Development of an icELISA and Immunochromatographic Assay for Methyl-3-Quinoxaline-2-Carboxylic Acid Residues in Fish

Rapid immunoassays for the detection of quinoxalines and their metabolites residues in animal-derived foods: A review

Quinoxalines are a class of veterinary drugs with antibacterial and growth-promoting functions. They are often widely used to treat and prevent animal diseases and are illegally used as animal growth promoters to increase economic benefits. Quinoxalines could be easily metabolized in animals to various residue markers and remain in animal-derived foods, which would pose a serious threat to human health. Consequently, it is necessary to detect the residues of quinoxalines and their metabolites. This article reviewed and evaluated immunoassays for quinoxalines and their metabolites in animal-derived foods, mainly including enzyme-linked immunosorbent assays, fluorescence immunosorbent assays, immunochromatography, and surface plasmon resonance biosensors. In addition, we deeply explored the design of haptens for quinoxalines and their metabolites and analyzed the effect of haptens on antibody performance. This paper aims to provide guidance and references for their accurate and sensitive detection, thereby ensuring food safety and human public health.

A fluorescent lateral flow immunoassay based on CdSe/CdS/ZnS quantum dots for sensitive detection of olaquindox in feedstuff

A portable fluorescence immunosensor based on the CdSe/CdS/ZnS quantum dots (QDs) with multiple-shell structure was fabricated for the precise quantification of olaquindox (OLA). The QDs labeled anti-OLA antibody used as bioprobe played an important role in the design and preparation of a lateral flow test strip. Due to the strong fluorescent intensity of QDs, the sensitivity is greatly improved. The quantitative results were obtained using a fluorescent strip scan reader within 8 min, and the calculated limit of detection for OLA at 0.12 µg/kg, which was 2.7 times more sensitive than that of the conventional colloidal gold-based strips method. Acceptable recovery of 85.0%-95.5% was obtained by the spiked samples. This newly established QDs-based strip immunoassay method is suitable for the on-site detection and rapid initial screening of OLA in swine feedstuff, and is potentially applied for the detection of other veterinary drugs to ensure food safety.

Ultrasensitive antibody production strategy based on hapten property for simultaneous immunoassay

A high-quality antibody production strategy is significant for immunoassay. In this work, four general haptens were proposed based on the 3D structure and surface electrostatic potential of molecular modeling. It was found that the sensitivity and specificity of polyclonal antibodies (pAbs) mainly depended on the bond angle of shapes liked "V" between haptens and proteins and hydrophobic parts of haptens. The quantified process was employed to obtain pAbs against cyhalofop-butyl and its metabolites (CAFs), with the IC₅₀ value of 4.9 μg·L^-1 under optimal conditions. The limit of quantization (LOQ) of the ultrasensitive icELISA in brown rice was 2 μg·kg^-1. The recoveries were 74%-110%, with a coefficient of variation (CV) less than 10%. This study indicated that the hapten property approach led to an improved immunoassay.

Immunochromatographic assay for the detection of kwakhurin and its application for the identification of Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham

INTRODUCTION

The plant Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham (PM), known by its common Thai name as white Kwao Krua, is sometimes misidentified because it presents similar botanical characteristics to those of Butea superba (red Kwao Krua). The phytochemicals in PM are phytoestrogens in the class of isoflavonoids, but Butea superba contains flavonoids that exhibit androgenic and antiestrogen effects.

OBJECTIVES

This research aims to develop a simple analytical method for identification and to differentiate PM from red Kwao Krua and other Pueraria species.

METHODS

A gold nanoparticle-based immunochromatographic assay (ICA) was developed for the detection of kwakhurin (Kwa), a unique compound found in PM. The parameters, including sensitivity, accuracy, precision, and specificity, were validated. All samples were analyzed using ICA and high-performance liquid chromatography with UV detector (HPLC-UV). The results of the two methods were compared for consistency checking.

RESULTS

The cutoff limit of Kwa detection was 160 ng/mL, which was lower than in the HPLC-UV method. The repeatability and reproducibility of the ICA preparation and assembly showed high precision. The cross-reactivity to related isoflavonoids was less than 0.32%, which implied high specificity of the ICA for Kwa. Moreover, false-positive and false-negative results from other plant extracts were not observed.

CONCLUSION

The developed ICA is applicable for distinguishing PM from red Kwao Krua and other Pueraria species. This simple analytical method can be applied for the identification of raw PM materials in the industrial and agricultural sectors.

Hapten synthesis and antibody production for the development of a paper immunosensor for lean meat powder zilpaterol

An anti-zilpaterol mAb with an IC₅₀ of 0.31 ng mL⁻¹ and a limit of detection (LOD) of 0.02 ng mL⁻¹ has been developed. For semi-quantitative detection in pork samples, the visual LOD is 0.5 ng mL⁻¹ and the cut-off value is 5 ng mL⁻¹.

Colloidal Gold Immunochromatographic Assay for Rapid Detection of Carbadox and Cyadox in Chicken Breast

Abused or misused carbadox (CBX) and cyadox (CYA) in animal feed may cause food safety concerns, threatening human health. Here, we describe the design of a novel hapten for preparation of a monoclonal antibody against CBX and CYA simultaneously. Using this antibody, colloidal gold immunochromatographic assay (GICA) was developed for screening of CBX and CYA residues in chicken breast. Under optimal conditions, semiquantitative analysis results were visible by eye, with a visual limit of detection of 8 μg/kg for CBX and CYA, and cut-off values of 20 μg/kg for CBX and 40 μg/kg for CYA in chicken breast. Quantitative analysis could be performed using a hand-held strip scanner, with a calculated limit of detection of 2.92 μg/kg for CBX and 2.68 μg/kg for CYA in chicken breast. Validated by liquid chromatography-MS/MS, the developed GICA provides a useful tool for rapid on-site CBX and CYA residue screening in chicken breast.

Colloidal Gold Immunochromatographic Strip Assay for the Detection of Azaperone in Pork and Pork Liver

In this study, a highly sensitive and specific monoclonal antibody (mAb) against azaperone was produced. The mAb belonged to the IgG2b subtype and its half maximal inhibitory concentration (IC₅₀) was 0.46 ng/mL. The limit of detection value was 0.081 ng/mL and the linear range (IC₂₀-IC₈₀) was 0.165-1.29 ng/mL. Based on this anti-azaperone mAb, a colloidal gold immunochromatographic strip assay method was established for the detection of azaperone in pork and pork liver samples. For pork samples, the cutoff value of the colloidal gold immunochromatographic strip assay was 10 ng/g, and the cutoff value was also 10 ng/g in pig liver samples. This colloidal gold immunochromatographic strip assay is a rapid, simple, and practical method for the detection of azaperone in pork and pork liver samples available in markets.

Fabrication of super pure single-walled carbon nanotube electrochemical sensor and its application for picomole detection of olaquindox

In this study, a novel and simple electrochemical sensor (ECS) was fabricated based on super pure single-walled carbon nanotubes (spSWCNTs) modified electrode. The ECS exhibited superior catalytic performance on the electrochemical reduction of olaquindox. A series of experimental parameters were systematically optimized to achieve optimal ECS performance. Compared with the bare gold electrode, the peak current increased 1700 times under the optimal experimental conditions. The ECS exhibited excellent sensitivity for the determination of trace olaquindox. The current response of the modified electrode was linear to the olaquindox concentration in the range of 0.1-500 nM with a detection limit of 30.0 pM (S/N = 3). The ECS was successfully applied for electrochemical recognition of olaquindox in real samples. In addition, the spSWCNTs modified electrode also exhibited remarkable electrocatalytic property in a wide potential range, so it had great potential for sensitive detection of various electroactive compounds.