The evolution of multiplex detection of mycotoxins using immunoassay platform technologies

Advances in mycotoxin detection techniques and the crucial role of reference material in ensuring food safety. A review

Mycotoxins, toxic secondary metabolites produced by fungi, pose a significant threat to food safety and human health. The occurrence of mycotoxins in food commodities necessitates accurate and reliable detection methods. Advanced detection techniques, such as chromatographic techniques and immunochemical assays, have improved sensitivity and specificity. However, the lack of standardized reference material, particularly in less privileged countries, hinders method validation and proficiency testing, ultimately affecting mycotoxin testing and regulation. Moreover, these techniques are complex as they require specialized equipment, and well-trained personnel, thus limiting their practical applications. This comprehensive review provides an up-to-date overview of the occurrence of mycotoxins and recent advancements in detection methods. It examines the crucial role of mycotoxin standards as reference materials for ensuring reliable results in mycotoxins analysis in agriculture commodities. The review addresses emerging challenges, knowledge gaps, and future research directions in mycotoxin detection and reference material development. By synthesizing existing literature, this review aims to provide valuable resources for researchers, policymakers, and other stakeholders in food safety, highlighting the importance of integrated approaches to mitigate mycotoxin contamination and ensuring food safety.

Emerging biosensors integrated with microfluidic devices: a promising analytical tool for on-site detection of mycotoxins

Rapid and sensitive detection of mycotoxins in foodstuffs is of great significance. As a powerful detection tool, biosensing technologies and microfluidic devices have shown a great potential in rapid and on-site detection of mycotoxins. This review comprehensively summarized the latest advances on the construction of microfluidic biosensors and their promising applications in on-site detection of mycotoxins. Finally, future challenges and chances in this significant and promising field were proposed.

Scalable flexographic printing of graphite/carbon dot nanobiosensors for non-faradaic electrochemical quantification of IL-8

Interleukin-8 (IL-8) is a key biomarker linked to inflammation and disability in neonates. However, current IL-8 detection methods are often costly, labor-intensive, and require highly trained personnel. While electrochemical techniques have been employed for sensitive IL-8 quantification, they typically rely on redox probes and three-electrode electrochemical cells, leading to issues such as toxicity, prolonged fabrication time, and increased waste generation. Additionally, conventional electrochemical biosensors fabrication techniques are expensive and time-consuming, limiting their scalability for mass disease screening. In this study, we introduce a low-cost, non-faradaic electrochemical nanobiosensor for the direct detection of IL-8. The sensor consists of interdigitated graphite/carbon dot conjugates flexographically printed onto a flexible polyimide substrate. The printed layer's physical properties were systematically characterized using SEM, AFM and surface profilometer, and biofunctionalization was achieved using aminopropyltriethoxysilane (APTES) and glutaraldehyde. Successful surface modification was confirmed through ATR-FTIR and EDS elemental mapping. Electrochemical impedance spectroscopy (EIS) analysis demonstrated the nanobiosensor's response to varying IL-8 concentrations, with capacitance, Zmod, Zreal, and Zimag measurements. Among these, Zimag exhibited the highest sensitivity, with a response of 2.7 kΩ/log(ng/mL) and a detection limit of 50 pg/mL-well below the clinically established threshold of 600 pg/mL. This study demonstrates that, in addition to capacitance, there are multiple parameters that warrant exploration in non-faradaic biosensors to improve their sensing performance. The nanobiosensor fabrication via flexographic printing enables scalable, cost-effective production while maintaining high sensitivity and selectivity through a non-faradaic detection mechanism. This work paves the way for the development of affordable, mass-producible biosensors for early biomarker detection, facilitating timely medical intervention and improved neonatal healthcare outcomes.

Colorimetric-fluorescent dual-mode nanosensor-powered enzyme immunoassay for ochratoxin A via alkaline phosphatase-mediated silver nanoparticle growth and fluorescence inner filter effect

Ochratoxin A (OTA) seriously threatens public health and agricultural ecosystems, necessitating sensitive detection methods. In view of that traditional immunoassays rely on animal-derived antibodies and toxic substrates, we developed a dual-mode nanosensor integrating colorimetric and fluorescent detection via alkaline phosphatase (ALP)-mediated silver nanoparticles (AgNPs) growth and inner filter effect (IFE). The Ag+-triggered aggregation-induced emission (AIE) enhancement of gold nanoclusters (AuNCs) was investigated for constructing a dual-mode nanosensor. The nanosensor employs an OTA-specific nanobody-ALP fusion (Nb-ALP) to dephosphorylate ascorbic acid 2-phosphate into ascorbic acid (AA), which reduces Ag⁺ to abundant AgNPs with NaBH4-reduced AgNPs seeds. AgNPs amplify plasmonic absorbance for colorimetric ALP detection, while quenching Ag⁺@AuNC fluorescence via IFE for fluorescent detection. The nanosensor was further combined with the Nb-ALP-based immunoassay to develop a dual-mode nanosensor-powered enzyme immunoassay (DMN-EIA). The DMN-EIA exhibited detection limits of 0.14 ng/mL (colorimetric) and 0.28 ng/mL (fluorescent) with high selectivity for OTA, with spike recovery rates of 93.5 %-108.7 % and relative standard deviations not exceeding 20 %. Furthermore, the colorimetric (R2 = 0.96) and fluorescent DMN-EIA (R2 = 0.93) correlated well with high-performance liquid chromatography in detection of ten real pepper samples. Therefore, the developed dual-mode nanosensor and DMN-EIA represent reliable and promising tools for detecting OTA.

Application of nanomaterials in the detection of pesticide residues in spices

With the development of global trade and the improvement of consumer safety awareness, the problem of pesticide residues in spices has received considerable attention. At the same time, with the advancement of nanotechnology, nanomaterials have shown great potential in pesticide residue detection. Given the wide variety of spices and their complex matrices, there has been a lack of a comprehensive review on the application of nanomaterials in pesticide residue detection in spices until now. In this study, the advancements in research on newly developed nanomaterials were examined for the detection of pesticide residues in spices over the last 10 years, focusing on the applications of carbon nanotubes, graphene and its derivatives, metal nanoparticles, metal-organic frameworks, molecularly imprinted polymers, and quantum dots. Additionally, this study also explores the advantages and challenges of different nanomaterials' applications and predicts their development trends, aiming to provide a reference for future research.

Triple-readout immunoassay based on copper ion trigger for the detection of ochratoxin A

BACKGROUND

Ochratoxin A (OTA) is a widespread mycotoxin with nephrotoxic, neurotoxic and immunotoxic properties. It exhibits elevated thermal stability and a prolonged half-life and is resistant to removal. Long-term exposure to OTA increases the risk of carcinogenesis and influences human health. The detection methods of single signal mode had poor anti-interference ability and were prone to false positive results, while the detection method of multi-signal mode has higher adaptability to conditions and can offset environmental interference through self-correction. Therefore, proposing multi-signal and high-sensitivity strategies to detect OTA levels in various foods is all-important.

RESULTS

A triple-readout immunoassay based on copper ions trigger was developed for detecting Ochratoxin A. The ascorbic acid 2-phosphate (AAP) was hydrolyzed to ascorbic acid (AA) by alkaline phosphatase (ALP). The unreacted AAP rapidly coordinated with Cu2+ to produce green Cu2+-AAP complexes which emitted blue/green (B/G) signals. Meanwhile, Cu2+ oxidized AA to produce dehydroascorbic acid (DHAA) which reacted with o-phenylenediamine (OPD) to form the blue-fluorescence quinoxaline derivative (DFQ). Simultaneously, Cu2+ oxidized the unreacted OPD to form yellow 2,3-diaminophenazine (DAP) which produced yellow signals (Y). The B/G and Y was read by a smartphone. The limits of detection (LOD) of B/G, fluorescence and Y value readout models were 0.13 ng/mL, 0.16 ng/mL and 0.15 ng/mL. Their linear ranges were 6.25-100 ng/mL, 6.25-200 ng/mL and 3.13-12.5 ng/mL. Besides, all three readout models showed excellent specificity for OTA, and the recovery rates were satisfactory from 94.79 % to 112.68 %.

SIGNIFICANCE

A triple-readout immunoassay based on copper ions trigger for the detection of ochratoxin A was constructed. The materials for detection are accessible and economical. Triple signal modes not only complement and verify each other to improve the reliability of the results but also can be selected according to the detection scenes to increase the freedom of detection. It can be used to detect other targets by altering the coated antigen and its corresponding antibody.

Spatially Resolved Electrochemiluminescent Biosensor Combined with Nanopore Screening Devices for Simultaneous Determination of Deoxynivalenol and Aflatoxin B1

Improving the preprocessing efficiency and creating multiple detection channels are crucial for building high-performance sensors. In this study, we developed a sensing platform that integrates a spatially resolved electrochemiluminescence (ECL) biosensor with a nanopore screening device for the simultaneous detection of deoxynivalenol (DON) and aflatoxin B1 (AFB1) in wheat. Zeolitic imidazolate framework-67(ZIF-67), which promotes the production of oxygen radicals (O2̇-), was integrated with luminol-capped silver nanoparticles (Luminol-AgNPs) to function as an ECL probe for DON detection. CON4H6-Ru, synthesized by covalently linking tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium(II) dichloride [Ru(dcbpy)3Cl2] and carbonyldiazide (CON4H6), was encapsulated in mesoporous silica nanoparticles (MSNs) and used as another ECL probe for the detection of AFB1. Subsequently, a reusable nanopore screening device was designed to eliminate macromolecular interference in the samples and improve the interference resistance of the sensing platform. Under the optimal experimental conditions, the sensing platform showed good linearity for DON concentrations from 0.005 to 150 μg/kg and AFB1 concentrations from 0.05 to 100 μg/kg, with detection limits of 1.80 × 10-4 and 1.09 × 10-3 μg/kg (S/N = 3), respectively.

Genetically engineered integrated aflatoxin B1 and deoxynivalenol bispecific nanobody as surrogate antigens for constructed time-resolved immunoassay dual detection methods

There is a phenomenon of combined contamination of fungal toxins, of which aflatoxin B1 (AFB1) is the most toxic, and deoxynivalenol (DON) contamination is common. The use of antigens for double or multiple testing of mycotoxins is easy to cause environmental pollution, and surrogate antigens have become necessary. The small molecule and susceptibility to genetic modification of nanobodies can be used to develop alternative antigens for mycotoxins. In this study, using the nanobody gene sequences of the heavy chain recognition regions of anti-aflatoxin and deoxynivalenol monoclonal antibodies, recombinant plasmids were successfully constructed by one-step cloning, and low-temperature-induced bispecific nanobodies against AFB1-DON were obtained, which can be used as alternative antigens to reduce the pollution of the environment from mycotoxin detection. Enzyme-linked immunosorbent assay validated the bispecific nanobody, and the semi-inhibitory concentration (IC50) of the bispecific nanobody were 0.47 μg/L and 149 μg/L for AFB1 and DON, respectively. Finally, a time-resolved fluorescent dual-detection test strip was constructed by this bispecific nanobody as a surrogate antigen for AFB1 and DON, which was capable of detecting AFB1 and DON at the same time, and the limits of detection (LOD) for the two toxins were 0.0254 μg/L and 21.4 μg/L, respectively. This method has satisfactory sensitivity and does not require antigen, which reduces the toxicity of using antigen.

Evaluation of Non-Faradaic Impedimetric Parameters for IL-8 Detection Using Gold Interdigitated Electrode-Based Biosensors: Towards Early Detection of Newborn Disability

Interleukin-8 (IL-8) is a critical biomarker associated with inflammation and disability in both adults and newborns. Conventional detection methods are often labor-intensive, time-consuming, and require highly trained personnel. Non-Faradaic impedimetric biosensors offer a label-free, rapid, and direct approach for IL-8 detection. While previous studies have primarily focused on capacitance and phase changes, the potential of other impedimetric parameters remains underexplored. In this study, a gold interdigitated electrode (Au-IDE)-based non-Faradaic biosensor was developed for IL-8 detection, evaluating multiple impedimetric parameters, including capacitance, impedance magnitude (Zmod), real impedance (Zreal), and imaginary impedance (Zimag). Among these, Zimag exhibited the lowest limit of detection (LoD) at 90 pg/mL, followed by Zmod at 120 pg/mL, and capacitance at 140 pg/mL, all significantly below the clinical threshold of 600 pg/mL. In contrast, Zreal displayed the highest LoD at 1.3 ng/mL. Sensitivity analysis revealed that Zimag provided the highest sensitivity at 13.1 kΩ/log (ng/mL), making it the most effective parameter for detecting IL-8 at low concentrations. The sensitivity of Zmod and Zreal was lower, while capacitance sensitivity was measured at 20 nF/log (ng/mL). These findings highlight the importance of investigating alternative impedimetric parameters beyond capacitance to optimize biosensor performance for biomarker detection. This study demonstrates that non-Faradaic biosensors, despite their capacitive-based nature, can achieve enhanced sensitivity and detection limits by leveraging additional impedimetric parameters, offering a promising approach for rapid and effective IL-8 detection.

Host-guest mediated recognition and rapid extraction of Fusarium mycotoxins in cereals by nickel ferrite magnetic calix[4]arene-derived covalent organic framework fabricated in room-temperature

Fusarium mycotoxins are toxic secondary fungal metabolites and widely distributed in cereals. Herein, a nickel ferrite magnetic calix[4]arene-derived covalent organic framework (NiFe2O4@CX4-COF) was meticulously designed and synthesized using a room-temperature method for the enrichment of mycotoxins. The CX4-COF exhibited a porous crystalline network with an eclipsed AA-stacking configuration. The ingenious integration of NiFe2O4, supramolecular calix[4]arene and COF contributed to host-guest mediated recognition, size-selectivity and high adsorption capacity, rapidly reaching adsorption equilibrium within only 3 min. Simulation calculations revealed that the host-guest interaction, size effect and abundant binding sites facilitated synergistically recognize and capture mycotoxins. NiFe2O4@CX4-COF has successfully applied for simultaneous extraction and analysis of mycotoxins in cereals, achieving negligible matrix effects (-14% to 13%), high sensitivity (LODs of 0.003-0.014 μg/L) and satisfactory recoveries (74.4%-116%). This work provides a prospective platform for constructing tailored macrocycle-based COFs under mild conditions for precise recognition and accurate analysis of trace hazardous substances in food.

Evaluating Methods for Aflatoxin B1 Monitoring in Selected Food Crops Within Decentralized Agricultural Systems

Aflatoxin B1 (AFB1) contamination of food crops pose severe public health risks, particularly in decentralized agricultural systems common in low-resource settings. Effective monitoring tools are critical for mitigating exposure, but their adoption is limited by barriers such as cost, infrastructure, and technical expertise. The objectives of this study were: (1) to evaluate common AFB1 detection methods, including enzyme-linked immunosorbent assays (ELISA) and lateral-flow assays (LFA), validated via high-performance liquid chromatography (HPLC), focusing on their suitability for possible applications in decentralized, low-resource settings; and (2) to conduct a barriers-to-use assessment for commonly available AFB1 detection methods and their applicability in low-resource settings. Among four ELISA kits, the AgraQuant Aflatoxin B1 2/50 ELISA Kit demonstrated the highest accuracy and precision, reliably quantifying AFB1 in maize and tortillas across 5-150 ppb with minimal cross-reactivity. For LFA, a smartphone-based algorithm achieved a high presence/absence accuracy rate of 84% but struggled with concentration prediction. The barriers-to-use analysis highlighted the practicality of low-cost tools like moisture readers for field screening but underscored their qualitative limitations. Advanced methods like HPLC and LC-MS offer greater precision but remain impractical due to their high costs and infrastructure requirements, suggesting a potential role for adapted ELISA or LFA methods as confirmatory approaches. These findings support the development of multi-tiered frameworks integrating affordable field tools with regional or centralized confirmatory testing. Addressing systemic barriers through capacity building, partnerships, and improved logistics will enhance AFB1 monitoring in decentralized systems, protecting public health in vulnerable communities.

Progress of machine learning-based biosensors for the monitoring of food safety: A review

Rapid urbanization and growing food demand caused people to be concerned about food safety. Biosensors have gained considerable attention for assessing food safety due to selectivity, and sensitivity but poor stability inherently limits their application. The emergence of machine learning (ML) has enhanced the efficiency of different sensors for food safety assessment. The ML combined with various noninvasive biosensors has been implemented efficiently to monitor food safety by considering the stability of bio-recognition molecules. This review comprehensively summarizes the application of ML-powered biosensors to investigate food safety. Initially, different detector-based biosensors using biological molecules with their advantages and disadvantages and biosensor-related various ML algorithms for food safety monitoring have been discussed. Next, the application of ML-powered biosensors to detect antibiotics, foodborne microorganisms, mycotoxins, pesticides, heavy metals, anions, and persistent organic pollutants has been highlighted for the last five years. The challenges and prospects have also been deliberated. This review provides a new prospect in developing various biosensors for multi-food contaminants powered by suitable ML algorithms to monitor in-situ food safety.

A multiplex microarray lateral flow immunoassay device for simultaneous determination of five mycotoxins in rice

Co-occurrence of multiple mycotoxins is a growing global food safety concern due to their harmful effects on humans and animals. This study developed an eco-friendly sample preparation method and an innovative multiplex microarray-based lateral flow immunoassay, using a novel portable reader for on-site simultaneous determination of five regulated mycotoxins-aflatoxin B1, T-2 toxin, zearalenone, deoxynivalenol, and fumonisin B1 in rice. The eco-friendly and ultrafast extraction procedure utilizes a bio-based solvent. Principally, the microarray signals generated through a novel luminescent organic dye were captured to quantify mycotoxin levels in samples using a portable reader installed with a user-friendly interface. The assay demonstrates accurate detection and quantification of these mycotoxins, with recoveries ranging from 77% to 127%. Detection limits ranged from 0.56 to 1.89 μg/kg, which were well below their regulatory limits, with a relative standard deviation below 25%. This analytical system provides an on-site method for detecting multiple mycotoxins in rice.

Antibody Recognition Profile-Aided Hapten Design to Modulate Antibody Generation with Anticipated Performance for Immunoassay Development

The hapten design to chemical compound currently considered only structural aspects of targets may suffer from the failure of antibody generation with anticipated performances, especially for broad-specific antibodies. To address the problem, this study proposed a novel strategy, named antibody recognition profile-aided hapten design (ARPHD), based on clues from both reported antibodies, haptens, and targets after uncovering antibody recognition profiles using fluorfenicol (FF) and fluorfenicol amine (FFA) as model analytes in this work. Specifically, we confirmed that the fluorine atom promoted the generation of antibodies to FFA, while the -COCHCl2 moiety was unfavorable for inducing broad-specific antibodies to FF and FFA. Based on the structural information from ARPHD, four novel haptens without -COCHCl2 and containing a fluorine atom are intentionally designed, then identified by computational chemistry and animal immunization, successfully inducing antibodies to FF and FFA with uniform IC50 values of 3.09 and 3.75 ng mL-1. The explanation of molecular mechanisms from the obtained antibodies has supported the scientific base behind ARPHD, and we also found that the light chain of the antibody contributed an important role in differential recognition of the antibody. Finally, an indirect competitive ELISA (icELISA) was developed for the simultaneous detection of FF and FFA in river water and animal-derived food with a LOD of 2.24-14.6 μg kg-1, which has never been achieved before. The study demonstrated that the ARPHD we proposed could rationally guide the design of haptens that modulate the generation of antibodies with appreciated performances and easily be extended to other chemical compounds as a versatile platform.

Quantitative determination of zearalenone in wheat by the CSA-NIR technique combined with chemometrics algorithms

In the current study, a colorimetric sensor array combined with near-infrared (NIR) spectroscopy was used to quantitatively analyze zearalenone in wheat. The portable NIR spectrometer was used to scan the porphyrin reaction points of the wheat colorimetric sensor and collect spectral data. Subsequently, based on all the NIR spectral data, the two models and three feature selection algorithms are compared, and the best performance model and the best feature variable input are selected. Concurrently, the Kernel-based Extreme Learning Machine (KELM) model optimized by the two parameter optimization algorithms was compared, and the best parameter optimization algorithm was selected. Among all evaluation models, the KELM model optimized by the Competitive Adaptive Reweighted Sampling algorithm combined with the rime optimization algorithm has the best prediction effect. The predicted RP2 is 0.9900, and the root mean square error of prediction (RMSEP) is 18.4610 μg∙kg-1.

Simultaneous detection of multiple mycotoxins in agricultural products: Recent advances in optical and electrochemical sensing methods

Mycotoxin contamination poses serious threats to human and animal health. Food and environmental systems are often simultaneously contaminated with multiple mycotoxins, a problem that is further exacerbated by the synergistic toxicological effects of these co-occurring mycotoxins. Consequently, the development of rapid detection methods capable of simultaneously identifying multiple mycotoxins in agricultural products is essential to prevent their entry into the food chain. Compared to standard detection methods, optical and electrochemical (EC) sensing methods have distinct advantages for the rapid detection of mycotoxins. This review comprehensively summarizes the latest advancements in the field of simultaneous detection of multiple mycotoxins using optical and EC sensing methods over the last 6 years (2018-2024). First, the review introduces the classification and relevant principles of optical and EC sensing methods. Thereafter, it emphasizes innovative simultaneous detection strategies within these approaches. Finally, it discusses current challenges and offers a reference for further research. Currently, the main challenge lies in the mutual interference among targets, making the development of an interference-free detection platform essential. Furthermore, the ongoing development of integrated technology is expected to aid regulatory authorities in improving the quality of agricultural products for field applications.

Aptamer-Conjugated Covalent-Organic Framework Nanochannels for Selective and Sensitive Detection of Aflatoxin B1

Sensitive and selective detection of trace aflatoxin B1 (AFB1) in foods is of great importance to guarantee food safety and quality but still challenging because of its trace amount and the interference from the complex food matrix. Here, we report the integration of aptamer (Apt) and an ordered 2D covalent organic framework (COF) to solid-state anodic aluminum oxide (AAO) nanochannels (Apt/COF/AAO) for selective and sensitive detection of trace AFB1. The high specificity of Apt for AFB1 led to a selective change in the surface charge of Apt/COF/AAO and in turn the current change of the nanochannel, permitting the selective and sensitive determination of trace AFB1 in complex food samples. The developed nanofluidic sensor gave a wide linear range (1-500 pg mL-1), low detection limit (0.11 pg mL-1), and good precision (relative standard deviation of 1.5% for 11 replicate determinations of 100 pg mL-1). In addition, the developed sensor was successfully used for the detection of AFB1 in food samples with the recovery of 86.9%-102.5%. The coupling of Apt-conjugated 2D COF with an AAO nanochannel provides a promising way for sensitive and selective determination of food contaminants in complex samples.

Ultrasensitive Imaging Assay of Multiple Mycotoxins Using Cobalt DNA-Inorganic Hybrid Superstructure with High Chemiluminescence Catalytic Property

A multiplex assay of mycotoxins in food and medicine is urgently needed and challenging due to synergistic hazards of trace mycotoxins and a lack of sensitive and user-friendly detection approaches. Herein, a cobalt DNA-inorganic hybrid superstructure (Co@DS) was developed through isothermal rolling circle amplification (RCA) for an ultrasensitive chemiluminescence (CL) imaging assay of multiple mycotoxins. Cobalt ions were enriched in the RCA product, endowing the Co@DS with a high CL catalytic property. Experimental studies elucidated the formation and CL catalytic mechanism of Co@DS. Co@DS was facilely integrated with biotinylated DNA to function as a universal platform and combined with a disposable immunosensor array chip. After a competitive immunoassay and biotin-avidin recognition, the CL signals of luminol and hydrogen peroxide, catalyzed by Co@DS captured on each testing zone of the array chip, were imaged simultaneously. Target mycotoxins can be quantitated by CL intensities. To validate the concept, the CL imaging approach was employed for joint determination of aflatoxin B1, ochratoxins A, and zearalenone. Under optimal conditions, it showed advantages including simple sample pretreatment, acceptable throughput, high accuracy, minimal sample consumption, broad linear ranges, and detection limits as low as 0.75, 0.62, and 0.61 pg mL-1, respectively. Furthermore, the approach was applied in analyzing real coix seed samples, showcasing excellent performance in effectively distinguishing qualified and contaminated medicine, revealing the great potential in managing the complex issue of mycotoxins cocontamination in food and medicine.

Ready-to-use ratiometric bioluminescence immunosensor for detection of ochratoxin a in pepper

Rapid, portable, and accurate detection tools for monitoring ochratoxin A (OTA) in food are essential for the guarantee of food safety and human health. Herein, as a proof-of-concept, this study proposed a ratiometric bioluminescence immunosensor (RBL-immunosensor) for homogeneous detection of OTA in pepper. The construct of the RBL-immunosensor consists of three components, including the large fragment of the split nanoluciferase (NanoLuc)-tagged nanobody (NLg), the small fragment of the split NanoLuc-tagged mimotope peptide heptamer (MPSm), and the calibrator luciferase (GeNL). The specific nanobody-mimotope peptide interaction between NLg and MPSm induces the reconstitution of the NanoLuc, which catalyzes the Nano-Glo substrate and produces a blue emission peak at 458 nm. Meanwhile, GeNL can produce a green emission peak at 518 nm upon substrate conversion via bioluminescent resonance energy transfer (BRET). Therefore, the concentration of OTA can be linked to the variation of the bioluminescence signal (λ458/λ518) measured by microplate reader and the variation of the blue/green ratio measured by smartphone via the competitive immunoreaction where OTA competes with MPSm to bind NLg. The immunosensor is ready-to-use and works by simply mixing the components in a one-step incubation of 10 min for readout. It has a limit of detection (LOD) of 0.98 ng/mL by a microplate reader and an LOD of 1.89 ng/mL by a smartphone. Good selectivity and accuracy were confirmed for the immunosensor by cross-reaction analysis and recovery experiments. The contents of OTA in 10 commercial pepper powder samples were tested by the RBL-immunosensor and validated by high-performance liquid chromatography. Hence, the ready-to-use RBL-immunosensor was demonstrated as a highly reliable tool for detection of OTA in food.

A disposable immunosensor array using cellulose paper assembled chemiresistive biosensor for simultaneous monitoring of mycotoxins AFB1 and FB1

Due to the common contamination of multiple mycotoxins in food, which results in stronger toxicity, it is particularly important to simultaneously test for various mycotoxins for the protection of human health. In this study, a disposable immunosensor array with low-cost was designed and fabricated using cellulose paper, polydimethylsiloxane (PDMS), and semiconducting single-walled carbon nanotubes (s-SWCNTs), which was modified with specific antibodies for mycotoxins AFB1 and FB1 detection. The strategy for fabricating the immunosensor array with two individual channels involved a two-step protocol starting with the form of two kinds of carbon films by depositing single-wall carbon nanotubes (SWCNTs) and s-SWCNTs on the cellulose paper as the conductive wire and sensing element, followed by the assembly of chemiresistive biosensor with SWCNTs strip as the wire and s-SWCNTs as the sensing element. After immobilizing AFB1-bovine serum albumin (AFB1-BSA) and FB1-bovine serum albumin (FB1-BSA) separately on the different sensing regions, the formation of mycotoxin-BSA-antibody immunocomplexes transfers to electrochemical signal, which would change with the different concentrations of free mycotoxins. Under optimal conditions, the immunosensor array achieved a limit of detection (LOD) of 0.46 pg/mL for AFB1 and 0.34 pg/mL for FB1 within a wide dynamic range from 1 pg/mL to 20 ng/mL. Furthermore, the AFB1 and FB1 spiked in the ground corn and wheat extracts were detected with satisfactory recoveries, demonstrating the excellent practicality of this established method for simultaneous detection of mycotoxins.

Evaluation of the Immune Response of Patulin by Proteomics

Patulin, an emerging mycotoxin with high toxicity, poses great risks to public health. Considering the poor antibody production in patulin immunization, this study focuses on the four-dimensional data-independent acquisition (4D-DIA) quantitative proteomics to reveal the immune response of patulin in rabbits. The rabbit immunization was performed with the complete developed antigens of patulin, followed by the identification of the immune serum. A total of 554 differential proteins, including 292 up-regulated proteins and 262 down-regulated proteins, were screened; the differential proteins were annotated; and functional enrichment analysis was performed. The differential proteins were associated with the pathways of metabolism, gene information processing, environmental information processing, cellular processes, and organismal systems. The functional enrichment analysis indicated that the immunization procedures mostly resulted in the regulation of biochemical metabolic and signal transduction pathways, including the biosynthesis of amino acid (glycine, serine, and threonine), ascorbate, and aldarate metabolism; fatty acid degradation; and antigen processing and presentation. The 14 key proteins with high connectivity included G1U9T1, B6V9S9, G1SCN8, G1TMS5, G1U9U0, A0A0G2JH20, G1SR03, A0A5F9DAT4, G1SSA2, G1SZ14, G1T670, P30947, P29694, and A0A5F9C804, which were obtained by the analysis of protein-protein interaction networks. This study could provide potential directions for protein interaction and antibody production for food hazards in animal immunization.

A novel core-shell up-conversion nanoparticles immunochromatographic assay for the detection of deoxynivalenol in cereals

Deoxynivalenol (DON) toxin is a type B group of trichothecene mycotoxins mainly originating from specific Fusarium fungi, seriously harming human and livestock health. Herein, a novel core-shell up-conversion nanoparticles immunochromatographic assay (CS-UCNPs-ICA) was developed for deoxynivalenol based on the competitive reaction principle. By exploiting the fluorescence intensity of the T and C lines of CS-UCNPs-ICA, the concentrations of DON were obtained sensitively and precisely under optimized conditions in 5 min with a detection limit of 0.1 ng/mL. The CS-UCNPs-ICA strips only specifically detect DON and its derivatives (3-Ac-DON and 15-Ac-DON), with no cross-reaction with other mycotoxins. The low CV values illustrated a modest intra- and inter-assay variation, confirming the superior precision of this method. In the spiked experiment, the mean recoveries of corn and wheat ranged from 94.74% to 100.90% and 96.21%-104.81%, respectively. Furthermore, the approach generated results that were in good agreement with data from HPLC and ELISA analyses of naturally contaminated feed and cereals, confirming that the significant advantages of proposed strips were their high practicality, rapidness, and simplicity. Therefore, the CS-UCNPs-ICA strips platform serves as a promising candidate for developing new approaches for rapid testing or high throughput screening from DON in food products.

Portable self-powered electrochemical aptasensing platform for ratiometric detection of mycotoxins based on multichannel photofuel cell

Self-powered electrochemical sensors based on photofuel cells have attracted considerable research interest because their unique advantage of not requiring an external electric source, but their application in portable and multiplexed targets assay is limited by the inherent mechanism. In this work, a portable self-powered sensor constructed with multichannel photofuel cells was developed for the ratiometric detection of mycotoxins, namely ochratoxin A (OTA) and patulin (PAT). The spatially resolved CdS/Bi2S3-modified photoanodes and a shared Prussian Blue cathode were integrated on an etched indium-tin oxide slide to fabricate the multichannel photofuel cell. The aptamers of OTA and PAT were covalently bonded to individual photoanode regions to build sensitive interfaces, and the specific recognition of analytes impaired the output performance of constructed PFC. Accordingly, ratiometric sensing of OTA and PAT was achieved by utilizing the output performance of a control PFC as a reference signal. This approach effectively eliminates the impact of light intensity on the accuracy of the detection. Under the optimal conditions, the proposed sensing chip exhibited linear ranges of 2.0-1000 nM and 5.0-500 nM for OTA and PAT, respectively. The detection limits (3 S/N) were determined to be 0.25 nM for OTA and 0.27 nM for PAT. The developed ratiometric sensing method demonstrated good selectivity and stability in the simultaneous detection of OTA and PAT. It was successfully utilized for the analysis of OTA and PAT real samples. This work provides a new perspective for construction of portable and ratiometric self-powered sensing platform.

Development of highly sensitive electrochemical immunosensor using PPy-MoS2-based nanocomposites modified with 90 MeV C6+ ion beams

The evaluation of electrochemical sensing activity of hydrothermally derived PPy-MoS2-based nanocomposites subjected to 90 MeV C6+ ion beam with fluence ranging, 1.0 × 1010-1.0 × 1013 ions/cm2, is reported. Cross-linking, chain scissioning, and ion track formation could occur in the irradiated systems, as revealed from Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) studies. Electrochemical studies, viz., cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed in 0.1 M phosphate buffer solution (PBS) containing 5 mM K3[Fe(CN)6] as redox probe. High redox activity, lower charge transfer resistance (Rct = 490 Ω) and larger electroactive area (A = 0.4485 cm2) were obtained in case of the composite system irradiated with a fluence of 3.5 × 1011 ions/cm2. Immunosensor fabrication was executed via immobilization of mouse IgG over the pristine and post-irradiated electrodes. Afterwards, differential pulse voltammetry (DPV) was performed within the potential window - 0.2 to + 0.6 V (vs. Ag/AgCl) for the detection of specific analyte. Noticeably, the electrode system irradiated with a fluence of 3.5 × 1011 ions/cm2 is characterized by a lower limit of detection (LOD) of 0.203 nM and a higher sensitivity value of 10.0 µA mL ng-1 cm-2. The energetic particle irradiation at a modest fluence can offer beneficial effects to the PPy-MoS2-based nanohybrid system providing immense scope as advanced electrochemical biosensor.

Nafion-Immobilized Functionalized MWCNT-based Electrochemical Immunosensor for Aflatoxin B1 Detection

The ubiquitous aflatoxin B1 (AFB1) contamination in foods and other complex matrices has brought great challenges for onsite monitoring. In this study, an ultrasensitive Nafion-immobilized functionalized multiwalled carbon nanotube (MWCNT)-based electrochemical (EC) immunosensor was developed for trace AFB1 detection. The introduced Nafion film could steadily stabilize functionalized MWCNTs with uniform distribution and tiling on the surface of a Au electrode. Functionalized MWCNTs with a large specific surface area, numerous active sites to couple with abundant anti-AFB1 monoclonal antibodies (mAbs), and high conductivity served as the signal amplifier for remarkably enhancing the sensing performance of the immunosensor. In the presence of AFB1, it was specifically captured by mAbs to reduce the amplified current signals, which were recorded by differential pulse voltammetry for the accurate quantitation of AFB1. Because of the synergistic effects of Nafion on the stabilization of functionalized MWCNTs as signal enhancers, the developed EC immunosensor exhibited an extremely high selectivity, excellent sensitivity with a limit of detection as low as 0.021 ng/mL, and a wide dynamic range of 0.05-100 ng/mL, besides fascinating merits of easy construction, low cost, good stability in 7 days, and good reusability. The anti-interference ability of the immunosensor was verified against three other mycotoxins, and the practicability and accuracy were confirmed by measuring AFB1 in fortified malt, lotus seed, and hirudo samples with a satisfactory recovery of 92.08-104.62%. This novel immunosensing platform could be extended to detect more mycotoxins in complex matrices to ensure food safety.

Highly Sensitive Microarray Immunoassay for Multiple Mycotoxins on Engineered 3D Porous Silicon SERS Substrate with Silver Nanoparticle Magnetron Sputtering

A high-throughput, rapid, and highly sensitive surface-enhanced Raman spectroscopy (SERS) microarray for screening multiple mycotoxins has been developed on a three-dimensional silver nanoparticle porous silicon (3D AgNP-Psi) SERS substrate, which was easy to be engineered by electrochemical etching and magnetron sputtering technology. The etching current density, etching waveform, and target material for magnetron sputtering have been investigated to obtain an optimal 3D SERS substrate. The optimized 3D AgNP-Psi SERS substrate showed an enhancement factor of 2.3 × 107 at 400 mA/cm2 constant current density etching for 20 s and Ag target magnetron sputtering for 200 nm thickness on the surface of Psi. The simulation electric field distribution showed the near-field enhancement can reach 3× higher than that of AuNPs. A protein microarray has been designed to screen multiple mycotoxins by AuNP Raman tags and a competitive immunoassay protocol on the surface of the 3D SERS substrate. The SERS protein microarray displayed wide linear detection ranges of 0.001-100 ng/mL for ochratoxin A, 0.01-100 ng/mL for aflatoxin B1, 0.001-10 ng/mL for deoxynivalenol, along with pg/mL low limit of detection, good recovery rates, repeatability, and reproducibility. The 3D SERS protein microarray is easily engineered and has a great potential application in medicine, environment, and food industry fields.

Magnetic nanoparticle-based immunosensors and aptasensors for mycotoxin detection in foodstuffs: An update

Mycotoxin contamination of food crops is a global challenge due to their unpredictable occurrence and severe adverse health effects on humans. Therefore, it is of great importance to develop effective tools to prevent the accumulation of mycotoxins through the food chain. The use of magnetic nanoparticle (MNP)-assisted biosensors for detecting mycotoxin in complex foodstuffs has garnered great interest due to the significantly enhanced sensitivity and accuracy. Within such a context, this review includes the fundamentals and recent advances (2020-2023) in the area of mycotoxin monitoring in food matrices using MNP-based aptasensors and immunosensors. In this review, we start by providing a comprehensive introduction to the design of immunosensors (natural antibody or nanobody, random or site-oriented immobilization) and aptasensors (techniques for aptamer selection, characterization, and truncation). Meanwhile, special attention is paid to the multifunctionalities of MNPs (recoverable adsorbent, versatile carrier, and signal indicator) in preparing mycotoxin-specific biosensors. Further, the contribution of MNPs to the multiplexing determination of various mycotoxins is summarized. Finally, challenges and future perspectives for the practical applications of MNP-assisted biosensors are also discussed. The progress and updates of MNP-based biosensors shown in this review are expected to offer readers valuable insights about the design of MNP-based tools for the effective detection of mycotoxins in practical applications.

Dual-layers Raman reporter-tagged Au@Ag combined with core-satellite assemblies for SERS detection of Zearalenone

Zearalenone (ZEN) is a prevalent mycotoxin identified in corn. A SERS-based immunosensor by constructing core-satellite assemblies was developed for ZEN detection. ZEN monoclonal antibody modified gold nanostars (AuNSs) were fabricated as the capture probe (core). The Raman signal probes (satellites) utilized ZEN antigen linked to the core-shell structures loaded with two layers of Raman reporter molecules (AuMBA@AgMBANPs). The coupling between AuNSs and AuMBA@AgMBANPs can produce a poweful electromagnetic field, thus considerably amplifying the Raman signal. The detection range of ZEN for corn samples under the optimal conditions was 5 ∼ 400 μg/kg with a LOD of 3 μg/kg, which completely satisfying the requirement of maximum residual level (60 μg/kg). Moreover, the proposed SERS method was consistent with the HPLC-FLD method for the detection of ZEN in naturally contaminated corn samples (90.58% ∼ 105.29%). Conclusively, fabricated immunosensor with exceptional sensitivity and specificity broaden the application of SERS in mycotoxin detection.

Fabrication of a disposable aptasensing chip for simultaneous label-free detection of four common coexisting mycotoxins

BACKGROUND

Coexisting multiple mycotoxins in food poses severe health risks on humans due to the augmented toxicity. Current multiplex detection methods for mycotoxins have evolved from instrumental analyses to rapid methods based on the specific recognition of antibody/aptamer using different signal transducers. However, nearly all of the reported aptasensors for multiple mycotoxins detection require external labels and can only simultaneous detection of two mycotoxins due to the limitation of distinguishable labels. The tedious labeling process definitely increases the operation complexity and the detection cost. Therefore, rapid method for simultaneous label-free detection of multiple mycotoxins in cereals is urgently needed.

RESULTS

A disposable aptasensing chip was designed for simultaneous label-free detection of fumonisin B1 (FB1), aflatoxin B1 (AFB1), zearalenone (ZEN), and ochratoxin A (OTA) in one sample. Specifically, ITO conductive glass was divided into a rectangle (35 × 25 mm) and then etched by laser to set aside the required four ITO working electrodes (6 mm in diameter) with respective conductive channels. Gold nanoparticles were electrodeposited on the working electrodes to provide abundant anchoring sites for thiolated aptamers immobilization. On this basis, a disposable aptasensing chip for simultaneous label-free detection of four common coexisting mycotoxins has been developed, which used electrochemical impedance spectroscopy as transducer to measure direct biorecognition of the aptamer and corresponding target. This aptasensing chip provided wide linear ranges of 5-1000, 10-250, 10-1250, 10-1500 ng/mL for FB1, AFB1, ZEN, OTA, respectively, with the respective detection limit of 2.47, 3.19, 5.38, 4.87 ng/mL (S/N = 3).

SIGNIFICANCE AND NOVELTY

This aptasensing chip shows fantastic characteristics of great simplicity and portability, easy operation, and multiple mycotoxins recognition. They are easy to produce on a large scale at low cost and the design concept can be easily expanded to screen a large panel of coexisting targets. This work provides a new avenue for multi-target detection and represents a substantial advance toward food quality and safety monitoring or other fields.

Current Trends in Mycotoxin Detection with Various Types of Biosensors

One of the most important tasks in food safety is to properly manage the investigation of mycotoxin contamination in agricultural products and foods made from them, as well as to prevent its occurrence. Monitoring requires a wide range of analytical methods, from expensive analytical procedures with high-tech instrumentation to significantly cheaper biosensor developments or even single-use assays suitable for on-site monitoring. This review provides a summary of the development directions over approximately a decade and a half, grouped according to the biologically sensitive components used. We provide an overview of the use of antibodies, molecularly imprinted polymers, and aptamers, as well as the diversity of biosensors and their applications within the food industry. We also mention the possibility of determining multiple toxins side by side, which would significantly reduce the time required for the analyses.

EFSA Panel on Contaminants in the Food Chain (CONTAM), Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nielsen E, Ntzani E, Sand S, Schwerdtle T, Vleminckx C, Wallace H, Gropp J, Antonissen G, Rychen G, Gómez Ruiz JÁ, Innocenti ML, Rovesti E, Petersen A. Risks for animal health related to the presence of ochratoxin A (OTA) in feed

In 2004, the EFSA Panel on Contaminants in the Food Chain (CONTAM) adopted a Scientific Opinion on the risks to animal health and transfer from feed to food of animal origin related to the presence of ochratoxin A (OTA) in feed. The European Commission requested EFSA to assess newly available scientific information and to update the 2004 Scientific Opinion. OTA is produced by several fungi of the genera Aspergillus and Penicillium. In most animal species it is rapidly and extensively absorbed in the gastro-intestinal tract, binds strongly to plasma albumins and is mainly detoxified to ochratoxin alpha (OTalpha) by ruminal microbiota. In pigs, OTA has been found mainly in liver and kidney. Transfer of OTA from feed to milk in ruminants and donkeys as well as to eggs from poultry is confirmed but low. Overall, OTA impairs function and structure of kidneys and liver, causes immunosuppression and affects the zootechnical performance (e.g. body weight gain, feed/gain ratio, etc.), with monogastric species being more susceptible than ruminants because of limited detoxification to OTalpha. The CONTAM Panel considered as reference point (RP) for adverse animal health effects: for pigs and rabbits 0.01 mg OTA/kg feed, for chickens for fattening and hens 0.03 mg OTA/kg feed. A total of 9,184 analytical results on OTA in feed, expressed in dry matter, were available. Dietary exposure was assessed using different scenarios based on either model diets or compound feed (complete feed or complementary feed plus forage). Risk characterisation was made for the animals for which an RP could be identified. The CONTAM Panel considers that the risk related to OTA in feed for adverse health effects for pigs, chickens for fattening, hens and rabbits is low.

Advancing Mycotoxin Detection: Multivariate Rapid Analysis on Corn Using Surface Enhanced Raman Spectroscopy (SERS)

Mycotoxin contamination on food and feed can have deleterious effect on human and animal health. Agricultural crops may contain one or more mycotoxin compounds; therefore, a good multiplex detection method is desirable to ensure food safety. In this study, we developed a rapid method using label-free surface-enhanced Raman spectroscopy (SERS) to simultaneously detect three common types of mycotoxins found on corn, namely aflatoxin B1 (AFB1), zearalenone (ZEN), and ochratoxin A (OTA). The intrinsic chemical fingerprint from each mycotoxin was characterized by their unique Raman spectra, enabling clear discrimination between them. The limit of detection (LOD) of AFB1, ZEN, and OTA on corn were 10 ppb (32 nM), 20 ppb (64 nM), and 100 ppb (248 nM), respectively. Multivariate statistical analysis was used to predict concentrations of AFB1, ZEN, and OTA up to 1.5 ppm (4.8 µM) based on the SERS spectra of known concentrations, resulting in a correlation coefficient of 0.74, 0.89, and 0.72, respectively. The sampling time was less than 30 min per sample. The application of label-free SERS and multivariate analysis is a promising method for rapid and simultaneous detection of mycotoxins in corn and may be extended to other types of mycotoxins and crops.

Recent progress in optical and electrochemical aptasensor technologies for detection of aflatoxin B1

AFB1 (Aflatoxin B1) contamination is becoming a global concern issue due to its extraordinary occurrence, severe toxicity, as well as the great influence on the economic losses, food safety and environment. Therefore, it is desirable to develop novel analytical techniques for simple, rapid, accurate, and even point-of-care testing of AFB1. Fortunately, aptamer, considered as a new generation bioreceptor and even superior to classic antibody and enzyme, has been emerged remarkable application in food hazards detection. Correspondingly, aptasensors have been well-established toward AFB1 determination with outstanding performance. In this article, we first discuss and summarize the recent progress in optical and electrochemical aptasensors to monitor AFB1 over the past three years. In particular, the embedding of advanced nanomaterials for their improved analytical performance is highlighted. Furthermore, the critical analysis on various signal transduction strategies for aptasensors construction is discussed. Finally, we reveal the challenges and provide our opinion in future opportunities for aptasensor development.

Advances in phage display based nano immunosensors for cholera toxin

Cholera, a persistent global public health concern, continues to cause outbreaks in approximately 30 countries and territories this year. The imperative to safeguard water sources and food from Vibrio cholerae, the causative pathogen, remains urgent. The bacterium is mainly disseminated via ingestion of contaminated water or food. Despite the plate method's gold standard status for detection, its time-consuming nature, taking several days to provide results, remains a challenge. The emergence of novel virulence serotypes raises public health concerns, potentially compromising existing detection methods. Hence, exploiting Vibrio cholerae toxin testing holds promise due to its inherent stability. Immunobiosensors, leveraging antibody specificity and sensitivity, present formidable tools for detecting diverse small molecules, encompassing drugs, hormones, toxins, and environmental pollutants. This review explores cholera toxin detection, highlighting phage display-based nano immunosensors' potential. Engineered bacteriophages exhibit exceptional cholera toxin affinity, through specific antibody fragments or mimotopes, enabling precise quantification. This innovative approach promises to reshape cholera toxin detection, offering an alternative to animal-derived methods. Harnessing engineered bacteriophages aligns with ethical detection and emphasizes sensitivity and accuracy, a pivotal stride in the evolution of detection strategies. This review primarily introduces recent advancements in phage display-based nano immunosensors for cholera toxin, encompassing technical aspects, current challenges, and future prospects.

Recent Progress in Screening of Mycotoxins in Foods and Other Commodities Using MXenes-Based Nanomaterials

Mycotoxin pollution in agricultural food products endangers animal and human health during the supply chains, therefore the development of accurate and rapid techniques for the determination of mycotoxins is of great importance for food safety guarantee. MXenes-based nanoprobes have attracted enormous attention as a complementary analysis and promising alternative strategies to conventional diagnostic methods, because of their fascinating features, like high electrical conductivity, various surface functional groups, high surface area, superb thermal resistance, good hydrophilicity, and environmentally-friendlier characteristics. In this study, we outline the state-of-the-art research on MXenes-based probes in detecting various mycotoxins like aflatoxin, ochratoxin, deoxynivalenol, zearalenone, and other toxins as a most commonly founded mycotoxin in the agri-food supply chain. First, we present the diverse synthesis approaches and exceptional characteristics of MXenes. Afterward, based on the detecting mechanism, we divide the biosensing utilizations of MXenes into two subcategories: electrochemical, and optical biosensors. Then their performance in effective sensing of mycotoxins is comprehensively deliberated. Finally, present challenges and prospective opportunities for MXenes are debated.

Dual-mode immunochromatographic assay based on dendritic gold nanoparticles with superior fluorescence quenching for ultrasensitive detection of E. coli O157:H7

We presented a colorimetric/fluorescent dual-mode immunochromatographic assay (ICA) for the sensitive detection of Escherichia coli O157:H7. The use of polydopamine (PDA)-modified gold nanoparticles (AuNPs) with broadband absorption allowed for excellent colorimetry signals for the ICA detection. Moreover, the absorption spectrum of PDA-AuNPs significantly overlaps with the excitation and emission spectra of ZnCdSe/ZnS quantum dots (QDs), resulting in effective quenching of the QDs fluorescence due to the inner filter effect. The fluorescence intensity changes induced by PDA-AuNPs were utilized for the sensitive detection of E. coli O157:H7, achieving a detection limit of 9.06 × 10¹ CFU/mL, which was 46-fold lower than that of traditional AuNPs-based immunoassay. The proposed immunosensor exhibited the recovery rate between 80.12% and 114.69% in detecting actual samples, indicating its reliability and satisfactory accuracy. This study provides insights into dual-mode signal outputs and the ICA development for food safety applications.

A Sensitive Fluorescence Polarization Immunoassay for the Rapid Detection of Okadaic Acid in Environmental Waters

In this study, a homogeneous fluorescence polarization immunoassay (FPIA) for the detection of hazardous aquatic toxin okadaic acid (OA) contaminating environmental waters was for the first time developed. A conjugate of the analyte with a fluorophore based on a fluorescein derivative (tracer) was synthesized, and its interaction with specific anti-OA monoclonal antibodies (MAbs) was tested. A MAbs-tracer pair demonstrated highly affine immune binding (KD = 0.8 nM). Under optimal conditions, the limit of OA detection in the FPIA was 0.08 ng/mL (0.1 nM), and the working range of detectable concentrations was 0.4-72.5 ng/mL (0.5-90 nM). The developed FPIA was approbated for the determination of OA in real matrices: river water and seawater samples. No matrix effect of water was observed; therefore, no sample preparation was required before analysis. Due to this factor, the entire analytical procedure took less than 10 min. Using a compact portable fluorescence polarization analyzer enables the on-site testing of water samples. The developed analysis is very fast, easy to operate, and sensitive and can be extended to the determination of other aquatic toxins or low-molecular-weight water or food contaminants.

Lateral Flow Immunoassay for Proteins

Protein biomarkers are useful for disease diagnosis. Identification thereof using in vitro diagnostics such as lateral flow immunoassays (LFIAs) has attracted considerable attention due to their low cost and ease of use especially in the point of care setting. Current challenges, however, do remain with respect to material selection for each component in the device and the synergistic integration of these components to display detectable signals. This review explores the principle of LFIA for protein biomarkers, device components including biomaterials and labeling methods. Medical applications and commercial status are examined as well. This review highlights critical methodologies in the development of new LFIAs and their role in advancing healthcare worldwide.

Advances in immunoassay-based strategies for mycotoxin detection in food: From single-mode immunosensors to dual-mode immunosensors

Mycotoxin contamination in foods and other goods has become a broad issue owing to serious toxicity, tremendous threat to public safety, and terrible loss of resources. Herein, it is necessary to develop simple, sensitive, inexpensive, and rapid platforms for the detection of mycotoxins. Currently, the limitation of instrumental and chemical methods cannot be massively applied in practice. Immunoassays are considered one of the best candidates for toxin detection due to their simplicity, rapidness, and cost-effectiveness. Especially, the field of dual-mode immunosensors and corresponding assays is rapidly developing as an advanced and intersected technology. So, this review summarized the types and detection principles of single-mode immunosensors including optical and electrical immunosensors in recent years, then focused on developing dual-mode immunosensors including integrated immunosensors and combined immunosensors to detect mycotoxins, as well as the combination of dual-mode immunosensors with a portable device for point-of-care test. The remaining challenges were discussed with the aim of stimulating future development of dual-mode immunosensors to accelerate the transformation of scientific laboratory technologies into easy-to-operate and rapid detection platforms.

Advantages of Multiplexing Ability of the Orbitrap Mass Analyzer in the Multi-Mycotoxin Analysis

In routine measurements, the length of the analysis time and nfumber of samples analysed during a time unit are crucial parameters, which are especially important for the food analysis, particularly in the case of mycotoxin determinations. High-resolution equipment, including time-of-flight or Orbitrap analyzators, can provide stable instrumental background for high-throughput analyses. In this report, a short, 1 min MS-based multi-mycotoxin method was developed with the application of a short column as a reduced chromatographic separation, taking advantages of the multiplexing and high-resolution capability of the QExactive Orbitrap MS possessing sub-1 ppm mass accuracy. The performance of the method was evaluated regarding selectivity, LOD, LOQ, linearity, matrix effect, and recovery, and compared to a UHPLC-MS/MS method. The final multiplexing method was able to quantify 11 mycotoxins in defined ranges (aflatoxins (corn, 2.8-600 μg/kg; wheat, 1.5-350 μg/kg), deoxynivalenol (corn, 640-9600 μg/kg; wheat, 128-3500 μg/kg), fumonisins (corn, 20-1500 μg/kg; wheat, 30-3500 μg/kg), HT-2 (corn, 64-5200 μg/kg; wheat, 61-3500 μg/kg), T-2 (corn, 10-800 μg/kg; wheat, 4-250 μg/kg), ochratoxin (corn, 4.7-600 μg/kg; wheat, 1-1000 μg/kg), zearalenone (corn, 64-4800 μg/kg; wheat, 4-500 μg/kg)) within one minute in corn and wheat matrices at the MRL levels stated by the European Union.

Ratiometric Detection of Ochratoxin A Using a Regenerable COF-Au-MB-Apt Signal Probe on a Thermal-Regulated Sensor Module

Ochratoxin A (OTA) frequently contaminates grains and consequently threatens human health. Herein, we develop a regenerable signal probe and apply it to a Au-based screen-printed electrode module (SPE) for OTA determination. The signal probe, containing a structural covalent organic framework, gold nanoparticles (AuNPs), indicative methylene blue (MB), and a highly selective aptamer, is synthesized with hydrothermal and self-assembly methods. The SPE is permanently functionalized with Prussian blue (PB), AuNPs, and semicomplementary ssDNA. The signal probe, absorbed onto this SPE via hybridization, is competitively expelled by OTA, providing a ratiometric readout of ΔIMB/IPB. Probe regeneration, to erase expired COF-Au-MB-Apt after each analysis, is established with the synergy of OTA-conducted Apt-ssDNA dissociation and on-chip thermal regulation. This advantage powerfully guarantees reduplicative analyses by avoiding irreversible Apt-OTA combination and accumulation on the sensing interface. Regenerations are performed in repetitive cycles (N = 7) with 98.5% reproduction efficiency, and IMB and IPB fluctuations are calculated as 1.45 and 1.12%. This method shows log-linear OTA response in a wide range from 0.2 pg/mL to 0.6 μg/mL, and the limit of detection is 0.12 pg/mL. During natural OTA determinations, recommended readouts match well with HPLC with less than 4.82% relative error.

MXene-based aptasensor for the detection of aflatoxin in food and agricultural products

The detection of toxins that contaminate food needs highly sensitive and selective techniques to prevent substantial monitory loss. In this regard, various nanostructured material-enabled biosensors, have recently been developed to improve the detection of food toxins among them aflatoxin is the prevalent one. The biosensor-based detection of aflatoxin is quick, cheaper, and needs less skilled personnel, therefore overcoming the shortcomings of conventional techniques such as LC/MS-MS, HPLC, and ELISA assays. 2D MXenes manifest as an efficient material for biosensing due to their desirable biocompatibility, magnificent mechanical strength, easiness of surface functionalization, and tuneable optical and electronic features. Contrary to this, aptamers as biorecognition elements (BREs) possess high selectivity, sensitivity, and ease of synthesis when compared to conventional BREs. In this review, we explored the most cutting-edge aptamer-based MXene-enabled biosensing technologies for the detection of the most poisonous mycotoxins (i.e., Aflatoxins) in food and environmental matrices. The discussion begins with the synthesis processes and surface functionalization/modification of MXenes. Computational approaches for designing aptasensors and advanced data analysis based on artificial intelligence and machine learning with special emphasis over Internet-of-Thing integrated biosensing devices has been presented. Besides, the advantages of aptasensors over conventional methods along with their limitations have been briefed. Their benefits, drawbacks, and future potential are discussed concerning their analytical performance, utility, and on-site adaptability. Additionally, next-generation MXene-enabled biosensing technologies that provide end users with simple handling and improved sensitivity and selectivity have been emphasized. Owing to massive applicability, economic/commercial potential of MXene in current and future perspective have been highlighted. Finally, the existing difficulties are scrutinized and a roadmap for developing sophisticated biosensing technologies to detect toxins in various samples in the future is projected.

Small Peptides in the Detection of Mycotoxins and Their Potential Applications in Mycotoxin Removal

Mycotoxins pose significant risks to humans and livestock. In addition, contaminated food- and feedstuffs can only be discarded, leading to increased economic losses and potential ecological pollution. Mycotoxin removal and real-time toxin level monitoring are effective approaches to solve this problem. As a hot research hotspot, small peptides derived from phage display peptide libraries, combinatorial peptide libraries, and rational design approaches can act as coating antigens, competitive antigens, and anti-immune complexes in immunoassays for the detection of mycotoxins. Furthermore, as a potential approach to mycotoxin degradation, small peptides can mimic the natural enzyme catalytic site to construct artificial enzymes containing oxidoreductases, hydrolase, and lyase activities. In summary, with the advantages of mature synthesis protocols, diverse structures, and excellent biocompatibility, also sharing their chemical structure with natural proteins, small peptides are widely used for mycotoxin detection and artificial enzyme construction, which have promising applications in mycotoxin degradation. This paper mainly reviews the advances of small peptides in the detection of mycotoxins, the construction of peptide-based artificial enzymes, and their potential applications in mycotoxin control.

Ochratoxin A in Dry-Cured Ham: OTA-Producing Fungi, Prevalence, Detection Methods, and Biocontrol Strategies-A Review

Traditional dry-cured hams are easily contaminated by toxigenic fungi during the fermentation and ripening stages. The detection and positive rates of ochratoxin A (OTA) are the highest among mycotoxins detected in traditional dry-cured hams, indicating that OTA in hams is a potential safety hazard to human health. This review addresses the mycotoxin-producing fungal species, the toxigenic conditions causing OTA contamination worldwide, the prevalence of OTA contamination in dry-cured hams, and the detection methods applied in OTA analysis. Additionally, this study introduces methods to prevent and control OTA in traditional dry-cured hams. The growth of common mycotoxin-producing fungi and the accumulation of mycotoxins in dry-cured ham can be controlled by a microbial starter. This review provides an important theoretical foundation for the research and control of OTA in traditional dry-cured hams.

Sensitive, simultaneous and quantitative detection of deoxynivalenol and fumonisin B1 in the water environment using lateral flow immunoassay integrated with smartphone

Deoxynivalenol (DON) and fumonisin B₁ (FB₁), as a group of highly toxic secondary metabolites, have become a potential source of water environmental pollutants. To minimize two mycotoxins exposure to consumers, a dual lateral flow immunoassay (LFIA) integrated with the smartphone was reported for simultaneous and quantitative detection of DON and FB₁ in the water environment. The significantly improved sensitivity was contributed to a smartphone-based device with the ability to image and analyze results. Under optimized conditions, the detection limits of DON and FB₁ were calculated to be 3.46 and 2.65 ng/mL, which were approximately 25 and 10 folds lower than those of the visual detection of the LFIA. This method showed good specificity and a good dynamic linear detection for DON and FB₁. The recoveries of DON and FB₁ were evaluated by the spiked lake water, river water, and pond water, ranging from 92.47% to 106.2% with the relative standard deviation under 9.13%. Moreover, the results of the developed LFIA showed a high correlation with enzyme-linked immunosorbent assay (ELISA) results, with a correlation coefficient of 0.999 for DON and 0.996 for FB₁, respectively. To sum up, the developed LFIA provides a promising platform for sensitive, simultaneous, quantitative, and on-site detection of DON and FB₁ in the water environment.