| Crop fungal diseases are an important factor affecting stable and increased crop yields.Mycotoxins produced by pathogenic fungi have caused huge losses of food and agricultural products worldwide,greatly hindering the green and sustainable development of agriculture and becoming a major threat to global food security.Aflatoxins are a series of mycotoxins mainly produced by Aspergillus sp.with bifuranocyclic coumarin as the skeleton,including more than ten toxic compounds of B,G and M groups.Among them,aflatoxin B1(AFB1)is one of the most widespread and harmful mycotoxins in agricultural products due to its strongly carcinogenic,teratogenic,mutagenic and acute hepatotoxic properties.Therefore,the development of technologies for AFB1 prevention and removal has now become a hot spot in food safety and agricultural research.In recent years,research on the application of nanotechnology in agriculture has developed rapidly due to the advantages in size tailoring,functionalized modification and physicochemical stability.Nanomaterials and systems have contributed greatly to the controlled release of pesticides,soil remediation and pathogen management,which provide new insights for the development of feasible technologies for mycotoxin prevention and removal.Accordingly,three functionalized nanosystems were designed and constructed in this paper for the green control,adsorption and photocatalytic degradation of AFB1 in agricultural products,respectively.The research in this paper consists of the following three parts:(1)We fabricated a series of nano-emulsions based on American mint and pectinata essential oils via high pressure homogenization with Tween-80 surfactant.Their morphology and stability via dynamic light scattering and scanning electron microscopy were explored.All these nano-emulsions,namely MNEO 1–5,exhibited obviously growth inhibition effect towards toxic strain Aspergillus flavus CF-79 and displayed remarkable prevention effect against AFB1 in storage simulation experiment on peanut seeds under hot and wet environments.Among them,the nanoemulsion with the highest content of mint essential oil(MNEO-1)showed the most prominent activity(IC50 = 4.70 mg g–1).GC-MS analysis proved that thymol is the main active ingredient in American mint essential oil(92.3%),which exhibited significant inhibition effect towards A.flavus CF-79(IC50 = 14.5μg g–1)and caused accumulation of reactive oxygen species and cell membrane damage in mycelium.High-throughput transcriptome sequencing was applied to screen for differentially expressed genes in thymol-treated samples,and gene-pathway enrichment analysis further revealed that thymol could enhance the tricarboxylic acid cycle and induce ROS accumulation in mycelial cells by regulating various metabolic pathways,leading to cell death of A.flavus CF-79.Moreover,thymol could reduce AFB1 production and accumulation by down-regulating the activity of related enzymes in the aflatoxin biosynthesis pathway.Nanoformulations developed from medicinal or edible plant essential oils may be the most safe and effective strategy to address mycotoxin contamination during agricultural products preservation.(2)We successfully synthesized MIL-101(Fe),a metal-organic framework(MOF)possessing super-high porosity and excellent dispersibility by solvothermal methods,and systematically investigated its removal capacity of AFB1 as adsorbent.The adsorption performance of MIL-101(Fe)on AFB1 under different conditions was tested,and the adsorption process was analyzed by combining adsorption thermodynamics,adsorption isotherm model and adsorption kinetic model.The results showed that the MIL-101(Fe)adsorbent exhibit excellent stability and superior loading capacity(30.58 mg g–1)on AFB1 compared to other adsorbents described in the existing literature.The interaction between AFB1 molecules and MIL-101(Fe)ligand was also established using molecular docking and computational chemistry stimulations.In addition,we obtained TMCS-MIL-101(Fe)by surface hydrophobic modification to improve the dispersion of the material in the hydrophobic phase,and achieved effective removal of AFB1 from peanut oil.This work provides a simple and effective approach for the removal of AFB1 in food.(3)A class of MOF nanoplatforms based on Fe3O4@Ui O-66 with versatile combination modes are designed and synthesized for the effective detoxification of AFB1.Benefiting from Ui O-66’s porous structure and Fe3O4’s catalytic enhancement,the composite systems achieved efficient adsorption and photodegradation of AFB1.A high AFB1 removal rate of up to 90% is obtained upon using these hybrid materials.In addition,SL-and LS-Fe3O4@Ui O-66 catalysts can be facilely recycled,maintaining more than 80% of the catalytic capacity after three cycles.Electron paramagnetic resonance spectroscopy showed that the abundant hydroxyl free radicals produced during the photocatalytic process drive the disruption of the AFB1 structure and thereby reduce its toxicity.To further investigate the reliability of photocatalytic detoxification in this study,a total of eleven products were characterized based on the UPLC-Q-TOFMS/MS data,and the accurate structure of seven main products(1–7)were identified by NMR analysis.According to the structural features of AFB1 photocatalytic products,the possible photocatalytic mechanisms were elucidated.Furthermore,3 different cell lines were used to comprehensively evaluate the cytotoxicity of AFB1 and seven main products.The results indicated that the Fe3O4@Ui O-66 system with synergistic effect of adsorption and photocatalysis is a reliable means of AFB1 removal,which opens up a new avenue for the development of novel mycotoxin photocatalysts with magnetic recycling ability.This study will provide guidance for the prevention of AFB1 in agricultural products,and provide theoretical support for the development of green and efficient technology for mycotoxin control,which is of great significance for the realization of sustainable agricultural development. |
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