. In this review, the type, occurrence, and toxicity of main mycotoxins in food and agro-food were introduced. Then, a variety of strategies to mitigate the mycotoxin contamination based on nano-semiconductors involving mycotoxins detection, inhibition of toxigenic fungi, and mycotoxins degradation were summarized. Finally, the outlook, opportunities, and challenges have prospected in the future for the mitigation of mycotoxins and toxigenic fungi based on nano-semiconductors.

Off-line magnetic Fe3O4@SiO2@MIPs-based solid phase dispersion extraction coupling with HPLC for the simultaneous determination of olaquindox and its metabolite in fish muscle and milk samples

An innovative core-shell magnetic molecularly imprinted polymers, Fe₃O₄@SiO₂@MIPs, was elaborately tailored for specific separation and enrichment of olaquindox (OLA) and its metabolic marker methyl-3-quinoxaline-2carboxylic acid (MQCA). Herein, benefiting from the combination of functionalized magnetic nanoparticles (Fe₃O₄@SiO₂) and MIPs, Fe₃O₄@SiO₂@MIPs not only possessed favorable magnetic properties and stability, avoiding tedious sample pretreatment process, but also demonstrated exceptional selective recognition ability and adsorption capacity, suppressing influence of coexisting interfering substances. Encouraged by prominent merits, Fe₃O₄@SiO₂@MIPs-based magnetic solid phase extraction with HPLC method was developed, realizing simultaneous measurement of OLA and MQCA. Under optimal conditions, excellent linear ranges of 0-100 μg/L with detection limit of 0.175-0.271 μg/L were obtained. The proposed method was finally utilized for determination of OLA and MQCA in fish muscle and milk samples with satisfactory recoveries (80.56-95.26%) and relative standard deviation below 8.1%, furnishing a reliable and sensitive strategy for enrichment and detection residual veterinary drugs in food samples.

Study on Molecularly Imprinted Polymers Obtained Sonochemically for the Determination of Aflatoxins in Food

Aflatoxins (AFs) are fungi secondary metabolites produced by the Aspergillus family. These compounds can enter the food chain through food contamination, representing a risk to human health. Commercial immunoaffinity columns are widely used for the extraction and cleanup of AFs from food samples; however, their high cost and large solvent consumption create a need for alternative strategies. In this work, an alternative strategy for producing molecularly imprinted polymers (MIPs) was proposed to extract aflatoxins AFB1, AFB2, AFG1, and AFG2 from complex food samples, using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The MIPs were synthesized via a low-cost and rapid (5 min) sonochemical free-radical polymerization, using 1-hydroxy-2-naphthoic acid as a dummy template. MIPs-based solid phase extraction performance was tested on 17 dietary supplements (vegetables, fruits, and cereals), obtaining appreciable recovery rates (65-90%) and good reproducibility (RSD ≤ 6%, n = 3); the selectivity towards other mycotoxins was proved and the data obtained compared with commercial immunoaffinity columns. The proposed strategy can be considered an alternative affordable approach to the classical immunoaffinity columns, since it is more selective and better performing.

Solid-phase extraction techniques based on nanomaterials for mycotoxin analysis: An overview for food and agricultural products

Mycotoxin contamination is a globally concerned problem for food and agricultural products since it may directly or indirectly induce severe threats to human health. Sensitive and selective screening is an efficient strategy to prevent or reduce human and animal exposure to mycotoxins. However, enormous challenges exist in the determination of mycotoxins, arising from complex sample matrices, trace-level analytes, and the co-occurrence of diverse mycotoxins. Appropriate sample preparation is essential to isolate, purify, and enrich mycotoxins from complicated matrices, thus decreasing sample matrix effects and lowering detection limits. With the cross-disciplinary development, new solid-phase extraction strategies have been exploited and integrated with nanotechnology to meet the challenges of mycotoxin analysis. This review summarizes the advance and progress of solid-phase extraction techniques as the methodological solutions for mycotoxin analysis. Emphases are paid on nanomaterials fabricated as trapping media of SPE techniques, including carbonaceous nanoparticles, metal/metal oxide-based nanoparticles, and nanoporous materials. Advantages and limitations are discussed, along with the potential prospects. This article is protected by copyright. All rights reserved.

Preparation and properties of aflatoxins imprinted polymer grafted onto the surface of mesoporous silica SBA-15 functionalized with double bonds

Mesoporous silica Santa Barbara-15 was functionalized by methacryloxypropyl trimethoxysilane. Taking this as the carrier material, a new mesoporous silica surface imprinted polymer was synthesized by using the C=C bond, functional monomer α-methacrylic acid, and crosslinker ethylene glycol dimethacrylate, which was used to extract aflatoxin from grain efficiently. It is different from the preparation of surface imprinted polymers which is physically wrapping carrier materials with polymer layers. The chemical grafting method makes the coating of the polymer layer more controllable. A new method for selective separation, enrichment, and determination of trace aflatoxin in grain was established by using the polymers as the filter of the solid-phase extraction column and high-performance liquid chromatography. The linear range of the method was 0.5-100 μg/kg, R²  = 0.9990-0.9993. The recovery of aflatoxin G2, G1, B2, and B1 was 98.9-119.7% and the relative standard deviation was 3.07-5.76%. By comparing the self-made column with the immunoaffinity column, it was found that the self-made column had better extraction performance for aflatoxins than the immunoaffinity column. It can be used for the analysis and detection of aflatoxins in cereal.

Molecularly imprinted solid-phase extraction of Chikusetsu saponin IVa from Panacis majoris Rhizoma

As the main active component of Panacis majoris Rhizoma, Chikusetsu saponin IVa has the activity of anti-oxidation, anti-inflammatory pain, and so on. Obtaining high purity Chikusetsu saponin IVa by simple purification steps is a prerequisite for its deep development. In this paper, the separation and purification of Chikusetsu saponin IVa were studied by molecular imprinting technique. By ultraviolet and visible spectrophotometry and computer molecular simulation, it was concluded that water-soluble 3-(2-carboxyethyl)-1-vinylimidazolium bromide ionic liquid was the best functional monomer compared with acrylic acid and acrylamide. The molecularly imprinted polymers were prepared by precipitation polymerization at 60℃ with Chikusetsu saponin IVa as template molecule, 3-(2-carboxyethyl)-1-vinylimidazolium bromide as functional monomer, ethylene glycol dimethacrylate as cross-linker, 2, 2'-azobisisobutyronitrile as initiator, and ethanol as porogen. The properties of molecularly imprinted polymers were studied by scanning electron microscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, nitrogen adsorption/desorption isotherm, and X-ray photoelectron spectroscopy. The maximum adsorption capacity was 171.33 mg/g, and the imprinting factor was 2.6. Finally, the polymers can be successfully used in the purification of Chikusetsu saponin IVa from Panacis majoris Rhizoma through a simple procedure, the content was significantly increased. The recoveries of the spiked samples for the CS-IVa ranged from 94.05 to 99.95% with relative standard deviation values lower than 2.67%. The results showed that the polymers demonstrated good adsorption capacity for Chikusetsu saponin IVa. Meanwhile, the polymers showed great stability and reusability during the application.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.

The Role of Suspension Array Technology in Rapid Detection of Foodborne Pollutants: Applications and Future Challenges

Food safety is an important livelihood issue, which has always been focused attention by countries and governments all over the world. As food supply chains are becoming global, food quality control is essential for consumer protection as well as for the food industry. In recent years, a great part of food analysis is carried out using new techniques for rapid detection. As the first biochip technology that has been approved by the Food and Drug Administration (FDA), there is an increasing interest in suspension array technology (SAT) for food and environmental analysis with advantages of rapidity, high accuracy, sensitivity, and throughput. Therefore, it is important for researchers to understand the development and application of this technology in food industry. Herein, we summarized the principle and composition of SAT and its application in food safety monitoring. The utility of SAT in detection of foodborne microorganisms, residues of agricultural and veterinary drugs, genetically modified food and allergens in recent years is elaborated, and the further development direction of SAT is envisaged.

Development and perspectives of rapid detection technology in food and environment

Food safety become a hot issue currently with globalization of food trade and food supply chains. Chemical pollution, microbial contamination and adulteration in food have attracted more attention worldwide. Contamination with antibiotics, estrogens and heavy metals in water environment and soil environment have also turn into an enormous threat to food safety. Traditional small-scale, long-term detection technologies have been unable to meet the current needs. In the monitoring process, rapid, convenient, accurate analysis and detection technologies have become the future development trend. We critically synthesizing the current knowledge of various rapid detection technology, and briefly touched upon the problem which still exist in research process. The review showed that the application of novel materials promotes the development of rapid detection technology, high-throughput and portability would be popular study directions in the future. Of course, the ultimate aim of the research is how to industrialization these technologies and apply to the market.

Immunoaffinity Extraction and Alternative Approaches for the Analysis of Toxins in Environmental, Food or Biological Matrices

The evolution of instrumentation in terms of separation and detection allowed a real improvement of the sensitivity and analysis time. However, the analysis of ultra-traces of toxins in complex samples requires often a step of purification and even preconcentration before their chromatographic analysis. Therefore, immunoaffinity sorbents based on specific antibodies thus providing a molecular recognition mechanism appear as powerful tools for the selective extraction of a target molecule and its structural analogs to obtain more reliable and sensitive quantitative analysis in environmental, food or biological matrices. This review focuses on immunosorbents that have proven their efficiency in selectively extracting various types of toxins of various sizes (from small mycotoxins to large proteins) and physicochemical properties. Immunosorbents are now commercially available, and their use has been validated for numerous applications. The wide variety of samples to be analyzed, as well as extraction conditions and their impact on extraction yields, is discussed. In addition, their potential for purification and thus suppression of matrix effects, responsible for quantification problems especially in mass spectrometry, is presented. Due to their similar properties, molecularly imprinted polymers and aptamer-based sorbents that appear to be an interesting alternative to antibodies are also briefly addressed by comparing their potential with that of immunosorbents.

New Advanced Materials and Sorbent-Based Microextraction Techniques as Strategies in Sample Preparation to Improve the Determination of Natural Toxins in Food Samples

Natural toxins are chemical substances that are not toxic to the organisms that produce them, but which can be a potential risk to human health when ingested through food. Thus, it is of high interest to develop advanced analytical methodologies to control the occurrence of these compounds in food products. However, the analysis of food samples is a challenging task because of the high complexity of these matrices, which hinders the extraction and detection of the analytes. Therefore, sample preparation is a crucial step in food analysis to achieve adequate isolation and/or preconcentration of analytes and provide suitable clean-up of matrix interferences prior to instrumental analysis. Current trends in sample preparation involve moving towards "greener" approaches by scaling down analytical operations, miniaturizing the instruments and integrating new advanced materials as sorbents. The combination of these new materials with sorbent-based microextraction technologies enables the development of high-throughput sample preparation methods, which improve conventional extraction and clean-up procedures. This review gives an overview of the most relevant analytical strategies employed for sorbent-based microextraction of natural toxins of exogenous origin from food, as well as the improvements achieved in food sample preparation by the integration of new advanced materials as sorbents in these microextraction techniques, giving some relevant examples from the last ten years. Challenges and expected future trends are also discussed.

Antibody-functionalized reduced graphene oxide films for highly selective capture and purification of aflatoxins

Pyrenylbutyric acid and streptavidin were coupled to films of reduced graphene oxide (rGO) and then conjugated to a biotinylated broad-spectrum monoclonal antibody against aflatoxins (AFs). It is shown that such films can efficiently and selectively capture AFs inculding AFB₁, AFB₂, AFG₁, AFG₂, AFM₁ and AFM₂. The rGO films were characterized by using scanning electron microscopy, energy-dispersive spectroscopy, and raman spectroscopy. The selectivity and purification performance of the antibody-loaded rGO films were investigated. They were applied to the purification of extremely small samples (100 μL) of AFs-spiked rabbit serum after enzymatic hydrolysis. The AFs were analyzed by ultra-performance liquid chromatography coupled to tandem mass spectrometry. The limits of detection for the six AFs investigated ranged from 50 to 170 pg·mL^-1. The average recoveries of AFs in spiked rabbit serum samples ranged from 55% to 75%, with relative standard deviations of less than 9.4%. Graphical abstract Design of a multifunctional sandwich film that consists of a reduced graphene oxide film base, a pyrenylbutyric acid middle layer and a broad-specificity anti-AF monoclonal antibody surface layer. It was successfully applied to the determination of aflatoxins in only 100 μL of rabbit serum samples with satisfactory selectivity and acceptable accuracy.