| Antibiotics are commonly used drugs in people's lives,which bring convenience to people,but also threaten people's health because of their unreasonable use,especially in poultry animal husbandry,the abuse of antibiotics is particularly common,the drug residues will slowly accumulate in animals,and the problem of drug residues will seriously threaten people's lives and safety.At present,the detection methods for antibiotic residues in food are generally complex,time-consuming,demanding for the detection environment,requiring professional testing personnel and expensive equipment.In this thesis,two aptamer based biosensors for the detection of Enrofloxacin(ENR)and Kanamycin(KAN)were developed.In this paper,two aptamers which can specifically bind to enrofloxacin were selected,and a biosensor based on amplifying detection signal after amplification of aptamers was prepared by sandwiched method with a dipstick as detection platform through the specific capture of two aptamers to enrofloxacin.The Aptamer was assembled on the surface of Au Nanoparticles(Au NPs,15 nm)by terminal deoxynucleotidyl transferase(Td Tase)and the 1 'end of the aptamer was amplified by T base.Then hybridize with the assembled poly A on the 15 nm Au NPs to obtain an irregular DNA dendriform gold nanoparticle complex(TAu C).The complex was characterized by UV spectroscopy,agarose gel electrophoresis and atomic force microscopy.The results show that the detection effect of the test strip based on the complex is obviously better than that of the test strip based on single particle nano-gold,the detection signal on the test strip is amplified,the detection limit of ENR is reduced to 0.1 ?g/L,and it has a wide linear range and good specificity,and it also has good precision for practical samples.In addition,through the use of intelligent cell phone cameras for pattern recognition in professional applications,data can be further automatically read in a quantitative way,which is of great significance for rapid field detection.The RCA technique was used to form a netlike structure to capture that enclose core/shell of the magnetic beads and the unlabeled core/shell,which was separated by magnetic separation technique and measured by Surface Enhanced Raman Spectroscopy(SERS)signal aptamer sensor.Aptamer was ligated to magnetic beads and hybridized with complementary DNA(c DNA),then different concentrations of KAN solution were added to the system,after the aptamer recognized KAN,c DNA was separated from the upstream of magnetic beads for RCA amplification,and the amplified c DNA wrapped the sealed magnetic beads with the core/shell.After magnetic separation,the SERS signal was detected.The success of rolling circle amplification was verified by agarose gel electrophoresis and atomic force microscopy,and the signal was detected by Raman spectroscopy.The results showed that the amount of c DNA released from the magnetic beads increased with the increase of kanamycin concentration.Furthermore,the amount of RCA amplification products will increase correspondingly,and the SERS signal detected will be higher and higher.The method is highly specific,highly selective and has a low detection limit as low as 0.867 pg/m L.At the same time,the recovery of kanamycin in milk and honey was 96% ? 118%,which proved that the biosensor could be used to detect kanamycin in real samples. |
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