Immunochromatographic Technology Of UPT Ten-channel Multiplex Detection Of Foodborne Pathogens

OBJECTIVE:1. To establish an up-converting phosphor technology-based ten-channel lateral flow (UPT-TC-LF) assay platform using up-converting phosphor(UCP) as a marker and UPT-LF single target strips as the experimental platform.2. To detect ten pathogenic bacteria causing food poison in different kinds of food using the UPT-TC-LF assay.METHODS:Firstly, each corresponding antibody to the target bacterium was conjugated covalently with UCP and coated onto the membrane for detecting the bacterium by double-antibody sandwich immunochromatographic method. Single strip was developed for each of ten target bacteria and its performance, including the linearity, specificity and sensitivity, was evaluated using the corresponding bacterium-spiked samples.Secondly, a universal sample treatment protocol was obtained through the optimization of each strip before the ten kinds of strips were integrated into one UPT-TC-LF disc for simultaneous detection of ten diffierent kinds of pathogenic bacteria under the same experimental condition. A biosensor with a scanning function was also developed to acquire the sample results by the aid of Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences.The consistency between the two methods was evaluated by detecting the spiked samples.Finally, 279 food samples that had been proven to be negative with all kinds of pathogenic bacteria and the corresponding bacterium-spiked samples were both detected using the UCP-TC-LF assay.RESULTS:1. Ten kinds of UPT-LF single pathogenic bacteria target strips were developed. As the experimental result showed, the sensitivity,linearity and specificity could meet the demand of high-speed detection of actual samples.2. The consistency between the UPT-LF single target strip assay and the UPT-TC-LF assay was excellent. The specificity of each channel and the compatibility among all the ten channels could meet the demand of high-speed detection of actual samples.3. There were no false-positive samples among the 279 ones that had been proved to be negative for all the ten target bacteria. The positive ratio was good after regulating the ingredients in the LB medium. CONCLUTION:The study successfully established the UPT-TC-LF system showing excellent performance in terms of sensitivity and specificity which was qualified for the multi-detection of the ten pathogenic bacteria causing food poison. The additive existing in the food sample and the special growing property of different strains were found to be impact factors to cause the low positive ratio.