The Development of A Fluorescence Polarization Immunoassay for Aflatoxin Detection

A fluorescence polarization immunoassay （FPIA） was developed for the analysis ofaflatoxins （AFs） using an anti-aflatoxin B1 （AFB1） monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed an IC50 value of 23.33 ng/mL with a limit of detection of 13.12 ng/mL for AFB1. The cross-reactivities of AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 with the antibody were 100%, 65.7%, 143%, 23.5%, 111.4%, and 2%, respectively. The group-specificity of anti-AFB1mAb indicated that the FPIA could potentially be used in a screening method for the detection of total AFs, albeit not AFG2 and AFM2. The total time required for analyzing 96 samples in one microplate was less than 5 rain. This study demonstrates the potential usefulness of the FPIA as a rapid and simple technique for monitoring AFs.

Development of a Rapid Multi-residue Assay for Detecting β-lactams Using Penicillin Binding Protein 2x

Objective To develop a rapid multi-residue assay for detecting 16 demanded by the European Union （EU）. Methods A recombinant penicillin-binding protein （PBP） 2x＊ from Streptococcus pneumoniae R6 was expressed in vitro and six β-1actams were conjugated to HRP by four methods. A rapid multi-residue assay for β-1actams was established with PBP2x＊ and HRP-conjugate. Results PBP2x＊ was expressed and purified successfully and the ideal HRP-conjugate was identified. The multi-residue assay was developed. After optimization, penicillin G, ampicillin, amoxicillin, cloxacillin, dicloxacillin, oxacillin, nafcillin, cephalexin, ceftiofur, cefalonium, cefquinome, cefazolin, cefoperazone, cephacetrile, and cephapirin can be detected at levels below MRL in milk with simple pretreatment. Conclusion This assay developed can detect all 16 β-1actams demanded by the European Union （EU）. The whole procedure takes only 45 min and can detect 42 samples and the standards with duplicate analysis.

Development of An Enzyme-Linked Immunosorbent Assay for Determination of the Furaltadone Etabolite,3-Amino-5-Morpholinomethyl-2-Oxazolidinone(AMOZ) in Animal Tissues

Objective To determine 3-amino-5-morpholinomethyl-2-oxazolidinone （AMOZ） residues released from protein bound AMOZ in animal tissues. Methods Polyclonal and monoclonal antibodies were produced in this study. A rapid, sensitive, and specific competitive direct enzyme-linked immunosorbent assay （cdELISA） was developed. Results Rabbit polyclonal antibodies were used in the optimized cdELISA method, and exhibited negligible cross-reactivity with other compounds structurally related to AMOZ. The IC50 of the polycional antibody was 0.16 ng/mL The method limit of detection in four different types of animal and fish tissues was less than 0.06 μg/kg. Recoveries ranged from 80% to 220% for fortified samples with the coefficient of variation values less than 15%. The results of the cdELISA method were in good agreement with the results from an established liquid chromatography-tandem mass spectrometry confirmatory method used for AMOZ residues. Conclusion The cdELISA method developed in the present study is a convenient practical tool for screening large numbers of animal and fish tissue samples for the the detection of released protein bound AMOZ residues.