Preparation of high-affinity and high-specificity monoclonal antibody and development of ultra-sensitive immunoassay for the detection of 1-aminohydantoin, the metabolite of nitrofurantoin

1-Aminohydantoin (AHD), the residual marker of nitrofurantoin, is usually detected after derivatisation using the derivatisation reagent 2-nitrobenzaldehyde. Avoiding the antibody recognition of the derivatisation reagent is essential for the accurate detection of AHD residues. In this paper, a novel hapten called hapten D was designed, and then, a monoclonal antibody that did not recognise 2-nitrobenzaldehyde was prepared based on this novel hapten. An ultra-sensitive indirect competitive enzyme linked-immunosorbent assay (icELISA) was established under optimal conditions. The 50% inhibition concentration and limit of detection of AHD were 0.056 and 0.0060 ng/mL, respectively, which improved the sensitivity by 9-37-fold compared with the previously reported icELISA methods. The average recovery rates were 88.1%-97.3%, and the coefficient of variation was <8.6%. The accuracy and reliability of the icELISA were verified using liquid chromatography-tandem mass spectrometry. These results demonstrated that the developed icELISA is a useful and reliable tool.

Metal (Au, Pt) Nanoparticle-Latex Nanocomposites as Probes for Immunochromatographic Test Strips with Enhanced Sensitivity

The development of a sensitive and rapid diagnostic test for early detection of infectious viruses is urgently required to defend against pandemic and infectious diseases including seasonal influenza. In this study, we developed noble metal (Au, Pt) nanoparticle-latex nanocomposite particles for use as probes for immunochromatographic test (ICT) strips. The nanocomposite particles were conjugated with monoclonal antibody (mAb) to detect an influenza A (H1N1) antigen. For comparison, Au nanoparticles conjugated with mAb were also prepared. The lowest detectable concentrations of the influenza A antigen were found to be 6.25 × 10^-3 and 2.5 × 10^-2 HAU/mL for Au nanoparticle-latex and Pt nanoparticle-latex nanocomposite particles, respectively, whereas it was 4.0 × 10^-1 HAU/mL for Au nanoparticles. These results clearly demonstrated that the nanocomposite probes were more sensitive than conventional nanoparticle-based probes for ICT. To expand the versatility of the nanocomposite probes, the surfaces of the probes were functionalized with biotinylated proteins to enable modification of their surfaces with desired biotinylated antibodies through biotin-avidin binding.

A fluorescent immunochromatographic strip test using a quantum dot-antibody probe for rapid and quantitative detection of 1-aminohydantoin in edible animal tissues

A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an activated ester method. Under optimal conditions, with the nitrophenyl derivative of AHD as the target, the ICST had a linear range from 0.1 to 100 ng/mL, with a correlation coefficient of 0.9656 and a 50% inhibitory concentration of 4.51 ng/mL. The limit of detection was 0.14 ng/g, which was below the minimum required performance limit of 1 μg/kg for AHD established by the European Commission. The recoveries for AHD ranged from 81.5% to 108.2%, with coefficients of variation below 13%, based on intraday and interday analysis. Furthermore, for AHD in real samples, the ICST showed high reliability and high correlation with liquid chromatography-tandem mass spectrometry (correlation coefficient of 0.9916). To the best of our knowledge, this is the first report of a novel and sensitive method based on a fluorescent ICST to detect AHD below the minimum required performance limit. The ICST demonstrated high reliability, and could be ideally suited for rapid, simple, and on-site screening of AHD contamination in animal tissues. Graphical abstract A rapid, simple, and sensitive fluorescent immunochromatographic strip test that is based on quantum dots was developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. 2-NBA 2-nitrobenzaldehyde, NP nitrophenyl.

Development of monoclonal antibody-based ultrasensitive enzyme-linked immunosorbent assay and fluorescence-linked immunosorbent assay for 1-aminohydantoin detection in aquatic animals

Monitoring and rapid evaluation of nitrofurantoin metabolite, 1-aminohydantoin (AHD), are important for food safety and human health. Herein, we established the monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and quantum dots (QDs)-fabricated fluorescence-linked immunosorbent assay (FLISA). Monoclonal antibody specific to nitrophenyl derivative of AHD was derived from hybridoma cell lines 3.2.4/5A8. For another, CdTe core QDs with emission wavelength of 605nm were also synthesized. The performances of the proposed ic-ELISA and FLISA were further examined and the corresponding results were also validated by standard LC-MS/MS analysis. The obtained results indicated that both ic-ELISA and FLISA exhibited good dynamic linear detection for NPAHD over the range from 0.1 to 3.0ngmL^-1. Meanwhile, proposed immunosorbent assays are characterized by satisfactory recovery rates of 81.5-113.7%. The experimental data suggested these two immunoassays could be facile, cost-effective and rapid tools for the prospective quantitative method for AHD analysis in food matrix.

A sensitivity-enhanced heterologous immunochromatographic assay based on a monoclonal antibody for the rapid detection of histamine in saury samples

An immunochromatograhic strip for rapid detection of histamine based on a sensitive monoclonal antibody against p-nitrobenzoylated histamine was firstly reported.

An immunochromatographic assay for rapid and direct detection of 3-amino-5-morpholino-2-oxazolidone (AMOZ) in meat and feed samples

BACKGROUND

Furaltadone (FTD) is a type of nitrofuran and has been banned in many countries as a veterinary drug in food-producing animals owing to its potential carcinogenicity and mutagenicity. FTD is unstable in vivo, rapidly metabolizing to 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ); thus AMOZ can be used as an indicator for illegal usage of FTD. Usually, for the determination of nitrofurans, the analyte is often a derivative of the metabolite rather than the metabolite itself. In this study, based on the monoclonal antibody (mAb) against AMOZ, a competitive immunochromatographic assay (ICA) using a colloidal gold-mAb probe for rapid and direct detection of AMOZ without a derivatization step in meat and feed samples was developed.

RESULTS

The intensity of red color in the test line is inversely related to the analyte concentration and the visual detection limit was found to be 10 ng mL⁻¹. The performance of this assay was simple and convenient because the tedious and time-consuming derivatization step was avoided. The ICA detection was completed within 10 min. The ICA strips could be used for 7 weeks at room temperature without significant loss of activity. The AMOZ spiked samples were detected by ICA and confirmed by enzyme-linked immunosorbent assay. The results of the two methods were in good agreement.

CONCLUSION

The proposed ICA provides a feasible tool for simple, sensitive, rapid, convenient and semi-quantitative detection of AMOZ in meat and feed samples on site. To our knowledge, this is the first report of the ICA for direct detection of AMOZ.

Comparison of the lateral flow immunoassays (LFIA) for the diagnosis of Helicobacter pylori infection

Helicobacter pylori infection is the most common human infection where approximately 50% of the world populations are infected. The diagnosis of such infection is mainly done by endoscopy where gastric biopsies are examined for the presence of H. pylori. Such invasive approach is costly, time consuming and generally requires more than one test to confirm the infection. Serology on the other hand is a non-invasive approach that can detect H. pylori exposure. The lateral flow immunoassays (LFIA) support the serological approach and have the advantage of being fast, economic and require no additional equipment or experience. In this review the principles, components of the LFIA, sensitivities and specificities of the commercially available H. pylori test strips were compared and discussed.