Ultra-sensitive electrochemical aptasensor for label-free detection of Aflatoxin B1 in wheat flour sample using factorial design experiments

Simultaneous detection of multiple mycotoxins using MXene-based electrochemical aptasensor array and a self-developed multi-channel portable device

In response to the pressing need for highly efficient simultaneous detection of multiple mycotoxins, which are often found co-occurring in food raw materials and feed, an MXene-based electrochemical aptasensor array (MBEAA) was developed. This aptasensor array utilizes high-specificity aptamers as recognition elements, enabling the capture of electrical signal changes in the presence of target mycotoxins. Based on this platform, a multi-channel portable electrochemical device, enabling rapid, cost-effective, and simultaneous detection of aflatoxin B1 (AFB1), ochratoxin A (OTA), and zealenone (ZEN) was further developed. The developed system boasts a wide detection range of 1.0 × 10-1 to 10.0 ng mL-1, with remarkable performance characterized by ultra-low detection limits of 41.2 pg mL-1, 27.6 pg mL-1, and 33.0 pg mL-1 for AFB1, OTA, and ZEN, respectively. Successfully applied in corn samples, this method offers a portable, easy-to-operate, and cost-effective solution for simultaneous multi-mycotoxin detection. Moreover, the application of the self-developed detection system could be expanded for simultaneous detection of many different targets when their specific aptamers or antibodies were available.

Progress on Electrochemical Biomimetic Nanosensors for the Detection and Monitoring of Mycotoxins and Pesticides

Monitoring agricultural toxins such as mycotoxins is crucial for a healthy society. High concentrations of these toxins lead to the cause of several chronic diseases; therefore, developing analytical systems for detecting/monitoring agricultural toxins is essential. These toxins are found in crops such as vegetables, fruits, food, and beverage products. Currently, screening of these toxins is mostly performed with sophisticated instrumentation such as chromatography and spectroscopy techniques. However, these techniques are very expensive and require extensive maintenance, and their availability is limited to metro cities only. Alternatively, electrochemical biomimetic sensing methodologies have progressed hugely during the last decade due to their unique advantages like point-of-care sensing, miniaturized instrumentations, and mobile/personalized monitoring systems. Specifically, affinity-based sensing strategies including immunosensors, aptasensors, and molecular imprinted polymers offer tremendous sensitivity, selectivity, and stability to the sensing system. The current review discusses the principal mechanisms and the recent developments in affinity-based sensing methodologies for the detection and continuous monitoring of mycotoxins and pesticides. The core discussion has mainly focused on the fabrication protocols, advantages, and disadvantages of affinity-based sensing systems and different exploited electrochemical transduction techniques.

Europium nanospheres based ultrasensitive fluorescence immunosensor for aflatoxin B1 determination in feed

In this work, a new competitive immunosensor for aflatoxin B1 (AFB1) detection was developed using europium (Eu) fluorescent nanospheres and magnetic beads. Firstly, Eu nanospheres were synthesized through two steps including carboxylated polystyrene nanospheres and Eu-doped polystyrene nanospheres preparation. Then Eu nanospheres were covalently tagged to anti-AFB1 monoclonal antibody (anti-AFB1 mAb) through an EDC coupling method. Carboxylated Fe3O4 magnetic beads were conjugated to AFB1-BSA through EDC/NHS crosslinking to obtain AFB1-BSA-Fe3O4. In the absence of AFB1, Eu-anti-AFB1 mAb were incubated with AFB1-BSA-Fe3O4 to form Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 in PBS buffer. However, in the presence of AFB1, the competitive interaction of AFB1 and AFB1-BSA-Fe3O4 to bind with Eu-anti-AFB1 mAb occurred. With the increasing concentration of AFB1, less Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 formed. So the fluorescence intensity of Eu-anti-AFB1 mAb-AFB1-BSA-Fe3O4 was gradually decreased after magnetic separation. The degree of fluorescence decrease was linear with respect to the logarithm of AFB1 concentration in the range of 0.01-2 ng/mL in both buffer solution and feed samples and the detection limit was 0.003 ng/mL. What's more, the immunosensor showed excellent specificity for AFB1 without being interfered by other mycotoxins. In consideration of the excellent performance of this immunosensor, we can speculate that the proposed method could be widely used in detecting food contaminants.

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.

Advances in aptamers, and application of mycotoxins detection: A review

Mycotoxin contamination in food products can easily cause serious health hazards and economic losses to human beings. How to accurately detect and effectively control mycotoxin contamination has become a global concern. Mycotoxins conventional detection techniques e.g; ELISA, HPLC, have limitations like, low sensitivity, high cost and time-consuming. Aptamer-based biosensing technology has the advantages of high sensitivity, high specificity, wide linear range, high feasibility, and non-destructiveness, which overcomes the shortcomings of conventional analysis techniques. This review summarizes the sequences of mycotoxin aptamers that have been reported so far. Based on the application of four classic POST-SELEX strategies, it also discusses the bioinformatics-assisted POST-SELEX technology in obtaining optimal aptamers. Furthermore, trends in the study of aptamer sequences and their binding mechanisms to targets is also discussed. The latest examples of aptasensor detection of mycotoxins are classified and summarized in detail. Newly developed dual-signal detection, dual-channel detection, multi-target detection and some types of single-signal detection combined with unique strategies or novel materials in recent years are focused. Finally, the challenges and prospects of aptamer sensors in the detection of mycotoxins are discussed. The development of aptamer biosensing technology provides a new approach with multiple advantages for on-site detection of mycotoxins. Although aptamer biosensing shows great development potential, still some challenges and difficulties are there in practical applications. Future research need high focus on the practical applications of aptasensors and the development of convenient and highly automated aptamers. This may lead to the transition of aptamer biosensing technology from laboratory to commercialization.

A Novel Preanalytical Strategy Enabling Application of a Colorimetric Nanoaptasensor for On-Site Detection of AFB1 in Cattle Feed

Aflatoxin contamination of cattle feed is responsible for serious adverse effects on animal and human health. A number of approaches have been reported to determine aflatoxin B1 (AFB1) in a variety of feed samples using aptasensors. However, rapid analysis of AFB1 in these matrices remains to be addressed in light of the complexity of the preanalytical process. Herein we describe an optimization on the preanalytical stage to minimize the sample processing steps required to perform semi-quantitative colorimetric detection of AFB1 in cattle feed using a gold nanoparticle-based aptasensor (nano-aptasensor). The optical behavior of the nano-aptasensor was characterized in different organics solvents, with acetonitrile showing the least interference on the activity of the nan-aptasensor. This solvent was selected as the extractant agent for AFB1-containing feed, allowing for the first time, direct colorimetric detection from the crude extract (detection limit of 5 µg/kg). Overall, these results lend support to the application of this technology for the on-site detection of AFB1 in the dairy sector.

Novel Sensor Approaches of Aflatoxins Determination in Food and Beverage Samples

The rapid quantification of toxins in food and beverage products has become a significant issue in overcoming and preventing many life-threatening diseases. Aflatoxin-contaminated food is one of the reasons for primary liver cancer and induces some tumors and cancer types. Advancements in biosensors technology have brought out different analysis methods. Therefore, the sensing performance has been improved for agricultural and beverage industries or food control processes. Nanomaterials are widely used for the enhancement of sensing performance. The enzymes, molecularly imprinted polymers (MIP), antibodies, and aptamers can be used as biorecognition elements. The transducer part of the biosensor can be selected, such as optical, electrochemical, and mass-based. This review explains the classification of major types of aflatoxins, the importance of nanomaterials, electrochemical, optical biosensors, and QCM and their applications for the determination of aflatoxins.

Development and Validation of an Automated Magneto-Controlled Pretreatment for Chromatography-Free Detection of Aflatoxin B1 in Cereals and Oils through Atomic Absorption Spectroscopy

A chromatography-free detection of aflatoxin B1 (AFB1) in cereals and oils through atomic absorption spectroscopy (AAS) has been developed using quantum dots and immunomagnetic beads. A magneto-controlled pretreatment platform for automatic purification, labeling, and digestion was constructed, and AFB1 detection through AAS was enabled. Under optimal conditions, this immunoassay exhibited high sensitivity for AFB1 detection, with limits of detection as low as 0.04 μg/kg and a linear dynamic range of 2.5–240 μg/kg. The recoveries for four different food matrices ranged from 92.6% to 108.7%, with intra- and inter-day standard deviations of 0.7–6.3% and 0.6–6.9%, respectively. The method was successfully applied to the detection of AFB1 in husked rice, maize, and polished rice samples, and the detection results were not significantly different from those of liquid chromatography-tandem mass spectrometry. The proposed method realized the detection of mycotoxins through AAS for the first time. It provides a new route for AFB1 detection, expands the application scope of AAS, and provides a reference for the simultaneous determination of multiple poisonous compounds (such as mycotoxins and heavy metals).

Functionalization and Modification of Polyethylene Terephthalate Polymer by AgCl Nanoparticles under Ultrasound Irradiation as Bactericidal

Polyethylene terephthalate polymer (PET) is widely used in diverse areas. In the current study, the surface of PET is modified in two steps in order to improve the quality. At first, the polymer was functionalized with carboxylic groups, and Fourier transform infrared spectroscopy studies were used to verify functionalization. Then, AgCl nanoparticles were synthesized on COOH functional groups on the surface of PET using a sonochemistry method by sequential dipping of the functionalized polymer in an alternating bath of potassium chloride and silver nitrate under ultrasonic irradiation. The effects of ultrasonic irradiation power, the number of dipping steps, and pH on the growth of AgCl nanoparticles as effective parameters on size and density of synthesized Ag nanoparticles were studied. The results of scanning electron microscopy studies showed that the size and density of AgCl nanoparticles under ultrasonic irradiation with a power of 100 W are better than those of AgCl nanoparticles under irradiation with a power of 30 W. Also, by 15 times dipping the polymer into the reagent solutions in pH = 9, the modified polymer with a greater number of nanoparticles with suitable size can be reached. Antibacterial properties of PET containing AgCl nanoparticles were investigated against six Gram-positive and Gram-negative bacteria species, and the results showed significant antibacterial activity, while functionalized PET did not have a significant effect on both types of bacteria.

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.

Developments in mycotoxin analysis: an update for 2020-2021

This review summarises developments published in the period from mid-2020 to mid-2021 on the analysis of a number of diverse matrices for mycotoxins. Notable developments in all aspects of mycotoxin analysis, from sampling and quality assurance/quality control of analytical results, to the various detection and quantitation technologies ranging from single mycotoxin biosensors to comprehensive instrumental methods are presented and discussed. The summary and discussion of this past year’s developments in detection and quantitation technology covers chromatography with targeted or non-targeted high resolution mass spectrometry, tandem mass spectrometry, detection other than mass spectrometry, biosensors, as well as assays using alternatives to antibodies. This critical review aims to briefly present the most important recent developments and trends in mycotoxin determination, as well as to address limitations of the presented methodologies.

Detection of aflatoxin B1 with a new label-free fluorescence aptasensor based on PVP-coated single-walled carbon nanohorns and SYBR Gold

This paper describes a novel fluorescence label-free aptasensor to detect aflatoxin B₁ (AFB₁) by utilizing SYBR Gold, aptamer, and single-walled carbon nanohorns (SWCNHs). In the presence of AFB₁, the conformation of AFB₁-specific aptamer went through and the spatial structure of this specific aptamer was transformed accordingly. Due to the resistance of the transformed aptamer when adsorbed on the surface of SWCNHs, the protection of the fluorescence of SYBR Gold was accomplished. Consequently, concentrations of AFB₁ showed a strong association with fluorescence intensity. The detection limit (LOD) of AFB₁ was 1.89 ng/mL, while the linear range was 5-200 ng/mL and fluorescence intensity satisfactorily correlated (R² = 0.9919) with the logarithm of AFB₁ concentration.

Recent Progress in Rapid Determination of Mycotoxins Based on Emerging Biorecognition Molecules: A Review

Mycotoxins are secondary metabolites produced by fungal species, which pose significant risk to humans and livestock. The mycotoxins which are produced from Aspergillus, Penicillium, and Fusarium are considered most important and therefore regulated in food- and feedstuffs. Analyses are predominantly performed by official laboratory methods in centralized labs by expert technicians. There is an urgent demand for new low-cost, easy-to-use, and portable analytical devices for rapid on-site determination. Most significant advances were realized in the field bioanalytical techniques based on molecular recognition. This review aims to discuss recent progress in the generation of native biomolecules and new bioinspired materials towards mycotoxins for the development of reliable bioreceptor-based analytical methods. After brief presentation of basic knowledge regarding characteristics of most important mycotoxins, the generation, benefits, and limitations of present and emerging biorecognition molecules, such as polyclonal (pAb), monoclonal (mAb), recombinant antibodies (rAb), aptamers, short peptides, and molecularly imprinted polymers (MIPs), are discussed. Hereinafter, the use of binders in different areas of application, including sample preparation, microplate- and tube-based assays, lateral flow devices, and biosensors, is highlighted. Special focus, on a global scale, is placed on commercial availability of single receptor molecules, test-kits, and biosensor platforms using multiplexed bead-based suspension assays and planar biochip arrays. Future outlook is given with special emphasis on new challenges, such as increasing use of rAb based on synthetic and naïve antibody libraries to renounce animal immunization, multiple-analyte test-kits and high-throughput multiplexing, and determination of masked mycotoxins, including stereoisomeric degradation products.

A review of the new multifunctional nano zero-valent iron composites for wastewater treatment: Emergence, preparation, optimization and mechanism

Nano zero-valent iron (NZVI) with high chemical reactivity and environmental friendliness had recently become one of the most efficient technologies for wastewater restoration. However, the unitary NZVI system had not met practical requirements for wastewater treatments. Expectantly, the development of NZVI would prefer multifunctional NZVI-based composites, which could be prepared and optimized by the combined methods and technologies. Consequently, a systematic and comprehensive summary from the perspective of multifunctional NZVI-composite had been conducted. The results demonstrated that the advantages of various systems were integrated by multifunctional NZVI-composite systems with a more significant performance of pollutant removal than those of the bare NZVI and its composites. Simultaneously, characteristics of the product prepared by the incorporation of numerous methods were superior to those by a simple method, resulting in the increase of the entirety efficiency. By comparison with other preparation methods, the ball milling method with higher production and field application potential was worthy of attention. After combining multiple technologies, the effect of NZVI and its composite systems could be dramatically strengthened. Preparation technology parameters and treatment effect of contaminants could be further optimized using more comprehensive experimental designs and mathematical models. The mechanism of the multifunctional NZVI system for contaminants treatment was primarily focused on adsorption, oxidation, reduction and co-precipitation. Multiple techniques were combined to enhance the dispersion, alleviating passivation, accelerating electron transfer efficiency or mass transfer action for optimizing the effect of NZVI composites.

Aptasensors for mycotoxins in foods: Recent advances and future trends

Mycotoxin contamination in foods has posed serious threat to public health and raised worldwide concern. The development of simple, rapid, facile, and cost-effective methods for mycotoxin detection is of urgent need. Aptamer-based sensors, abbreviated as aptasensors, with excellent recognition capacity to a wide variety of mycotoxins have attracted ever-increasing interest of researchers because of their simple fabrication, rapid response, high sensitivity, low cost, and easy adaptability for in situ measurement. The past few decades have witnessed the rapid advances of aptasensors for mycotoxin detection in foods. Therefore, this review first summarizes the reported aptamer sequences specific for mycotoxins. Then, the recent 5-year advancements in various newly developed aptasensors, which, according to the signal output mode, are divided into electrochemical, optical and photoelectrochemical categories, for mycotoxin detection are comprehensively discussed. A special attention is taken on their strengths and limitations in real-world application. Finally, the current challenges and future perspectives for developing novel highly reliable aptasensors for mycotoxin detection are highlighted, which is expected to provide powerful references for their thorough research and extended applications. Owing to their unique advantages, aptasensors display a fascinating prospect in food field for safety inspection and risk assessment.

Carbon-Based Nanocomposite Smart Sensors for the Rapid Detection of Mycotoxins

Carbon-based nanomaterials have become the subject of intensive interest because their intriguing physical and chemical properties are different from those of their bulk counterparts, leading to novel applications in smart sensors. Mycotoxins are secondary metabolites with different structures and toxic effects produced by fungi. Mycotoxins have low molecular weights and highly diverse molecular structures, which can induce a spectrum of biological effects in humans and animals even at low concentrations. A tremendous amount of biosensor platforms based on various carbon nanocomposites have been developed for the determination of mycotoxins. Therefore, the contents of this review are based on a balanced combination of our own studies and selected research studies performed by academic groups worldwide. We first address the vital preparation methods of biorecognition unit (antibodies, aptamers, molecularly imprinted polymers)-functionalized carbon-based nanomaterials for sensing mycotoxins. Then, we summarize various types of smart sensors for the detection of mycotoxins. We expect future research on smart sensors to show a significant impact on the detection of mycotoxins in food products.

An overview of nanomaterial based biosensors for detection of Aflatoxin B1 toxicity in foods

Aflatoxin B1 (AFB1) is one of the most potent mycotoxin contaminating several foods and feeds. It suppresses immunity and consequently increases mutagenicity, carcinogenicity, teratogenicity, hepatotoxicity, embryonic toxicity and increasing morbidity and mortality. Continuous exposure of AFB1 causes liver damage and thus increases the prevalence of cirrhosis and hepatic cancer. This article was planned to provide understanding of AFB1 toxicity and provides future directions for fabrication of cost effective and user-friendly nanomaterials based analytical devices. In the present article various conventional (chromatographic & spectroscopic), modern (PCR & immunoassays) and nanomaterials based biosensing techniques (electrochemical, optical, piezoelectrical and microfluidic) are discussed alongwith their merits and demerits. Nanomaterials based amperometric biosensors are found to be more stable, selective and cost-effective analytical devices in comparison to other biosensors. But many unresolved issues about their stability, toxicity and metabolic fate needs further studies. In-depth studies are needed for development of advanced nanomaterials integrated biosensors for specific, sensitive and fast monitoring of AFB1 toxicity in foods. Integration of biosensing system with micro array technology for simultaneous and automated detection of multiple AFs in real samples is also needed. Concerted efforts are also required to reduce their possible hazardous consequences of nanomaterials based biosensors.

A novel electrochemical aflatoxin B1 immunosensor based on gold nanoparticle-decorated porous graphene nanoribbon and Ag nanocube-incorporated MoS2 nanosheets

The accurate and precisive monitoring of aflatoxin B1 (AFB1), which is one of the most hazardous mycotoxins, especially in agricultural products, is significant for human and environmental health.