Study On The Method Of Quickly Determinition Of Shigella Flexnerl Based On Magnateic Nanobeads And Quantum Dots

In recent years, the issue of the quality safety of the daily eating food becomes serious.And it was deeply concerned by people. As a kind of food-borne pathogenic bacteria, theShigella flexneri is one of the most common intestinal infectious bacteria. Until now theinfection of Shigella flexneri bacteria is still the important problem which endangers thepublic health security, and it presented endemic in many developing countries.In order to better prevent and control of the Shigella flexneri threat to human health. Inthis study, the target bacteria were captured by the immuno magnetic nanobeads by made.And then were labeled with the Quantum Dots to detect its fluorescence intensity. Finally, thequantities relation model between target bacteria number and fluorescence intensity value wasestablished combining with the traditional plate counting method. The results of scientificresearch in this paper are as follows.1. At first, in order to make it specificity, the streptavidin nanobeads was modified by thebiotin conjugated anti Shigella antibody to capture the target bacteria. Moreover, studying thecomparison of the capture efficiency combining the traditional plate counting method, andoptimizes the amount of bacteria in the preparation of magnetic nanobeads. The resultsshowed that the60μL of immuno-nanobeads made by the optimized amount of70μL antibodycan capture61.2%target bacteria at103CFU/mL concentrate. And it could capture the targetbacteria at levels as low as100CFU/mL to the pure bacterium liquid, and the time could becontrolled within1hour.2. Then the fluorescently specificity of the antibody-quantum dots compounds was usedto label the captured target bacteria. Finally the “magnetic nanobeads-target bacteria-QuantumDots” compounds was formed. In addition, we measured the fluorescence intensity of thecompounds. Also the actual value of the different concentrations of the target bacteria wasmeasured using the plate count method. The linear regression equation was calculated.y=12.31x+28.97，R~2=0.9274. This study could quickly and easily texted the target bacteria inless than2hours and detect the target bacteria at levels as low as10~2CFU/0.1mL to the purebacterium liquid. This study mainly based on the superparamagnetism of the magnetic nano-beads, thespecificity of the antigen and antibody, and the fluorescence properties of quantum dots tobuild a rapidly, accurately, and easily method to detect the quantitative of the Shigella flexneribacteria. And this thesis plays a great significance to the disease preventing and food safetyensuring.