A signal amplification strategy based on antibody–gold nanoparticle–DNAzyme assembly in capillary electrophoresis based chemiluminescent immunoassays (CE-CLIA) was developed. In this CE-CLIA, ...antibody–AuNP–G-quadruplex/hemin was incubated with limited amount of antigen, and the formed immunocomplex and unreacted antibody–AuNP–G-quadruplex/hemin were then separated by CE and detected by CL. Due to the strong CL catalytic ability of G-quadruplex/hemin DNAzyme and a high loading ratio of DNAzyme on each AuNP, the assay was very sensitive. By taking carbohydrate antigen 19-9 (CA19-9), one of the most important carbohydrate tumor marker as the model analyte, the proposed CE-CLIA method for CA19-9 detection showed a linear range from 0.025 to 1.00U/mL with a detection limit of 0.016U/mL (signal/noise=3), which was more sensitive than the methods previously reported for CA19-9 quantification. The method was applied to quantify CA19-9 in human serum samples, and analytical results were in a good agreement with those obtained by using an established ELISA method.
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•An assembly of antibody–AuNP–DNAzyme was designed for signal amplification in CE-CLIA.•The design was based on the DNAzyme׳s high CL catalytic efficiency on AuNP surface.•A novel CE-CLIA method was developed for quantifying CA19-9.•The CE-CLIA method exhibited high sensitivity and selectivity for CA19-9 detection.
A rapid and sensitive chemiluminescence immunoassay (CLIA) based on magnetic nanoparticles (MNPs) was developed to detect aflatoxin B1 (AFB1), which is a potent carcinogen in nature. We prepared ...monodisperse MNPs (300 nm in diameter) according to the solvothermal synthesis reaction and the MNPs were coated with silica by the Stöber method. Triethox was used as a one-step carboxylation reagent, and 3-aminopropyltriethoxysilane (APTES) an amination reagent, to modify the MNPs. We prepared two types of solid phase antigens using the above synthesized functionalized MNPs coupled with the later prepared AFB1-oxime active ester and the purchased BSA-AFB1 respectively. 2',6'-dimethylcarbonylphenyl-10-sulfopropylacridinium-9-carboxylate 4'-N-hydroxysuccinimide (4'-NHS) ester (NSP-DMAE-NHS), as a novel luminescent reagent, was used to label anti-AFB1 antibodies. The two CLIA calibration curves based on the two types of solid phase antigens were obtained and compared. The acquired limit of detection (LOD) was about 0.001 ng/mL for the two functionalized MNPs-based immunoassays, and the half maximal inhibitory concentration (IC
) was 0.51 ng/mL for the MNPs-AFB1-based method and 0.72 ng/mL for the MNPs-BSA-AFB1-based method.
Direct competitive chemiluminescence immunoassays (CLIA) based on gold-coated magnetic nanospheres (Au-MNPs) were developed for rapid analysis of chloramphenicol (CAP). The Au-MNPs were modified with ...carboxyl groups and amino groups by 11-mercaptoundecanoic acid (MUA) and cysteamine respectively, and then were respectively conjugated with CAP base and CAP succinate via an activating reaction using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). NSP-DMAE-NHS, a new and effective luminescence reagent, was employed to label anti-CAP antibody (mAb) as a tracer in direct CLIA for CAP detection using a 'homemade' luminescent measurement system that was set up with a photomultiplier tube (PMT) and a photon counting unit linked to a computer. The sensitivities and limits of detection (LODs) of the two methods were obtained and compared according to the inhibition curves. The 50% inhibition concentration (IC50 ) values of the two methods were about 0.044 ng/mL and 0.072 ng/mL respectively and LODs were approximately 0.001 ng/mL and 0.006 ng/mL respectively. To our knowledge, they were much more sensitive than any traditional enzyme-linked immunosorbent assay (ELISA) ever reported. Moreover, the new luminescence reagent NSP-DMAE-NHS is much more sensitive and stable than luminol and its derivatives, contributing to the sensitivity enhancement.
L'évaluation de l'automate d'immunoanalyse Vitros ECi (Ortho Clinical Diagnostics) a été réalisée selon le protocole établi par la Société française de biologie clinique (SFBC). Les performances de ...l'automate Vitros ECi (précision, linéarité, sensibilité…), et des réactifs ont été évaluées à partir de 2 000 dosages, contrôles inclus. Du point de vue analytique, les coefficients de variation intra- et inter-essais sont satisfaisants et très souvent inférieurs à 10 %. Les dosages effectués sur 921 sérums provenant de différentes catégories cliniques ont permis des études de comparaison Vitros ECi versus Elecsys (Roche Diagnostics). Les coefficients de corrélation calculés s'échelonnent entre 0,77 et 0,99. Enfin, le logiciel de gestion de l'immunoanalyseur est d'utilisation aisée et performant, aussi bien en pratique de routine que d'urgence.
The assessment of the Vitros ECi, an automated chemiluminescence system, was carried out according to the Société française de biologie clinique (SFBC) protocol. Analytical performances of the ECi system (precision, linearity, sensitivity…) and the reagents were recorded from 2000 tests including controls, with good results. In almost all cases, the within and between-run coefficients of variation were acceptable and often less than 10 %. Comparative study ECi versus Elecsys with a panel of 921 sera belonging to different clinical patterns showed a good correlation for the different analyses within a range between 0,77 and 0,99. Finally, the software was globally satisfactory for routine and emergency diagnostic needs.
Ce travail presente une technique microscopique rapide et specifique pour la detection et l'identification des bacteries lactiques dans les mouts, les vins ou dans une culture de levures ou de ...bacteries. Grace a l'utilisation de trois anticorps fluorescents, on a pu detecter la presence de Leuconostoc oenos en moins de deux heures avec des seuils de sensibilite de l'ordre de 10(2) bacteries/ml. L'etude de vins alteres a montre la fiabilite des reactifs sur les bacteries vivantes ou mortes, avec toutefois des bacilles non detectes en fluorescence dans un vin d'origine argentine. L'immunofluorescence s'est revelee comme une technique facile a mettre en oeuvre. Les methodes plus sensibles de culture necessitant plusieurs jours d'incubation avant la lecture du resultat, cette technique est aujourd'hui a considerer comme un outil d'aide a une decision technologique
