A Robust Homogeneous Fluorescence Polarization Immunoassay for Rapid Determination of Erythromycin in Milk.

Erythromycin (ERY) is one of the most common macrolides applied in veterinary medicine to treat diseases or as a feed additive for animal growth promotion. Long-term irrational use of ERY could lead to residues in animal-derived food and the emergence of drug-resistant strains, posing potential threats to human health. In this study, a highly sensitive, specific, robust, and rapid fluorescence polarization immunoassay (FPIA) for the determination of ERY in milk has been described.

Synthesis and characterization of tracers and development of a fluorescence polarization immunoassay for amantadine with high sensitivity in chicken.

Fluorescence polarization immunoassay (FPIA) is a homogeneous and rapid analytical method that is suitable for high-throughput screening of large numbers of samples. However, FPIA typically suffers from lower sensitivity than the well-established enzyme-linked immunosorbent assay (ELISA), limiting its wide application as an analytical tool that can be run with trace levels of an analyte. Herein, a highly sensitive FPIA for detecting amantadine (AMD) in chicken is described.

Hapten synthesis, monoclonal antibody production and immunoassay development for direct detection of 4-hydroxybenzehydrazide in chicken, the metabolite of nifuroxazide.

Derivatization is usually employed in immunoassay for detection of metabolites of nitrofurans and avoiding derivatization could be preferable to achieve an efficient screening. In the study, we designed four haptens of 4-hydroxybenhydrazide (HBH), the nifuroxazide metabolite. The effect of hapten structures on antibody affinity were evaluated and one monoclonal antibody was produced by using the Hapten C with a linear alkalane spacer arm.

Magnetic assisted fluorescence immunoassay for sensitive chloramphenicol detection using carbon dots@CaCO nanocomposites.

Analytical methods with high sensitivities and short assay times are urgently required for the screening of "zero tolerance" hazardous substances in food. Herein, we propose a fluorescent immunoassay for the highly sensitive and rapid analysis of chloramphenicol (CAP) based on carbon dots (CDs)-encapsulated CaCO nanospheres and magnetic nanoparticles (MNPs). The fluorescent immunoprobes were prepared by coupling the anti-CAP antibodies to carboxymethyl cellulose-functional CDs@CaCO nanospheres.

A simple and rapid immunochromatography test based on readily available filter paper modified with chitosan to screen for 13 sulfonamides in milk.

In this study, we developed a novel, simple, rapid, and low-cost colloidal gold-based immunochromatography method, with filter paper replacing nitrocellulose membrane as the substrate. To obtain adequately immobilized protein, chitosan was used to functionalize the filter paper. After conditions and parameters were optimized, the novel immunochromatography method was applied for detection of sulfonamide residues in milk.

High throughput detection of antibiotic residues in milk by time-resolved fluorescence immunochromatography based on QR code.

Herein, we have successfully established a novel, rapid, and simple lateral-flow immunoassay based on time-resolved fluorescence and biotin-streptavidin to detect the residues of various antibiotics in milk. The fluorescence signal and sensitivity of immunochromatography were enhanced through biotinylated antibody coupled with streptavidin europium microspheres. Moreover, due to the use of a QR Code and fluorescent reader, quantitative detection and real-time data uploading can be achieved.

Highly sensitive chromatographic time-resolved fluoroimmunoassay for rapid onsite detection of streptomycin in milk.

Antibiotic residues are major contaminants in milk because of their use in agriculture and animal husbandry. In particular, streptomycin, an aminoglycoside antibiotic, is a potential risk to consumers because of its ototoxicity, anaphylaxis, and growth inhibition. Herein, monoclonal antibodies for streptomycin were conjugated with europium microspheres to serve as detection probes for the development of a chromatographic time-resolved fluoroimmunoassay to detect streptomycin residues in milk.

Homogeneous fluorescent immunoassay for the simultaneous detection of chloramphenicol and amantadine via the duplex FRET between carbon dots and WS nanosheets.

Herein, we proposed a duplex and homogeneous fluorescent immunoassay for the simultaneous detection of amantadine (AMD) and chloramphenicol (CAP) residue in chicken breast with both high sensitivity and short assay time. The immunoassay was based on the fluorescence resonance energy transfer (FRET) between hapten-labeled carbon dots (CDs) and antibody-modified WS nanosheets. To achieve the duplex FRET, polyethyleneimine-functionalized blue and green emissive CDs with separated emission were synthesized via a one-pot hydrothermal method and directly coupled with the haptens of AMD and CAP, serving as the energy donors.

Comparison of soybean peroxidase with horseradish peroxidase and alkaline phosphatase used in immunoassays.

Enzyme labeling of an antigen or an antibody helps to visualize and amplify the signal and is an important reagent used in immunoassays for the detection of a target of interest. In this research, soybean peroxidase (SBP), a less commonly used enzyme reporter, was compared in immunoassays with the two most commonly used reagents, horseradish peroxidase (HRP) and alkaline phosphatase (ALP). The enzyme-antibody conjugates were evaluated by their performance in an indirect competitive enzyme-linked immunosorbent assay (icELISA) and in an indirect competitive chemiluminescent enzyme immunoassay (icCLEIA) for ractopamine (RAC).

Fluorescence immunoassay based on the inner-filter effect of carbon dots for highly sensitive amantadine detection in foodstuffs.

Immunoassays with ultra-high sensitivity for the rapid detection of chemical contaminants in food are urgently required. However, conventional enzyme-linked immunosorbent assay (ELISA) usually suffer from the moderate sensitivity. Herein, we aim to improve the sensitivity of conventional ELISA by employing the fluorescent carbon dots (CDs) as the signal probes based on the principle of inner filter effect (IFE).

Portable Multiplex Immunochromatographic Assay for Quantitation of Two Typical Algae Toxins Based on Dual-Color Fluorescence Microspheres.

A multiplex immunochromatographic assay (ICA) based on dual-color fluorescent microspheres (FMs) as a sensitive label was developed for the first time. Two typical algae toxins, microcystin-LR (MC-LR) and okadaic acid (OA), were chosen as proof-of concept targets to evaluate the feasibility of this ICA format. Commercial red- and green-colored FMs were selected to couple with monoclonal antibodies as fluorescent probes.

Immunochromatographic fluorometric determination of clenbuterol with enhanced sensitivity.

A method is described to enhance the sensitivity of an immunochromatographic assay for clenbuterol (CLE) by making use of dually-labeled gold nanoparticles (GNPs), background fluorescence blocking, and immunomagnetic separation. The GNPs were labeled with biotinylated antibody and streptavidin, respectively, and dually labeled GNPs were obtained via the biotin-streptavidin interaction to amplify the detection signal. The fluorescent signal was blocked by dually labeled GNPs and decreased as the dually labeled GNPs aggregation increases on nitrocellulose membrane, which derived from fluorescent polyvinylchloride card.

Quantitative and rapid detection of amantadine and chloramphenicol based on various quantum dots with the same excitations.

Herein, we developed a sensitive and quantitative flow assay for simultaneous detection of amantadine (AMD) and chloramphenicol (CAP) in chicken samples based on different CdSe/ZnS quantum dots (QDs). In contrast to other reports, the QDs could be excited by the same excitations that lowered the requirements for the matching instruments. Under the optimal conditions, the strategy permitted sensitive detection of AMD and CAP in a linear range of 0.

Highly luminescent green-emitting Au nanocluster-based multiplex lateral flow immunoassay for ultrasensitive detection of clenbuterol and ractopamine.

A multiplex lateral flow immunoassay sensor based on highly luminescent green-emitting Au nanoclusters (AuNCs-MLFIA sensor) was successfully established for the simultaneous and quantitative determination of clenbuterol (Clen) and ractopamine (RAC) in swine urine. The antigens of Clen and RAC were dispersed on a nitrocellulose membrane as two test lines, and the Au nanoclusters were synthesized from 6-aza-2-thiothymine and l-arginine to obtain highly green luminescence and ultra-small nanoparticles (Arg/ATT/AuNCs). Free carboxyl groups on Arg/ATT/AuNCs enabled conjugation with biomolecules to afford an indicator for the biosensor.

Multiplex Lateral Flow Immunoassays Based on Amorphous Carbon Nanoparticles for Detecting Three Fusarium Mycotoxins in Maize.

The detecting labels used for lateral flow immunoassays (LFAs) have been traditionally gold nanoparticles (GNPs) and, more recently, luminescent nanoparticles, such as quantum dots (QDs). However, these labels have low sensitivity and are costly, in particular, for trace detection of mycotoxins in cereals. Here, we provided a simple preparation procedure for amorphous carbon nanoparticles (ACNPs) and described multiplex LFAs employing ACNPs as labels (ACNP-LFAs) for detecting three Fusarium mycotoxins.