Detection Of Foodborne Pathogenic Bacteria And Imaging Of Biology By Nanomaterials

Food security has been a problem which people pay attentionto in daily life. Food-borne pathogens are major factor of food safetyincidents. Detection of food-borne pathogens is the key aspect ofprevention and control of food-borne diseases. There is an urgent needto develop a rapid and sensitive method for detection of food-bornebacteria to ensure the safety of food.In recent years, nano-technology has become a hot study in theworld. Due to the unique physical and chemical properties ofnano-materials, nano-technology is widely used in the biological area,including biochemistry, cell biology, molecular biology, genomics,proteomics, medical diagnostics, drug screening and so on.This experiments are based on immunological principle. We haveconstructed two kinds of bio-functional nano-particles of different size.Combing with low-field magnetic resonance instrument and magneticseparation apparatus and fluorescence microscopy, we haveestablished two kinds of high sensitivity, fast and convenient foodbornepathogenic bacteria detection methods. Also, we set up a new type ofquantum dots which can be applied in biological Imaging. In theresearch of detection of Enterobacter sakazakii by MRS sensor, wesynthesised the Fe3O4magnetic nanoparticles by high thermaldecomposition and coated the nanoparticles with silica. The magneticnanoparticles were then modified with amino group to couple withantibody. We developed a stable and high specificity biofunctionalizedmagnetic nanoparticle immunoassay for the determination ofEnterobacter sakazakii in dairy samples. This method is able to detectEnterobacter sakazakii in milk powder and cheese samples at1to10CFU/mL using an optimal dilution of10-1, within an incubation period ofless than2hours. A long incubation time (>4hrs) and high pH (>7) will decrease the method sensitivity. This method is not fit for the detectionof bacteria at high concentrations (>103CFU/mL). This powerful methodholds tremendous promise as a useful tool for rapid detection ofbacterial contamination in food, environmental and agriculturalsamples. In the research of detection method of varieties of food-bornepathogenic bacteria via quantum dots as fluorescence marks, wedeveloped four kinds of specificity biofunctionalized magneticnanoparticle and biofunctionalized QDs. Food-borne pathogenicbacteria were enriched by biofunctionalized magnetic nanoparticleand then marked by biofunctionalized QDs. The fluorescencemicroscopy and fluorescence spectrophotometer were used toexamine the fluorescence of the food samples.The results show that thedetection method is rapid, specificity and can be used for fast Visualdetection. The last experiment was the research of synthesis of a newtype of water soluble quantum dots. Experimental results show that twokinds of water soluble quantum dots have good biocompatibility andbetter stability. Fluorescence quantum yields remain good. Thequantum-dots coated with adenosine are less toxic and can beapplied to cell Imaging.In short, we developed two kinds of rapid detection methods forfood-borne pathogens, providing theoretical basis for detection offood-borne pathogens. In addition, we studied one new type ofwater-soluble quantum dots, providing theoretical basis for cellImaging.