Metal-organic frameworks with peroxidase-like activity for efficient removal of aflatoxin B1

Colorimetric and fluorometric determination of uric acid by a suspension-based assay using enzyme-immobilized micro-sized particles

Daily monitoring of serum uric acid levels is very important to provide appropriate treatment according to the constitution and lifestyle of individual hyperuricemic patients. We have developed a suspension-based assay to measure uric acid by adding a sample solution to the suspension containing micro-sized particles immobilized on uricase and horseradish peroxidase (HRP). In the proposed method, the mediator reaction of uricase, HRP, and uric acid produces resorufin from Amplex red. This resorufin is adsorbed onto enzyme-immobilized micro-sized particles simultaneously with its production, resulting in the red color of the micro-sized particles. The concentration of resorufin on the small surface area of the microscopic particles achieves a colorimetric analysis of uric acid with superior visibility. In addition, ethanol-induced desorption of resorufin allowed quantitative measurement of uric acid using a 96-well fluorescent microplate reader. The limit of detection (3σ) and RSD (n = 3) were estimated to be 2.2 × 10-2 μg/mL and ≤ 12.1%, respectively. This approach could also be applied to a portable fluorometer.

CRISPR-powered microfluidic biosensor for preamplification-free detection of ochratoxin A

The CRISPR technology, which does not require complex instruments, expensive reagents or professional operators, has attracted a lot of attention. When utilizing the CRISPR-Cas system for detection, the pre-amplification step is often necessary to enhance sensitivity. However, this approach tends to introduce complexity and prolong the time required. To address this issue, we employed Pd@PCN-222 nanozyme to label single-stranded DNA, referred to as Pd@PCN-222 CRISPR nanozyme, which serves as the reporter of the CRISPR system. Pd@PCN-222 nanozyme possess exceptional catalytic activity for the reduction of H2O2. Compared with traditional electrochemical probe ferrocene and methylene blue without catalytic activity, there is a significant amplification of the electrochemical signal. So the need for pre-amplification was eliminated. In this study, we constructed a CRISPR-Cas system for ochratoxin A, utilizing the Pd@PCN-222 CRISPR nanozyme to amplified signal avoiding pre-amplification with outstanding detection of 1.21 pg/mL. Furthermore, we developed a microfluidic electrochemical chip for the on-site detection of ochratoxin A. This achievement holds significant promise in establishing a practical on-site detection platform for identifying food safety hazards.

Activate hydrogen peroxide for facile and efficient removal of aflatoxin B1 by magnetic Pd-chitosan/rice husk-hercynite biocomposite and its impact on the quality of edible oil

Due to the high heat and chemical stability of aflatoxin B1 (AFB1) with significant impacts on humans/animals and thus it needs to develop a practical and efficient approach for its removal. Herein, we fabricated a magnetic Pd-chitosan/glutaraldehyde/rice husk/hercynite (Pd@CRH-x) composite for efficient detoxification of AFB1. The Pd@CRH-x was obtained by a simple wet-impregnation procedure of CRH complexes followed by pyrolysis. The results confirmed that the unique structure of Pd@CRH-400 effectively improves dispersity, and mass transfer subsequently enhancing removal efficiency in batch conditions. Results indicate 94.30 % of AFB1 was efficiently degraded by 0.1 mg mL-1 Pd@CRH-400 with 4.0 mM H2O2 at wide pH ranges (3.0-10) at 60 min with a decomposition rate constant of 0.0467 min-1. Besides, by comparing the quality factors of edible oil (i.e., acid value, peroxide value, iodine value, moisture, volatile matters, anisidine value, and fatty acid composition), it was confirmed that there was no obvious influence on the physicochemical indicators of edible oil after removal/storage process. Subsequently, the systematic kinetic study and AFB1 degradation mechanism were presented. This study provides a new strategy for the efficient construction of controllable and dispersed Pd-based catalysts using CRH-x as a spatial support for alleviating the risk of toxic pollutants.

Adsorptive removal of aflatoxin B1 from water and edible oil by dopamine-grafted biomass chitosan-iron-cobalt spinel oxide nanocomposite: mechanism, kinetics, equilibrium, thermodynamics, and oil quality

Currently, the use of magnetic physical adsorbents for detoxification is widely applied in the food industry; however, the fabrication of high-efficiency low-cost absorbents without damaging the nutritional quality of food is a major challenge. Herein, a simple, green, efficient, and cost-effective method for the magnetic solid-phase extraction of aflatoxin B1 (AFB1) from edible oils and aqueous matrices was developed using a dopamine-loaded biomass chitosan-iron-cobalt spinel oxide nanocomposite (DC/CFOS NC). The characterization, physicochemical processes, mechanism, and reusability of DC/CFOS were systematically evaluated in detail. It was found that the adsorption characteristic of DC/CFOS NC was accurately represented by the pseudo-second-order kinetics (k2 = 0.199 g mg-1 min-1) and Freundlich isotherm models (Kf = 1.139 (mg g-1) (L mg-1), R2 = 0.991)), and its adsorptive process is feasible, spontaneous, and exothermic. Benefiting from its high specific surface area, microporous structure, and polar/non-polar active sites, the as-prepared DC/CFOS exhibited an excellent adsorption performance for AFB1 (50.0 μg mL-1), as measured using the Freundlich isotherm model. The mechanistic studies demonstrated that the synergistic effects of the surface complexation and electrostatic interactions between the functional groups of DC/CFOS NC and AFB1 were the dominant adsorption pathways. Besides, DC/CFOS exhibited negligible impacts on the nutritional quality of the oil after the removal process and storage. Thus, DC/CFOS NC showed sufficient efficacy and safety in the removal of AFB1 from contaminated edible oil.

Endocrine Effect of Some Mycotoxins on Humans: A Clinical Review of the Ways to Mitigate the Action of Mycotoxins

Fungi such as Aspergillus spp. and Fusarium spp., which are commonly found in the environment, pose a serious global health problem. This study aims to present the results of epidemiological studies, including clinical cases, on the relationship between human exposure to some mycotoxins, especially zearalenone and aflatoxin, and the occurrence of reproductive disorders. In addition, examples of methods to reduce human exposure to mycotoxins are presented. In March 2023, various databases (PubMed, Google Scholar, EMBASE and Web of Science) were systematically searched using Google Chrome to identify studies evaluating the association between exposure to mycotoxins and the occurrence of complications related to impaired fertility or cancer incidence. The analysed data indicate that exposure to the evaluated mycotoxins is widespread and correlates strongly with precocious puberty, reduced fertility and increased cancer incidence in women and men worldwide. There is evidence to suggest that exposure to the Aspergillus mycotoxin aflatoxin (AF) during pregnancy can impair intrauterine foetal growth, promote neonatal jaundice and cause perinatal death and preterm birth. In contrast, exposure to the Fusarium mycotoxin zearalenone (ZEA) leads to precocious sexual development, infertility, the development of malformations and the development of breast cancer. Unfortunately, the development of methods (biological, chemical or physical) to completely eliminate exposure to mycotoxins has limited practical application. The threat to human health from mycotoxins is real and further research is needed to improve our knowledge and specific public health interventions.

Optimization of aflatoxin B1 removal efficiency of DNA by resonance light scattering spectroscopy

In this paper, firstly, the resonance light scattering spectra of aflatoxin B₁ (AFB₁) and DNA were measured by resonance light scattering spectroscopy (RLS), and the DNA binding saturation value (DBSV) of AFB₁ was calculated from their spectral results. Then the interaction intensity between DNA and AFB₁ and the effects of some external factors on the interaction between DNA and AFB₁ were evaluated by corresponding DBSVs, so as to establish and optimize a way for removing AFB₁ by DNA. DBSV of AFB₁ was 2.04 at 30℃ and pH 7.40. However, after adding sodium ion, calcium ion, vitamin E, vitamin C and D-glucose, DBSV of AFB₁ was changed to 2.72, 3.17, 2.67, 1.68 and 1.33 respectively. Correspondingly, the removal efficiency of AFB₁ by DNA was changed from 90.05% to 93.25%, 95.48%, 93.08%, 82.36% and 78.90% respectively. These results indicated that the external factors had a significant impact on the interaction between DNA and AFB₁. Among them, some factors enhanced the interaction between DNA and AFB₁, while some factors weakened the interaction between DNA and AFB1. The change of these external factors led to the corresponding changes in DBSV and the removal efficiency of AFB₁. DBSV of AFB₁ could really be used as an index to evaluate the intensity of the interaction between DNA and AFB₁, and to optimize the removal efficiency of AFB₁ by DNA. The experimental data also showed that the adsorption of AFB₁ to DNA was consistent with the pseudo-second-order kinetic model and the Freundlich isothermal model, was an exothermic and spontaneous process. All these results will give good references for establishing and optimizing a way of AFB₁ removal via DNA intercalation.

Superparamagnetic MnFe alloy composite derived from cross-bindered of chitosan/rice husk waste/iron aluminate spinel hercynite for rapid catalytic detoxification of aflatoxin B1: Structure, performance and synergistic mechanism

The contamination of foodstuffs with aflatoxins B1 (AFB1) as carcinogen/mutagens toxin produced by Aspergillus fungi that are a major threat to the economy, safe food supply, and human health. To, we present a facile wet-impregnation and co-participation strategies for the construction of a novel superparamagnetic MnFe biocomposite (MF@CRHHT), in which dual metal oxides MnFe were anchored in/on agricultural/forestry residues (chitosan/rice husk waste/hercynite hybrid nanoparticles) and applied for rapid AFB1 detoxification by destroying in a non-thermal/microbial way. Structure, and morphology were comprehensively characterized by various spectroscopic analyses. The AFB1 removal in PMS/MF@CRHHT system followed pseudo-first-order kinetics, and exhibited excellent efficiency (99.3 % in 20 min and 83.1 % in 5.0 min) over a broad pH range (5.0-10.0). Importantly, relationship between high efficiency and physical-chemical properties, and mechanistic insight reveals that the synergistic effect could be related to the formation MnFe bond in MF@CRHHT and then mutual electron transfer between them to enhanced electron density and generate reactive oxygen species. An AFB1 decontamination pathway proposed was based on the free radical quenching experiments and analysis of the degradation intermediates. Thus, the MF@CRHHT can be applied as an efficient, cost-effective, recoverable, environment-friendly and highly efficient biomass-based activator for remediate pollution.

Metal-organic frameworks for food contaminant adsorption and detection

Metal-organic framework materials (MOFs) have been widely used in food contamination adsorption and detection due to their large specific surface area, specific pore structure and flexible post-modification. MOFs with specific pore size can be targeted for selective adsorption of some contaminants and can be used as pretreatment and pre-concentration steps to purify samples and enrich target analytes for food contamination detection to improve the detection efficiency. In addition, MOFs, as a new functional material, play an important role in developing new rapid detection methods that are simple, portable, inexpensive and with high sensitivity and accuracy. The aim of this paper is to summarize the latest and insightful research results on MOFs for the adsorption and detection of food contaminants. By summarizing Zn-based, Cu-based and Zr-based MOFs with low cost, easily available raw materials and convenient synthesis conditions, we describe their principles and discuss their applications in chemical and biological contaminant adsorption and sensing detection in terms of stability, adsorption capacity and sensitivity. Finally, we present the limitations and challenges of MOFs in food detection, hoping to provide some ideas for future development.

Advanced mycotoxin control and decontamination techniques in view of an increased aflatoxin risk in Europe due to climate change

Aflatoxins are toxic secondary metabolites produced by Aspergillus spp. found in staple food and feed commodities worldwide. Aflatoxins are carcinogenic, teratogenic, and mutagenic, and pose a serious threat to the health of both humans and animals. The global economy and trade are significantly affected as well. Various models and datasets related to aflatoxins in maize have been developed and used but have not yet been linked. The prevention of crop loss due to aflatoxin contamination is complex and challenging. Hence, the set-up of advanced decontamination is crucial to cope with the challenge of climate change, growing population, unstable political scenarios, and food security problems also in European countries. After harvest, decontamination methods can be applied during transport, storage, or processing, but their application for aflatoxin reduction is still limited. Therefore, this review aims to investigate the effects of environmental factors on aflatoxin production because of climate change and to critically discuss the present-day and novel decontamination techniques to unravel gaps and limitations to propose them as a tool to tackle an increased aflatoxin risk in Europe.

Metal-porphyrinic framework nanotechnologies in modern agricultural management

Metal-porphyrinic frameworks are an important subclass of metal-organic frameworks (MOFs). These porous materials exhibit a large number of applications for sustainable development and related environmental considerations. Their attractive features include (1) as a free base or metalated with zinc(II) or iron(II or III), they are environmentally benign, and (2) they absorb visible light and are emissive and semi-conducting, making them convenient tools for sensing agrochemicals. But the key feature that makes these nano-sized pristine materials or their composites in many ways superior to most MOFs is their ability to photo-generate reactive oxygen species with visible light, including singlet oxygen. This review describes important issues related to agriculture, including controlled delivery of pesticides and agrochemicals, detection of pesticides and pathogenic metals, elimination of pesticides and toxic metals, and photodynamic antimicrobial activity, and has an important implication for food safety. This comprehensive review presents the progress of the rather rapid developments of these functional and increasingly nano-sized materials and composites in the area of sustainable agriculture.

Nanozyme based on ZIF-8 for the colorimetric detection of sulfonamides in cow milk

A simple and time-saving colorimetric method was developed to quantify sulfonamides (SAAs) in milk via inhibition of the human carbonic anhydrase II (hCAII)-like activity of ZIF-8 that can hydrolyze p-nitrophenyl acetate (pNPA) to p-nitrophenol (pNP), following the color change from yellow to colorless. Effects of different reaction conditions, including pH, temperature, amount of ZIF-8, and incubation time, were investigated. The value of Michaelis-Menten constant (K_m) is measured to be 0.15 mM, which exhibits high affinity to pNPA. The IC₅₀ (0.17, 0.24, and 0.60 mM) and inhibition constant (K_i) (0.09, 0.13, and 0.33 mM) of sulfamethazine (SD), sulfadimethoxine (SDM), and sulfathiazole (ST) on ZIF-8 were measured, respectively. Moreover, the activity of ZIF-8 remains more than 90.0% of its initial activity after 30 days' storage. The colorimetric method for SD, SDM, and ST determination was established at the linear ranges of 6.3-750.0 μM (1.75-208.75 mg/kg), 6.3-750.0 μM (1.96-232.75 mg/kg), and 5.0-1250.0 μM (1.28-319.15 mg/kg) with limit of detection of 4.3, 3.2, and 3.9 mΜ (1.2, 0.99, and 0.96 mg/kg), respectively. In addition, the spiked recoveries of SAAs in milk sample are in the range of 81.6%-106.7% with RSD less than 6.5%. In short, the developed colorimetric method can achieve rapid analysis of SAAs in milk with simple operations.