Research For Detecting Microorganism Based On Aptamer-Fluorescence Resonance Energy Transfer

In recent decades, problems of food safety frequently threated the world, such as”Poison cucumber event in Germany”,”The monocyte listeria event in America”.The food safety problems caused by microorganism is drawing much more and more attention.Facing the challenging severity food safety problems, it is extremely urgent to have a quick,accurate, efficient microorganism detecting technique to detect the pathogenic bacteria in the food in order to control the foodborne disease.Being a general detecting method, the photochemical technique has many advantages including simple, easy and high sensitivity. Fluorescence Resonance Energy Transfer(FRET)is a special optical phenomenon which describes the energy transfer phenomenon between two fluorescent molecules. When the emission spectrum of the donor fluorescent molecule and the absorption spectrum of the receptor fluorescent molecule overlap, furthermore if the distance between the two fluorescent molecules is less than 10 nanometers, a kind of non radioactive energy transfer occurs namely FRET. FRET has been widely applied to all fields of biological science, for example, the study of the layout space of the protein conformation and structure, immunoassay, ion concentration and dynamic characteristics described in the cell,cell signal transduction. Thus, the optical sensor based on FRET is becoming a very active area of research. But the researches on the FRET analysis of bacteria based on graphene oxide and aptamer were very limited.Based on graphene oxide, this thesis builds two kinds of FRET sensor with single aptamer and multiple aptamers in order to set up high sensitive microorganism analysis tool,mainly two parts:(1) First, with the fluorescence labeling aptamer as the donor and the grapheme oxide(GO) as the receptor, the FRET phenomenon were verified. Furthermore, the experimental conditions for the detection of three common food-borne pathogenic bacteria include Escherichia coil, vibrio parahemolyticus and Enterobacter sakazakii were optimized.(2) Based on FRET, with the use of aptamers which are specific binding to thecorresponding bacteria, the thesis established the new methods to detect three kinds of bacteria through FRET. The single aptamer and the multiple aptamers were also compared.It was turned out that multiple aptamers outperformed the single aptamer especially in detection sensitivity.