| The food safety problem caused by the mycotoxin has become the focus of the world.At present,there are many methods for the detection of mycotoxin,but each method has its own advantages and disadvantages.In order to meet the needs of detection,it is very important to establish a rapid and sensitive method to detect mycotoxin.With the development of science and technology,nanomaterials have attracted more and more attention because of their unique structures and properties.Its application in the field of life science has become the mainstream of research in this field.The combination of nano materials and biosensors is mainly involved in many fields,such as life medicine,chemistry and chemical engineering,biology and so on.This paper based on the specific recognition ability of aptamer and the special properties of nano materials in optics,chemistry and biology,and established three methods for the determination of ochratoxin A.Therefore,the high sensitivity,high selectivity,high efficiency methods for identification and detection of ochratoxin A were achieved.1.A simple method based quantum dot fluorescence resonance energy transfer for the detection of ochratoxin AWe report here a method based on the principle of fluorescence resonance energy transfer between streptavidin modified QDs and fluorescence quenching group labeled aptamer for the detection of ochratoxin A(OTA).A fluorescent probe was constructed by QDs labeling OTA'aptamer and fluorescence quenching group labeled hybridization.In the presence of OTA,the amount of fluorescence quenching group in sensing was reduced because of high affinity between aptamers and OTA,and the fluorescence enhancement.Thus,a fluorescence analysis method for the detection of OTA was established.This is a simple,sensitive and selective method for the detection of OTA.Under optimized conditions,the assay showed a linear response toward OTA concentration in the range of 0.2 ?M to 1.6 ?M.The regression equation was determined to be?F=92.2c+95.06(c is the concentration of OTA,?M)with a correlation of 0.9955.The limit of detection for OTA was experimentally determined to be 0.16 ?M.2.Aptamer-based fluorescent detection of ochratoxin A by quenching of gold nanoparticlesA simple,sensitive method for the detection of OTA was built based on the better quenching effect of dispersed Au NPs than aggregated.In the presence of OTA,the conformation of aptamer changed due to specific binding with OTA,aptamers were not absorbed onto the surface of Au NPs,which reduced the stability of Au NPs against salt-induced aggregation,and the fluorescence enhancement.Therefore,a simple,rapid and low cost method based on the aptamer sensing technology for detection of OTA was established.In the experiment,the salt concentration and reaction time were optimized.Under optimized conditions,the assay showed a linear response toward OTA concentration in the range of 25 n M to 300 n M.The regression equation was determined to be ?F=0.293c+4.263(c is the concentration of OTA,n M)with a correlation of 0.9957.The limit of detection for OTA was experimentally determined to be 22.7 n M.3.A new method of fluorescence immunoassy for ochratoxin A based on antibody-coatedA new simple,sensitive method of fluorescence immunoassy for detection ochratoxin A has established based on Ig G and hapten antigen combine competitively with immobilized antibody.This experiment adopts the competition immune response pattern.OTA and Ig G-FITC combine competitively with antibody.The amount of Ig G-FITC combined with antibody decreased gradually with the increase in concentration of OTA,and the fluorescence intensity decreased gradually.Under optimized conditions the assay showed a linear toward OTA concentration in the range of 1 n M to 100 ?M.The regression equation was determined to be ?F=43.68 lg C+4.619(c is the concentration of OTA,n M)with a correlation of 0.9918.The limit of detection for OTA was experimentally determined to be 0.34 n M. |
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