| Immunochromatographic test strip has a high specificity and sensitivity. This method enjoys the advantages of convenience, the large capacity of analysis and the detection of low cost.What’s more, its qualitative detection does not require auxiliary equipments, and the sample preparation step is simple and convenient. This ideal for field testing may not only provide serialized products and technology products can be commercialized, but also to help the detection for the industry to create economic value for society.We designed two immunochromatographic rapid test strips for AOZ with goldmagnetic composite particles and CdTe quantum dots instead of the colloidal goldlabeled monoclonal antibody AOZ, respectively. It combines nano-markers and immune chromatography, marked by magnetic microspheres and CdTe QDs fluorescence-labeled antibody. Comparing with the same colloidal gold labeled, it improved the sensitivity. In qualitative analysis process, the former can be directly judged by the naked eye and the latter can be tested through a portable ultraviolet light; In quantitative analysis process, the former can be numbered by magnetic analysis instrument, which can be read by a fluorescence reader, respectively, on the chromatographic carrier number and the three-dimensional magnetic fluorescent signal, got the signal values directly,.We obtained the quantitative detection value through the establishment of a standard curve.The magnetic multilayer metal composite particles with uniform size and good dispersion were synthesized and successfully conjugated with the AOZ monoclonal antibody. As to explore the best coupling conditions,we got these as follows: pH 7.4 for the environment, 1 mg GoldMag can be the optimum content of the composite particle surface with the 170 μg AOZ-Mc Ab conjugation, the contection content of antibody was 480 μg the coupling ratio was 35.43%. the blocking reaction needed 50 min in the Pbs(5% BSA, pH = 7.4) and finall probes saved in Pbs which contained the 0.2% BSA, 2% sucrose, 0.8% Triton-X-100, 0.05% PVP, 0.2% Tween-20, and 0.02% NaN3. It can provide a reference for other magnetic particles labeled antibody. And the chromatographic material mat comprising a nitrocellulose membrane, sample pad and conjugate pad were optimized: Satorius CN140, GL-b02, Ahlstrom8964 respectively; sample pad, conjugation pad and the treatment liquid had been explored in the experiment, each containing 0.5% BSA, 2% Triton, 0.2% NaCl, ultrapure water 2% PVP as the best solution, and the sample pad treated with 1% sucrose, 0.2% Triton, ultra-pure aqueous 0.2% Tween-20 as the best combination of pad processing solution. We assembled AOZ magnetic gold immunochromatographic strip successfully through the conditions of above, and the test strip performance was evaluated. the sensitivity of the test strip was 8 ng/mL.It had no cross-reactivity with other nitrofuran metabolites, high specificity, and good repeatability, one year storage at room temperature, 4 ℃ can be stored for up to 2 years.The high fluorescence quantum yield of CdTe QDs with uniform size and good dispersion were synthesized with the high quantum yield of 42.3%. With good spectral properties,it can be used as a fluorescent labeled antibody excellent material; preferably purified solution of quantum dots program, the acetone precipitation method was superior to dialysis purification, treatment of quantum dots with a high reference value; fluorescent probe for coupling conditions were optimized. We choiced the reaction time of 50 min as the best time of CdTe-AOZ-Mc Ab probe coupling reacting, and the amount ratio of QDs and AOZ-Mc Ab was 1: 0.75. Fluorescent probes obtained had excellent spectral, providing the reference for other fluorescence-labeled antibody materials properties as the feasibility coupling methods; the nitrocellulose membrane, the sample pad and conjugate pad were selected: Millipore 135, GL-b02, Ahlstrom8964, respectively. Under these conditions, we obtained AOZ fluorescent test strip successfully, and the test strip performance was evaluated, the sensitivity was 5 ng/mL. it had no cross-reactivity with other nitrofuran metabolites, and the high specificity repeatability and stability were excellent.Compared with the above two test strips, the AOZ gold labelled test strip was prepared. The AOZ gold labelled test strips were assembled successfully after using the best material and processing method, the sensitivity was 10 ng/mL, the performance of detection was excellent. By making the test strip, further evidence of this study about magnetic strip and fluorescent strip had the advantages of high sensitivity, can increase 1-2 orders of magnitude through the auxiliary instrument sensitivity test strip, far more than the market. It can not only make up the limit of detection of the gold labelled test strip, but also lay the foundation for the development of new test strip, with great significance and development value. |
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