Microfabricated biosensor for the simultaneous amperometric and luminescence detection and monitoring of Ochratoxin A

Latest strategies for rapid and point of care detection of mycotoxins in food: A review

Mycotoxins contaminated in agricultural products are often highly carcinogenic and genotoxic to humans. With the streamlining of the food industry chain and the improvement of food safety requirements, the traditional laboratory testing mode is constantly challenged due to the expensive equipment, complex operation steps, and lag in testing results. Therefore, rapid detection methods are urgently needed in the food safety system. This review focuses on the latest strategies that can achieve rapid and on-site testing, with particular attention to the nanomaterials integrated biosensors. To provide researchers with the latest trends and inspiration in the field of rapid detection, we summarize several strategies suitable for point of care testing (POCT) of mycotoxins, including enzyme-linked immunoassay (ELISA), lateral flow assay (LFA), fluorescence, electrochemistry, and colorimetry assay. POCT-based strategies are all developing towards intelligence and portability, especially when combined with smartphones, making it easier to read signals for intuitive access and analysis of test data. Detection performance of the devices has also improved considerably with the integration of biosensors and nanomaterials.

The Bioanalytical and Biomedical Applications of Polymer Modified Substrates

Polymers with different structures and morphology have been extensively used to construct functionalized surfaces for a wide range of applications because the physicochemical properties of polymers can be finely adjusted by their molecular weights, polydispersity and configurations, as well as the chemical structures and natures of monomers. In particular, the specific functions of polymers can be easily achieved at post-synthesis by the attachment of different kinds of active molecules such as recognition ligand, peptides, aptamers and antibodies. In this review, the recent advances in the bioanalytical and biomedical applications of polymer modified substrates were summarized with subsections on functionalization using branched polymers, polymer brushes and polymer hydrogels. The review focuses on their applications as biosensors with excellent analytical performance and/or as nonfouling surfaces with efficient antibacterial activity. Finally, we discuss the perspectives and future directions of polymer modified substrates in the development of biodevices for the diagnosis, treatment and prevention of diseases.

Novel Nondestructive Biosensors for the Food Industry

An increasing number of foodborne outbreaks, growing consumer desire for healthier products, and surging numbers of food allergy cases necessitate strict handling and screening of foods at every step of the food supply chain. Current standard procedures for detecting food toxins, contaminants, allergens, and pathogens require costly analytical devices, skilled technicians, and long sample preparation times. These challenges can be overcome with the use of biosensors because they provide accurate, rapid, selective, qualitative, and quantitative detection of analytes. Their ease of use, low-cost production, portability, and nondestructive measurement techniques also enable on-site detection of analytes. For this reason, biosensors find many applications in food safety and quality assessments. The detection mechanisms of biosensors can be varied with the use of different transducers, such as optical, electrochemical, or mechanical. These options provide a more appropriate selection of the biosensors for the intended use. In this review, recent studies focusing on the fabrication of biosensors for food safety or food quality purposes are summarized. To differentiate the detection mechanisms, the review is divided into sections based on the transducer type used.

Nanostructures in Hydrogen Peroxide Sensing

In recent years, several devices have been developed for the direct measurement of hydrogen peroxide (H2O2), a key compound in biological processes and an important chemical reagent in industrial applications. Classical enzymatic biosensors for H2O2 have been recently outclassed by electrochemical sensors that take advantage of material properties in the nano range. Electrodes with metal nanoparticles (NPs) such as Pt, Au, Pd and Ag have been widely used, often in combination with organic and inorganic molecules to improve the sensing capabilities. In this review, we present an overview of nanomaterials, molecules, polymers, and transduction methods used in the optimization of electrochemical sensors for H2O2 sensing. The different devices are compared on the basis of the sensitivity values, the limit of detection (LOD) and the linear range of application reported in the literature. The review aims to provide an overview of the advantages associated with different nanostructures to assess which one best suits a target application.

On the intersection of molecular bioelectronics and biosensors: 20 Years of C3B

Formed in 2000 at Virginia Commonwealth University, the Center for Bioelectronics, Biosensors and Biochips (C3B®) has subsequently been located at Clemson University and at Texas A&M University. Established as an industry-university collaborative center of excellence, the C3B has contributed new knowledge and technology in the areas of i) molecular bioelectronics, ii) responsive polymers, iii) multiplexed biosensor systems, and iv) bioelectronic biosensors. Noteworthy contributions in these areas include i) being the first to report direct electron transfer of oxidoreductase enzymes enabled by single walled carbon nanotubes and colloidal clays, ii) the molecular level integration of inherently conductive polymers with bioactive hydrogels using bi-functional monomers such as poly(pyrrole-co-3-pyrrolylbutyrate-conj-aminoethylmethacrylate) [PyBA-conj-AEMA] and 3-(1-ethyl methacryloylate)aniline to yield hetero-ladder electroconductive hydrogels, iii) the development of a multi-analyte physiological status monitoring biochip, and iv) the development of a bioanalytical Wien-bridge oscillator for the fused measurement to lactate and glucose. The present review takes a critical look of these contributions over the past 20 years and offers some perspective on the future of bioelectronics-based biosensors and systems. Particular attention is given to multiplexed biosensor systems and data fusion for rapid decision making.

Advances in biosensors for the detection of ochratoxin A: Bio-receptors, nanomaterials, and their applications

Ochratoxin A (OTA) is a class of mycotoxin mainly produced by the genera Aspergillus and Penicillium. OTA can cause various forms of kidney, liver and brain diseases in both humans and animals although trace amount of OTA is normally present in food. Therefore, development of fast and sensitive detection technique is essential for accurate diagnosis of OTA. Currently, the most commonly used detection methods are enzyme-linked immune sorbent assays (ELISA) and chromatographic techniques. These techniques are sensitive but time consuming, and require expensive equipment, highly trained operators, as well as extensive preparation steps. These drawbacks limit their wide application in OTA detection. On the contrary, biosensors hold a great potential for OTA detection at for both research and industry because they are less expensive, rapid, sensitive, specific, simple and portable. This paper aims to provide an extensive overview on biosensors for OTA detection by highlighting the main biosensing recognition elements for OTA, the most commonly used nanomaterials for fabricating the sensing interface, and their applications in different read-out types of biosensors. Current challenges and future perspectives are discussed as well.

Molecular Modeling and Simulation Tools in the Development of Peptide-Based Biosensors for Mycotoxin Detection: Example of Ochratoxin

Mycotoxin contamination of food and feed is now ubiquitous. Exposures to mycotoxin via contact or ingestion can potentially induce adverse health outcomes. Affordable mycotoxin-monitoring systems are highly desired but are limited by (a) the reliance on technically challenging and costly molecular recognition by immuno-capture technologies; and (b) the lack of predictive tools for directing the optimization of alternative molecular recognition modalities. Our group has been exploring the development of ochratoxin detection and monitoring systems using the peptide NFO4 as the molecular recognition receptor in fluorescence, electrochemical and multimodal biosensors. Using ochratoxin as the model mycotoxin, we share our perspective on addressing the technical challenges involved in biosensor fabrication, namely: (a) peptide receptor design; and (b) performance evaluation. Subsequently, the scope and utility of molecular modeling and simulation (MMS) approaches to address the above challenges are described. Informed and enabled by phage display, the subsequent application of MMS approaches can rationally guide subsequent biomolecular engineering of peptide receptors, including bioconjugation and bioimmobilization approaches to be used in the fabrication of peptide biosensors. MMS approaches thus have the potential to reduce biosensor development cost, extend product life cycle, and facilitate multi-analyte detection of mycotoxins, each of which positively contributes to the overall affordability of mycotoxin biosensor monitoring systems.

Bioinspired recognition elements for mycotoxin sensors

Mycotoxins are low molecular weight molecules produced as secondary metabolites by filamentous fungi that can be found as natural contaminants in many foods and feeds. These toxins have been shown to have adverse effects on both human and animal health, and are the cause of significant economic losses worldwide. Sensors for mycotoxin analysis have traditionally applied elements of biological origin for the selective recognition purposes. However, since the 1970s there has been an exponential growth in the use of genetically engineered or synthetic biomimetic recognition elements that allow some of the limitations associated with the use of natural receptors for the analyses of these toxins to be circumvented. This review provides an overview of recent advances in the application of bioinspired recognition elements, including recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, to the development of sensors for mycotoxins based on different transduction elements. Graphical abstract Novel analytical methods based on bioinspired recognition elements, such as recombinant antibodies, peptides, aptamers, and molecularly imprinted polymers, can improve the detection of mycotoxins and provide better tools than their natural counterparts to ensure food safety.

Hydrogel Based Sensors for Biomedical Applications: An Updated Review

Biosensors that detect and convert biological reactions to a measurable signal have gained much attention in recent years. Between 1950 and 2017, more than 150,000 papers have been published addressing the applications of biosensors in different industries, but to the best of our knowledge and through careful screening, critical reviews that describe hydrogel based biosensors for biomedical applications are rare. This review discusses the biomedical application of hydrogel based biosensors, based on a search performed through Web of Science Core, PubMed (NLM), and Science Direct online databases for the years 2000⁻2017. In this review, we consider bioreceptors to be immobilized on hydrogel based biosensors, their advantages and disadvantages, and immobilization techniques. We identify the hydrogels that are most favored for this type of biosensor, as well as the predominant transduction strategies. We explain biomedical applications of hydrogel based biosensors including cell metabolite and pathogen detection, tissue engineering, wound healing, and cancer monitoring, and strategies for small biomolecules such as glucose, lactate, urea, and cholesterol detection are identified.

Detection of ochratoxin A by aptamer-assisted real-time PCR-based assay (Apta-qPCR)

Detection of food toxins with high sensitivity is very important and challenging. Ochratoxin A (OTA) is frequently present as food contaminant in contaminated grains and grain derivatives such as bread and beer. In this work, a target-induced dissociation (TID) based aptamer-assisted real-time PCR-based assay (apta-qPCR) is developed that features effective detection of OTA. Apta-qPCR effectively combines the capabilities of aptamer to be amplified, being a nucleotide sequence, with its specific interaction with the corresponding target molecule. Compared to commonly used fluorescence-based and colorimetric methods, the sensitivity of qPCR to detect a nucleotide sequence (aptamer) has ameliorated the sensitivity of the aptamer-based detection of OTA. Here, the OTA aptamer was immobilized on the magnetic beads coated with d(T)₂₅ (dT beads). A sequence complementary to the OTA-binding portion of the aptamer was used as a linker between dT beads and the aptamer sequence. When OTA was added, the aptamer was released from the dT beads due to TID. The resulting assay was able to detect 0.009 ng/mL OTA with a wide dynamic range of 0.039-1000 ng/mL. Apta-qPCR can be easily transferred to other small molecules for highly sensitive detection using corresponding aptamers.

Evaluation of Ochratoxin Recognition by Peptides Using Explicit Solvent Molecular Dynamics

Biosensing platforms based on peptide recognition provide a cost-effective and stable alternative to antibody-based capture and discrimination of ochratoxin-A (OTA) vs. ochratoxin-B (OTB) in monitoring bioassays. Attempts to engineer peptides with improved recognition efficacy require thorough structural and thermodynamic characterization of the binding-competent conformations. Classical molecular dynamics (MD) approaches alone do not provide a thorough assessment of a peptide's recognition efficacy. In this study, in-solution binding properties of four different peptides, a hexamer (SNLHPK), an octamer (CSIVEDGK), NFO4 (VYMNRKYYKCCK), and a 13-mer (GPAGIDGPAGIRC), which were previously generated for OTA-specific recognition, were evaluated using an advanced MD simulation approach involving accelerated configurational search and predictive modeling. Peptide configurations relevant to ochratoxin binding were initially generated using biased exchange metadynamics and the dynamic properties associated with the in-solution peptide-ochratoxin binding were derived from Markov State Models. Among the various peptides, NFO4 shows superior in-solution OTA sensing and also shows superior selectivity for OTA vs. OTB due to the lower penalty associated with solvating its bound complex. Advanced MD approaches provide structural and energetic insights critical to the hapten-specific recognition to aid the engineering of peptides with better sensing efficacies.