Toxicant substitutes in immunological assays for mycotoxins detection: A mini review

Comparative evaluation of biological, physical, and chemical approaches for the mitigation of sterigmatocystin: Mycotoxin of growing concern

Sterigmatocystin is a carcinogenic and genotoxic mycotoxin that remains a significant health risk to human and animal populations. The present study examined three different methods (biological, physical, and chemical) for STC removal. The nanolignin indicated 81.76 ± 3.94 % removal of STC, with a reaction rate of 4.0 × 10-5 min-1. In the chemical-induced method, the application of gaseous ozone for effective removal and degradation of STC was studied. Ozone treatment resulted in 84.12 ± 4.23 % degradation of STC with a half-life of 15.51 min. The adsorption behaviour of lactic acid bacteria, in the biological method indicated a 79.75 ± 2.92 % removal of STC. Kinetic parameters and isotherms were analysed followed by parameter optimization by response surface methodology for maximum removal of STC. The requirement of less time and a relatively lower dose of ozone for removal of STC indicates this method to be a potential option for the mitigation of the toxin.

Nanobody-Based Immunoassays for the Detection of Food Hazards-A Review

Food safety remains a significant global challenge that affects human health. Various hazards, including microbiological and chemical threats, can compromise food safety throughout the supply chain. To address food safety issues and ensure public health, it is necessary to adopt rapid, accurate, and highly specific detection methods. Immunoassays are considered to be an effective method for the detection of highly sensitive biochemical indicators and provide an efficient platform for the identification of food hazards. In immunoassays, antibodies function as the primary recognition elements. Nanobodies have significant potential as valuable biomolecules in diagnostic applications. Their distinctive physicochemical and structural characteristics make them excellent candidates for the development of reliable diagnostic assays, and as promising alternatives to monoclonal and polyclonal antibodies. Herein, we summarize a comprehensive overview of the status and prospects of nanobody-based immunoassays in ensuring food safety. First, we begin with a historical perspective on the development of nanobodies and their unique characteristics. Subsequently, we explore the definitions and boundaries of immunoassays and immunosensors, before discussing the potential applications of nanobody-based immunoassays in food safety testing that have emerged over the past five years, and follow the different immunoassays, highlighting their advantages over traditional detection methods. Finally, the directions and challenges of nanobody-based immunoassays in food safety are discussed. Due to their remarkable sensitivity, specificity and versatility, nanobody-based immunoassays hold great promise in revolutionizing food safety testing and ensuring public health and well-being.

Mimotope peptides for nanobodies: A nontoxic alternative to ochratoxin A and its application in chemiluminescence immunoassays for analysis of pepper samples

Ochratoxin A (OTA) is a common food contaminant and poses a significant threat to human health, which requires rigorous monitoring. Mimotope peptides (MPs) are commonly used as non-toxic alternatives to toxic small molecules in eco-friendly immunoassays. Herein, with an anti-OTA nanobody as the target protein, cyclic 7-mer MPs of OTA were screened using phage display and immunomagnetic separation. The phage MPs (PMP) with the highest sensitivity and its alkaline phosphatase-tagged MP fusion (ALP-MP) were used to develop a PMP-based chemiluminescent immunoassay (PMP-CLIA) and an ALP-MP-based CLIA (AMP-CLIA). After optimization, PMP-CLIA and AMP-CLIA exhibited a limit of detection of 0.128 ng/mL and 0.232 ng/mL. Good accuracy and selectivity were confirmed for both CLIAs by recovery experiments and cross-reactions. Moreover, they were validated by high performance liquid chromatography in detecting real pepper samples. Thus, two CLIAs based on the nanobody and MPs were demonstrated as reliable tools for monitoring OTA in pepper.

On-site detection of OTA and AFB1 based on branched hybridization chain reaction coupled with lateral flow assay

Mycotoxins are widely prevalent in various agricultural commodities, whose excessive consumption can pose significant risks to human health. In this study, we developed a facile mycotoxin detection platform based on branched hybridization chain reaction coupled with lateral flow assay. Ochratoxin A/Aflatoxin B1 bind to aptamers triggering the release of initiators, which leads to bHCR amplification and forms three-dimensional dendritic DNA nanostructures. Using the functionalized quantum dots as a fluorescent label, by leveraging smartphones and handheld ultraviolet lamps, the qualitative and quantitative detection of OTA and AFB1 can be achieved with a significantly enhanced sensitivity level, surpassing that of commercial test strips by 2-3 orders of magnitude. The visual detection limits for OTA and AFB1 were 30 pg/mL and 4 pg/mL, respectively. This approach eliminates the necessity for enzyme catalysis or the preparation and purification of antibodies and/or hapten, thereby reducing testing expenses and streamlining operational procedures. Moreover, substituting aptamer and nucleic acid sequences can effectively expand the scope of detection targets. Consequently, the as-proposed strategy exhibits great potential as a versatile technique, suitable for various analytical scenarios due to its sensitivity, accuracy, simplicity, and portability.

Revolutionizing Cancer Treatment: Recent Advances in Immunotherapy

Cancer immunotherapy has emerged as a transformative approach in oncology, utilizing the body's immune system to specifically target and destroy malignant cells. This review explores the scope and impact of various immunotherapeutic strategies, including monoclonal antibodies, chimeric antigen receptor (CAR)-T cell therapy, checkpoint inhibitors, cytokine therapy, and therapeutic vaccines. Monoclonal antibodies, such as Rituximab and Trastuzumab, have revolutionized treatment paradigms for lymphoma and breast cancer by offering targeted interventions that reduce off-target effects. CAR-T cell therapy presents a potentially curative option for refractory hematologic malignancies, although challenges remain in effectively treating solid tumors. Checkpoint inhibitors have redefined the management of cancers like melanoma and lung cancer; however, managing immune-related adverse events and ensuring durable responses are critical areas of focus. Cytokine therapy continues to play a vital role in modulating the immune response, with advancements in cytokine engineering improving specificity and reducing systemic toxicity. Therapeutic vaccines, particularly mRNA-based vaccines, represent a frontier in personalized cancer treatment, aiming to generate robust, long-lasting immune responses against tumor-specific antigens. Despite these advancements, the field faces significant challenges, including immune resistance, tumor heterogeneity, and the immunosuppressive tumor microenvironment. Future research should address these obstacles through emerging technologies, such as next-generation antibodies, Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-based gene editing, and AI-driven drug discovery. By integrating these novel approaches, cancer immunotherapy holds the promise of offering more durable, less toxic, and highly personalized treatment options, ultimately improving patient outcomes and survival rates.

Shark anti-idiotypic variable new antigen receptor specific for an alpaca nanobody: Exploration of a nontoxic substitute to ochratoxin A in immunoassay

Nontoxic substitutes to mycotoxins can facilitate the development of eco-friendly immunoassays. To explore a novel nontoxic substitute to ochratoxin A (OTA), this study screened shark anti-idiotypic variable new antigen receptors (VNARs) against the alpaca anti-OTA nanobody Nb28 through phage display. After four rounds of biopanning of a naïve VNAR phage display library derived from six adult Chiloscyllium plagiosum sharks, one positive clone, namely, P-3, was validated through a phage enzyme-linked immunosorbent assay (phage ELISA). The recombinant anti-idiotypic VNAR AId-V3 was obtained by prokaryotic expression, and the interactions between Nb28 and AId-V3 were investigated via computer-assisted simulation. The affinity of AId-V3 for Nb28 and its heptamer Nb28-C4bpα was measured using Biacore assay. Combining Nb28-C4bpα with AId-V3, a novel direct competitive ELISA (dcELISA) was developed for OTA analysis, with a limit of detection of 0.44 ng/mL and a linear range of 1.77-32.25 ng/mL. The good selectivity, reliability, and precision of dcELISA were confirmed via cross-reaction analysis and recovery experiments. Seven commercial pepper powder samples were tested using dcELISA and validated using high-performance liquid chromatography. Overall, the shark anti-idiotypic VNAR was demonstrated as a promising nontoxic substitute to OTA, and the proposed method was confirmed as a reliable tool for detecting OTA in food.

Solar/ClO2 system inactivates fungal spores in drinking water: Synergy, efficiency and mechanisms

The risk of fungal pollution in drinking water has been paid attention. Solar/chlorine dioxide (ClO2) combined system is an environment-friendly, economical and efficient disinfection method, especially for countries and regions that are economically backward and still exposed to unsafe drinking water. In this paper, the kinetics, influencing factors, mechanism and regrowth potential of inactivated Aspergillus niger (A. niger) spores by solar/ClO2 were reported for the first time. The inactivation curve can be divided into three stages: instant inactivation within 1-2 min, slow linear inactivation and finally a tail. The synergistic factors produced by solar/ClO2 in terms of log reduction and maximum inactivation rate were 1.194 and 1.112, respectively. The inhibitory effect on the regrowth of A. niger spores inactivated by solar/ClO2 was also stronger than that by ClO2 alone. Strongly oxidizing reactive species produced by solar/ClO2 accelerated the accumulation of endogenic reactive oxygen species (ROS) caused by oxidation stress of A. niger spores, improving the inactivation ability of the system. The inactivation order of A. niger spores was: loss of culturability, accumulation of intracellular ROS, loss of membrane integrity, leakage of intracellular species and change of morphology. The inactivation performance of solar/ClO2 was better than solar/chlor(am)ine according to the comparison of inactivation efficiency and regrowth potential. Results also suggested that solar/ClO2 process was more suitable for the treatment of ground water sources.

A novel sustainable immunoassay for sensitive detection of atrazine based on the anti-idiotypic nanobody and recombinant full-length antibody

Immunoassays have been widely used to determine small-molecule compounds in food and the environment, meeting the challenge of obtaining false positive or negative results because of the variance in the batches of antibodies and antigens. To resolve this problem, atrazine (ATR) was used as a target, and anti-idiotypic nanobodies for ATR (AI-Nbs) and a recombinant full-length antibody against ATR (ATR-rAb) were prepared for the development of a sustainable enzyme-linked immunosorbent assay (ELISA). AI-Nb-7, AI-Nb-58, and AI-Nb-66 were selected from an immune phage display library. ATR-rAb was produced in mammalian HEK293 (F) cells. Among the four detection methods explored, the assay using AI-Nb-66 as a coating antigen and ATR-rAb as a detection reagent yielded a half maximal inhibitory concentration (IC50) of 1.66 ng mL-1 for ATR and a linear range of 0.35-8.73 ng mL-1. The cross-reactivity of the assay to ametryn was 64.24%, whereas that to terbutylazine was 38.20%. Surface plasmon resonance (SPR) analysis illustrated that these cross-reactive triazine compounds can bind to ATR-rAb to varying degrees at high concentrations; however, the binding/dissociation kinetic curves and the response values at the same concentration are different, which results in differences in cross-reactivity. Homology modeling and molecular docking revealed that the triazine ring is vital in recognizing triazine compounds. The proposed immunoassay exhibited acceptable recoveries of 84.40-105.36% for detecting fruit, vegetables, and black tea. In conclusion, this study highlights a new strategy for developing sustainable immunoassays for detecting trace pesticide contaminants.

Generation of anti-idiotypic antibodies mimicking Cry2Aa toxin from an immunized mouse phage display library as potential insecticidal agents against Plutella xylostella

This study tried to generate anti-idiotypic antibodies (Ab2s) which mimic Cry2Aa toxin using a phage-display antibody library (2.8 × 107 CFU/mL). The latter was constructed from a mouse immunized with F (ab')2 fragments digested from anti-Cry2Aa polyclonal antibodies. The F (ab')2 fragments and Plutella xylostella (P. xylostella) brush border membrane vesicles (BBMV) were utilized as targets for selection. Eight mouse phage-display single-chain variable fragments (scFvs) were isolated and identified by enzyme-linked immunoassay (ELISA), PCR and DNA sequencing after four rounds of biopanning. Among them, M3 exhibited the highest binding affinity with F (ab')2, while M4 bound the best with the toxin binding region of cadherin of P. xylostella (PxCad-TBR). Both of these two fragments were chosen for prokaryotic expression. The expressed M3 and M4 proteins with molecular weights of 30 kDa were purified. The M4 showed a binding affinity of 29.9 ± 2.4 nM with the PxCad-TBR and resulted in 27.8 ± 4.3 % larvae mortality against P. xylostella. Computer-assisted molecular modeling and docking analysis showed that mouse scFv M4 mimicked some Cry2Aa toxin binding sites when interacting with PxCad-TBR. Therefore, anti-idiotypic antibodies generated by BBMV-based screening could be useful for the development of new bio-insecticides as an alternative to Cry2Aa toxin for pest control.

Combination of nanobody and peptidomimetic to develop novel immunoassay platforms for detecting ochratoxin A in cereals

Mimotope-based immunoassays for mycotoxins eliminate the requirement for large amounts of mycotoxin standards for the chemosynthesis of artificial antigens. Herein, the nanobody-based magnetic beads were used to screen the mimotope (peptidomimetic) of ochratoxin A (OTA) from the phage-displayed peptide library. The interactions between nanobody and the most sensitive Y4 peptidomimetic were investigated by computer-assisted simulation and compared with those between nanobody and OTA. By combining the nanobody, the phage-displayed Y4 and alkaline phosphatase-tagged Y4 fusion protein as the competing antigens, were used to develop two novel immunoassay platforms (PN-ELISA and APN-ELISA). The two methods are advantageous in the use of nontoxic substitutes of OTA and avoiding the use of monoclonal antibodies. Moreover, good analytical performances of both methods were obtained and confirmed by liquid chromatography tandem mass spectrometry. Therefore, the proposed novel methods based on nanobody and peptidomimetic were demonstrated to be highly reliable for detecting OTA in food.

Nanoassemblies Based on a Cationic Perylene Diimide Derivative and Sodium Dodecyl Sulfate: A Simple Fluorescent Platform for Efficient Analysis of Aflatoxin B1

Aflatoxin B₁ (AFB₁) is a kind of potently carcinogenic fungal metabolite in food threatening human health, and it is crucial and challenging to develop advanced nonimmune approaches for AFB₁ determination. Addressing this challenge, we successfully constructed a nanoassembly (PdE-PDI/SDS) by noncovalently coupling a cationic perylene diimide derivative (PdE-PDI) and sodium dodecyl sulfate (SDS), exhibiting high-density charges and a specific surface area for rapid sensing of AFB₁. The large electronic conjugate structure and rigid plane of PdE-PDI enable it to form more stable σ-π, π-π coordination, and hydrogen bonds with AFB₁. Additionally, the introduction of SDS significantly amplifies noncovalent interactions and enhances the quenching efficiency of PdE-PDI toward AFB₁. The proposed PdE-PDI/SDS exhibited excellent specificity to AFB₁ and showed dosage-sensitive detection with detection limit as low as 0.74 ng mL^-1. Finally, the PdE-PDI/SDS was successfully applied in cereal samples with good recoveries from 94.61 to 109.92%. To our knowledge, this is the first time a fluorescent strategy from the point of self-assembly for AFB₁ determination is reported, which holds great promise for wide applications of perylene diimide derivative in food safety.

Kinetics of Immunolatex Deposition at Abiotic Surfaces under Flow Conditions: Towards Quantitative Agglutination Assays

Physicochemical properties of immunolatex, prepared by incubation of negatively charged polystyrene microparticles with polyclonal rabbit IgGs, were determined by a variety of experimental techniques. These comprised dynamic light scattering (DLS), laser Doppler velocimetry (LDV) and atomic force microscopy (AFM). The particle diffusion coefficient, the hydrodynamic diameter, the electrophoretic mobility, the zeta potential and the suspension stability were determined as a function of pH for different ionic strengths. The deposition of the immunolatex on bare and polyallylamine (PAH) functionalized mica was investigated using the microfluidic oblique impinging-jet cell, with an in situ, real-time image analysis module. The particle deposition kinetics was acquired by a direct particle enumeration procedure. The measurements enabled us to determine the range of pH where the specific deposition of the immunolatex on these substrates was absent. We argue that the obtained results have practical significance for conducting efficient flow immunoassays governed by specific antigen/antibody interactions.

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.

CRISPR-Cas-based detection for food safety problems: Current status, challenges, and opportunities

Food safety is one of the biggest public issues occurring around the world. Microbiological, chemical, and physical hazards can lead to food safety issues, which may occur at all stages of the supply chain. In order to tackle food safety issues and safeguard consumer health, rapid, accurate, specific, and field-deployable detection methods meeting diverse requirements are one of the imperative measures for food safety assurance. CRISPR-Cas system, a newly emerging technology, has been successfully repurposed in biosensing and has demonstrated huge potential to establish conceptually novel detection methods with high sensitivity and specificity. This review focuses on CRISPR-Cas-based detection and its current status and huge potential specifically for food safety inspection. We firstly illustrate the pending problems in food safety and summarize the popular detection methods. We then describe the potential applications of CRISPR-Cas-based detection in food safety inspection. Finally, the challenges and futuristic opportunities are proposed and discussed. Generally speaking, the current food safety detection methods are still unsatisfactory in some ways such as being time-consuming, displaying unmet sensitivity and specificity standards, and there is a comparative paucity of multiplexed testing and POCT. Recent studies have shown that CRISPR-Cas-based biosensing is an innovative and fast-expanding technology, which could make up for the shortcomings of the existing methods or even replace them. To sum up, the implementation of CRISPR-Cas and the integration of CRISPR-Cas with other techniques is promising and desirable, which is expected to provide "customized" and "smart" detection methods for food safety inspection in the coming future.

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.

The recent development of nanozymes for food quality and safety detection

As potential mimics of natural enzymes, nanozymes overcome many disadvantages of natural enzymes such as complex preparation and purification process, high price, poor stability and low recycling efficiency. Combined with...

Mimotope-Based Immunoassays for the Rapid Analysis of Mycotoxin: A Review

Mycotoxins are toxic contaminants in foods and feeds that are naturally occurring and largely unavoidable. Determining their contents in these products is essential to protect humans from harm. Immunoassays of mycotoxins have been well-established because they are fast, sensitive, simple, and cost-effective. However, a major limitation of immunoassays is the requirement of toxic mycotoxins as competing antigens, standards, or competing tracers. Mimotopes are peptides or proteins that can specifically bind to antibodies and compete with analytes for binding sites by mimicking antigenic epitopes. They can be employed as substitutes for competing antigens, standards, or competing tracers to avoid use of mycotoxins. This review summarizes the production and functionalization of the two main kinds of mimotopes, mimic peptides and anti-idiotypic antibodies (Ab2), and their applications in rapid analysis of mycotoxins.

Construction of Bio-Nano Interfaces on Nanozymes for Bioanalysis

Nanomaterials with enzyme-like activity (nanozymes) have been of great interest in broad applications ranging from biosensing to biomedical applications. Despite that much effort has been devoted to the development of the synthesis and applications of nanozymes, it is essential to understand the interactions between nanozymes and most commonly used biomolecules, i.e., avidin, streptavidin (SA), bovine serum albumin (BSA), immunoglobulin G (IgG), and glutathione (GSH), yet they have been rarely explored. Here, a series of bio-nano interfaces were constructed through direct immobilization of proteins on a variety of iron oxide and carbon-based nanozymes with different dimensions, including Fe₃O₄ nanoparticles (NPs, 0D), Fe₃O₄@C NPs (0D), Fe₃O₄@C nanowires (NWs, 1D), and graphene oxide nanosheets (GO NSs, 2D). Such interfaces enabled the modulation of the catalytic activities of the nanozymes with varying degrees, which allowed a good identification of multiplex proteins with high accuracy. Given the maximum inhibition on Fe₃O₄@C NP by BSA, we established molecular switches based on aptamer and toehold DNA, as well as Boolean logic gates (AND and NOR) in response to both DNA and proteins. Also importantly, we developed an on-particle reaction strategy for colorimetric detection of GSH with ultrahigh sensitivity and good specificity. The proposed sensor achieved a broad dynamic range spanning 7 orders of magnitude with a detection limit down to 200 pg mL^-1, which was better than that of an in-solution reaction-based biosensor by 2 orders of magnitude. Furthermore, we explored the mechanisms of the interactions at bio-nano interfaces by studying the interfacial factors, including surface coverage, salt concentration, and the curvature of the nanozyme. This study offered new opportunities in the elaborate design and better utilization of nanozymes for bioanalysis in clinical diagnosis and in vivo detection.