Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor

Smartphone-enabled colorimetric immunoassay for deoxynivalenol based on Mn2+-mediated aggregation of AuNPs

Deoxynivalenol (DON) is a common mycotoxin in food that mainly pollutes grain crops and feeds, such as barley, wheat and corn. DON has caused widespread concern in the field of food and feed safety. In this study, a colorimetric immunoassay was proposed based on the aggregation of gold nanoparticles (AuNPs) due to the decomposition of Mn2+ from gold-coated manganese dioxide (AuNP@MnO2) nanosheets. In this study, 2-(dihydrogen phosphate)-l-ascorbic acid (AAP) was hydrolyzed by alkaline phosphatase (ALP) and converted to ascorbic acid (AA). Then, AuNP@MnO2 was reduced to Mn2+ and AuNPs aggregation occurred. Using the unique optical characteristics of AuNPs and AuNP@MnO2, visible color changes realized simple detection of DON with high sensitivity and portability. With increasing DON content, the color changed more obviously. To quantitatively detect DON, pictures can be taken and the blue value can be read by a smartphone. The detection limit (Ic10) of this method was 0.098 ng mL-1, which was 326 times higher than that of traditional competitive ELISA, and the detection range was 0.177-6.073 ng mL-1. This method exhibited high specificity with no cross-reaction in other structural analogs. The average recovery rate of DON in corn flour samples was 89.1 %-110.2 %, demonstrating the high accuracy and stability of this assay in actual sample detection. Therefore, the colorimetric immunoassay can be used for DON-related food safety monitoring.

Novel Cytochrome P450-3A4 Enzymatic Nanobiosensor for Lapatinib (a Breast Cancer Drug) Developed on a Poly(anilino-co-4-aminobenzoic Acid-Green-Synthesised Indium Nanoparticle) Platform

Breast cancer (BC) is one of the most common types of cancer disease worldwide and it accounts for thousands of deaths annually. Lapatinib is among the preferred drugs for the treatment of breast cancer. Possible drug toxicity effects of lapatinib can be controlled by real-time determination of the appropriate dose for a patient at the point of care. In this study, a novel highly sensitive polymeric nanobiosensor for lapatinib is presented. A composite of poly(anilino-co-4-aminobenzoic acid) co-polymer {poly(ANI-co-4-ABA)} and coffee extract-based green-synthesized indium nanoparticles (InNPs) was used to develop the sensor platform on a screen-printed carbon electrode (SPCE), i.e., SPCE||poly(ANI-co-4-ABA-InNPs). Cytochrome P450-3A4 (CYP3A4) enzyme and polyethylene glycol (PEG) were incorporated on the modified platform to produce the SPCE||poly(ANI-co-4-ABA-InNPs)|CYP3A4|PEG lapatinib nanobiosensor. Experiments for the determination of the electrochemical response characteristics of the nanobiosensor were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The nanobiosensor calibration for 0-100 ng/mL lapatinib was linear and gave limit of detection (LOD) values of 13.21 ng/mL lapatinib and 18.6 ng/mL lapatinib in physiological buffer and human serum, respectively. The LOD values are much lower than the peak plasma concentration (Cmax) of lapatinib (2.43 µg/mL), which is attained 4 h after the administration of a daily dose of 1250 mg lapatinib. The electrochemical nanobiosensor also exhibited excellent anti-interference performance and stability.

Recent Progress in Electrochemical Nano-Biosensors for Detection of Pesticides and Mycotoxins in Foods

Pesticide and mycotoxin residues in food are concerning as they are harmful to human health. Traditional methods, such as high-performance liquid chromatography (HPLC) for such detection lack sensitivity and operation convenience. Efficient, accurate detection approaches are needed. With the recent development of nanotechnology, electrochemical biosensors based on nanomaterials have shown solid ability to detect trace pesticides and mycotoxins quickly and accurately. In this review, English articles about electrochemical biosensors in the past 11 years (2011-2022) were collected from PubMed database, and various nanomaterials are discussed, including noble metal nanomaterials, magnetic metal nanoparticles, metal-organic frameworks, carbon nanotubes, as well as graphene and its derivatives. Three main roles of such nanomaterials in the detection process are summarized, including biomolecule immobilization, signal generation, and signal amplification. The detection targets involve two types of pesticides (organophosphorus and carbamate) and six types of mycotoxins (aflatoxin, deoxynivalenol, zearalenone, fumonisin, ochratoxin A, and patulin). Although significant achievements have been made in the evolution of electrochemical nano-biosensors, many challenges remain to be overcome.

Rapid Detection of Deoxynivalenol in Dry Pasta Using a Label-Free Immunosensor

This work focused on the development and optimization of an impedimetric label-free immunosensor for detecting deoxynivalenol (DON). A monoclonal antibody for DON detection was immobilized on a modified gold electrode with a cysteamine layer and polyamidoamine (PAMAM) dendrimers. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to monitor the layer-by-layer development of the immunosensor design, while electrochemical impedance spectroscopy and differential pulse voltammetry were employed to investigate the antigen/antibody interaction. The PAMAM dendrimers, allowing to immobilize a large number of monoclonal antibodies, permitted reaching, through the DPV technique, a high sensitivity and a low limit of detection equal to 1 ppb. The evaluation of the possible reuse of the immunosensors highlighted a decrease in the analytical performances of the regenerated immunosensors. After evaluating the matrix effect, the developed immunosensor was used to quantify DON in pasta samples spiked with a known mycotoxin concentration. Taking into consideration the DON extraction procedure used for the pasta samples and the matrix effect related to the sample, the proposed immunosensor showed a limit of detection of 50 ppb, which is lower than the maximum residual limit imposed by European Regulation for DON in dry pasta (750 ppb).

Rapid, Sensitive On-Site Detection of Deoxynivalenol in Cereals Using Portable and Reusable Evanescent Wave Optofluidic Immunosensor

This paper develops an improved portable and reusable evanescent wave optofluidic immunosensor (OIP-v2) for rapid and sensitive on-site determination of deoxynivalenol (DON), one of the most frequently detected mycotoxins mainly produced by Fusarium species. Using the bifunctional reagent N,N'-Disuccinimidyl carbonate, deoxynivalenol-bovine-serum-albumin (DON-BSA) were covalently modified onto a bio-probe surface as biorecognition elements, whose robustness allowed it to perform multiple detections without significant activity loss. An indirect competitive immunoassay strategy was applied for DON detection. Under optimal conditions, the limit of detection of 0.11 μg/L and the linear dynamic detection range of 0.43 to 36.61 μg/L was obtained when the concentration of the Cy5.5-anti-DON antibody was 0.25 μg/mL. The OIP-v2 was also applied to detect DON in various cereals, and the recoveries ranged from 81% to 127%. The correlation between OIP-v2 and enzyme-linked immunosorbent assay (ELISA) through the simultaneous detection of maize-positive samples was in good agreement (R2 = 0.9891).

Distance Effects of Phenylpiperazine-Containing Methacrylic Polymers on Optical and Structural Properties

New materials based on methacrylic polymers modified with 1-(4-nitrophenyl)piperazine side chains, differing in the distance of the chromophore from the polymer main chain and/or the separation between the chromophoric units in the chain, are obtained and characterized in terms of their potential applications in optoelectronic devices. The surface, structural, and optical properties of the investigated materials are determined using atomic force microscopy, spectroscopic ellipsometry combined with transmission measurements, Raman and Fourier transform infrared spectroscopy, as well as cyclic voltammetry. The relevant model systems are additionally analyzed with quantum chemical density functional theory calculations in order to enable the generalization of the structure-photophysical property relationships for the optimization of the material features. It is found that the structural modification of the material, relying on the transit of the piperazine moiety away from the main polymer chain, leads to the hypsochromic shift of the absorption spectrum. Moreover, the lowest refractive index values are obtained for the polymer with a distant ethylene group in the side-chains and increased separation between the piperazine units. It was shown that the optical energy band gaps of the investigated piperazine-containing polymers are in the range from 2.73 to 2.81 eV, which reveals their promising potential for the advances in photovoltaics, field effect transistors, or electrochromic devices as an alternative for other widely applied polymer materials.

Advances in gold nanoparticles for mycotoxin analysis

Mycotoxins are toxic secondary metabolites naturally produced by fungi. They can cause various kinds of acute and chronic diseases in both humans and animals since food usually contains trace amounts of mycotoxins. Thus, it is important to develop a rapid and sensitive technique for mycotoxin detection. Except for the original and classical enzyme-linked immunosorbent assays (ELISA), a series of biosensors has been developed to analyze mycotoxins in food in the last decade with the advantages of rapid analysis, simplicity, portability, reproducibility, stability, accuracy, and low cost. Nanomaterials have been incorporated into biosensors for the purpose of achieving better analytical performance in terms of limit of detection, linear range, analytical stability, low production cost, etc. Gold nanoparticles (AuNPs) are one of the most extensively studied and commonly used nanomaterials, which can be employed as an immobilization carrier, signal amplifier, mediator and mimic enzyme label. This paper aims to present an extensive overview of the recent progress in AuNPs in mycotoxin detection through ELISA and biosensors. The details of the detection methods and their application principles are described, and current challenges and future prospects are discussed as well.

Patulin and Trichothecene: characteristics, occurrence, toxic effects and detection capabilities via clinical, analytical and nanostructured electrochemical sensing/biosensing assays in foodstuffs

Patulin and Trichothecene as the main groups of mycotoxins in significant quantities can cause health risks from allergic reactions to death on both humans and animals. Accordingly, rapid and highly sensitive determination of these toxics agents is of great importance. This review starts with a comprehensive outlook regarding the characteristics, occurrence and toxic effects of Patulin and Trichothecene. In the following, numerous clinical and analytical approaches have been extensively discussed. The main emphasis of this review is placed on the utilization of novel nanomaterial based electrochemical sensing/biosensing tools for highly sensitive determination of Patulin and Trichothecene. Furthermore, a detailed and comprehensive comparison has been performed between clinical, analytical and sensing methods. Subsequently, the nanomaterial based electrochemical sensing platforms have been approved as reliable tools for on-site analysis of Patulin and Trichothecene in food processing and manufacturing industries. Different nanomaterials in improving the performance of detecting assays were investigated and have various benefits toward clinical and analytical methods. This paper would address the limitations in the current developments as well as the future challenges involved in the successful construction of sensing approaches with the functionalized nanomaterials and also allow exploring into core-research works regarding this area.

A highly-sensitive and selective antibody-like sensor based on molecularly imprinted poly(L-arginine) on COOH-MWCNTs for electrochemical recognition and detection of deoxynivalenol

A new strategy to mimic antibody for electrochemical recognition and detection of deoxynivalenol (DON) using a highly-sensitive and selective antibody-like sensor based on molecularly imprinted poly(l-arginine) (P-Arg-MIP) on carboxylic acid functionalized carbon nanotubes (COOH-MWCNTs) was proposed. l-arginine as functional monomer was screened to prepare imprinted electrode via its electro-polymerization in the presence of DON onto the surface of COOH-MWCNTs electrode coupled with theoretical calculation. Surface morphology, structural characteristics, and electrochemical properties of P-Arg-MIP/COOH-MWCNTs were characterized by SEM, EDS, FTIR, and CV, respectively. P-Arg-MIP/COOH-MWCNTs displayed relatively high conductivity, high effective surface area, antibody-like molecular recognition and affinity, and a good response towards DON in a linear range from 0.1 to 70 μM with LOD of 0.07 μM in wheat flour samples with satisfactory recovery and feasible practicability in comparison with HPLC. This method provides a promising biomimetic sensing platform for the determination of mycotoxins in food and agro-products.

Impedimetric Microcystin-LR Aptasensor Prepared with Sulfonated Poly(2,5-dimethoxyaniline)–Silver Nanocomposite

This paper presents a novel impedimetric aptasensor for cyanobacterial microcystin-LR (L, l-leucine; R, l-arginine) (MC-LR) containing a 5′ thiolated 60-mer DNA aptamer (i.e., 5′-SH-(CH2)6GGCGCCAAACAGGACCACCATGACAATTACCCATACCACCTCATTATGCCCCATCT CCGC-3′). A nanocomposite electrode platform comprising biocompatible poly(2,5-dimethoxyaniline) (PDMA)-poly(vinylsulfonate) (PVS) and silver nanoparticle (Ag0) on a glassy carbon electrode (GCE), i.e., (GCE/PDMA–PVS–Ag0) was used in the biosensor development. Small-angle X-ray scattering (SAXS) spectroscopic analysis revealed that the PDMA–PVS–Ag0 nanocomposites were polydispersed and contained embedded Ag0. Electrochemical impedance spectroscopy (EIS) responses of the aptasensor gave a dynamic linear range (DLR) and limit of detection (LOD) values of 0.01–0.1 ng L−1 MC-LR and 0.003 ng L−1 MC-LR, respectively. The cross-reactivity studies, which was validated with enzyme-linked immunosorbent assay (ELISA), showed that the aptasensor possesses excellent selectivity for MC-LR.

A review on graphene-based electrochemical sensor for mycotoxins detection

This work focuses on the study of nanomaterial-based sensors for mycotoxins detection. Due to their adverse effects on humans and animals, mycotoxins are heavily regulated, and the foodstuff and feed stocks with a high probability of being contaminated are often analyzed. In this context, the recent developments in graphene-based electrochemical sensors for mycotoxins detection were examined. The mycotoxins' toxicity implications on their detection and the development of diverse recognition elements are described considering the current challenges and limitations.

Tailoring the performance of electrochemical biosensors based on carbon nanomaterials via aryldiazonium electrografting

Carbon nanomaterials (CNs) offer some of the most valuable properties for electrochemical biosensing applications, such as good electrical conductivity, wide electrochemical stability, high specific surface area, and biocompatibility. Regardless the envisioned sensing application, endowing CNs with specific functions through controlled chemical functionalization is fundamental for promoting the specific binding of the analyte. As a versatile and straightforward method of surface functionalization, aryldiazonium chemistry have been successfully used to accommodate in a stable and reproducible way different functionalities, while the electrochemical route has become the favourite choice since the deposition conditions can be readily controlled and adapted to the substrate. In particular, the modification of CNs by electrochemical reduction of aryl diazonium salts is established as a powerful tool which allows tailoring the chemical and electronic properties of the sensing platform. By outlining the stimulating results disclosed in the last years, this article provides not only a comprehensively review, but also a rational assessment on contribution of aryldiazonium electrografting in developing CNs-based electrochemical biosensors. Furthermore, some of the emerging challenges to be surpassed to effectively implement this methodology for in vivo and point of care analysis are also highlighted.

Mycotoxins aptasensing: From molecular docking to electrochemical detection of deoxynivalenol

This work proposes a voltammetric aptasensor to detect deoxynivalenol (DON) mycotoxin. The development steps of the aptasensor were partnered for the first time to a computational study to gain insights onto the molecular mechanisms involved into the interaction between a thiol-tethered DNA aptamer (80mer-SH) and DON. The exploited docking study allowed to find the binding region of the oligonucleotide sequence and to determine DON preferred orientation. A biotinylated oligonucleotide sequence (20mer-BIO) complementary to the aptamer was chosen to carry out a competitive format. Graphite screen-printed electrodes (GSPEs) were electrochemically modified with polyaniline and gold nanoparticles (AuNPs@PANI) by means of cyclic voltammetry (CV) and worked as a scaffold for the immobilization of the DNA aptamer. Solutions containing increasing concentrations of DON and a fixed amount of 20mer-BIO were dropped onto the aptasensor surface: the resulting hybrids were labeled with an alkaline phosphatase (ALP) conjugate to hydrolyze 1-naphthyl phosphate (1-NPP) substrate into 1-naphthol product, detected by differential pulse voltammetry (DPV). According to its competitive format, the aptasensor response was signal-off in the range 5.0-30.0 ng·mL^-1 DON. A detection limit of 3.2 ng·mL^-1 was achieved within a 1-hour detection time. Preliminary experiments on maize flour samples spiked with DON yielded good recovery values.

Electrochemical Immuno- and Aptasensors for Mycotoxin Determination

Modern analysis of food and feed is mostly focused on development of fast and reliable portable devices intended for field applications. In this review, electrochemical biosensors based on immunological reactions and aptamers are considered in the determination of mycotoxins as one of most common contaminants able to negatively affect human health. The characteristics of biosensors are considered from the point of view of general principles of bioreceptor implementation and signal transduction providing sub-nanomolar detection limits of mycotoxins. Moreover, the modern trends of bioreceptor selection and modification are discussed as well as future trends of biosensor development for mycotoxin determination are considered.

Thin Films Sensor Devices for Mycotoxins Detection in Foods: Applications and Challenges

Mycotoxins are a group of secondary metabolites produced by different species of filamentous fungi and pose serious threats to food safety due to their serious human and animal health impacts such as carcinogenic, teratogenic and hepatotoxic effects. Conventional methods for the detection of mycotoxins include gas chromatography and high-performance liquid chromatography coupled with mass spectrometry or other detectors (fluorescence or UV detection), thin layer chromatography and enzyme-linked immunosorbent assay. These techniques are generally straightforward and yield reliable results; however, they are time-consuming, require extensive preparation steps, use large-scale instruments, and consume large amounts of hazardous chemical reagents. Rapid detection of mycotoxins is becoming an increasingly important challenge for the food industry in order to effectively enforce regulations and ensure the safety of food and feed. In this sense, several studies have been done with the aim of developing strategies to detect mycotoxins using sensing devices that have high sensitivity and specificity, fast analysis, low cost and portability. The latter include the use of microarray chips, multiplex lateral flow, Surface Plasmon Resonance, Surface Enhanced Raman Scattering and biosensors using nanoparticles. In this perspective, thin film sensors have recently emerged as a good candidate technique to meet such requirements. This review summarizes the application and challenges of thin film sensor devices for detection of mycotoxins in food matrices.

Affinity Biosensors for Detection of Mycotoxins in Food

This chapter reviews recent achievements in methods of detection of mycotoxins in food. Special focus is on the biosensor technology that utilizes antibodies and nucleic acid aptamers as receptors. Development of biosensors is based on the immobilization of antibodies or aptamers onto various conventional supports like gold layer, but also on nanomaterials such as graphene oxide, carbon nanotubes, and quantum dots that provide an effective platform for achieving high sensitivity of detection using various physical methods, including electrochemical, mass sensitive, and optical. The biosensors developed so far demonstrate high sensitivity typically in subnanomolar limit of detection. Several biosensors have been validated in real samples. The sensitivity of biosensors is similar and, in some cases, even better than traditional analytical methods such as ELISA or chromatography. We believe that future trends will be focused on improving biosensor properties toward practical application in food industry.

A new kind of highly sensitive competitive lateral flow immunoassay displaying direct analyte-signal dependence. Application to the determination of the mycotoxin deoxynivalenol

A new kind of competitive immunochromatographic assay is presented. It is based on the use of a test strip loaded with (a) labeled specific antibodies, (b) a hapten-protein conjugate at the control zone, and (c) antibodies interacting with the specific antibodies in the analytical zone. In the case where a sample does not contain the target antigen (hapten), all labeled antibodies remain in the control zone because of the selected ratio of reactants. The analytical zone remains colorless because the labeled antibodies do not reach it. If an antigen is present in the sample, it interferes with the binding of the specific antibodies in the control zone and knocks them out. Some of these antibodies pass the control zone to form a colored line in the analytical zone. The intensity of the color is directly proportional to the amount of the target antigen in the sample. The assay has an attractive feature in that an appearance in coloration is more easily detected visually than a decoloration. Moreover, the onset of coloration is detectable at a lower concentration than a decoloration. The new detection scheme was applied to the determination of the mycotoxin deoxynivalenol. The visual limit of detection is 2 ng·mL^-1 in corn extracts (35 ng per gram of sample). With the same reagents, this is lower by a factor of 60 than the established test strip. The assay takes only 15 min. This new kind of assay has wide potential applications for numerous low molecular weight analytes. Graphical abstract Competitive immunochromatography with direct analyte-signal dependence is proposed. It provides a 60-fold decrease of the detection limit for mycotoxin deoxynivalenol. The analyte-antibody-label complexes move along the immobilized antigen (control zone) and bind with anti-species antibodies (test zone).

Mycotoxin Determination in Foods Using Advanced Sensors Based on Antibodies or Aptamers

Mycotoxin contamination threatens health and life of humans and animals throughout the food supply chains. Many of the mycotoxins have been proven to be carcinogens, teratogens and mutagens. The reliable and sensitive sensing methods are requested to monitor mycotoxin contamination. Advanced sensors based on antibodies or aptamers boast the advantages of high sensitivity and rapidity, and have been used in the mycotoxin sensing. These sensors are miniaturized, thereby lowering costs, and are applicable to high-throughput modes. In this work, the latest developments in sensing strategies for mycotoxin determination were critically discussed. Optical and electrochemical sensing modes were compared. The sensing methods for single mycotoxin or multiple mycotoxins in food samples were reviewed, along with the challenges and the future of antibody or aptamer-based sensors. This work might promote academic studies and industrial applications for mycotoxin sensing.

Advances in Biosensors, Chemosensors and Assays for the Determination of Fusarium Mycotoxins

The contaminations of Fusarium mycotoxins in grains and related products, and the exposure in human body are considerable concerns in food safety and human health worldwide. The common Fusarium mycotoxins include fumonisins, T-2 toxin, deoxynivalenol and zearalenone. For this reason, simple, fast and sensitive analytical techniques are particularly important for the screening and determination of Fusarium mycotoxins. In this review, we outlined the related advances in biosensors, chemosensors and assays based on the classical and novel recognition elements such as antibodies, aptamers and molecularly imprinted polymers. Application to food/feed commodities, limit and time of detection were also discussed.

New advances in electrochemical biosensors for the detection of toxins: Nanomaterials, magnetic beads and microfluidics systems. A review

The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised.