Development of an indirect competitive enzyme-linked immunosorbent assay for formononetin and its application in a cell-based assay using MC3T3-E1 cells

Application of Monoclonal Antibodies against Naturally Occurring Bioactive Ingredients

Monoclonal antibodies (Mabs) are widely used in a variety of fields, including protein identification, life sciences, medicine, and natural product chemistry. This review focuses on Mabs against naturally occurring active compounds. The preparation of Mabs against various active compounds began in the 1980s, and now there are fewer than 50 types. Eastern blotting, which was developed as an antibody staining method for low-molecular-weight compounds, is useful for its ability to visually represent specific components. In this method, a mixture of lower-molecular-weight compounds, particularly glycosides, are separated by thin-layer chromatography (TLC). The compounds are then transferred to a membrane by heating, followed by treatment with potassium periodate (KIO4) to open the sugar moiety of the glycoside on the membrane to form an aldehyde group. Proteins are then added to form Schiff base bonds to enable adsorption on the membrane. A Mab is bound to the glycoside moiety on the membrane and reacts with a secondary antibody to produce color. Double Eastern blotting, which enables the simultaneous coloration of two glycosides, can be used to evaluate quality and estimate pharmacological effects. An example of staining by Eastern blotting and a component search based on the results will also be presented. A Mab-associated affinity column is a method for isolating antigen molecules in a single step. However, the usefulness of the wash fractions that are not bound to the affinity column is unknown. Therefore, we designated the wash fraction the "knockout extract". Comparing the nitric oxide (NO) production of a glycyrrhizin (GL)-knockout extract of licorice with a licorice extract revealed that the licorice extract is stronger. Therefore, the addition of GL to the GL-knockout extract of licorice increased NO production. This indicates that GL has synergic activity with the knockout extract. The GL-knockout extract of licorice inhibited high-glucose-induced epithelial-mesenchymal transition in NRK-52E cells, primarily by suppressing the Notch2 pathway. The real active constituent in licorice may be constituents other than GL, which is the causative agent of pseudohyperaldosteronism. This suggests that a GL-knockout extract of licorice may be useful for the treatment of diabetic nephritis.

A self-assembled 3D nanoflowers based nano-ELISA platform for the sensitive detection of pyridaben

Biomimetic methods are invariably employed to synthesize hybrid organic-inorganic multilevel structure nanoflowers with self-assembly processes in aqueous solutions, which is an ideal way to meet the challenges of immobilizing antibodies or enzymes in nanomaterial based enzyme-linked immunosorbent assay (nano-ELISA). In this study, we developed protein-inorganic hybrid 3D nanoflowers composed of bovine serum albumin (BSA), horseradish peroxidase (HRP)-conjugated goat anti-mouse IgG (IgG-HRP) and copper(Ⅱ) phosphate (BSA-(IgG-HRP)-Cu3(PO4)2) using a self-assembly biomimetic method. The preparation process avoided the use of any organic solvent and protein immobilization did not require covalent modifications. Additionally, the unique hierarchical structure enhances the thermal and storage stability of HRP. The BSA-(IgG-HRP)-Cu3(PO4)2 hybrid 3D nanoflower was then applied to a nano-ELISA platform for pyridaben detection, achieving a 50% inhibition concentration of 3.90 ng mL-1. The nano-ELISA achieved excellent accuracy for pyridaben detection. Such a novel BSA-(IgG-HRP)-Cu3(PO4)2 hybrid 3D nanoflower provide an excellent reagent for small molecule immunoassay.

A facile fluorescence microplate immunoassay based on an in situ fluorogenic reaction for the detection of two highly toxic anticoagulant rodenticides in food and biological matrix

Bromadiolone and brodifacoum, the most frequently used anticoagulant rodenticides, are highly toxic and pose a threat to public health by causing food poisoning incidents. Here, we developed a fluorescence microplate immunoassay for facile and sensitive detection of bromadiolone and brodifacoum by introducing three commercial chemicals (p-phenylenediamine, polyethyleneimine, H2O2) as a new substrate of horseradish peroxidase and then generating fluorescence signals based on an in situ fluorogenic reaction (detection time within 75 min). This assay exhibited higher efficiency in generating fluorescence signals, thereby exhibiting a 6-fold improvement in sensitivity compared with colorimetric ELISA. The limit of detection was 0.23-0.28 ng/mL (ng/g) for bromadiolone and 0.34-0.61 ng/mL (ng/g) for brodifacoum in corn and human serum, with recovery ratios higher than 82.3 %. These satisfactory results illustrated our proposed assay was a potential tool for food analysis and poisoning diagnosis caused by bromadiolone and brodifacoum.

Inactivation mechanism of cold plasma combined with 222 nm ultraviolet for spike protein and its application in disinfecting of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible virus that has precipitated a worldwide pandemic of coronavirus disease since 2019. Developing an effective disinfection strategy is crucial to prevent the risk of surface cross-contamination by SARS-CoV-2. This study employed pseudovirus and the receptor-binding domain (RBD) protein of SARS-CoV-2 as models to investigate the spike protein inactivation process and its underlying mechanisms using a novel nonthermal technology. Cold plasma combined with 222 nm ultraviolet (CP+UV) treatment was applied to accelerate the generation of reactive species and enhance sterilization efficiency. The results indicated that the binding activity of RBD protein was completely inhibited at specific concentrations (0.01-0.05 mg/cm2) with corresponding treatment times of 15-30 s. The mechanism potentially involves the reactive species generated by CP+UV, which react with the spike protein RBD of SARS-CoV-2, leading to the loss of SARS-CoV-2 infectivity by causing damage to the β-sheet structure and chemical bonds in the RBD protein. Validated by a biosafety level 3 (BSL3) laboratory, the CP+UV treatment for 30 s could completely inactivate SARS-CoV-2 with a concentration of 19054 ± 1112 TCID50/cm2. Therefore, this study potentially provides a novel disinfection strategy for the inactivation of SARS-CoV-2 on surface cross-contamination.

Highly sensitive indirect competitive enzyme-linked immunosorbent assay based on a monoclonal antibody against saikosaponin b2 for quality control of Kampo medicines containing Bupleuri radix

Saikosaponins are naturally occurring oleanane-type triterpenoids that are found in Bupleuri radix (root of Bupleurum falcatum) and exhibit a broad biological activity spectrum. Saikosaponin b2 (SSb2) is the main saikosaponin in Kampo medicine extracts and is a designated quality control marker for the same in the Japanese Pharmacopeia. Although some monoclonal antibodies (mAbs) against saikosaponins have been produced to evaluate the quality of Bupleuri radix and related products, anti-SSb2 mAbs have not been used to quantify SSb2 in Kampo medicines. To address this knowledge gap, we herein established a new hybridoma cell line secreting a highly specific anti-SSb2 mAb and developed an indirect competitive enzyme-linked immunosorbent assay (icELISA) based on this mAb for the detection of SSb2 in Bupleuri radix-containing Kampo medicines. The generated SSb2-recognized mAb exhibited high specificity to SSb2 in icELISA. The developed assay featured high sensitivity (linearity range = 1.95-125 ng/ml), accuracy, precision and reproducibility (coefficient of variation < 5%), and the thus determined SSb2 contents were strongly correlated with those obtained using liquid chromatograph-mass spectrometer. These results suggest that the anti-SSb2 mAb-based icELISA method can be used for the quality control and standardization of Kampo medicines containing Bupleuri radix.

Research advances of SERS analysis method based on silent region molecules for food safety detection

Food safety is a critical issue that is closely related to people's health and safety. As a simple, rapid, and sensitive detection technique, surface-enhanced Raman scattering (SERS) technology has significant potential for food safety detection. Recently, researchers have shown a growing interest in utilizing silent region molecules for SERS analysis. These molecules exhibit significant Raman scattering peaks in the cellular Raman silent region between 1800 and 2800 cm-1 avoiding overlapping with the SERS spectrum of biological matrices in the range 600-1800 cm-1, which could effectively circumvent matrix effects and improve the SERS accuracy. In this review, the application of silent region molecules-based SERS analytical technique for food safety detection is introduced, detection strategies including label-free detection and labeled detection are discussed, and recent applications of SERS analysis technology based on molecules containing alkyne and nitrile groups, as well as Prussian blue (PB) in the detection of pesticides, mycotoxins, metal ions, and foodborne pathogens are highlighted. This review aims to draw the attention to the silent region molecules-based SERS analytical technique and to provide theoretical support for its further applications in food safety detection.