Production of Group Specific Monoclonal Antibody to Aflatoxins and its Application to Enzyme-linked Immunosorbent Assay

Quantitative Determination of Aflatoxin B1 in Maize and Feed by ELISA and Time-Resolved Fluorescent Immunoassay Based on Monoclonal Antibodies

In this study, a highly sensitive monoclonal antibody (mAb) was developed for the detection of aflatoxin B1 (AFB1) in maize and feed. Additionally, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluorescence immunoassay assay (TRFICA) were established. Firstly, the hapten AFB1-CMO was synthesized and conjugated with carrier proteins to prepare the immunogen for mouse immunization. Subsequently, mAb was generated using the classical hybridoma technique. The lowest half-maximal inhibitory concentration (IC50) of ic-ELISA was 38.6 ng/kg with a linear range of 6.25-100 ng/kg. The limits of detections (LODs) were 6.58 ng/kg and 5.54 ng/kg in maize and feed, respectively, with the recoveries ranging from 72% to 94%. The TRFICA was developed with a significantly reduced detection time of only 21 min, from sample processing to reading. Additionally, the limits of detection (LODs) for maize and feed were determined to be 62.7 ng/kg and 121 ng/kg, respectively. The linear ranges were 100-4000 ng/kg, with the recoveries ranging from 90% to 98%. In conclusion, the development of AFB1 mAb and the establishment of ic-ELISA for high-throughput sample detection, as well as TRFICA for rapid detection presented robust tools for versatile AFB1 detection in different scenarios.

Quantitative detection of aflatoxin B1 using quantum dots-based immunoassay in a recyclable gravity-driven microfluidic chip

To achieve rapid and sensitive detection of aflatoxin B₁ (AFB₁), we developed a polydimethylsiloxane gravity-driven cyclic microfluidic chip using the two-signal mode strategy. The structural design of the chip, together with the two-wavelength quantum dot ratio fluorescence, effectively eliminates the influence of environmental factors, improves the signal stability, and ensures that the final detection result positively correlates with the target concentration. Moreover, the theoretical analysis performed for the established physical model of the three-dimensional reaction interface inside the chip confirmed the improved reaction rate of immune adsorption in the microfluidic strategy. Overall, the method exhibited a wide analytic range (0.2-500 ng mL^-1), low detection limit (0.06 ng mL^-1), high specificity, good precision (coefficient of variation < 5%), excellent reusability (20 times, 89.1%) and satisfactory practical sample analysis capacity. Furthermore, the reusability and designability of this chip provide a reliable scheme for field detection of AFB₁, analysis of other small molecules, and establishment of high-throughput detection systems under different conditions.

Development of a microarray lateral flow strip test using a luminescent organic compound for multiplex detection of five mycotoxins

While lateral flow immunoassay (LFIA) is a simple technique that offers a rapid, robust, user friendly, and point-of-care test, its capacity for multiplex detection is rather limited. This study therefore combined the multiplexity of microarray technique and the simple and rapid characteristics of LFIA to enable simultaneous and quantitative detection of five mycotoxins, namely aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin B1 (FUMB1), T-2 toxin (T-2), and zearalenone (ZON). In addition, we have synthesized a novel extra-large Stokes shift and strong fluorescence organic compound to be used as a reporter molecule which can be detected under UV light without light filter requirement. Many parameters including microarray spotting buffer, blocking buffer, and concentrations of mycotoxin antibodies were optimized for the microarray LFIA (μLFIA) construction. With the optimal conditions, the μLFIA could accurately and quantitatively detect multiple mycotoxins at the same time. The limits of detection of AFB1, DON, FUMB1, T-2, and ZON were 1.3, 0.5, 0.4, 0.4, and 0.9 ppb, respectively. The recoveries of these five mycotoxins were 70.7%-119.5% and 80.4%-124.8% for intra-assay and inter-assay, respectively. Combining the advantages of the novel reporter molecule and the multiplex capability of μLFIA test, this system could simultaneously detect multiple mycotoxins in one sample with high specificity and high sensitivity. Moreover, this system presents a promising affordable point-of-care platform to detect other analytes as well.

Development of a quantum dot-based lateral flow immunoassay with high reaction consistency to total aflatoxins in botanical materials

Total aflatoxins (AFTs) are an important safety indicator for botanical materials, but at present, rapid detection technology for AFTs is seldom reported. In this study, the monoclonal antibody with similar reactivity to total aflatoxins was produced, and the quantum dot-based lateral flow immunoassay (QD-LFIA) coupled with a portable device was developed to rapidly determine AFT residues in botanical materials. The half maximal inhibitory concentrations (IC50) of the QD-LFIA for AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 were 10.57, 12.64, 11.34, 12.67, 10.13, and 12.75 μg kg^-1, respectively, which show high reaction consistency to total aflatoxins. For different botanical materials, the sample was simply extracted with methanol-water and diluted with PBS, and the sample solution was directly loaded onto the QD-LFIA strip for determination. To overcome interference from the matrix effects, specific standard curves were established for each kind of botanical material. The detection limit of AFTs in 6 different botanical materials was 0.95~2.03 μg kg^-1 with a linear range of 2~120 μg kg^-1. The spiked recoveries of AFTs in botanical materials of different species and localities of growth were 75~105% with a coefficient of variation below 15%. The test results of the actual samples are consistent with the Chinese national standard test method. This study provides an easy-to-use method to rapidly determine AFTs in different botanical materials. Graphical abstract.

Advances in Antibody Preparation Techniques for Immunoassays of Total Aflatoxin in Food

Aflatoxin (AF) contamination is a major concern in the food and feed industry because of its prevalence and toxicity. Improved aflatoxin detection methods are still needed. Immunoassays are an important method for total aflatoxin (TAF) analysis in food due to its technical advantages such as high specificity, sensitivity, and simplicity, but require high-quality antibodies. Here, we first review the three ways to prepare high-quality antibodies for TAF immunoassay, second, compare the advantages and disadvantages of antigen synthesis methods for B-group and G-group aflatoxins, and third, describe the status of novel genetic engineering antibodies. This review can provide new methods and ideas for the development of TAF immunoassays.

Aspergillus-specific antibodies - Targets and applications

Aspergillus is a fungal genus comprising several hundred species, many of which can damage the health of plants, animals and humans by direct infection and/or due to the production of toxic secondary metabolites known as mycotoxins. Aspergillus-specific antibodies have been generated against polypeptides, polysaccharides and secondary metabolites found in the cell wall or secretions, and these can be used to detect and monitor infections or to quantify mycotoxin contamination in food and feed. However, most Aspergillus-specific antibodies are generated against heterogeneous antigen preparations and the specific target remains unknown. Target identification is important because this can help to characterize fungal morphology, confirm host penetration by opportunistic pathogens, detect specific disease-related biomarkers, identify new candidate targets for antifungal drug design, and qualify antibodies for diagnostic and therapeutic applications. In this review, we discuss how antibodies are raised against heterogeneous Aspergillus antigen preparations and how they can be characterized, focusing on strategies to identify their specific antigens and epitopes. We also discuss the therapeutic, diagnostic and biotechnological applications of Aspergillus-specific antibodies.