The Detection Of Ochratoxin A Based On Aptamer Sensor

The crops can be easily contaminated by mycotoxins,during growth,harvest,storage.As one of the highly toxic mycotoxins,Ochratoxin A(OTA)has attracted much more attention due to its teratogenic and carcinogenic effect on humans.Conventional instrumental analysis such as high performance liquid chromatography is popular because of its high sensitivity and accurate results.However,they exist some draw-backs such as sophisticated equipments,high cost and requirement of technical skills.The method of enzyme-linked immunosorbent assay based on antigen-antibody binding has the advantages of simple,rapid and easy to promote.However,the antibody preparation process is complex and time-consuming,high cost,and the antibody itself is unstable,immunogenic and false.So it can not be used as a final confirmation method,which hindes its wider application.In this paper,the electrochemical aptamer biosensor based on carbon aerogels and cPC-AuNPs for the rapid detection of OTA in the crops is developed,which utilized the superiority of aptamer including strong affinity,high stability,and easy modification of functional groups,combined with the advantages of electrochemical methods such as fast response,simple operation,easy to miniaturization of the instrument,and used the properties of carbon-based materials with large surface area and good conductivity.The research contents are as follows:1.The carbon aerogels-cDNA/aptamer/AuE sensor was developed by immobilizing the aptamer on the surface of AuE surface,and hybriding aptamer with the complementary DNA(cDNA),which was immobilized by carbon aerogels because of its advantages including good biocompatibility,specific surface area and strong conductivity.Using methylene blue(MB)as the electrochemical signal probe,the detection of OTA was studied.The current value of MB of the carbon aerogels-cDNA/aptamer/AuE sensor is 100.4% higher than that of cDNA/aptamer/AuE sensor,which indicates that carbon aerogels have good signal amplification.The optimum conditions were as follows: the optimal concentration of aptamer was 4μM,the time of hybridization of aptamer and complementary DNA was 2h,and the best fixation method of MB was immersion.When the concentration of OTA was 0.01-20ng/mL,it shows a good linear relationship,and the detection limit is 1.0×10-4ng/mL.The correlationcoefficient is 0.996.Using the prepared sensor to test the spiked corn samples,the average recovery was 89.3%.2.In the previous experiment,it was found that the immobilization of aptamer on the AuE surface might affect the conformational change when it was bound to OTA.In this experiment,cDNA was immobilized on the AuE surface.Combining the advantages of the porous carbon such as open pore structure,large specific surface area and strong conductivity with good properties of AuNPs including conductivity and bio-affinit,the cPC-AuNPs was prepared to modify AuE for improving the cDNA immobilization and enhancing the signal amplication.By hybridization of aptamer and cDNA,the aptamer/cDNA/cPC-AuNPs/AuE sensor was construted.When the OTA concentration was 5.0×10-6-5.0×10-4ng/mL,it shows a good linear relationship.The coefficient is 0.997 and the detection limit is 5.0×10-6ng/m L.The average recovery for the spiked corn samples is 103%.Repetitive experiments show that the sensor has good reproducibility,stability and specificity.