Fluorescence Detection Of Citrinin Based On Aptamers Labeled By Carbon Quantum Dots

Citrinin is a toxic mycotoxin,which mainly produced by the metabolism of Penicillium,Aspergillus and Monascus,and found in grains,fruits,meat and related products.With the increase of food types,the contamination of citrinin in food is becoming more and more serious.After consuming these contaminated foods for a long time,it accumulates in the body,causing the nephropathy,and even causing the formation and tumor,which pose a major threat to people's physical health.Therefore,it is urgent to establish a quantitative and rapid detection method for the food.In this thesis,the amino-modified aptamers were combined with carbon quantum dots to form fluorescence-modified aptamers,and then the fluorescence of carbon quantum dots was quenched by adding graphene.Then,add citrinin,the fluorescence-modified aptamers were far away from graphene,the fluorescence of carbon quantum dots was restored,and a biosensor based on carbon quantum dots and aptamers was constructed.The carbon quantum dots were characterized in the experiment,including the calculation of carbon quantum dot fluorescence quantum efficiency,carbon quantum dot fourier transform infrared spectroscopy(FTIR)characterization and carbon quantum dot transmission electron microscopy(TEM)characterization.In the biosensor,the concentration of aptamer,the graphene concentration for quenching carbon quantum dot,the time for graphene to quench carbon quantum dot,the reaction temperature and time for aptamer binding to citrinin,and the pH of reaction buffer were optimized.Under the optimal experimental conditions,the constructed biosensors based on carbon quantum dots and aptamers showed a good linear relationship with the fluorescence intensity(F-F0)/Fowhen the concentration of citrinin was in 12.5-250 ?g/L,The detection limit was 10 ?g/L.The sensor was applied to spiked recovery experiment of white vinegar and rice.The recovery rate was between 71.06-82.39%and RSD was between 4.3%and 7.6%.And the results obtained by the sensor have high consistency with the results of high performance liquid chromatography,indicating that the sensor for the detection of citrinin provides a new method.The method is also suitable for the analysis of citrinin in real samples.