Development of Immunochromatographic Strip for Detection of αB-VxXXIVA-Conotoxin Based on 5E4 Monoclonal Antibody

A sensitive gold nanoflower-based lateral flow assay coupled with gold staining technique for the detection of SARS-CoV-2 antigen

An enhanced lateral flow assay (LFA) is presented for rapid and highly sensitive detection of acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigens with gold nanoflowers (Au NFs) as signaling markers and gold enhancement to amplify the signal intensities. First, the effect of the morphology of gold nanomaterials on the sensitivity of LFA detection was investigated. The results showed that Au NFs prepared by the seed growth method showed a 5-fold higher detection sensitivity than gold nanoparticles (Au NPs) of the same particle size, which may benefit from the higher extinction coefficient and larger specific surface area of Au NFs. Under the optimized experimental conditions, the Au NFs-based LFA exhibited a detection limit (LOD) of 25 pg mL-1 for N protein using 135 nm Au NFs as the signaling probes. The signal was further amplified by using a gold enhancement strategy, and the LOD for the detection of N protein achieved was 5 pg mL-1. The established LFA also exhibited good repeatability and stability and showed applicability in the diagnosis of SARS-CoV-2 infection.

Zebrafish (Danio rerio) TRβ- and TTR-based electrochemical biosensors: Construction and application for the evaluation of thyroid-disrupting activity of bisphenols

Thyroid-disrupting chemicals (TDCs) have received increasing concerns because of their negative health impacts on both wildlife and humans. This study aimed to develop in vitro screening assays for TDCs based on thyroid hormone receptor β (TRβ) and transthyretin (TTR) proteins. Firstly, the recombinant ligand-binding domain of TRβ (TRβ-LBD) and TTR proteins of zebrafish were produced by eukaryotic expression system and then used as bio-recognition components to construct electrochemical biosensors. In the biosensors, the supported bilayer lipid membrane (s-BLM) was used as a matrix to immobilize proteins, and gold nanoflowers (AuNFs) were used to improve the sensitivity by increasing electroactive surface area. Under the optimizing conditions, the zfTRβ-LBD/AuNFs/s-BLM/GCE biosensor had a detection range of 0.23 nM-1.92 μM and a detection limit of 0.07 nM for triiodothyronine (T₃), while the zfTTR/AuNFs/s-BLM/GCE biosensor had a detection range of 0.46 nM-3.84 μM, with a detection limit of 0.13 nM. Based on the constructed biosensors, the order of T₃ equivalent concentrations of bisphenols was BPA ≈ BPS > BPF > BPAF ≈ BPAP > BPZ, which was similar to the results of recombinant TRβ two-hybrid yeast assay. Furthermore, the reliability of the biosensors was validated by molecular docking, in which BPA and BPS showed higher binding affinity to zfTRβ-LBD. Therefore, this study provided a valuable tool for efficiently screening TDCs.

Establishment and application of multiple immunoassays for environmental estrogens based on recombinant Japanese flounder (Paralichthys olivaceus) choriogenin protein

Environmental estrogens have generated great concern because of their potential threat to aquatic organisms; however, the commonly used vitellogenin (Vtg) biomarker detection methods are not capable of detecting estrogenic activity below 10 ng/L 17β-estradiol. In this study, we developed multiple immunoassays based on Japanese flounder (Paralichthys olivaceus) choriogenin (Chg), a highly sensitive biomarker of environmental estrogens. Chg genes (ChgL and ChgH) of Japanese flounder were cloned for the first time, and a recombinant ChgL protein with a molecular weight of approximately 52 kDa was prepared using a prokaryotic expression system and purified using Ni-affinity column chromatography. Subsequently, specific monoclonal antibodies against ChgL were prepared and used to develop sandwich enzyme-linked immunosorbent assays (ELISAs), which had a detection range of 3.9-250 ng/mL and detection limit of 1.9 ng/mL. An immunofluorescence method was also established and used to visually detect ChgL induction in the tissues. In addition, a lateral flow immunoassay for ChgL that could detect estrogen activity within 10 min was developed. Finally, the reliability of the immunoassays was examined by measuring ChgL induction in the plasma and tissues of Japanese flounder exposed to 0, 2, 10, and 50 ng/L 17α-ethinylestradiol (EE₂). The results showed that 2 ng/L EE₂ notably increased ChgL levels in the plasma, demonstrating that ChgL is more sensitive than Vtg to environmental estrogens; 50 ng/L EE₂ induced obvious Chg induction in the sinusoidal vessels of the liver. Conclusions taken together, this study provides reliable methods for sensitive and rapid detection of estrogenic activity in aquatic environments.