Novel Dual-Color Immunochromatographic Assay Based on Chrysanthemum-like Au@polydopamine and Colloidal Gold for Simultaneous Sensitive Detection of Paclobutrazol and Carbofuran in Fruits and Vegetables

Multiplex immunochromatographic assay based on triple-color aggregation-induced emission fluorescent microspheres with good biocompatibility for the simultaneous detection of veterinary drugs in aquatic products

BACKGROUND

The simultaneous presence of multiple veterinary drug residues in a single sample poses a significant challenge for food safety analysis. Compared with traditional single-target detection, multiplex detection can not only provide richer sample information to raise the detection efficiency and reduce the possibility of false positives and omissions, but also decrease sample volume, shorten detection time, and lower costs. The luminance of aggregation-induced emission fluorescent microspheres (AIEFMs) can be enhanced by loading more fluorophores. The AIEFMs exhibit more advantages such as bright colors, excellent monodispersity, and high photostability, making them widely applicable in food safety.

RESULTS

We successfully developed a multiplex immunochromatographic assay (ICA) using triple-color AIEFMs as signal labels for the simultaneous detection of three veterinary drugs: chloramphenicol (CAP), diethylstilbestrol (DES), and diazepam (DZP). AIEFMs with good biocompatibility were synthesized via a simple and quick one-pot method based on the self-aggregation of AIEgens and the coating of metal-polyphenol network formed through the coordination of proanthocyanidin and Fe3+ in a tetrahydrofuran/water mixed solution. The as-prepared AIEFMs were rapidly conjugated with antibodies to synthesize AIEFM probes without any coupling reagent, and the multiplex AIEFMs-ICA was established for the detection of CAP, DES, and DZP. Under optimal conditions, the detection limits for CAP, DES, and DZP were 1.67, 410, and 5 pg/mL, respectively. The average recoveries of these veterinary drugs in fish and shrimp samples ranged from 85.40 % to 113.15 %, demonstrating the reliability and stability of the multiplex AIEFMs-ICA.

SIGNIFICANCE

The multiplex AIEFMs-ICA exhibited excellent signal output capacity, high specificity, and remarkable sensitivity. In brief, the developed multiplex AIEFMs-ICA shows great potential in the on-site detection of veterinary drugs and other targets.

A broad-spectrum antibody-based lateral flow immunoassay for detection of carbofuran and 3-hydroxy-carbofuran

Simultaneous detection of carbofuran (CBF) and 3-hydroxy carbofuran (3-OH-CBF) in fruits and vegetables is important due to their high toxicity and widespread use in pest control. However, most lateral flow immunoassay (LFA) approaches only detection CBF. To overcome this limitation, two haptens, 6-((2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)oxy)hexanoic acid and 6-((((2,2-dimethyl-2,3-dihydroben zofuran-7-yl)oxy)carbonyl)amino)hexanoic acid, named H1 and H2, were designed for broad-spectrum antibody detection of CBF and 3-OH-CBF. The highly specific monoclonal antibody (mAb) 3F4 based on hapten H1 only recognized CBF, while broad-spectrum mAbs 1D3, 6B7 and 6E8 based on hapten H2 recognized both compounds. The carbon bond to the hydroxyl group of 3-OH-CBF adopts a 28.55° angle relative to the same carbon bond of CBF, explaining the specificity of the H1-based mAb against CBF. After optimizing the antigen-antibody combination, a sensitive colloidal gold-LFA (CG-LFA) strip was constructed based on mAb 1D3 and H2-BSA for CBF and 3-OH-CBF detection following simple sample pretreatment. The established LFA had a limit of detection of 0.49-6.63 ng/mL, and adequate recoveries (69.3-105.7 %) for CBF and 3-OH-CBF in 26 fruit and vegetable samples.

An AgPd NP-based lateral flow immunoassay for simultaneous detection of glycocholic acid and alpha-fetoprotein

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality globally, ranking third in cancer deaths. Early diagnosis of HCC markers is imperative for effective prognosis and treatment. This study explores the utility of glycocholic acid (GCA) and alpha-fetoprotein (AFP) as biomarkers for liver diseases, with a specific focus on their simultaneous detection for enhanced diagnostic and prognostic capabilities. Harnessing the benefits of lateral flow immunoassay (LFIA), such as operational simplicity, speed, and accuracy, we engineered AgPd nanocomposites with antibodies targeting GCA and AFP. Under the optimized conditions, the visual detection limit for GCA was established at 50 ng mL-1 and the cut-off value at 104 ng mL-1. And for AFP, the visual detection limit was 0.1 ng mL-1 and the cut-off value was 500 ng mL-1. The accuracy and feasibility of the strips were validated through the detection of 39 actual serum samples. The results highlight the potential of LFIA as a rapid and effective tool for clinical diagnosis. The developed LFIA method not only demonstrates accuracy and feasibility but also presents a promising avenue for the early diagnosis of hepatocellular carcinoma.