Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

Contributing to the management of viral infections through simple immunosensing of the arachidonic acid serum level

A trendsetting direct competitive-based biosensing tool has been developed and implemented for the determination of the polyunsaturated fatty acid arachidonic acid (ARA), a highly significant biological regulator with decisive roles in viral infections. The designed methodology involves a competitive reaction between the target endogenous ARA and a biotin-ARA competitor for the recognition sites of anti-ARA antibodies covalently attached to the surface of carboxylic acid-coated magnetic microbeads (HOOC-MµBs), followed by the enzymatic label of the biotin-ARA residues with streptavidin-horseradish peroxidase (Strep-HRP) conjugate. The resulting bioconjugates were magnetically trapped onto the sensing surface of disposable screen-printed carbon transducers (SPCEs) to monitor the extent of the biorecognition reaction through amperometry. The operational functioning of the exhaustively optimized and characterized immunosensing bioplatform was highly convenient for the quantitative determination of ARA in serum samples from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-) and respiratory syncytial virus (RSV)-infected individuals in a rapid, affordable, trustful, and sensitive manner.

Recent Advances in Electrochemical Sensing Strategies for Food Allergen Detection

Food allergy has been indicated as the most frequent adverse reaction to food ingredients over the past few years. Since the only way to avoid the occurrence of allergic phenomena is to eliminate allergenic foods, it is essential to have complete and accurate information on the components of foodstuff. In this framework, it is mandatory and crucial to provide fast, cost-effective, affordable, and reliable analysis methods for the screening of specific allergen content in food products. This review reports the research advancements concerning food allergen detection, involving electrochemical biosensors. It focuses on the sensing strategies evidencing different types of recognition elements such as antibodies, nucleic acids, and cells, among others, the nanomaterial role, the several electrochemical techniques involved and last, but not least, the ad hoc electrodic surface modification approaches. Moreover, a selection of the most recent electrochemical sensors for allergen detection are reported and critically analyzed in terms of the sensors’ analytical performances. Finally, advantages, limitations, and potentialities for practical applications of electrochemical biosensors for allergens are discussed.

Tracking Arachis hypogaea Allergen in Pre-Packaged Foodstuff: A Nanodiamond-Based Electrochemical Biosensing Approach

The present work reports a nanodiamond-based voltammetric immunosensing platform for the analysis of a food allergen (Ara h 1) present in peanuts (Arachis hypogaea). The possibility of the usage of nanodiamonds (d = 11.2 ± 0.9 nm) on screen-printed carbon electrodes (SPCE/ND) in a single-use two-monoclonal antibody sandwich assay was studied. An enhanced electroactive area (~18%) was obtained and the biomolecule binding ability was improved when the 3D carbon-based nanomaterial was used. The antibody-antigen interaction was recognized through the combination of alkaline phosphatase with 3-indoxyl phosphate and silver ions. Linear Sweep Voltammetry (LSV) was applied for fast signal acquisition and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) support the voltammetric approach and confirm the presence of silver particles on the electrode surface. The proposed immunosensor provided a low limit of detection (0.78 ng·mL−1) and highly precise (RSD < 7.5%) and accurate results. Quantification of Ara h 1 in commercial foodstuffs (e.g., crackers, cookies, protein bars) that refer to the presence of peanuts (even traces) on the product label was successfully achieved. The obtained data were in accordance with recovery results (peanut addition, %) and the foodstuff label. Products with the preventive indication “may contain traces” revealed the presence of peanuts lower than 0.1% (m/m). The method’s results were validated by comparison with an enzyme-linked immunosorbent assay. This allows confident information about the presence of allergens (even at trace levels) that leads to profitable conditions for both industry and consumers.

An immunochromatographic assay utilizing magnetic nanoparticles to detect major peanut allergen Ara h 1 in processed foods

This study describes an immunomagnetic nanoparticle (IMNP)-based lateral flow assay (LFA) for detecting the major peanut allergen Ara h 1. We developed a clearly specific method in identifying peanut from ten other seeds and nuts, and a good visual limit of detection (vLOD) of 0.01 μg/mL Ara h 1 in PBS. PBS that contains 1 M NaCl and 2% Tween 20 was determined to be the optimal extraction buffer for isolating Ara h 1 from cookie, milk and chocolate with vLOD values of 0.5 μg/g, 0.5 μg/mL, and 1 μg/g, respectively. Forty two processed foods were simultaneously analyzed using this method and an AOAC-approved ELISA kit. The specificity and sensitivity of this assay were thus determined to be 100 and 95%, respectively. This new IMNP-based LFA has potential as a rapid tool for screening processed foods for Ara h 1 residues.

Voltammetric Immunosensor to Track a Major Peanut Allergen (Ara h 1) in Food Products Employing Quantum Dot Labels

Tracking unreported allergens in commercial foods can avoid acute allergic reactions. A 2-step electrochemical immunosensor was developed for the analysis of the peanut allergen Ara h 1 in a 1-h assay (<15 min hands-on time). Bare screen-printed carbon electrodes (SPCE) were used as transducers and monoclonal capture and detection antibodies were applied in a sandwich-type immunoassay. The short assay time was achieved by previously combining the target analyte and the detection antibody. Core/shell CdSe@ZnS Quantum Dots were used as electroactive label for the detection of the immunological interaction by differential pulse anodic stripping voltammetry. A linear range between 25 and 1000 ng·mL-1 (LOD = 3.5 ng·mL-1), an adequate precision of the method (Vx0 ≈ 6%), and a sensitivity of 23.0 nA·mL·ng-1·cm-2 were achieved. The immunosensor was able to detect Ara h 1 in a spiked allergen-free product down to 0.05% (m/m) of peanut. Commercial organic farming cookies and cereal and protein bars were tested to track and quantify Ara h 1. The results were validated by comparison with an ELISA kit.

Advances on the rapid and multiplex detection methods of food allergens

With the gradually increasing prevalence of food allergy in recent years, food allergy has become a major public health problem worldwide. The clinical symptoms caused by food allergy seriously affect people's quality of life; there are unknown allergen components in novel food and hidden allergens caused by cross contamination in food processing, which pose a serious risk to allergy sufferers. Thus, rapid and multiplex detection methods are required to achieve on-site detection or examination of allergic components, so as to identify the risk of allergy in time. This paper reviews the progress of high-efficiency detection of food allergens, including enhanced traditional detection techniques and emerging detection techniques with the ability high-throughput detection or screening potential food allergen, such as xMAP, biosensors, biochips, etc. focusing on their sensitivity, applicability of each method in food, along with their pretreatment, advantages, limitation in the application of food analysis. This paper also introduces the challenges faced by these high-efficiency detection technologies, as well as the potential of customized allergen screening methods and rapid on-site detection technology as future research directions.

Surface plasmon resonance (SPR) biosensors for food allergen detection in food matrices

Food allergies are recognized as a growing public health concern, with an estimated 3% of adults and 6-8% of children affected by food allergy disorders. Hence, food allergen detection, labeling, and management have become significant priorities within the food industry, and there is an urgent requirement for reliable, sensitive, and user-friendly technologies to trace food allergens in food products. In this critical review, we provide a comprehensive overview of the principles and applications of surface plasmon resonance (SPR) biosensors in the identification and quantification of food allergens (milk, egg, peanut, and seafood), including fiber-optic surface plasmon resonance (FOSPR), surface plasmon resonance imaging (SPRI), localized surface plasmon resonance (LSPR), and transmission surface plasmon resonance (TSPR). Moreover, the characteristics and fitness-for-purpose of each reviewed SPR biosensor is discussed, and the potential of newly developed SPR biosensors for multi-allergen real-time detection in a complex food system is highlighted. Such SPR biosensors are also required to facilitate the reliable, high-throughput, and real-time detection of food allergens by the food control industry and food safety control officials to easily monitor cross-contamination during food processing.

Magnetic nanoparticles for smart electrochemical immunoassays: a review on recent developments

This review (with 129 refs) summarizes the progress in electrochemical immunoassays combined with magnetic particles that was made in the past 5 years. The specifity of antibodies linked to electrochemical transduction (by amperometry, voltammetry, impedimetry or electrochemiluminescence) gains further attractive features by introducing magnetic nanoparticles (MNPs). This enables fairly easy preconcentration of analytes, minimizes matrix effects, and introduces an appropriate label. Following an introduction into the fundamentals of electrochemical immunoassays and on nanomaterials for respective uses, a large chapter addresses method for magnetic capture and preconcentration of analytes. A next chapter discusses commonly used labels such as dots, enzymes, metal and metal oxide nanoparticles and combined clusters. The large field of hybrid nanomaterials for use in such immunoassays is discussed next, with a focus on MNPs composites with various kinds of graphene variants, polydopamine, noble metal nanoparticles or nanotubes. Typical applications address clinical markers (mainly blood and urine parameters), diagnosis of cancer (markers and cells), detection of pathogens (with subsections on viruses and bacteria), and environmental and food contaminants as toxic agents and pesticides. A concluding section summarizes the present status, current challenges, and highlights future trends. Graphical abstract Magnetic nanoparticles (MNP) with antibodies (Ab) capture and preconcentrate analyte from sample (a) and afterwards become magnetically (b) or immunospecifically (c) bound at an electrode. Signal either increases due to the presence of alabel (b) or decreases as the redox probe is blocked (c).

Electrochemical sensor for rapid determination of fibroblast growth factor receptor 4 in raw cancer cell lysates

The first electrochemical immunosensor for the determination of fibroblast growth factor receptor 4 (FGFR4) biomarker is reported in this work. The biosensor involves a sandwich configuration with covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic microcarriers (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs). The biosensor exhibits a great analytical performance regarding selectivity for the target protein and a low LOD of 48.2 pg mL^-1. The electrochemical platform was successfully applied for the determination of FGFR4 in different cancer cell lysates without any apparent matrix effect after a simple sample dilution and using only 2.5 μg of the raw lysate. Comparison of the results with those provided by a commercial ELISA kit shows competitive advantages by using the developed immunosensor in terms of simplicity, analysis time, and portability and cost-affordability of the required instrumentation for the accurate determination of FGFR4 in cell lysates.

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface.

Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered.

Standardization and Regulation of Allergen Products in the European Union

Product-specific standardization is of prime importance to ensure persistent quality, safety, and efficacy of allergen products. The regulatory framework in the EU has induced great advancements in the field in the last years although national implementation still remains heterogeneous. Scores of methods for quantification of individual allergen molecules are developed each year and also the challenging characterization of chemically modified allergen products is progressing. However, despite the unquestionable increase in knowledge and the subsequent improvements in control of quality parameters of allergen products, an important aim has not been reached yet, namely cross-product comparability. Still, comparison of allergen product potency, either based on total allergenic activity or individual allergen molecule content, is not possible due to a lack of standard reference preparations in conjunction with validated standard methods. This review aims at presenting the most recent developments in product-specific standardization as well as activities to facilitate cross-product comparability in the EU.

Electrochemical immunosensor for sensitive determination of transforming growth factor (TGF) - β1 in urine

The first amperometric immunosensor for the quantification of TGF-β1, a cytokine proposed as a biomarker for patients having or at risk for renal disease, is described in this work. The immunosensor design involves disposable devices using carboxylic acid-functionalized magnetic microparticles supported onto screen-printed carbon electrodes and covalent immobilization of the specific antibody for TGF-β1 using Mix&Go polymer. A sandwich-type immunoassay was performed using biotin-anti-TGF and conjugation with peroxidase-labeled streptavidin (poly-HRP-Strept) polymer. Amperometric measurements were carried out at -0.20V by adding hydrogen peroxide solution onto the electrode surface in the presence of hydroquinone as the redox mediator. The calibration plot allowed a range of linearity extending between 15 and 3000pg/mL TGF-β1 which is adequate for the determination of the cytokine in plasma and urine. The limit of detection, 10pg/mL, is notably improved with respect to those obtained with ELISA kits. The usefulness of the immunosensor for the determination of low TGF-β1 concentrations in real samples was evaluated by analyzing spiked urine at different pg/mL concentration levels.

Development of a real-time quantitative PCR assay using a TaqMan minor groove binder probe for the detection of α-lactalbumin in food

Here, we report the development of a real-time PCR assay using a TaqMan minor groove binder (MGB, Genecore, NCBI: AF249896.1, 806-820) probe and primer sets designed to recognize the α-lactalbumin gene from the cow (Bos taurus). We evaluated the efficacy of this assay for detecting and quantifying cow α-lactalbumin in commercial foods. Our results demonstrated that the developed method was highly sensitive and showed high specificity for cow milk, with consistent detection of 0.05 ng of bovine DNA. We tested 42 commercial food samples with or without cow milk listed as an ingredient by using the developed assay. Among the 42 samples, 26 products that listed milk as an ingredient and 3 products might contain milk showed positive signals, whereas the other 9 products that did not contain milk and 4 products that might contain milk tested negative. Therefore, this method could be widely used for the detection of cow milk allergens in food.