Exploration of Specific Nanobodies As Immunological Reagents to Detect Milk Allergen of β-Lactoglobulin without Interference of Hydrolytic Peptides

Microfluidic paper-based analysis device applying black phosphorus nanosheets@MWCNTs-COOH: A portable and efficient strategy for detection of β-Lactoglobulin in dairy products

This study prepared a novel, portable and cost-effective microfluidic paper-based electrochemical analysis device (μ-PAD) using black phosphorus nanosheets@carboxylated multi-walled carbon nanotubes (BPNSs@MWCNTs-COOH) nanocomposites for β-lactoglobulin (β-LG) detection. At the appreciate ratio, the synthesized BPNSs@MWCNTs-COOH was demonstrated to not only serve as a high-quality substrate for the specific aptamer immobilization, but also improve the electron transfer capability of the sensing interface. The μ-PADs, utilizing BPNSs@MWCNTs-COOH and aptamer recognition, exhibited a wider detection range (10-1000 ng mL-1) and lower detection limit (LOD: 0.12 ng mL-1) for β-LG, and demonstrated enhanced specificity, satisfactory anti-interference ability and stability. When applied to the β-LG determination in dairy samples, the μ-PAD yielded β-LG concentrations highly correlated with those obtained using the HPLC method (R2: 0.9982). These results emphasized the reliable performance of the developed μ-PADs in β-LG allergen quantification, highlighting their potential as an efficient platform for the rapid screening of β-LG allergens.

Trimeric Bet v 1-specific nanobodies cause strong suppression of IgE binding

Background

Around 20% of the population in Northern and Central Europe is affected by birch pollen allergy, with the major birch pollen allergen Bet v 1 as the main elicitor of allergic reactions. Together with its cross-reactive allergens from related trees and foods, Bet v 1 causes an impaired quality of life. Hence, new treatment strategies were elaborated, demonstrating the effectiveness of blocking IgG antibodies on Bet v 1-induced IgE-mediated reactions. A recent study provided evidence for the first time that Bet v 1-specific nanobodies reduce patients´ IgE binding to Bet v 1. In order to increase the potential to outcompete IgE recognition of Bet v 1 and to foster cross-reactivity and cross-protection, we developed Bet v 1-specific nanobody trimers and evaluated their capacity to suppress polyclonal IgE binding to corresponding allergens and allergen-induced basophil degranulation.

Methods

Nanobody trimers were engineered by adding isoleucine zippers, thus enabling trimeric formation. Trimers were analyzed for their cross-reactivity, binding kinetics to Bet v 1, and related allergens, and patients' IgE inhibition potential. Finally, their efficacy to prevent basophil degranulation was investigated.

Results

Trimers showed enhanced recognition of cross-reactive allergens and increased efficiency to reduce IgE-allergen binding compared to nanobody monomers. Furthermore, trimers displayed slow dissociation rates from allergens and suppressed allergen-induced mediator release.

Conclusion

We generated high-affine nanobody trimers that target Bet v 1 and related allergens. Trimers blocked IgE-allergen interaction by competing with IgE for allergen binding. They inhibited IgE-mediated release of biological mediators, demonstrating a promising potential to prevent allergic reactions caused by Bet v 1 and relatives.

A bispecific nanobody with high sensitivity/efficiency for simultaneous determination of carbaryl and its metabolite 1-naphthol in the soil and rice samples

The simultaneous determination of carbaryl and its metabolite 1-naphthol is essential for risk assessment of pesticide exposure in agricultural and environmental samples. Herein, several bispecific nanobodies (BsNbs) with different lengths of hydrophilic linkers and junction sites were prepared and characterized for the simultaneous recognition of carbaryl and its metabolite 1-naphthol. It was found that the affinity of BsNbs to the analytes could be regulated by controlling linker length and linking terminal. Additionally, molecular simulation revealed that linker lengths affected the conformation of BsNbs, leading to alteration in sensitivity. The BsNb with G4S linker, named G4S-C-N-VHH, showing good thermal stability and sensitivity was used to develop a bispecific indirect competitive enzyme-linked immunosorbent assay (Bic-ELISA). The assay demonstrated a limit of detection of 0.8 ng/mL for carbaryl and 0.4 ng/mL for 1-naphthol in buffer system. Good recoveries from soil and rice samples were obtained, ranging from 80.0% to 112.7% (carbaryl) and 76.5%-110.8% (1-naphthol), respectively. Taken together, this study firstly provided a BsNb with high sensitivity and efficiency against environmental pesticide and its metabolite, and firstly used molecular dynamics simulation to explore the influence of linker on recognition. The results are valuable for the application of immunoassay with high efficiency in the fields of environment and agriculture.

One-Step Purification of IgE Epitope-Specific Antibody Using Immunomagnetic Beads and Highly Sensitive Detection of Bovine β-Lactoglobulin for the Prediction of Milk Allergenicity in Foods

Bovine β-lactoglobulin (BLG) is a common allergen found in milk, and the immunoglobulin E (IgE) epitope plays a crucial role in cow milk allergy. Therefore, targeting the IgE epitope could be useful in accurately detecting BLG and assessing its allergenicity. However, producing an IgE epitope-specific antibody (IgE-EsAb) through traditional methods requires complex and time-consuming procedures. Here, IgE-EsAb was purified from rabbit anti-BLG sera by immunomagnetic beads in one step. Then, a sandwich ELISA (sELISA) based on the IgE-EsAb was developed to detect BLG and predict the potential milk allergenicity in foods. The obtained IgE-EsAb could specifically recognize the target IgE epitope of BLG and exhibited high affinity and specificity. The developed IgE-EsAb-based sELISA demonstrated an ultra-wide linear range of 3.9-1.28 × 105 ng/mL, with a limit of detection of 0.49 ng/mL for BLG. Additionally, the proposed immunoassay showed high specificity and recoveries (91.24-109.61%). The ability of the IgE-EsAb-based sELISA to evaluate the potential milk allergenicity in foods was validated using sera from cow milk allergy patients. These results suggest that immunomagnetic beads are an effective tool for rapidly obtaining the IgE-EsAb, and our proposed sELISA could be a reliable and user-friendly method for monitoring trace amounts of BLG and predicting the potential milk allergenicity of food samples.

Development of a Biotinylated Nanobody-Based Gold Nanoparticle Immunochromatographic Assay for the Detection of Procymidone in Crops

A heavy-chain antibody (VHH) library against procymidone (PRM) was constructed via immunizing Bactrian camels. Through careful biopanning, seven nanobodies (Nbs) with different sequences were obtained. The variability in their performance was primarily attributed to the amino acid differences in complementarity-determining region 3 (CDR3), as analyzed by molecular docking. The Nb exhibiting the highest sensitivity, named NbFM5, was biotinylated and conjugated to streptavidin-labeled gold nanoparticles to preserve the epitope's activity and prevent a decrease in sensitivity due to traditional random electrostatic adsorption. Subsequently, a simple and sensitive immunochromatographic assay (ICA) was developed for rapid detection of PRM based on biotinylated Nb (btNb). The developed btNb-ICA showed a cut-off value of 200 ng/mL for visual judgment and a half-inhibitory concentration (IC50) of 6.04 ng/mL for quantitative detection. The limit of detection (LOD) was as low as 0.88 ng/mL. The recoveries in actual samples of crops ranged from 82.2 to 117.3%, aligning well with the results obtained from GC-MS/MS (R2 = 0.995). In summary, the developed btNb-ICA demonstrated high specificity and good accuracy for the rapid detection of PRM residues in vegetables. The total analysis time from preparing the sample to obtaining the result was less than 25 min.

Detection of β-lactoglobulin under different thermal-processing conditions by immunoassay based on nanobody and monoclonal antibody

The problems of inaccurate detection values of thermal-processed β-lactoglobulin (β-LG) content seriously affect the screening of allergens. A monoclonal antibody (mAb) against β-LG was successfully prepared and a highly sensitive sandwich ELISA (sELISA) was constructed with specific nanobody (Nb) as the capture antibody with detection limit of 0.24 ng/mL. Based on this sELISA, the ability of Nb and mAb to recognize β-LG and β-LG interacting with milk components was explored. Combined with protein structure analysis to elaborate the mechanism of shielding β-LG antigen epitopes during thermal-processing, thus enabling the differentiation between pasteurized and ultra-high temperature sterilized milk, the detection of milk content in milk-containing beverages, and the highly sensitive detection and analysis of β-LG allergens in dairy-free products. The method provides methodological support for identifying the quality of dairy products and reducing the risk of β-LG contamination in dairy-free products.