Giant magnetoresistive sensor array for sensitive and specific multiplexed food allergen detection

Adaptive biosensing platform using immune cell-based nanovesicles for food allergen detection

Inspired by an adaptive immune system, we have developed a bioelectronic sensing platform which relies on nanovesicles for a signal amplification and can be easily adapted for the detection of new food allergens. In this work, nanovesicles with anti-immunoglobulin E (anti-IgE) antibody receptors were extracted from immune cells and immobilized on a carbon nanotube-based transistor to build a highly sensitive and selective biosensing platform. Our sensor could detect peanut allergen, arachis hypogaea 2 (Ara h 2), down to 0.1 fM and selectively discriminate target allergens in real food samples such as peanut and egg white. As a proof of concept, we demonstrated the detection of different target molecules using the same nanovesicles linked with different antibodies. Our sensor platform was also utilized to quantitatively evaluate the effect of allergy drug such as cromolyn. In this regard, our strategy can be utilized for basic research and versatile applications in food and pharmacological industries.

Giant Magnetoresistance Biosensors for Food Safety Applications

Nowadays, the increasing number of foodborne disease outbreaks around the globe has aroused the wide attention of the food industry and regulators. During food production, processing, storage, and transportation, microorganisms may grow and secrete toxins as well as other harmful substances. These kinds of food contamination from microbiological and chemical sources can seriously endanger human health. The traditional detection methods such as cell culture and colony counting cannot meet the requirements of rapid detection due to some intrinsic shortcomings, such as being time-consuming, laborious, and requiring expensive instrumentation or a central laboratory. In the past decade, efforts have been made to develop rapid, sensitive, and easy-to-use detection platforms for on-site food safety regulation. Herein, we review one type of promising biosensing platform that may revolutionize the current food surveillance approaches, the giant magnetoresistance (GMR) biosensors. Benefiting from the advances of nanotechnology, hundreds to thousands of GMR biosensors can be integrated into a fingernail-sized area, allowing the higher throughput screening of food samples at a lower cost. In addition, combined with on-chip microfluidic channels and filtration function, this type of GMR biosensing system can be fully automatic, and less operator training is required. Furthermore, the compact-sized GMR biosensor platforms could be further extended to related food contamination and the field screening of other pathogen targets.

Giant Magnetoresistance Biosensors in Biomedical Applications

The giant magnetoresistance (GMR) effect has seen flourishing development from theory to application in the last three decades since its discovery in 1988. Nowadays, commercial devices based on the GMR effect, such as hard-disk drives, biosensors, magnetic field sensors, microelectromechanical systems (MEMS), etc., are available in the market, by virtue of the advances in state-of-the-art thin-film deposition and micro- and nanofabrication techniques. Different types of GMR biosensor arrays with superior sensitivity and robustness are available at a lower cost for a wide variety of biomedical applications. In this paper, we review the recent advances in GMR-based biomedical applications including disease diagnosis, genotyping, food and drug regulation, brain and cardiac mapping, etc. The GMR magnetic multilayer structure, spin valve, and magnetic granular structure, as well as fundamental theories of the GMR effect, are introduced at first. The emerging topic of flexible GMR for wearable biosensing is also included. Different GMR pattern designs, sensor surface functionalization, bioassay strategies, and on-chip accessories for improved GMR performances are reviewed. It is foreseen that combined with the state-of-the-art complementary metal-oxide-semiconductor (CMOS) electronics, GMR biosensors hold great promise in biomedicine, particularly for point-of-care (POC) disease diagnosis and wearable devices for real-time health monitoring.

Current Progress of Magnetoresistance Sensors

Magnetoresistance (MR) is the variation of a material’s resistivity under the presence of external magnetic fields. Reading heads in hard disk drives (HDDs) are the most common applications of MR sensors. Since the discovery of giant magnetoresistance (GMR) in the 1980s and the application of GMR reading heads in the 1990s, the MR sensors lead to the rapid developments of the HDDs’ storage capacity. Nowadays, MR sensors are employed in magnetic storage, position sensing, current sensing, non-destructive monitoring, and biomedical sensing systems. MR sensors are used to transfer the variation of the target magnetic fields to other signals such as resistance change. This review illustrates the progress of developing nanoconstructed MR materials/structures. Meanwhile, it offers an overview of current trends regarding the applications of MR sensors. In addition, the challenges in designing/developing MR sensors with enhanced performance and cost-efficiency are discussed in this review.

Visible on-site detection of Ara h 1 by the switchable-linker-mediated precipitation of gold nanoparticles

Biosensors have been widely applied in tests for allergens, but on-site detection remains a challenge. Herein, we proposed a detection procedure for peanut Ara h 1 as a representative allergen, which was extracted from a cookie, thereby minimising the need for any complex pretreatment that was difficult to perform, and enabling the visual detection of the target without the use of analytical equipment. The extraction procedure was performed in less than 30 min using a syringe and filter (0.45 μm). The detection method for Ara h 1 was based on the aggregation of switchable linkers (SL) and gold nanoparticles (AuNP), and the presence of 0.19 mg peanut protein per 30 g of cookie could be confirmed within 30 min based on the AuNP/SL concentration ratio by the precipitation. This proposed procedure could be successfully applied to the detection of a wide range of food allergens.

A Systematic Review of Food Allergy: Nanobiosensor and Food Allergen Detection

Several individuals will experience accidental exposure to an allergen. In this sense, the industry has invested in the processes of removing allergenic compounds in food. However, accidental exposure to allergenic proteins can result from allergenic substances not specified on labels. Analysis of allergenic foods is involved in methods based on immunological, genetic, and mass spectrometry. The traditional methods have some limitations, such as high cost. In recent years, biosensor and nanoparticles combined have emerged as sensitive, selective, low-cost, and time-consuming techniques that can replace classic techniques. Nevertheless, each nanomaterial has shown a different potential to specific allergens or classes. This review used Preferred Reporting Items for Systematic Reviews and the Meta-Analysis guidelines (PRISMA) to approach these issues. A total of 104 articles were retrieved from a standardized search on three databases (PubMed, Scopus and Web of Science). The systematic review article is organized by the category of allergen detection and nanoparticle detection. This review addresses the relevant biosensors and nanoparticles as gold, carbon, graphene, quantum dots to allergen protein detection. Among the selected articles it was possible to notice a greater potential application on the allergic proteins Ah, in peanuts and gold nanoparticle-base as a biosensor. We envision that in our review, the association between biosensor and nanoparticles has shown promise in the analysis of allergenic proteins present in different food samples.

Early Multiplexed Detection of Cirrhosis using Giant Magnetoresistive Biosensors with Protein Biomarkers

Liver cirrhosis is one of the leading causes of death in adults worldwide. It is highly prevalent in developing countries and is growing in prevalence in developed countries mostly because of chronic liver diseases, such as chronic hepatitis B and C and alcoholic and nonalcoholic fatty liver disease. However, the prevalence of cirrhosis may be highly underestimated because early stages are asymptomatic and current early detection methods are inadequate. Here, we evaluate the potential of a set of novel cirrhotic protein biomarkers, including soluble intercellular adhesion molecule-1 and mac-2 binding protein glycosylation isomer, for early detection of cirrhosis in a multiplexed assay using our giant magnetoresistive (GMR) sensor arrays. We evaluated the diagnostic performance of the biomarkers, individually and in combination, using multivariate logistic regression and random forest in a blinded proof-of-concept retrospective case-controlled study. The biomarkers in combination exhibited high diagnostic performance in both logistic regression and random forest models, with an area under the curve of 0.98 (0.94-1.00). In addition, the combination of biomarkers resulted in a high sensitivity of 0.97 (0.95-1.00) and a high specificity of 1.00. We showed that the diagnostic performance of our novel set of cirrhotic protein biomarkers on our multiplexed GMR sensor arrays is higher than the performance of currently used clinical biomarkers and factors (i.e., age, sex, alanine aminotransferase, aspartate aminotransferase, etc.). With this combination of novel biomarkers and GMR technology, we could potentially boost the diagnostic power of early cirrhosis detection.

Point-of-Care Diagnostics: Molecularly Imprinted Polymers and Nanomaterials for Enhanced Biosensor Selectivity and Transduction

Significant healthcare disparities resulting from personal wealth, circumstances of birth, education level, and more are internationally prevalent. As such, advances in biomedical science overwhelmingly benefit a minority of the global population. Point-of-Care Testing (POCT) can contribute to societal equilibrium by making medical diagnostics affordable, convenient, and fast. Unfortunately, conventional POCT appears stagnant in terms of achieving significant advances. This is attributed to the high cost and instability associated with conventional biorecognition: primarily antibodies, but nucleic acids, cells, enzymes, and aptamers have also been used. Instead, state-of-the-art biosensor researchers are increasingly leveraging molecularly imprinted polymers (MIPs) for their high selectivity, excellent stability, and amenability to a variety of physical and chemical manipulations. Besides the elimination of conventional bioreceptors, the incorporation of nanomaterials has further improved the sensitivity of biosensors. Herein, modern nanobiosensors employing MIPs for selectivity and nanomaterials for improved transduction are systematically reviewed. First, a brief synopsis of fabrication and wide-spread challenges with selectivity demonstration are presented. Afterward, the discussion turns to an analysis of relevant case studies published in the last five years. The analysis is given through two lenses: MIP-based biosensors employing specific nanomaterials and those adopting particular transduction strategies. Finally, conclusions are presented along with a look to the future through recommendations for advancing the field. It is hoped that this work will accelerate successful efforts in the field, orient new researchers, and contribute to equitable health care for all.

Biomarkers detection with magnetoresistance-based sensors

Biosensing platforms for detecting and quantifying biomarkers have played an important role in the past decade. Among them, platforms based on magnetoresistance (MR) sensing technology are attractive. The resistance value of the material changes with the externally applied magnetic field is the core mechanism of MR sensing technology. A typical MR-based sensor has the characteristics of cost-effective, simple operation, high compactness, and high sensitivity. Moreover, using magnetic nanoparticles (MNPs) as labels, MR-based sensors have the ability to overcome the high background noise of complex samples, so they are particularly suitable for point-of-care testing (POCT). However, the problem still exists. How to obtain high-throughput, that is, multiple detections of biomarkers in MR-based sensors, thereby improving detection efficiency and reducing the burden on patients is an important issue in future work. This paper reviews three MR-based detection technologies for the detection of biomarkers, i.e., anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunneling magnetoresistance (TMR). Based on these three common technologies, different typical applications that include biomedical diagnosis, food safety, and environmental monitoring are presented. Furthermore, the existing MR-based detection method is better expanded to make it more in line with present detection needs by combining different advanced technologies including microfluidics, Microelectromechanical systems (MEMS), and Immunochromatographic test strips (ICTS). And then, a brief discussion of current challenges and perspectives of MR-based sensors are pointed out.

The Pros and Cons of Using Oat in a Gluten-Free Diet for Celiac Patients

A therapeutic gluten-free diet often has nutritional limitations. Nutritional qualities such as high protein content, the presence of biologically active and beneficial substances (fiber, beta-glucans, polyunsaturated fatty acids, essential amino acids, antioxidants, vitamins, and minerals), and tolerance by the majority of celiac patients make oat popular for use in gluten-free diet. The health risk of long-time consumption of oat by celiac patients is a matter of debate. The introduction of oat into the diet is only recommended for celiac patients in remission. Furthermore, not every variety of oat is also appropriate for a gluten-free diet. The risk of sensitization and an adverse immunologically mediated reaction is a real threat in some celiac patients. Several unsolved issues still exist which include the following: (1) determination of the susceptibility markers for the subgroup of celiac patients who are at risk because they do not tolerate dietary oat, (2) identification of suitable varieties of oat and estimating the safe dose of oat for the diet, and (3) optimization of methods for detecting the gliadin contamination in raw oat used in a gluten-free diet.

Immunological Methods in Gluten Risk Analysis: A Snapshot

Gluten is among the 14 major food allergens officially recognized by Regulation (EU) No. 1169/2011. The risk to coeliac patients from gluten presence in the food products they consume is likely due to the unintentional contamination of naturally gluten-free (GF) and GF-labelled products, or to hidden sources of gluten in processed GF products. The aim of this paper is to provide a snapshot of gluten risk analysis, with emphasis on immunological methods currently used in gluten detection. The study highlights that immunoassays have some advantages over other analytical methods in gluten determination and are suitable for routine tests. However, some factors (e.g., complexity of the food matrix, type of the applied antibody, gluten extraction procedures and lack of reference material) affect the reliability of obtained results. Hence, efforts are required at an analytical level to overcome the drawbacks of the immunological methods currently available. Harmonization is necessary, so as to assist both consumers in making safe food choices, and the food industry in gluten risk assessment, management and communication.

Magneto-nanosensor smartphone platform for the detection of HIV and leukocytosis at point-of-care

The advent of personalized medicine has brought an increased interest in personal health among general consumers. As a result, there is a great need for user-centric point-of-care (POC) health devices. Such devices are equally pertinent in developing countries or resource-limited settings for performing diagnostic tests. However, current POC tests for diseases such as human immunodeficiency virus (HIV) or leukocytosis do not provide adequate levels of sensitivity or do not exist at all. Here, we extend our mobile magneto-nanosensor platform to point-of-care HIV and leukocytosis detection. The platform can be multiplexed, and the circuitry enables portability and sensitivity in the POC setting. A smartphone application simplifies operation and provides guidance to facilitate self-testing. Commercially available POC test kits typically provide only qualitative or semi-quantitative results of a single analyte. The magneto-nanosensor platform can provide users with pleasant user-experience while demonstrating robust sensitive and specific multiplexed quantification and detection of common diseases.

Quantification of cDNA on GMR biosensor array towards point-of-care gene expression analysis

Gene expression analysis at the point-of-care is important for rapid disease diagnosis, but traditional techniques are limited by multiplexing capabilities, bulky equipment, and cost. We present a gene expression analysis platform using a giant magnetoresistive (GMR) biosensor array, which allows multiplexed transcript detection and quantification through cost-effective magnetic detection. In this work, we have characterized the sensitivity, dynamic range, and quantification accuracy of Polymerase chain reaction (PCR)-amplified complementary DNA (cDNA) on the GMR for the reference gene GAPDH. A synthetic GAPDH single-stranded DNA (ssDNA) standard was used to calibrate the detection, and ssDNA dilutions were qPCR-amplified to obtain a standard curve. We demonstrate that the GMR platform provides a dynamic range of 4 orders of magnitude and a limit of detection of 1 pM and 0.1 pM respectively for 15 and 18-cycle amplified synthetic GAPDH PCR products. The quantitative results of GMR analysis of cell-line RNA were confirmed by qPCR.

Recent Advances Incorporating Superparamagnetic Nanoparticles into Immunoassays

Superparamagnetic nanoparticles (SPMNPs) have attracted interest for various biomedical applications due to their unique magnetic behavior, excellent biocompatibility, easy surface modification, and low cost. Their unique magnetic properties, superparamagnetism, and magnetophoretic mobility have led to their inclusion in immunoassays to enhance biosensor sensitivity and allow for rapid detection of various analytes. In this review, we describe SPMNP characteristics valuable for incorporation into biosensors, including the use of SPMNPs to increase detection capabilities of surface plasmon resonance and giant magneto-resistive biosensors. The current status of SPMNP-based immunoassays to improve the sensitivity of rapid diagnostic tests is reviewed, and suggested strategies for the successful adoption of SPMNPs for immunoassays are presented.

Nanotechnology: Review of concepts and potential application of sensing platforms in food safety

In recent years a number of new nanotechnology based platforms have been developed for detection of wide variety of targets including infectious agents, protein biomarkers, nucleic acids, drugs, and cancer cells. Nanomaterials such as magnetic nanoparticles, quantum dots, carbon nanotubes, nanowires, and nanosensors like giant magnetoresistance (GMR) sensors are used to quantitatively detect biomolecules with, experimentally, relatively good accuracy. There has been a growing interest in the use of magnetic fields in biosensing applications. Because biological samples have no ferromagnetic property and therefore there is no interference with complex sample matrix, detection of infectious agents from minimally processed samples is possible. Here, we provide a brief overview of the recent emergence of nanotechnology-based techniques for the detection and monitoring of foodborne diseases. In addition, the potential applications and future perspectives of nanotechnology on food safety are discussed. Ultimately, the review is expected to stimulate and provide directions to the development and application of nanotechnology-based tests for the early detection, and eventual control of foodborne diseases.

A selective and sensitive nanosensor for fluorescent detection of specific IgEs to purified allergens in human serum

Food allergies are increasingly recognized as a major healthcare concern. In order to sensitively and specifically detect allergies from blood samples of at-risk allergic patients, an effective magnetic fluorescence sensing platform (EMFP) was constructed. The EMFP incorporated hollow mesoporous silica nanospheres (HMNs) to amplify signal from the target IgE in addition to magnetic nanoparticles (MNPs) to capture and separate the target IgE. The application of EMFP to immunoassays indicated a detection limit of 0.0159 ng mL⁻¹ for low concentration specific immunoglobulin E (sIgE) against purified shellfish Metapenaeus ensis (Meta. E.) allergens, which is 15 fold more sensitive than the commercially available Food and Drug Administration-approved analyzers. Notably, EMFP was specific for the targeted sIgE even with interference by other sIgEs. In addition, the detection time is only 75 min, considerably faster than current commercial ELISA kits for IgE assays. Together, these results demonstrated that EMFP has excellent sensitivity and selectivity for the rapid detection of sIgE. The method thus exhibits potential toward the rapid monitoring of sIgE against Meta. E. allergens in clinical application.

The effective magnetic fluorescence sensing platform was employed to amplify signal and capture target IgE in one step.

Magnetic sensing platform technologies for biomedical applications

Detection and quantification of a variety of micro- and nanoscale entities, e.g. molecules, cells, and particles, are crucial components of modern biomedical research, in which biosensing platform technologies play a vital role. Confronted with the drastic global demographic changes, future biomedical research entails continuous development of new-generation biosensing platforms targeting even lower costs, more compactness, and higher throughput, sensitivity and selectivity. Among a wide choice of fundamental biosensing principles, magnetic sensing technologies enabled by magnetic field sensors and magnetic particles offer attractive advantages. The key features of a magnetic sensing format include the use of commercially available magnetic field sensing elements, e.g. magnetoresistive sensors which bear huge potential for compact integration, a magnetic field sensing mechanism which is free from interference by complex biomedical samples, and an additional degree of freedom for the on-chip handling of biochemical species rendered by magnetic labels. In this review, we highlight the historical basis, routes, recent advances and applications of magnetic biosensing platform technologies based on magnetoresistive sensors.

Metal-Organic Framework as a Protective Coating for Biodiagnostic Chips

Zeolitic imidazolate framework-8 (ZIF-8) grown around antibodies anchored to plasmonic nanostructures serves as a protective layer to preserve the biorecognition ability of antibodies stored at room and elevated temperatures for several days. The biofunctionality of the ZIF-8-protected biochip can be restored by a simple water-rinsing step, making it highly convenient for use in point-of-care and resource-limited settings.