Development of a monoclonal antibody assay and a lateral flow strip test for the detection of paromomycin residues in food matrices

Synthesis of hapten, production of monoclonal antibody, and development of immunoassay for ribavirin detection in chicken

Ribavirin (RBV) is an effective antiviral drug, whose use is prohibited in animal husbandry worldwide. In this work, a novel immunizing hapten of RBV, named Hapten 4, was designed by comparing the conformational and electronic properties of RBV and haptens based on computational chemistry. Hapten 4 was synthesized and conjugated with carrier proteins to produce monoclonal antibody (mAb). The obtained mAb 4C3 for RBV exhibited an IC₅₀ value of 6.24 ng/ml in an indirect competitive enzyme-linked immunosorbent assay (icELISA) and displayed no cross-reaction with five other antiviral drugs, including amantadine. The applicability of the developed icELISA was verified in chicken, with a calculated limit of detection of 4.23 µg/kg. The recoveries in spiked chicken were 79.2%-107.3% with a coefficient of variation less than 15.9%. The results indicated that the produced antibody from the new hapten was reliable and would be useful for RBV screening in chicken. PRACTICAL APPLICATION: RBV is a broad-spectrum antiviral drug, which is commonly used illegally in poultry farms. A high-affinity mAb 4C3 against RBV was produced and used to develop icELISA with acceptable sensitivity and accuracy. The constructed icELISA has excellent performance for detecting RBV residues in chicken.

Visible and eco-friendly immunoassays for the detection of cyclopiazonic acid in maize and rice

Cyclopiazonic acid (CPA) is an indole-tetramine mycotoxin commonly produced by Penicillium and Aspergillus and is widely found in agricultural products, fermented food, and feed. Food contaminated with CPA poses a substantial health risk to consumers. Therefore, eco-friendly immunoassays, including an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a lateral flow immunochromatographic strip (LFICS), were developed to monitor CPA in maize and rice samples. For this purpose, a monoclonal antibody (3H12) posed highly resistant to pH (5.6 to 9.6) and ethanol (≤50%) was generated by mouse immunization. Negative maize and rice samples or samples spiked with CPA were extracted with ethanol/0.01 M sodium borate buffer (4/1, v/v, pH 8.4). For ic-ELISA analysis, the limits of detection (LODs) were 0.48 and 0.28 ng/g for maize and rice samples, respectively. The recovery for spiked maize was 76.9% to 83.5% with the highest variable coefficient (CV_max ) being 9.32%. For spiked rice, the recovery was 85.3% to 105.1% with a CV_max of 8.56%. For LFICS analysis, the visible LODs were 2.5 and 1 ng/g and cutoff values were 5 and 2.5 ng/g for maize and rice samples, respectively. The LFICS method gave results within 5 to 10 min, providing an auxiliary analytical tool for the rapid, sensitive, and portable screening of the massive samples onsite.

Gold Immunochromatographic Assay for Rapid On-Site Detection of Lincosamide Residues in Milk, Egg, Beef, and Honey Samples

Lincosamides (LMs), include clindamycin (CLIN), lincomycin (LIN), and pirlimycin (PIR), that are widely used as veterinary drugs. LM residues in edible animal origin foods endanger human health and are in urgent need of establishing fast, simple, and highly sensitive detection methods. A gold immunochromatographic strip is prepared to detect CLIN, LIN, and PIR residues simultaneously with a single monoclonal antibody. This antibody is obtained with the design of a novel Hapten and can simultaneously recognize CLIN, LIN, and PIR. Under optimized conditions, the strip results can be semi-quantitatively evaluated with the naked eye within 15 min, with cut-off values in phosphate-buffered saline of 1 ng mL^-1 for CLIN, 10 ng mL^-1 for LIN, and 25 ng mL^-1 for PIR, respectively. Besides, the strip can also be quantified using a hand-held strip scanner, and the spiked samples are used for establishing matrix curves. The limits of detection for CLIN, LIN, and PIR in spiked milk, egg, beef, and honey samples can satisfy the detection requirement. The utility of this strip is also confirmed by positive honey sample. In short, this strip should be expected to be a useful tool for the rapid on-site screening of lincosamide residues in milk, egg, beef, and honey samples.

Preparation of an anti-isoprocarb monoclonal antibody and its application in developing an immunochromatographic strip assay

In this study, a carboxyl group was introduced into the isoprocarb molecule to obtain an isoprocarb hapten, which was then coupled with a protein to obtain an artificial antigen. Three monoclonal antibody cell lines, 1D11, 6E6 and 1B5, were finally obtained by mouse immunization, cell fusion and subcloning, and the antibody produced by cell line 1B5 had the best affinity and sensitivity. The monoclonal antibody was highly sensitive and specific for isoprocarb, with an IC₅₀ of 2.09 ng/ml and a cross-reactivity rate of <0.21%. By optimizing the indirect competitive (ic)-ELISA, the optimal conditions were determined to be pH 7.4, 0% methanol and 0.8% NaCl, the limit of detection value was 0.23 ng/ml, and the linear range of the ic-ELISA was 0.46-9.62 ng/ml. The recovery rate of the isoprocarb cucumber sample was 97-99% for the ic-ELISA method. In addition, we successfully developed an immunochromatographic test strip for the detection of isoprocarb residues. The cutoff values in phosphate-buffered saline and cucumber extract were 10 and 25 ng/ml, respectively. Both methods met the requirements for isoprocarb residue detection in agricultural products, and can be used for semiquantitative and qualitative analysis of isoprocarb in vegetables.

Biomimetic Membranes with Transmembrane Proteins: State-of-the-Art in Transmembrane Protein Applications

In biological cells, membrane proteins are the most crucial component for the maintenance of cell physiology and processes, including ion transportation, cell signaling, cell adhesion, and recognition of signal molecules. Therefore, researchers have proposed a number of membrane platforms to mimic the biological cell environment for transmembrane protein incorporation. The performance and selectivity of these transmembrane proteins based biomimetic platforms are far superior to those of traditional material platforms, but their lack of stability and scalability rule out their commercial presence. This review highlights the development of transmembrane protein-based biomimetic platforms for four major applications, which are biosensors, molecular interaction studies, energy harvesting, and water purification. We summarize the fundamental principles and recent progress in transmembrane protein biomimetic platforms for each application, discuss their limitations, and present future outlooks for industrial implementation.

Generic Hapten Synthesis, Broad-Specificity Monoclonal Antibodies Preparation, and Ultrasensitive ELISA for Five Antibacterial Synergists in Chicken and Milk

An antibody with broad specificity and principally depending on hapten structure and size is a key reagent for developing a class-selective immunoassay. In the present study, three new generic haptens of antibacterial synergists (ASGs) were proposed using trimethoprim as the starting molecule. These haptens contained carboxyl groups on the meta position of trimethoxybenzene for conjugating to protein, while, the common moiety of ASGs, i.e., diaminopyrimidine, was intentionally and maximally exposed to the immune system in animals in order to induce antibodies with broad specificity against ASGs. Five monoclonal antibodies (mAbs) were finally obtained, and 5C4 from the hapten with a short spacer arm, named Hapten A, showed not only uniform broad specificity but also high affinity to all five ASGs. We further determined the possible recognition mechanism of mAbs in terms of conformational and electronic aspects. An indirect competitive ELISA (icELISA)-based 5C4 was established and exhibited IC₅₀ values of 0.067-0.139 μg L^-1 with cross-reactivity of 48.2%-418.7% for the five ASGs in buffer under optimal conditions. The calculated limits of detection of the icELISA for chicken and milk were 0.06-0.8 μg kg^-1 and 0.05-0.6 μg L^-1, respectively. The recoveries in spiked chicken and milk samples were 75.2%-101.4% with a coefficient of variation less than 14.3%. In summary, we have developed, for the first time, a rapid and reliable icELISA for ASGs with significantly improved sensitivity and class selectivity.