Extraction of aflatoxins by using mesoporous silica (type UVM-7), and their quantitation by HPLC-MS

Synthesis of a core-shell magnetic covalent organic framework for the enrichment and detection of aflatoxin in food using HPLC-MS/MS

A porous magnetic covalent organic framework, Fe3O4@TPBD-TPA (terephthalaldehyde (TPA) , N, N, N', N'-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD)), was synthesized using the Schiff base reaction under mild reaction conditions. This adsorbent exhibited excellent adsorption performance for aflatoxins. The adsorption capacity of Fe3O4@TPBD-TPA for aflatoxins ranged from 64.4 to 84.4 mg/g. A magnetic solid-phase extraction combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method based on Fe3O4@TPBD-TPA was developed for the efficient determination of four types of aflatoxins in food samples (maize, maize oil, peanut, and peanut oil). The determination coefficients (R2) were ≥0.9972. The method exhibited detection limits ranging from 0.01 to 0.06 μg/kg and spiked recoveries of 80.0 to 113.1%. The intra-day and inter-day precision were less than 6.77%, indicating good repeatability. The adsorbent showed promising prospects for the efficient enrichment of trace amounts of aflatoxins in complex food matrices.

Effect of the Structure of Highly Porous Silica Extracted from Sugarcane Bagasse Fly Ash on Aflatoxin B1 Adsorption

Sugarcane bagasse fly ash is industrial waste produced by incinerating biomass to generate power and steam. The fly ash contains SiO₂ and Al₂O₃, which can be used to prepare aluminosilicate. This latter material exhibits high potential as an adsorbent in various applications, including the livestock industry where issues related to contamination of aflatoxins in animal feeds need to be addressed; addition of adsorbents can help decrease the concentration of aflatoxins during feed digestion. In this study, the effect of the structure of silica prepared from sugarcane bagasse fly ash on physicochemical properties and aflatoxin B1 (AFB1) adsorption capability compared with that of bentonite was investigated. BPS-5, Xerogel-5, MCM-41, and SBA-15 mesoporous silica supports were synthesized using sodium silicate hydrate (Na₂SiO₃) from sugarcane bagasse fly ash as a silica source. BPS-5, Xerogel-5, MCM-41, and SBA-15 exhibited amorphous structures, while sodium silicate possessed a crystalline structure. BPS-5 possessed larger pore size, pore volume, and pore size distribution with a bimodal mesoporous structure, while Xerogel-5 exhibited lower pore size and pore size distribution with a unimodal mesoporous structure. BPS-5 with a negatively charged surface exhibited the highest AFB1 adsorption capability compared with other porous silica. However, the AFB1 adsorption capability of bentonite was superior to those of all porous silica. Sufficient pore diameter with high total pore volume as well as high intensity of acid sites and negative charge on the surface of the adsorbent is required to increase AFB1 adsorption in the in vitro gastrointestinal tract of animals.

Mesoporous silica nanoparticles adsorb aflatoxin B1 and reduce mycotoxin-induced cell damage

The present study examined the effects of mesoporous silica nanoparticles (MSNs) on its adsorption capacity of aflatoxin B₁ (AFB₁). Moreover, the study evaluated the toxicity of MSNs with AFB₁ using NIH3T3 cells and hemolysis test. The obtained MSNs were spherical, irregular-like in shape, having a mean size of 39.97 ± 7.85 nm and a BET surface area of 1195 m²/g. At 0.1 mg mL^-1 concentration of MSN, the AFB₁ adsorption capacity was 30%, which reached 70% when the MSN concentration increased to 2.0 mg mL^-1. Our findings showed that AFB₁ was adsorbed (∼67%) in the first few minutes on being in contact with MSNs, reaching an adsorption capacity of ∼70% after 15 min. Thereafter, the adsorption capacity remained constant in solution, demonstrating that the MSNs adsorbed toxins even beyond overnight. MSN treatment (0.5-2.0 mg mL^-1) using NIH3T3 cells did not result in any reduction in cell viability. In addition, MSN treatment completely reversed the cytotoxic effect of AFB₁ at all concentrations. Hemolysis test also revealed no hemolysis in MSNs evaluated alone and in those combined with AFB₁. To the best of our knowledge, this study is the first to demonstrate that MSN can reduce cell toxicity produced by AFB₁ due to its potential to adsorb mycotoxins.

Recent advances of ordered mesoporous silica materials for solid-phase extraction

This review mainly focuses on the development and application of ordered mesoporous silica materials for solid-phase extraction in recent years. It overviews not only bare mesoporous silica but also the functionalized mesoporous silica with organic groups, molecularly imprinted polymers, and magnetic materials. These mesoporous silica materials were used as the extraction adsorbents in cartridge solid-phase extraction, dispersive solid-phase extraction, magnetic solid-phase extraction, micro-solid-phase extraction and matrix solid phase dispersion. Coupled with atomic emission spectrometry, chromatography or other detection methods, these techniques efficiently extracted and sensitively determined various targets, such as metal ions, perfluorocarboxylic acids, pesticides, drugs, endocrine disruptors, phenols, flavanones, polycyclic aromatic hydrocarbons, parabens and so on. Based on unique advantages of mesoporous silica materials, the developed analytical method successfully analyzed different matrix samples, like environmental water samples, soil samples, food samples, biological samples and cosmetics. In addition, the prospects of these materials in solid-phase extraction are presented, which can offer an outlook for the further development and applications.

Application of Nanomaterials for Coping with Mycotoxin Contamination in Food Safety: From Detection to Control

Mycotoxins, which are toxic secondary metabolites produced by fungi, are harmful to humans. Mycotoxin-induced contamination has drawn attention worldwide. Consequently, the development of reliable and sensitive detection methods and high-efficiency control strategies for mycotoxins is important to safeguard food industry safety and public health. With the rapid development of nanotechnology, many novel nanomaterials that provide tremendous opportunities for greatly improving the detection and control performance of mycotoxins because of their unique properties have emerged. This review comprehensively summarizes recent trends in the application of nanomaterials for detecting mycotoxins (fluorescence, colorimetric, surface-enhanced Raman scattering, electrochemical, and point-of-care testing) and controlling mycotoxins (inhibition of fungal growth, mycotoxin absorption, and degradation). These detection methods possess the advantages of high sensitivity and selectivity, operational simplicity, and rapidity. With research attention on the control of mycotoxins and the gradual excavation of the properties of nanomaterials, nanomaterials are also employed for the inhibition of fungal growth, mycotoxin absorption, and mycotoxin degradation, and impressive controlling effects are obtained. This review is expected to provide the readers insight into this state-of-the-art area and a reference to design nanomaterials-based schemes for the detection and control of mycotoxins.

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.

Magnetic beads-assisted fluorescence aptasensing approach based on dual DNA tweezers for detection of ochratoxin A and fumonisin B1 in wine and corn

A magnetic beads (MBs)-assisted fluorescence aptasensing approach based on dual DNA tweezers and magnetic separation was established for the detection of ochratoxin A (OTA) and fumonisin B₁ (FB₁). A dual DNA tweezers structure with four ends linked with fluorophores (FAM, ROX) and quenchers (BHQ₁, BHQ₂) was designed, and produced the high initial fluorescence signals because of the long spatial distance between FAM and BHQ₁, ROX, and BHQ₂. Bio-aptamer/anti-aptamer of OTA and bio-aptamer/anti-aptamer of FB₁ were respectively annealed to form dsDNA, and immobilized to MBs coated with streptavidin (SA). With the existence of OTA and FB₁, OTA and FB₁ preferentially bound with their respective bio-aptamers, which made anti-aptamers dissociate from dsDNA coupled on MBs. After magnetic separation, the dissociated anti-aptamers reacted with dual DNA tweezers, respectively, which made DNA tweezers close and the fluorescence was quenched. The linear ranges of approach for OTA and FB₁ detection were 0.05-20 ng/mL and 0.1-40 ng/mL, respectively. The limit of detection for OTA and FB₁ was 0.029 ng/mL and 0.061 ng/mL. The prepared MBs-assisted fluorescence aptasensing approach was applied to detect OTA and FB₁ in spiked red wine and corn samples, which showed good recoveries between 92 and 106%.

Enhancing extraction performance of organophosphorus flame retardants in water samples using titanium hierarchical porous silica materials as sorbents

A sorbent for the extraction of organophosphorus flame retardants has been proposed, based on UVM-7 (University of Valencia Materials) mesoporous silica doped with titanium. Designed cartridges have been applied to the extraction and preconcentration of flame retardants in water samples, followed by gas chromatography coupled to a mass spectrometry detector. Firstly, UVM-7 materials with different contents of titanium were synthesized and characterized by several techniques, thus confirming the proper mesoporous architecture. The potential of these materials was assessed in comparison with their morphological properties, resulting Ti50-UVM-7 the best solid phase. Several extraction parameters were also optimized. Analytical parameters were also evaluated, and limits of detection from 0.019 to 0.21 ng mL^-1 were obtained, as well as intra-day relative standard deviation below 11% for all analytes. Extraction efficiencies above 80% in water samples were achieved. The reusability of the material was also proved. Finally, the designed protocol was applied for the analysis of real water samples, and quantifiable concentrations of tris(2-chloroisopropyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPhP) were obtained in some samples. The method was compared with a United States Environmental Protection Agency general method with C18 cartridges.

Cyclodextrins as a Key Piece in Nanostructured Materials: Quantitation and Remediation of Pollutants

Separation and pre-concentration of trace pollutants from their matrix by reversible formation of inclusion complexes has turned into a widely studied field, especially for the benefits provided to different areas. Cyclodextrins are non-toxic oligosaccharides that are well known for their host–guest chemistry, low prices, and negligible environmental impact. Therefore, they have been widely used as chiral selectors and delivery systems in the pharmaceutical and food industry over time. However, their use for extraction purposes is hampered by their high solubility in water. This difficulty is being overcome with a variety of investigations in materials science. The setting-up of novel solid sorbents with improved properties thanks to the presence of cyclodextrins at their structure is still an open research area. Some properties they can offer, such as an increased selectivity or a good distribution along the surface of a solid support, which provides better accessibility for guest molecules, are characteristics of great interest. This systematic review reports the most significant uses of cyclodextrins for the adsorption of pollutants in different-origin samples based on the works reported in the literature in the last years. The study has been carried out indistinctly for quantitation and remediation purposes.

Amphiphilic block copolymer-grafted magnetic multi-walled carbon nanotubes as QuEChERS adsorbent for simultaneous determination of mycotoxins and pesticides in grains via liquid chromatography tandem mass spectrometry

An amphiphilic block copolymer consisting of poly(N-acryloyl-glucosamine) (PAGA) and poly(tert-butyl methacrylate) (PtBMA) was designed and grafted on magnetic multi-walled carbon nanotubes (Fe₃O₄MWCNTs). The resultant Fe₃O₄MWCNTs@copolymer was proposed as QuEChERS adsorbent for determination of 15 mycotoxins and 25 pesticides in grains via liquid chromatography tandem mass spectrometry. The adsorbent was characterized by a transmission electron microscope, scanning electron microscope, elemental analysis, and other techniques. The common matrix interferences were efficiently removed by the proposed adsorbent, such as pigment, fatty acids, and the saccharide. PAGA segment played an important role in removing the hydrophilic interferences through hydrogen bonding due to the high density of hydroxyl groups. PtBMA segment removed the fatty residues through its strong hydrophobic carbon moiety. In comparison with the commercially available QuEChERS adsorbents, the proposed adsorbent had higher adsorption capacities towards the typical matrix interferences. To achieve satisfactory recoveries of analytes, various parameters in the QuEChERS procedure were comprehensively investigated. Under the optimal conditions, 95.0% of the analytes showed satisfactory recoveries in the range 70.0-120% as well as negligible matrix effects. The limits of detection (LOD) were in the range 0.00015-1.3 μg kg^-1. Compared with previously reported QuEChERS methods, the proposed method had improved sensitivity and benefited from low matrix effects. The recoveries of analytes in various grains were in the range 60.8-108% with relative standard deviations (RSD) less than 13%. Moreover, the Fe₃O₄MWCNTs@copolymer exhibited good synthetic reproducibility and rapid magnetic separation (less than 10 s). The research provides a versatile platform to develop multi-functional QuEChERS adsorbents based on the amphiphilic block copolymer.

Bimodal porous silica nanomaterials as sorbents for an efficient and inexpensive determination of aflatoxin M1 in milk and dairy products

An extraction procedure was developed for the determination of aflatoxin M₁ in milk and dairy products. A sorbent based on UVM-7 mesoporous silica was used as solid phase for the sample clean-up, and the analyte determination was carried out by HPLC coupled to a fluorescence detector. The material architecture was characterized by transmission electronic microscopy, X-ray diffraction, ²⁹Si NMR and nitrogen adsorption-desorption. After the optimization of extraction parameters, the influence of the matrix has been evaluated, obtaining recoveries in the range 78-105% for whole and skimmed milk and yogurt matrix. The reusability of the material was also proved. The sensitivity of the method was also evaluated, and a LOQ (0.015 μg kg^-1) below the European legislation limit was obtained. The procedure was successfully applied for the determination of aflatoxin M₁ in real samples. The results were compared with those obtained with a reference method, being the results statistically comparable.